El aalamia (aquatec) for plastic industry

Training Report

By:

Mahmoud Ali Mohamed Mahmoud

(20071406)

Supervised by:

DR Mohamed Fakery

Eng/El Sayed Asaad

Department of mechanical engineering

Higher Technological Institute

2012

Contents

1. Introduction

2. Raw material

3. Pipe Extrusion process

4. Parts of Pipe Extrusion production line

5. Steps for production pipes

6. Quality engineering

7. Testing

8. Maintenance of extrusion machines

9. Industrial safety

AcknowledgementsI would like to acknowledge the advice and guidance of DR Mohamed fakery and Eng El Sayed Asaad; I also thank the members of my graduate committee for their guidance and suggestions.

I would like to thank the members who helped me in Aquatic industry includes engineers, workers and employees.

I would like to thank my family members because of their encouragements.

AbstractThis report is talking about the pipes and the technique that produce them

Talking about plastics, extruder and industrial safety that make the industry safe.

Pipes produced in extrusion production line

1. IntroductionA plastic material is any of a wide range of synthetic or semi-synthetic organic solids that are moldable. Plastics are typically organic polymers of high molecular mass, but they often contain other substances. They are usually synthetic, most commonly derived from petrochemicals, but many are partially natural.

CompositionMost plastics contain organic polymers. The vast majority of these polymers are based on chains of carbon atoms alone or with oxygen, sulfur, or nitrogen as well. The backbone is that part of the chain on the main "path" linking a large number of repeat units together. To customize the properties of a plastic, different molecular groups "hang" from the backbone (usually they are "hung" as part of the monomers before linking monomers together to form the polymer chain). The structure of these "side chains" influences the properties of the polymer. This fine tuning of the properties of the polymer by repeating unit's molecular structure has allowed plastics to become an indispensable part of the twenty-first century world.

1.1.1 Additives

Most plastics contain other organic or inorganic compounds blended in. The amount of additives ranges from zero percentage for polymers used to wrap foods to more than 50% for certain electronic applications. The average content of additives is 20% by weight of the polymer. Fillers improve performance and/or reduce production costs. Stabilizing additives include fire retardants to lower the flammability of the material. Many plastics contain fillers, relatively inert and inexpensive materials that make the product cheaper by weight. Typically fillers are mineral in origin, e.g., chalk. Some fillers are more chemically active and are called reinforcing agents. Since many organic polymers are too rigid for particular applications, they are blended with plasticizers, oily compounds that confer improved theology. Colorants are common additives, although their weight contribution is small. Many of the controversies associated with plastics are associated with the additives

1.2 ClassificationPlastics are usually classified by their chemical structure of the polymer's backbone and side chains. Some important groups in these classifications are the acrylics, polyesters, silicones, polyurethanes, and halogenated plastics. Plastics can also be classified by the chemical process used in their synthesis, such as condensation, poly addition, and cross-linking

1.2.1 Thermoplastics and thermosetting polymers

There are two types of plastics: thermoplastics and thermosetting polymers. Thermoplastics are the plastics that do not undergo chemical change in their composition when heated and can be molded again and again. Examples include polyethylene, polypropylene, polystyrene, polyvinyl chloride, and polytetrafluoroethylene (PTFE). Common thermoplastics range from 20,000 to 500,000 is, while thermo sets are assumed to have infinite molecular weight. These chains are made up of many repeating molecular units, known as repeat units, derived from monomers; each polymer chain will have several thousand repeating units.

Thermo sets can melt and take shape once; after they have solidified, they stay solid. In the thermosetting process, a chemical reaction occurs that is irreversible. The vulcanization of rubber is a thermosetting process. Before heating with sulfur, the poly isoprene is a tacky, slightly runny material, but after vulcanization the product is rigid and non-tacky.

1.2.1 Other classifications

Other classifications are based on qualities that are relevant for manufacturing or product design. Examples of such classes are the thermoplastic and thermo set, elastomeric, structural, biodegradable, and electrically conductive. Plastics can also be classified by various physical properties, such as density, tensile strength, glass transition temperature, and resistance to various chemical products.

1.2.1.1 Biodegradability

Biodegradable plastics break down (degrade) upon exposure to sunlight (e.g., ultra-violet radiation), water or dampness, bacteria, enzymes, wind abrasion, and in some instances, rodent, pest, or insect attack are also included as forms of biodegradation or environmental degradation. Some modes of degradation require that the plastic be exposed at the surface, whereas other modes will only be effective if certain conditions exist in landfill or composting systems. Starch powder has been mixed with plastic as a filler to allow it to degrade more easily, but it still does not lead to complete breakdown of the plastic. Some researchers have actually genetically engineered bacteria that synthesize a completely biodegradable plastic, but this material, such as Biopol, is expensive at present. The German chemical company BASF makes Ecoflex, fully biodegradable polyester for food packaging applications.

1.2.1.2 Natural vs. synthetic

Most plastics are produced from petrochemicals. Motivated by the finiteness of petrochemical reserves and possibility of global warming, bioplastics are being

developed. Bioplastics are made substantially from renewable plant materials such as cellulose and starch

In comparison to the global consumption of all flexible packaging, estimated at 12.3 million tones/year, estimates put global production capacity at 327,000 tones/year for related bio-derived materials.

1.2.1.3 Crystalline vs. amorphous

Some plastics are partially crystalline and partially amorphous in molecular structure, giving them both a melting point (the temperature at which the attractive intermolecular forces are overcome) and one or more glass transitions (temperatures above which the extent of localized molecular flexibility is substantially increased). The so-called semi-crystalline plastics include polyethylene, polypropylene, poly (vinyl chloride), polyamides (nylons), polyesters and some polyurethane. Many plastics are completely amorphous, such as polystyrene and its copolymers, poly (methyl methacrylate), and all thermo sets.

1.3 PolystyrenePolystyrene is a rigid, brittle, inexpensive plastic that has been used to make

plastic model kits and similar knick-knacks. It would also be the basis for one of the most popular "foamed" plastics, under the name styrene foam or Styrofoam. Foam plastics can be synthesized in an "open cell" form, in which the foam bubbles are interconnected, as in an absorbent sponge, and "closed cell", in which all the bubbles are distinct, like tiny balloons, as in gas-filled foam insulation and flotation devices. In the late 1950s, high impact styrene was introduced, which was not brittle. It finds much current use as the substance of toy figurines and novelties.

1.3.1 Polyvinyl chloride

Polyvinyl chloride (PVC, commonly called "vinyl") incorporates chlorine atoms. The C-C bonds in the backbone are hydrophobic and resist oxidation (and burning). PVC is stiff, strong, heat and weather resistant, properties that recommend its use in devices for plumbing, gutters, house siding, enclosures for computers and other electronics gear. PVC can also be softened with chemical processing, and in this form it is now used for shrink-wrap, food packaging, and rain gear.

Vinyl chloride polymerization

All PVC polymers are degraded by heat and light. When this happens, hydrogen chloride is released into the atmosphere and oxidation of the compound occurs. Because hydrogen chloride readily combines with water vapor in the air to form hydrochloric acid, polyvinyl chloride is not recommended for long-term archival storage of silver, photographic film or paper (mylar is preferable)

2. Raw materialIn pipes production line we used two main raw materials :

PVCPolyethylene

2.1 PVCPolyvinyl chloride, commonly abbreviated PVC, is the third-most widely produced plastic, after polyethylene and polypropylene. PVC is used in construction because it is cheaper and stronger than more traditional alternatives such as copper or ductile iron. It can be made softer and more flexible by the addition of plasticizers, the most widely used being phthalates. In this form, it is used in clothing and upholstery, electrical cable insulation, inflatable products and many applications in which it replaces rubber.

Pure polyvinyl chloride without any plasticizer is a white, brittle solid. It is insoluble in alcohol, but slightly soluble in tetrahydrofuran.

2.1.1 Discovery and production

PVC was accidentally discovered at least twice in the 19th century, first in 1835 by Henri Victor Regnault and then in 1872 by Eugen Baumann. On both occasions the polymer appeared as a white solid inside flasks of vinyl chloride that had been left exposed to sunlight. In the early 20th century the Russian chemist Ivan Ostromislensky and Fritz Klatte of the German chemical company Griesheim-Elektron both attempted to use PVC in commercial products, but difficulties in processing the rigid, sometimes brittle polymer blocked their efforts. Waldo Semen and the B.F. Goodrich Company developed a method in 1926 to plasticize PVC by blending it with various additives. The result was a more flexible and more easily processed material that soon achieved widespread commercial use.

Polyvinyl chloride is produced by polymerization of the monomer vinyl chloride (VCM), as shown.

About 80% of production involves suspension polymerization. Emulsion polymerization accounts for about 12 % and bulk polymerization accounts for 8 %. Suspension polymerizations afford particles with average diameters of 100 – 180 μm, whereas emulsion polymerization gives much smaller particles of average size around 0.2 μm. VCM and water are introduced into the reactor and a polymerization initiator, along with other additives. The reaction vessel is pressure tight to contain the VCM. The contents of the reaction vessel are continually mixed to maintain the suspension and ensure a uniform particle size of the PVC resin. The reaction is exothermic, and thus requires cooling. As the volume is reduced during the reaction (PVC is denser than VCM), water is continually added to the mixture to maintain the suspension

The polymerization of VCM is started by compounds called initiators that are mixed into the droplets. These compounds break down to start the radical chain reaction. Typical imitators include dioctanoyl peroxide and dactyl peroxydicarbonate, both of which have fragile O-O bonds. Some initiators start the reaction rapidly but decay quickly and other initiators have the opposite effect. A combination of two different initiators is often used to give a uniform rate of polymerization. After the polymer has grown by about 10x, the short polymer precipitates inside the droplet of VCM, and polymerization continues with the precipitated, solvent-swollen particles. The weight average molecular weights of commercial polymers range from 100,000 to 200,000 and the number average molecular weights range from 45,000 to 64,000.

Once the reaction has run its course, the resulting PVC slurry is degassed and stripped to remove excess VCM, which is recycled. The polymer is then passed though a centrifuge to remove water. The slurry is further dried in a hot air bed, and the resulting powder sieved before storage or pelletization. Normally, the resulting PVC has a VCM content of less than 1 part per million. Other production processes, such as micro-suspension polymerization and emulsion polymerization, produce PVC with smaller particle sizes (10 μm vs. 120–150 μm for suspension PVC) with slightly different properties and with somewhat different sets of applications.

2.1.1.1 Microstructure

The polymers are linear. The monomers are mainly arranged head-to-tail, meaning that there are chlorides on alternating carbon centers. PVC has mainly an atactic stereochemistry, which means that the relative stereochemistry of the chloride centers are random. Some degree of syndiotacticity of the chain gives a few percent crystallinity that is influential on the properties of the material. About 57% of the

mass of PVC is chlorine. The presence of chloride groups gives the polymer very different properties from the structurally related material polyethylene

2.1.2 Applications

PVC's relatively low cost, biological and chemical resistance and workability have resulted in it being used for a wide variety of applications. It is used for sewerage pipes and other pipe applications where cost or vulnerability to corrosion limit the use of metal. With the addition of impact modifiers and stabilizers, it has become a popular material for window and door frames. By adding plasticizers, it can become flexible enough to be used in cabling applications as a wire insulator. It has been used in many other applications.

2.1.2.1Pipes

Roughly half of the world's polyvinyl chloride resin manufactured annually is used for producing pipes for municipal and industrial applications. In the water distribution market it accounts for 66% of the market in the US, and in sanitary sewer pipe applications, it accounts for 75%. Its light weight, and low cost make it attractive. However, it must be carefully installed and bedded to ensure longitudinal cracking and overbelling does not occur. Additionally, PVC pipes can be fused together using various solvent cements, or heat-fused (butt-fusion process, similar to joining HDPE pipe), creating permanent joints that are virtually impervious to leakage. These pipes can, however, be subject to long longitudinal cracks that migrate through the pipe joints, and in some cases, the entire length of the installed pipeline.

In February, 2007 the California Building Standards Code was updated to approve the use of chlorinated polyvinyl chloride (CPVC) pipe for use in residential water supply piping systems. CPVC has been a nationally accepted material in the US since 1982; California, however, has permitted only limited use since 2001. The Department of Housing and Community Development prepared and certified an environmental impact statement resulting in a recommendation that the Commission adopt and approve the use of CPVC. The Commission's vote was unanimous and CPVC has been placed in the 2007 California Plumbing Code.

In the United States and Canada, PVC pipes account for the largest majority of pipe materials used in buried municipal applications for drinking water distribution and wastewater mains. Buried PVC pipes in both water and sanitary sewer applications that are 4 inches (100 mm) in diameter and larger are typically joined by means of a gasket-sealed joint. The most common type of gasket utilized in North America is a metal reinforced elastomer, commonly referred to as a Reiber sealing system.

2.1.3 Health and safety

PVC is a useful material because of its inertness and this inertness is the basis of its low toxicity: "There is little evidence that PVC powder itself causes any significant

medical problems." The main health and safety issues with PVC are associated with "VCM", its carcinogenic precursor, the products of its incineration (dioxins under some circumstances), and the additives mixed with PVC, which include heavy metals and potential endocrine disruptors. "Fear of litigation ... has all but eliminated fundamental research into VCM polymerization."

2.2 PolyethylenePolyethylene (abbreviated PE) or polythene (IUPAC name polyethene or poly (methylene)) is the most common plastic. The annual production is approximately 80 million metric tons. Its primary use is within packaging (plastic bag, plastic films, geomembranes, containers including bottles, etc.). Many kinds of polyethylene are known, but they almost always have the chemical formula (C2H4)nH2. Thus PE is usually a mixture of similar organic compound that differ in terms of the value of n.

2.2.1 Properties

2.2.1.1 Physical properties

Polyethylene is a thermoplastic polymer consisting of long hydrocarbon chains. Depending on the crystalline and molecular weight, a melting point and glass transition may or may not be observable. The temperature at which these occur varies strongly with the type of polyethylene. For common commercial grades of medium- and high-density polyethylene the melting point is typically in the range 120 to 130 °C (248 to 266 °F). The melting point for average, commercial, low-density polyethylene is typically 105 to 115 °C (221 to 239 °F).

2.2.1.2 Chemical properties

Most LDPE, MDPE and HDPE grades have excellent chemical resistance, meaning that it is not attacked by strong acids or strong bases. It is also resistant to gentle oxidants and reducing agents. Polyethylene burns slowly with a blue flame having a yellow tip and gives off an odor of paraffin. The material continues burning on removal of the flame source and produces a drip. Crystalline samples do not dissolve at room temperature. Polyethylene (other than cross-linked polyethylene) usually can be dissolved at elevated temperatures in aromatic hydrocarbons such as toluene or xylene, or in chlorinated solvents such as trichloroethane or dichlorobenzene.

3. Pipe Extrusion process

3.1 ExtrusionExtrusion is a process used to create objects of a fixed cross-sectional profile. A material is pushed or drawn through a die of the desired cross-section. The two main advantages of this process over other manufacturing processes are its ability to create very complex cross-sections and work materials that are brittle, because the material only encounters compressive and shear stresses. It also forms finished parts with an excellent surface finish.

Extrusion may be continuous (theoretically producing indefinitely long material) or semi-continuous (producing many pieces). The extrusion process can be done with the material hot or cold.

Commonly extruded materials include metals, polymers, ceramics, concrete and foodstuffs.

Hollow cavities within extruded material cannot be produced using a simple flat extrusion die, because there would be no way to support the center barrier of the die.

Instead, the die assumes the shape of a block with depth, beginning first with a shape profile that supports the center section. The die shape then internally changes along its length into the final shape, with the suspended center pieces supported from the back of the die.

3.1.1 History

In 1797, Joseph Braham patented the first extrusion process for making lead pipe. It involved preheating the metal and then forcing it through a die via a hand driven plunger. The process wasn't developed until 1820 when Thomas Burr constructed the first hydraulic powered press. At this time the process was called squirting. In 1894, Alexander Dick expanded the extrusion process to copper and brass alloys.

3.1.2 Process

Extrusion of a round blank through a die.

The process begins by heating the stock material (for hot or warm extrusion). It is then loaded into the container in the press. A dummy block is placed behind it where the ram then presses on the material to push it out of the die. Afterward the

extrusion is stretched in order to straighten it. If better properties are required then it may be heat treated or cold worked.

The extrusion ratio is defined as the starting cross-sectional area divided by the cross-sectional area of the final extrusion. One of the main advantages of the extrusion process is that this ratio can be very large while still producing quality parts.

3.2 Plastics extrusion

Cross-section of a plastic extruder to show the screw

Plastics extrusion is a high volume manufacturing process in which raw plastic material is melted and formed into a continuous profile. Extrusion produces items such as pipe/tubing, weather stripping, fence, deck railing, window frames, plastic films, thermoplastic coatings, and wire insulation.

3.2.1 History

The first thermoplastic extrusion was in 1935 by Paul Toaster in Germany. Shortly after, Roberto Colombo of LMP developed the first twin screw extruders in Italy.

3.2.2 Process

In the extrusion of plastics, raw thermoplastic material in the form of small beads (often called resin in the industry) is gravity fed from a top mounted hopper into the barrel of the extruder. Additives such as colorants and UV inhibitors (in either liquid or pellet form) are often used and can be mixed into the resin prior to arriving at the hopper.

The material enters through the feed throat (an opening near the rear of the barrel) and comes into contact with the screw. The rotating screw (normally turning at up to 120 rpm) forces the plastic beads forward into the barrel which is heated to the desired melt temperature of the molten plastic (which can range from 200 °C (392 °F) to 275 °C (527 °F) depending on the polymer). In most processes, a heating profile is set for the barrel in which three or more independent PID controlled heater zones gradually increase the temperature of the barrel from the rear (where the plastic enters) to the front. This allows the plastic beads to melt gradually as they are pushed through the barrel and lowers the risk of overheating which may cause degradation in the polymer.

Extra heat is contributed by the intense pressure and friction taking place inside the barrel. In fact, if an extrusion line is running a certain material fast enough, the heaters can be shut off and the melt temperature maintained by pressure and friction alone inside the barrel. In most extruders, cooling fans are present to keep the temperature below a set value if too much heat is generated. If forced air cooling proves insufficient then cast-in heater jackets are employed, and they generally use a closed loop of distilled water in heat exchange with tower or city water.

Plastic extruder cut in half to show the components

At the front of the barrel, the molten plastic leaves the screw and travels through a screen pack to remove any contaminants in the melt. The screens are reinforced by a breaker plate (a thick metal puck with many holes drilled through it) since the pressure at this point can exceed 5000 psi (34 MPa). The screen pack/breaker plate assembly also serves to create back pressure in the barrel. Back pressure is required for uniform melting and proper mixing of the polymer, and how much pressure is generated can be 'tweaked' by varying screen pack composition (the number of screens, their wire weave size, and other parameters). This breaker plate and screen pack combination also does the function of converting "rotational memory" of the molten plastic into "longitudinal memory".

After passing through the breaker plate molten plastic enters the die. The die is what gives the final product its profile and must be designed so that the molten plastic evenly flows from a cylindrical profile, to the product's profile shape. Uneven flow at this stage would produce a product with unwanted stresses at certain points in the profile. These stresses can cause warping upon cooling. Almost any shape imaginable can be created so long as it is a continuous profile.

The product must now be cooled and this is usually achieved by pulling the extradite through a water bath. Plastics are very good thermal insulators and are therefore difficult to cool quickly. Compared with steel, plastic conducts its heat away 2000 times more slowly. In a tube or pipe extrusion line, a sealed water bath is acted upon by a carefully controlled vacuum to keep the newly formed and still molten tube or pipe from collapsing. For products such as plastic sheeting, the cooling is achieved by pulling through a set of cooling rolls.

Sometimes on the same line a secondary process may occur before the product has finished its run. In the manufacture of adhesive tape, a second extruder melts adhesive and applies this to the plastic sheet while it’s still hot. Once the product has cooled, it can be spooled, or cut into lengths for later use.

3.2.3 Screw design

There are five possible zones in a thermoplastic screw. Since terminology is not standardized in the industry, different names may refer to these zones. Different types of polymer will have differing screw designs, some not incorporating all of the possible zones.

A simple plastic extrusion screw

Most screws have these three zones:

Feed zone. Also called solids conveying. This zone feeds the resin into the extruder, and the channel depth is usually the same throughout the zone.

Melting zone. Also called the transition or compression zone. Most of the resin is melted in this section, and the channel depth gets progressively smaller.

Metering zone. Also called melt conveying. This zone, in which channel depth is again the same throughout the zone, melts the last particles and mixes to a uniform temperature and composition.

In addition, a vented (two-stage) screw will have:

Decompression zone. In this zone, about two-thirds down the screw, the channel suddenly gets deeper, which relieves the pressure and allows any trapped gases (usually moisture or air) to be drawn out by vacuum.

Second metering zone. This zone is like the first metering zone, but with greater channel depth, and depressurizes the melt to get it through the resistance of the screens and the die.

Often screw length is referenced to its diameter as L: D ratio. For instance, a 6-inch (150 mm) diameter screw at 24:1 will be 144 inches (12 ft) long, and at 32:1 it is 192 inches (16 ft) long. An L: D ratio of 24:1 is common, but some machines go up to 32:1 for more mixing and more output at the same screw diameter. Two-stage (vented) screws are typically 36:1 to account for the two extra zones.

Each zone is equipped with one or more thermocouples or RTDs in the barrel wall for temperature control.

3.2.4 Geometrical possibilities

There are many geometrical possibilities when using extrusion. Thin film (flat or tubular) is the most common product. Other extruded products include pipe and tubing, coated paper or foil, monofilaments and textile fibers, flat sheet (anything over 0.010 inch (0.25 mm)), wire and cable covering, and a great variety of profiles such as window frames, gaskets and channels, and house siding. The products can be cut to length or rolled up as needed.

3.2.5 Typical extrusion materials

Typical plastic materials that are used in extrusion include but are not limited to: polyethylene (PE), polypropylene, acetyl, acrylic, nylon (polyamides), polystyrene, polyvinyl chloride (PVC), acrylonitrile butadiene styrene (ABS) and polycarbonate.

3.2.6 Extrusion Method

By plasticizing way, there are dry extrusion and wet extrusion. By pressurizing way, there are continuous extrusion and intermittent extrusion.

3.2.6 Features

Continuous production, high efficiency, simple operation, a wide range of applications, such as tubing extrusion, sheet/film extrusion etc.

3.2.7 Types

3.2.7.1 Sheet/film extrusion

For products such as plastic sheet or film, the cooling is achieved by pulling through a set of cooling rolls (calendar or "chill" rolls), usually 3 or 4 in number. Running too fast creates an undesirable condition called "nerve"- basically, inadequate contact time is allowed to dissipate the heat present in the extruded plastic. In sheet extrusion, these rolls not only deliver the necessary cooling but also determine sheet thickness and surface texture (in case of structured rolls; i.e. smooth, Levant, hair cell, etc.).

Often co-extrusion is used to apply one or more layers on top of a base material to obtain specific properties such as UV-absorption, soft touch or "grip", matte surface, or energy reflection, where it is needed : on the surface.

A common post-extrusion process for plastic sheet stock is thermoforming, where the sheet is heated until soft (plastic), and formed via a mold into a new shape. When vacuum is used, this is often described as vacuum forming. Orientation (i.e. ability/ available density of the sheet to be drawn to the mold which can vary in depths from 1 to 36 inches typically) is highly important and greatly affects forming cycle times for most plastics.

Thermoforming can go from line bended pieces (e.g. displays) to complex shapes (computer housings), which often look like they have been injection molded, thanks to the various possibilities in thermoforming, such as inserts, undercuts, divided moulds.

Plastic extrusion onto paper is the basis of the liquid packaging industry (juice cartons, wine boxes...); usually an aluminum layer is present as well. In food packaging plastic film is sometimes metalized, see metalized film.

3.2.7.2 Blown film extrusion

The manufacture of plastic film for products such as shopping bags is achieved using a blown film line.

This process is the same as a regular extrusion process up until the die. The die is an upright cylinder with a circular opening similar to a pipe die. The diameter can be a few centimeters to more than three meters across. The molten plastic is pulled upwards from the die by a pair of nip rolls high above the die (4 meters to 20 meters or more depending on the amount of cooling required). Changing the speed of these nip rollers will change the gauge (wall thickness) of the film. Around the die sits a Cooling Ring. The air flow cools the film as it travels upwards. In the centre of the die is an air outlet from which compressed air can be forced into the centre of the extruded circular profile, creating a bubble. This expands the extruded circular cross section by some ratio (a multiple of the die diameter). This ratio, called the “blow-up ratio” can be just a few percent to more than 200 percent of the original diameter. The nip rolls flatten the bubble into a double layer of film whose width (called the “lay flat”) is equal to ½ the circumference of the bubble. This film can then be spooled or printed on, cut into shapes, and heat sealed into bags or other items.

An advantage of blown film extrusion over traditional film extrusion is that in the latter there are edges where there can be quality (thickness,) variations.

Blown Film Extruders require Compressed Air for two operations: 1) to increase the film width by adding compressed air inside the bubble. Once the bubble is inflated, no additional air is required. The air trapped inside, with the help of the top nip rolls and cooling air, shapes the plastic tube into a desired width and thickness. The VOLUME of air required initially depends highly on the size of the machine and width to be extruded. This can be anywhere from 50L to 400L of uncompressed air. As this is only required once in a production run, Flow rate is to be considered as insignificant. A compressor with a tank size of about 200L at a working pressure of 8 Bar can store more than 1000L of uncompressed air.

2) To apply pressure on the nip rolls. The Niprolls need to be pressurized so that the material can be pulled up. It is important that even and regulated pressure is used to ensure proper Thickness control. The pressure required can be regulated by a Regulator attached to the machine. The incoming pressure needs to be more than 6 Bars. Ideally, a compressor with more than 8 Bars but less than 11 Bars can be used in tandem with the regulator to maintain the pressure. As the application is only to apply pressure, the Air loss is only through leakage. AS per ISO standards, 0.1L/connection/hr is the maximum allowable leakage for pneumatics. There are about 36 connections in an average Blown film extruder. So a leakage rate of 3.6 L/hour, which is 0.06L/min. This is also very low for any industrial compressor.

3.2.7.3 over jacketing extrusion

In a wire coating process, bare wire (or bundles of jacketed wires, filaments, etc.) is pulled through the center of a die similar to a tubing die. Many different materials are used for this purpose depending on the application. Essentially, an insulated wire is a thin walled tube which has been formed around a bare wire.

There are two different types of extrusion tooling used for coating over a wire. They are referred to as either "pressure" or "jacketing" tooling. The selection criteria for choosing which type of tooling to use is based on whether the particular application requires intimate contact or adhesion of the polymer to the wire or not. If intimate contact or adhesion is required, pressure tooling is used. If it is not desired, jacketing tooling is chosen.

The main difference in jacketing and pressure tooling is the position of the pin with respect to the die. For jacketing tooling, the pin will extend all the way flush with the die. When the bare wire is fed through the pin, it does not come in direct contact with the molten polymer until it leaves the die. For pressure tooling, the end of the pin is retracted inside the crosshead, where it comes in contact with the polymer at a much higher pressure.

3.2.7.4 Tubing extrusion

–Extruded tubing process, such as drinking straws and medical tubing, is manufactured the same as a regular extrusion process up until the die. Hollow sections are usually extruded by placing a pin or mandrel inside of the die and in most cases positive pressure is applied to the internal cavities through the pin.

Tubing with multiple lumens (holes) must be made for specialty applications. For these applications, the tooling is made by placing more than one pin in the center of the die, to produce the number of lumens necessary. In most cases, these pins are supplied with air pressure from different sources. In this way, the individual lumen sizes can be adjusted by adjusting the pressure to the individual pins.

3.2.7.5 Co extrusion

Co extrusion is the extrusion of multiple layers of material simultaneously. This type of extrusion utilizes two or more extruders to melt and deliver a steady volumetric throughput of different viscous plastics to a single extrusion head (die) which will extrude the materials in the desired form. This technology is used on any of the processes described above (blown film, over jacketing, tubing, and sheet). The layer thicknesses are controlled by the relative speeds and sizes of the individual extruders delivering the materials.

There are a variety of reasons a manufacturer may choose co extrusion over single layer extrusion. One example is in the vinyl fencing industry, where co extrusion is

used to tailor the layers based on whether they are exposed to the weather or not. Usually a thin layer of compound that contains expensive weather resistant additives are extruded on the outside while the inside has an additive package that is more suited for impact resistance and structural performance.

3.2.7.6 Extrusion coating

Extrusion coating is using a blown or cast film process to coat an additional layer onto an existing roll stock of paper, foil or film. For example, this process can be used to improve the characteristics of paper by coating it with polyethylene to make it more resistant to water. The extruded layer can also be used as an adhesive to bring two other materials together. A famous product that uses this technology is tetrapak.

3.2.7.7 Compound extrusions

Compounding extrusion is a process that mixes one or more polymers with additives to give plastic compounds. The feeds may be pellets, powder and/or liquids, but the product is usually in pellet form, to be used in other plastic-forming processes such as extrusion and injection molding. Machine size varies from tiny lab machines to the biggest extruders in the industry, running as much as 20 tons per hour, as used by the chemical companies that make the base resins. Usually twin-screw extruders are preferred because they give better mixing at lower melt temperatures. Most of these have screws and barrels made up of smaller segments (mixing, conveying, venting and additive feeding) so that the design can be changed to meet the production and product needs. Single-screw extruders can be used for compounding as well, especially with appropriate screw design and static mixers after the screw. Selection of the components to be mixed (viscosities, additive carriers) is as important as the equipment.

4. Parts of Pipe Extrusion production line

Product line consists of a number of machines and devices that heat the raw materials and convert them to pipes.

Product line consists of: 1. Extruder:

A machine for producing more or less continuous lengths of plastic sections. It's essential elements are a tubular barrel, usually electrically heated; a revolving screw, ram or plunger within the barrel; a hopper at one end from which the material to be extruded is fed to the screw, ram or plunger; and a die at the opposite end for shaping the extruded mass, this machine is the most important machine in production line because it make many tasks on the production line where they are mixing the raw material and heated and pushed it to stanb and determine the pipe diameter and produced and paid for the cooling Calibration Tanks.

2. Die head: It is the die which determines the shape of an extradite

3. Cooling & vacuum Calibration Tanks: this part in production line which makes the pipe smooth and makes sure the pipe is incomplete rotation, and that’s by make the pressure around the pipe is less than Atmospheric pressure, and cooling pipes by Water sprinklers.

4. cooling Calibration Tanks : this Part is used in case of additional production P.V.C pipes because it need for more cooling because it formatted in temperature higher than Polyethylene pipes, the cooling in this part is by Water sprinklers too.

5. Belt haul-offs are used for continuous extraction of pipes and profiles. They are known for especially consistent performance even at high production speeds. The belts are driven by brushless AC servo drives. Both belt carriers can be mechanically or pneumatically adjusted in height. The belts can also be supplied with a cellular vulcanized or rubber layer. This part is responsible for the movement of pipes in the production line and move it in the direction of the scissors in the case of continuous production (normal situation) or in the direction of the Extruder in case of reset line.

6. The printer uses to print on the pipe producing their own data, such as the manufacturer and type of matter and pressure

7. Saw: Machines suitable for cutting and chamfering plastic pipes by means of rotating cutters. The machine’s main characteristic is their dust-free cutting operation. Due to a special central clamping device idle time is kept to a minimum. When high extrusion speed, short cutting lengths and small tolerances are precision cutting saws are the perfect solution. The saw carriage (driven by an AC servo drive) moves along with the extruded material, keeping trace and speed synchronously. Very narrow tolerances are therefore guaranteed.

8. Pipe Extrusion Socketing Machines: for making pipe joints. There are several types for different applications available.

Socket Systems:

Sewer socket for sewer pipesCement sockets for sewer pipes with air mandrelCement sockets for sewer pipes with rubber ring mandrelCement sockets for pressure pipes with expanding mandrel

Spin welding machines to connect pipe and socket by friction welding

4.1 EXTRUDER

In order to produce satisfactory extradite it is necessary to apply heat to the granules in order to soften them and make the resulting melt capable of flow under some pressure. This is carried out rotated in the barrel by means of gear box and variable screw driver or Eddy current motor.

Therefore the screw barrel has following functions:

pumping

heating

mixing

pressurizing

In order to make each function as effective as possible it is normal practice to divide the screw into 3 zones:

feed zone at hopper end

compression zone (transition) at the middle

Melt zone (melting zone) at the die end.

The function of the feed zone is to collect granules from the feed hopper and transport (pump) them up the screw channel. At the same time the granules should begin to heat up and compact and build up pressure as they advance towards screw tip (die end). For efficient pumping the granules must not be allowed to lie in the screw channel. They must therefore show high degree of slippage on the screw channel surface and a low degree of slippage on the barrel.

The maximum delivery of granules by the feed section may be achieved by:

A relatively deep channel

a low degree of friction between the granules and screw

a high degree of friction between granules and barrel wall

an optimum helix angle (20 degree for LDPE)

With many polymers, such as polyethylene, it is found that the friction of polymer to metal increases with temperature up to about 120 degrees C. For optimum pumping we should therefore in theory try to have a cold screw in feed zone and hot barrel.

In practice it is found that screw cooling reduces output. This is due to other effects occurring further down the screw.

As the material goes from feed zone to melt zone there is an increase in the screw root diameter. This results in the decrease in the volume of space enclosed by the thread and the surface of the root in one complete turn of the screw.

Granules melting should occur around the compression zone.

The compression zone or Transition zone could be of two types.

gradual transition, long compression zone

sudden transition , short compression zone

The screw with sudden transition is required for plastic material with a narrow melting range such as nylon and screws with gradual transition are material with wide melting range

4.1.2 COMPRESSION RATIO

The ratio of the volume of the first turns of the channel of the screw (at hopper end) to the volume of the last turn of the channel (at the die end) is known as the compression ratio. This ratio usually between 1.5:1 to 4:1 depending upon the material.

2.3 for rigid PVC

3-3.4 for PS/HIPS/HDPE/ soft PVC

4 for LDPE

4 for PP/slippery material

In the melt zone (melting zone) the polymer melt is brought to the correct consistency and pressure required for extrusion. The melt should be pumped to the die at a constant rate, consistency and pressure. These properties may vary from point to point but when measured to a particular point should not change with time. Higher melt pressure is required in the metering zone in order to mix melt to give it constant properties throughout hence obtain smooth extradite.

This pressure is generated by (a) restriction to flow in the melt zone and (b) restriction in the die head, (c) increase in melt viscosity.

The restriction to flow in the metering zone is increased by

Decreasing channel depth,

Decreasing channel width,

Water cooling of the screw. Screw cooling hardens the layer of polymer adjacent to the surface and reduces the effective channel depth.

Replacing all or part of the metering zone section of the screw with a smear head attached to and revolving with the screw. This has an effect of increasing the restriction. It will have an added advantage in increasing frictional heating (when desirable) increasing the degree of mixing of the melt and damping out any pulsations in output.

4.1.2 BREAKER PLATE

At the end of the melt zone, there is often a breaker plate fixed between the barrel and die adapter. The thickness of breaker plate is slightly more than the two recesses (steps) cut in the barrel and the die head

Breaker plate has following important functions:

It helps to further increase back pressure.

It turns rotational flow of the melt into floe parallel to the screw axis.

It holds back impurities.

It holds back unplasticised material.

To make these functions more effective it may be necessary to interpose stainless steel wire mesh screens between the breaker plate and screw.

4.1.3 L/D RATIO

The screw should have a sufficient length and diameter in order to accommodate the feed, compression and melt zones so that the melt is in the correct state when it enters the die. Screw dimensions such as helix angle, channel depth and width are all significant.

4.1.4 MELT TEMPERATURE CONTROL

In order to melt the granules, heat is generated either internally by friction or by applying external heat from heaters wrapped around the barrel. It is necessary to control the heat supply because if the material becomes too hot it may decompose, degrade for become too fluid. If too cold it will be insufficiently plasticized, variations in temperature will also cause variations in flow rate.

To prevent the overheating of the barrel through which cooling water or forced draught air may be circulated.

OUTPUT OF THE EXTRUDER

It depends on

(a) Screw dimensions

(b) Die dimensions

(c) Screw rpm

The following factors will increase output

(1) Increase of screw speed

(2) Increase of screw diameter

(3) The helix angle up to a maximum about 30 degrees

(4) An increase in die diameter

When molten polymer emerges from a die many of its molecules will have been oriented in a direction parallel to the axis of the die orifice. When no longer constrained by die wall the molecules tend to recoil causing a contraction in the direction of extrusion and expansion in the iron section of the extradite. This phenomenon is known as die swell.

For this reason extradite, unless hauled off at a greater rate than they are extruded show greater cross sections than those of the corresponding die orifice.

Extruder is consisting from:Dc motorgearboxcontrol panel Hopperscrewheatershoodbreaker plateoven cylinder

4.1.5.1 DC motor

The extruder machine is feed by 3-phase dc motor with 50 Hz frequency

The motor is cooling by small fan which rotate by small AC motor

4.1.5.2 Gearbox

The gearbox is used to increase torque while reducing the speed of a prime mover output shaft (e.g. a motor crankshaft). This means that the output shaft of a gearbox will rotate at a slower rate than the input shaft, and this reduction in speed will produce a mechanical advantage, causing an increase in torque.

4.1.5.3 Control panel

There is one control panel control in all production lines, and this panel is digital this control panel is control in all production lines such as the martial on Hopper, screw speed, heat of plastic in oven, move the cooling basin and the saw.

4.1.5.4 Hopper

It is contest from main hopper which is big and there are small ac motor above it to add raw martial to the hopper and this hopper is used in continuous production

And there are small hopper to add cleaning martial (martial used in maintained and in stop production

4.1.5.5 Screw

Therefore the screw barrel has following functions:

pumping

heating

mixing

pressurizing

In order to make each function as effective as possible it is normal practice to divide the screw into 3 zones:

feed zone at hopper endcompression zone (transition) at the middleMelt zone (melting zone) at the die end.

These types of machines use twin screws in several cases, for example when there is a process of compounding and extrusion of any mixing and granulation at the same time produce a final product. It is also used in abundance in the operations of mixing and granulation of colors and additives for the formation of other processes such as Injection (injection molding), extrusion, and that of the short time and the quality of the product. Of the advantages of twin screw machines that residence time decreases with increase of production output as well as the shear increases. It is known that twin screw possible that melted and mixed and transferred to a molten material in less time and the best machines in short is better than single screw. This makes the price higher.

There are two types of twin screw:counter-rotating: which is that both of the screw is going in opposite directions, and is used for extrusion processes for up, and the reason is that this type gives a better quality of nutrition and the transfer of molten material and also control the steady temperature and residence time better.

co rotating: is that going both screws in the same direction, and is used for mixing and granulation, as well as it is suitable for the rest of products that do not have the sensitivity of the high temperature at high speeds such as polyethylene pe and gives uniformity over the material molten in a shorter time.

4.1.5.6 Heaters

There are more than 12 electric heaters plastic around screw

This heater set in range between 150-200 C in polyethylene pipes and set at range between 170 – 300 C in produce P.V.C pipes.

4.1.5.7 Hood

Hood is used to intake air from extruder

The advantage to use hood is:

decrease pressure on screw and oven Prevent combustion of plastics as a result of high temperature

4.1.5.8 Breaker plate

At the end of the melt zone, there is often a breaker plate fixed between the barrel and die adapter. The thickness of breaker plate is slightly more than the two recesses (steps) cut in the barrel and the die head

Breaker plate has following important functions:

It helps to further increase back pressure.

It turns rotational flow of the melt into floe parallel to the screw axis.

It holds back impurities.

It holds back unplasticised material.

To make these functions more effective it may be necessary to interpose stainless steel wire mesh screens between the breaker plate and screw.

Oven cylinder

Cylinder is located between heaters and plastic , plastic grind here between the fuse screw and the cylinder to move to the mold Given the exposed cylinder pressure up to 700 kg / cm 2 and elevated temperatures an escalating _ so you must:1 _ to be made of corrosion-resistant material (heat treated alloy steel)2 _ address the inner surface and lining material resistant to corrosion (chrome)3 _ Number of heaters vary depending on the length of cylinder4 _ heating temperatures depend on the electric heaters and heat generated from friction between the raw material and fuse (screw) and cylinder

4.2 DIES:

(1) It is the die which determines the shape of an extradite. Thermoplastic polymer molecules consist of long chains which tend to take up a randomly coiled configuration whenever possible. When such materials flow or forced through a die, the molecules become partially straightened or oriented.

(2) When molten polymer emerges from a die many of its molecule will have been oriented in a direction parallel to the axis of the die orifice. When no longer constrained in the direction of extrusion and expansion in the iron section of the extradite. This phenomenon is known as die swell.

(3) For this reason extradite, unless hauled off at a greater rate than they are extradite show greater cross sections than those of corresponding die orifice.

(4) Under normal circumstances die swell may be reduced by the following:

Decreasing extrusion rate

Increasing melt temperature (keeping extrusion rate constant)

Increasing the length of the die land

Increasing the draw down rate (ratio of haul off rate to natural extrusion rate) without affecting output.

(5) To get square cross section the shape of the die will be

(6) When a polymer melt flows through a tube the rate of flow is much greater in the center of the tube than near the walls. In fact there is no flow at the walls.

(7) If we assume semicircle distribution of velocities in a given plane then the volumetric flow rate is less than half in the smaller tube than that of the larger tube.

4.2 Cooling and Vacuum Calibration Tanks

Are used for calibrating and cooling pipes made of thermoplastic materials by means of spray cooling. The spray cooling method prevents the formation of water boundary layers and is more efficient in cooling than the full water tanks.

Furthermore, there are no buoyancy problems that could distort the pipe. Spray-cooling increases the heat exchange rate significantly, compared to full-water-bath cooling. However, optionally all tanks can be supplied as full water tanks.

The tank can move horizontal on rod in direction of end of production line when maintained or to direction extruder

Cooling and Vacuum Calibration Tanks are help in determine the dimension of pipes in special cases such as if there is no die in required dimension so we use the nearest larger dimensions of die and make the pipe pass in the tank

But this process needs to high Experience and skill from team work and work in low speed

The cooling & vacuum calibration tank is contest of:

Tank body2 Water pumpsWater sprinklersWater level sensorWater filter glass Hood

4.2.1 Tank body

Tank body is made of stainless steel to prevent corrosion caused by water and is made by casting, but is required to have a large wall thickness to withstand the force resulting from the large pressure difference between atmospheric pressure and the pressure inside the tankAnd consists of the tank roof windows are made of glass bear the pressure, or from any other transparent material for high pressure but must be surrounded with glass insulator from plastic so that you can prevent the leakage of air into the tank

4.2.1.1 Accessories

There are accessories to the tank body and are classified as part of the body of the tank because it mainly affects on the body and play a large part of its missionThis accessory is:

Calibration SleevesHorizontal movement motor

4.2.2 Calibration selves

Thanks to the vacuum calibration sleeve system, it allows the extrusion of pipes with dimensions in accordance with the international standards.The vacuum calibration sleeve that transmits the heat excellent as the sleeve is highly wear resistant. They also provide perfect sliding for the pipe during the calibration process.

We have developed conventional and adjustable calibration sleeves for the extrusion market. Our wide product range is a guarantee for fulfilling the demands of pipe production. Especially the inlet area which is of great importance for the production can be adjusted very easily to the production conditions. The ROTEC cooling has been implemented as an innovation. By this type of cooling the heat is discharged much more effective. In connection with the inlet lubrication the ROTEC cooling produces a constant water film which minimizes deposits and quality problems. The red bronze alloy chosen to has proved to be very abrasion-resistant.

The feature of our adjustable calibration sleeves is a profound and patented mechanics. Even under difficult conditions (aggressive cooling medium) there is no occurrence of wear or blockings. For changing the diameter it is not necessary to reduce the vacuum.

4.2.3 Horizontal movement motor

This motor is used with screw to move the tank in direction of heal when stop production line to make maintaince or to dies to work in continuous production

4.2.4 Water pump

There are 2 water pump in tank the first pump is to pump water to sprinklers and it work when the production line work and the anther water pump is to absorb water from tank When the water reaches a specified level in the sensor

When water reach the specified level in the sensor the pump reduce pumping water in tank and the anther pump which absorb water from tank work automatic

4.2.5 Water sprinklers

The aim of water sprinklers is to spray water on the pipe to cooling it

This sprinklers mounted on 4 plastic tubes made of a substance or PVR PVC pipes and the four surrounding this pipe to be cooled from the four to make sure the cooling pipe on all sides

4.2.6 Water level sensor

This sensor determines the water level inside the tank and to make sure not to submerge the pipe with water, which affects the pressure and the resulting pressure on the lead pipe in this progress report to the occurrence of bumps and irregularities in the form of pipe

And this sensor is connected to automatic valve that control in pump which absorb water from tank When water reach the specified level in the sensor the pump reduce pumping water in tank and the anther pump which absorb water from tank work automatic

But for more safety and fear of a sudden malfunction in the sensor or pump there are key for running manual suction pump in case of any malfunction in the automatic system

4.2.7 Water filter glass

Water Filter glass is used to determine the quality of the water inside the tank and to make sure they clean water so as not to result in the use of water is not good at producing or dirty pipe sticking out any impurities affect the shape or brightness, or rotated

As the filter purifies water from any impurities and filter glass thickness up to 1 cm to remain coherent in the case of the entry of any impurities and to him a heavy collision with the walls of the filter

4.2.8 Hood

The hood pull air from inside the tank to reduce the pressure to 0.2 bar, leading to the full rotation of the pipe ,The hood pull air from inside the tank to reduce the pressure to 0.2 bar, leading to the full rotation of the pipe

And contains a hood on the valve prevents water from entering the hood to the body in order to prevent an imbalance in the motor

Hood and related hoses inside the tank to pull the air, especially at the top of the tank where we need to reduce the pressure at the sleeves to make sure the full rotation of the pipe producing

In the case of production of the PVC pipes we use the two tanks first tank is to the vacuum and cooling produce pipe and the other tank to be more because of the cooling pipes of PVC industry needs a high temperature, which double the cooling period

As in the case of polyethylene pipes job by using a single tank for cooling and vacuum because the formation heat of this type of pipes do not require very high temperatures

4.3 Belt haul-offs Are used for continuous extraction of pipes and profiles. They are known for especially consistent performance even at high production speeds. The belts are driven by brushless AC servo drives. Both belt carriers can be mechanically or pneumatically adjusted in height. The belts can also be supplied with a cellular

vulcanized or rubber layer. This part is responsible for the movement of pipes in the production line and move it in the direction of the scissors in the case of continuous production (normal situation) or in the direction of the Extruder in case of reset line.

4.4 PrinterThe printer uses to print on the pipe producing their own data, such as the manufacturer and type of matter and pressure

And the printer used for printing by tossing

4.5 saw

Machines suitable for cutting and chamfering plastic pipes by means of rotating cutters. The machine’s main characteristic is their dust-free cutting operation. Due to a special central clamping device idle time is kept to a minimum. When high extrusion speed, short cutting lengths and small tolerances are precision cutting saws are the perfect solution. The saw carriage (driven by an AC servo drive) moves along with the extruded material, keeping trace and speed synchronously. Very narrow tolerances are therefore guaranteed.

4.6 Pipe Extrusion Socketing MachinesFor making pipe joints. There are several types for different applications available.

Socket Systems:

Sewer socket for sewer pipesCement sockets for sewer pipes with air mandrelCement sockets for sewer pipes with rubber ring mandrelCement sockets for pressure pipes with expanding mandrel

Spin welding machines to connect pipe and socket by friction welding

And noted that this machine is not placed directly on the line, but be isolated and when compiling the 20 pipe for example, this Machine run and do Socket

5. Steps for production pipes

Step 1We adding cleaning raw material (martial used in maintained and in

stop production) to small hopper after remove polyethylene or P.V.C raw material

the cleaning raw material is martial used in maintained and in stop production because it bear high temperature of extruder machine and this cleaning material used only in produce polyethylene pipes because polyethylene raw material not bear the high temperature for long time because if it be in high temperature for long time it will be Chars and be harder that is leads to break screw and destroy the extruder machine.

Step 2Reducing speed of screw by control panel for reduce the pressure of

plastic into the cylinder and reduce pressure on dies.

Step 3Removing heaters connection with electricity to reduce temperature

of plastic, cylinder, and dies.

Step 4Shutting out plastic from the extruder for change dies.

Step 5Stop hauls off.

Step 6Moving cooling & vacuum tank in direction of haul and away from

extruder in vertical axis.

Step 7Stop water pump to push water in cooling & vacuum tank and make

the anther pump which response on absorb water from tank working to absorb water.

Step 8Opening the valve which responsible the pressure in cooling &

vacuum tank to increase pressure in it.

Step 9Remove old die and change it by new die with dimension of Pipe to be

produced.

Step 10Remove old sleeves and change it by new with dimension of Pipe to

be produced.

Step 11Re connect heaters and set them at range 150: 200 C for Polyethylene

pipes and at range 200:300 for PVC pipes

Because PVC is formatting in higher temperature more than polyethylene formatting temperature.

Step 12Adding raw material of PVC or polyethylene to main hopper by the

hood above it.

Step 13Let cleaning material to leave the extruder die.

Step 14Turn the direction of production line haul off to make the pipe which

in cooling & vacuum tank gets out from tank.

Step 15Make hole in the previous pipe.

Step 16After all raw material get out from screw connect the new pipe with previous pipe

Step 17Switch the pump which pushes water in cooling & vacuum tank on

and open water sprinkler to cooling the pipe

Step 18After the connection between the previous and new pipe out from

cooling & vacuum tank set the dimension of haul off and saw.

Step 19After the connection between the previous and new pipe out from

cooling & vacuum tank set the pressure in cooling & vacuum tank at 0.2 bars.

Step 20Moving cooling & vacuum tank in direction of extruder and away from haul in

vertical axis.

Step 21Now the production line we work in continuous production.

Step 22After make amount pipes such as 20 for example take this pipes to

make socket by Pipe Extrusion Socketing Machines.

6. Quality engineering

Function of quality engineers in companies PVC pipes

6.1 visual inspection of the pipe: -The quality engineer measured length of the pipe using a meter after the formation of the upper head and then the observation of morphology of the pipe where:

Homogeneity of color and firmnessInternal and external surface smoothness to the pipe and free of cracks and bumps and deep lines.Rotate the pipe rotated so full there are no parts of the oval shape.The absence of impurities the product.Integrity of the pipe section of the bumps and cracks.Safety form cliffs and lack of any impeding the emergence of the stability of the Juan or the presence of any cracks within the cliffs or any deformities.

As may be otherwise considered unacceptable production

6.2 Test go & no gothe factor with pieces of pipe line at random for each test and the entry and exit socket her.If not enter the head of the tail in the production or refuses to be re-formed againWhen entering the tail in the head must not exceed the difference between them of 4 mm so as not to reject the production.

6.3 measure the length of pipe: Shall measure the height of the pipe using a meter after the formation of the upper headin more length or less length cut the increase placed on the product card shows the length of the real

6.4 Measuring the dimensions of socketIn terms of the length of the lip Socket and the length of the pipe according to the specifications attached to each size.As may be otherwise considered unacceptable production

6.5 Measure the diameterNote: You must take into account when measuring the outer diameter of the pipe to be cold pipe and the outer surface completely clean and smooth and there are no protrusions of any pipe shall be a full rotation.Screw diameter measuring device around the pipe and pull tightly on the outside diameter of the pipe and is not tilted vertically and then record the reading of the country.

Make sure the result is identical to the specificationsTake a reading every hour and in the beginning of the run size or re-butchery, or the beginning reboot after any malfunction.If the country within the allowable accepts productionif the diameter outside the allowable production rejects

6.3 measure the thickness of the pipeNote: You must be taking into account the internal and external surface of the pipe smooth and there are no impurities or any bump or rise.Make four signs on the outside diameter of the pipe at the beginning of the pipe (using the pen), and then measuring the thickness at each marker device "Measuring the thickness"Log reading and shall be in the specifications and repeat the measurement on the other side of the pipe and repeated with several pipes to make sure to read and proven results.

If the thickness within the allowable accept productionIf the thickness refuse outside the allowable production

7. TestingThe main objective of the tests is to determine the properties and translate numbers give the semantics understood by the specialists and tests multi-and many by ad-hoc basis there is mechanical tests and the physical and thermal and optical and other and all give us the specifications of the product and whether it is appropriate for the application or use of the designated or not.Here are some of the most famous of these tests and devices used have

7.1 tensile testsThis test is in knowing how the durability of the sample to flatten at temperatures appropriate to the use of this type are measured tensile strength and elongation, stress and extent of the change in composition with temperature change (thermal stability).

Devices used:

instron universal testerextensometers

7.2 melt flow rateand the test sample is required on the device so placed under the influence of certain temperature where the melts calculated plastic then flows through a tube or a small hole and it is a test flow rate of fusion.

Are measured: • flow rate flow rate.• Time.• Flow rate of fusion melt flow rate.Also can be done this test before the manufacturing process so as to know the right temperature for pouring the mixture into the Molds (molds) casting.Equipment required:csi melt flow indexer (extrusion plastometer)

7.3 Hardness test hardness testWhich is to determine the hardness of the plastic material and testing Rockwell hardness Rockwell hardness test is one way where it is specifically a strong impact on the segment by the head of the cone for a certain period and then calculate the depth and thus hardness

Equipment required:Rockwell hardness tester

7.4 density and specific gravityMeasuring the density and specific gravity is, inter alia, the way in which the weight plastic piece by a sensitive balance and record reading and then the weight of piece of plastic and are dipped and installed within the distilled water at room temperature and then taken readings and through them is the expense of specific weight and density, taking into account that the weight of a full immersion system have been determined by taking the weight submerge piece.

This is some of each as the stander for each test are presented

8. Maintenance of extrusion machines

In order to continue to drag (extrusion) operates the largest period of time without any problems must follow the following steps

1 - must use clean raw materials2 - non-use of materials (Filer) because they contain calcium carbonate and some other materials lead to eat screw in the period of time not exceeding three to six months from the date of use of the materials mentioned in the sense of Machine production 100 kilometers per hour after six months will be the output of 40 kilometers per hour and this from the reality of practical experience on more than one.

8.1 Methods of maintenanceincluding:

the maintenance of dailymaintenance of weeklymonthly maintenancemaintenance of Semi-annualannual maintenance

8.1.1 Day maintenance

And which are at the beginning of the working day

check oil on the gearbox and make sure it does not have a shortage of it and found a deficiency to be supplied Because the shortage of oil leads to the hottest gear and the resulting damage to the screw Sacrificing the cycle to stop the machine and the disruption of production and change the screw

make sure gears for the transfer of movement from the motor as the main sound and does not have the disadvantagesmake sure that all the motors on clouds (extrusion) and works naturally

making sure that all heaters operate normally

making sure your thermostat is working aschecking for crystals of the air as the working normally

making sure of links that there is no air leaking from

making sure the cylinder drag (extrusion) and the upper works naturally

making sure processing unit it is working properly

8.1.2 Weekly maintenance

lubrication and lubrication are all places to be greased or screw and the succession

The oil on the check gearbox motors and other machineis to make sure belts of it is working and intact

make sure it is working heaters and intact

make sure of hours as a thermal and thermostat is working properly and the state

8.1.3 Monthly maintenance

making sure the main motor and other motors

checking on gearbox and knowledge of its oil

checking on the control panel and review the hours and thermal heaters and thermostat

making sure that the head of machine clean and no impurities by And that he would have preferred jaw and head cleaning machine because the use of colored materials in abundance Leads to deposition of some material on the sides with a machine which in turn leads to the appearance of lines on the film during the

withdrawal process (extrusion)

8.1.4 Semi-annual maintenanceand the need to arrest the machine from one to two days depending on the nature of the work in the Machine:

making sure the control panel and all the keys

making sure heaters and clocks and thermostatchecking for screw and gearbox and make sure there is no leakage of oil

Removing the top of the machine and cleaningdecode screw and clean it and clean cylinder (the internal body of the screw)

lubrication is all the screws with a machine during installation thermal flap So that we can easily jaw during jaw againlubrication the screw by flapmake sure that processing unit is working wellto change the oil, gearbox every six months due to case of used oil, according to the country atmospherecheck oil on the gearbox and make sure it does not have a shortage of it and found a deficiency to be supplied Because the shortage of oil leads to the hottest gear and the resulting damage to the screw Sacrificing the cycle to stop the machine and the disruption of production and change the screwis the examination of the crystal at the air on the screw's body and make sure it is working normally

cleaning the air in the glaze on the top of the machine from dust and dirt

8.1.5 Annual maintenanceand where the currency is what has in the semi-annual maintenance as well as to add parts are replaced at this stage

Began to be as a pre-determined by the charge of the maintenance

9. Industrial safety

Purpose of studying industrial safety

To Prevent the occur of accident.

Some definitions

Accident

It is unplanned and UN controlled event which cause

Personal injuries and damage to Plant.

Injury

Harm caused to the employers.

Notice

In every factory a safety organization must be found.

Functions of safety organization

1-To establish a Procedures for collecting data concerning

-miner and major causes of accidents and fires.

-statistics showing disabling injury showing disabling injury frequency.

2-To prepare a safety program for new employees.

3-To recommend safe operating procedures and to participate in technical training programs for employees.

4-to organize first aid training courses.

5-To study available safety services as booklets, postures and films.

6-To suggest protective clothing.

7-To communicate with safety people in other plants.

8-To suggest maintenance procedures.

9-To recommend a disaster control program.

10-To suggest the style and amount of firefighting equipment.

Hazard classified into

First degree hazard

1-presence of flammable or combustible or toxic materials.

2-presence of heat sources.

3-presence of ignition sources.

4-presence of oxygen and compressed gases.

5-possibility of human error.

6-possibility of mechanical failure.

7-movement of people and equipment through plant.

8-Reduced visibility from vapors.

Second degree hazard

This hazard cause damage to life and limps and property because the accident occurred.

Hazard classification

1-chemical hazards.

2-electrical hazards.

3-mechanical hazards.

4-fires and explosion hazards.

5-Physical and environmental hazards.

-Radiant energy.

-Excessive noise.

-Excessive vibration.

-Extremes of temperature and humidity.

-Abnormal pressure.

Electrical hazard

Its causes

1-Touching live parts.

2-Short circuit.

3-Accidental ground.

4-Overload.

5-Breaking connections.

6-Defective Insulation.

Classes of electrical hazards

-Electrical shock.

-Electrical burns.

-Eye flashing.

Fires and explosion hazards

Fire triangle

-Fuel.

-Oxygen.

-Heat.

Fire preventation

1-Prevent the start of fire.

2-Provide for early detection of fire.

3-Prevent the spread of fire.

4-Provide for prompt extinguishment.

5-Provide for prompt and orderly evacuation of personal.

Sources of fires

1-Matches and smoking.

2-Heating and cooking.

3-Housekeeping and rubbish.

4-Electrical wiring apparatuses.

5-Open flames and sparks.

6-Flammable liquid.

Causes of accidents

-Un safe act.

-Un safe environment