Methods Manufacturing

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Methods of Manufacturing

Manufacturing or production is a transformation process which converts inputs in tooutputs.1)The Inputs are men, material, machines, specifications, drawings, instructions etc.2)The transformation process, whether mechanical or chemical, involves following activities. ● Planning and control of factors of production. ● Procurement of materials. ● Receipt, storage and issue of materials. ● Material handling. ● Inspection of in-process and parts. ● Assembly and testing of products. ● Storage of finished goods. ● Retrieval, as necessary.3) The output which includes the goods and services produced.The combination of the operations and activities, as stated above, employed to creategoods and services, is known as manufacturing system(or method).

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Factors Influencing choice of manufacturing system:The selection of a manufacturing system is a strategic decision for most organizationssince changes at a later stage are expensive. The system selected should be such that itcan give desired output, required quality, and is cost effective.Various factors which determine the choice of the manufacturing process are as under.(a) Effect of volume/variety: High product variety requires highly skilled labors, general purpose machines, and sophisticated production, planning and control systems.On the other hand low production variety (i.e. one or few products, produced in largevariety) enables the use of low skilled labor, highly automated mass productionprocesses using special purpose machines and simple production planning and controlsystems.

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(b) Capacity of the Plant:The projected sales volume is a major influencing factor in determining whether the firmshould go for intermittent or continuous process.At low volumes, it is cheaper to install Intermittent process and it is economical to go forcontinuous process for high volumes.The next slide may be referred , which illustrates the concept.(c)Flexibility:Flexibility implies the ability of the company to satisfy varied customer’s requirements.Flexibility and variety are interrelated .For more varieties to be manufactured, the Manufacturing facilities need to be commonalized, which leads to intermittentmanufacturing, higher inventories, longer lead times and elaborate planning and control.(d)Lead or delivery time:Higher lead times, in a competitive market situations, entails maintaining of inventoriesand manufacturing using batch/mass production.(e) Efficiency:Efficiency measures the speed and cost of manufacturing system. Efficiency is greater when the product is mass produced. However, for producing in mass, sales volumes are required.Hence, depending on the sales volume, and considering product variety, the process giving thebest efficiency in terms of machine and manpower utilization will have to be selected.

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(f) Environment:Environment brings in new technologies and forces adoption of new processes ofmanufacturing. For instance, wooden furniture is being replaced by, steel and plasticfurniture .Hence the furniture manufacturer has to adopt to newmanufacturing processes (i.e. batch production in place of one off process) to fall in linewith changing times. Similarly, as the market preferences change due to fashion or otherreasons, the manufacturing system has to change accordingly.

Classification of Manufacturing Systems:Manufacturing can be basically classified in to 5 groups.1) Project Production.2) Jobbing production.3) Batch Production.4) Mass and flow Production.5) Process Production.

1) Project Production: In this, a single assignment of complex nature is undertaken for Completion within given time period and with fixed expenditure.Examples of project are ships, locomotives, aircrafts, construction of roads, buildings, etc.

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Characteristics of Project production:a) Definite beginning and definite end.b) Non-uniform requirement of resources: In the beginning, the resources required are

low. As the project progresses the resources ( Men, machines, material) requirement builds up fast. At the end, the resources are required to be deployed elsewhere.c) Involvement of different agencies: A project has many tasks and each task has its own specialization and required to be performed by different agencies. The tasks generally have strict precedence and close coordination between the agencies is of

utmost importance. d) Fixed position layout: Where the output of the project is a product, such products are

generally characterized by immobility during transformation. Operations on such products are carried out in “ fixed position assembly type layout” which can be observed in the production of ships, locomotives, aircrafts, etc.

e) High cost overruns: Generally, large projects, due to their complexity and involvement of number of agencies tend to get delayed. This results in to inflationary cost rise.

Also the delays in completion may warrant penalties, which results in to high cost

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f) Personnel problems: ● When there is a fast build up of project, labors are either transferred from other

departments or hired on temporary basis, for short duration. As a result, they have limited interest in the project.

● Since projects have limited duration, the staff starts spending more time getting prepared for the next project.

● The site of the project generally is a remote, in underdeveloped region, which changes from project to project, which causes dislocation of the normal life.

g) Scheduling and control: Networking techniques like PERT/CPM are useful in overcoming the complexities of the projects, their precedence relationships etc.

2) Jobbing production: This type is characterized by one or few numbers of single productDesigned, and manufactured , strictly as per customer specifications, within the givenperiod and within the price fixed prior to the contract. Some examples are general repair shops, special purpose machine manufacturers, building contractors, tool rooms,Tailoring shops manufacturing made-to-measure suite of clothes, manufacturers of cranes, furnaces, and other manufacturing articles made to customers’ orders.

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Characteristics of jobbing production: a) Small production runs: As one or few pieces are involved , the production runs are small.b) Discontinuous flow of materials. The flow of materials and components between different

stages of manufacturing is highly discontinuous, due to imbalance in operation wise work content.

c) General purpose machines and process layout: Plant and equipment are procured and arranged to obtain maximum flexibility. The machines are grouped together to give process layout. e.g. presses are kept at one place, milling machines are kept at

another place, drilling machines at third place, and so on and so forth. Each group of machines is designated as a work center or a section of a shop.

The grouping of machines gives lot of flexibility in loading and scheduling. Temporary machine breakdowns and operator’s absenteeism can be taken care of by shifting job from one machine to another or by shifting the operator from less important jobs to more important jobs.

e) Highly skilled labor force: The workforce is highly skilled-highly qualifies apprentices, expected to work independently with minimum instructions and display lot of initiative and

judgment. They are required to set up their own machines and prepare their own special tool or production aids to further the manufacture of a part or an assembly.

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f) Highly competent and knowledgeable supervisors: Highly competent engineers are engaged as supervisors in the base work shop and site engineers, practical men with thorough training, and who can take independent charge at the site are employed to work at site. Besides their routine, these people are expected to improvise on the work methods, determine tool requirements, select the best process and provide management with reliable estimate of the labor and material requirements for specific orders. The span of control-the number of workers to be supervised by a supervisor-is kept low due to the technical nature of the job.g) Large work-in-progress: The WIP in a jobbing production is generally very large as detailed scheduling and process control in this type of production is infeasible.h) Limited functions of production, planning and control: The success of the jobbing production mainly depends on the ability of the engineer incharge of the contract. ● Materials are indented and purchased only on receipt of orders unlike batch or mass production, where material are planned well in advance. ● Tool control function is simple. Standard tools are stocked and special tools are either made on shop floor or procured. ● Process planning activity is almost absent. The drawings and specifications are given to supervisors who decides the machines to be used, processes to be employed, workmen to be put, and

the time estimate for completion of the job.

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Methods of Manufacturing3.Batch Production: Batch production is characterized by manufacture of limited number of a product( but many such quantities of different products) produced at periodic intervals and stocked in stores/warehouses as finished goods(or parts) awaiting sales or withdrawal for assembly.Typial examples are medium and heavy industry engaged in the manufacture of electric motors, switch gears, heavy motor vehicles, Internal combustion engines, manufacturers of ready made garments: sub-contractors who take on machining of batches of components to the drawings of a large manufacturer etc. Characteristics of batch production: a) Short run: b) Skilled labor in specific trades. Labor force is expected to possess special skill in one specific manufacturing process: turning, milling, drilling, grinding, welding, hobbing, fitting etc. c) Supervisor to possess knowledge of a specific process: A supervisor must have sound knowledge of the specific area under his supervison.e.g. A supervisor of grinding section, need not have knowledge of turning section, but he must be thorough in knowledge of various grinding methods.

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d) Limited span of control:e) General purpose machines and process type layout: Plant and equipment are procured and arranged to obtain maximum flexibility. The machines are grouped together to give process layout. e.g. presses are kept at one place, milling machines are kept at another place, drilling machines at third place, and so on and so forth. Each group of machines is designated as a work center or a section of a shop. The grouping of machines gives lot of flexibility in loading and scheduling. Temporary machine breakdowns and operator’s absenteeism can be taken care of by shifting job from one machine to another or by shifting the operator from less important jobs to more important jobs.f) Manual material handling: Material handling in batch production as compared to jobbing production is small. Individual parts and components are placed on trolleys or trays and transported as unit loads. Material handling can be mechanized by using power driven trucks.g) Manufacturing cycle time affected by queues:

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The manufacturing cycle time is comparatively less than that of jobbing production but is much more than mass and flow production. The batches of work tend to queue up at different machines due to differing cycle times, batch sizes and sequence of operations.h) Large work-in-progress: Work in progress is comparatively large due to varying work content of different components, imbalance in manufacturing times, and formation of queues between the machines.i) Flexibility of production schedules: The grouping of machines gives lot of flexibility in loading and scheduling. Temporary machine breakdowns and operator’s absenteeism can be taken care of by shifting job from one machine to another or by shifting the operator from less important jobs to more important jobs.j) Need to have production planning and control: Functions of PPC, are more complex than those in jobbing production or Mass and flow production. ● Material and tool control are important functions. Some kind of replenishment system

is required.

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● Operation layout and route sheets for each part are required to be prepared. ● Loading and scheduling is very important as each machine is required to be scheduled. ● Collecting information on Progressing the work is very important, as each job needs to be tracked for its progress. ● Expediting is generally necessary since quite often jobs, due to imbalances in work content, tend to lag behind. 4.Mass and flow Production: This is characterized by the manufacture of a several number of standard products produced and stocked in the warehouses as finished goods awaiting sales. The goods under mass production are manufactured either with single operation or series of operations on one machine. In flow production, goods are manufactured by series of operations on different machines, arranged as per sequence of operations. Typical examples of mass production units are plastic goods, sintered products, hardware etc. Typical examples of flow production are manufacture and assembly units of automobiles, refrigerators, radios, television sets, electric fans, domestic appliances etc.

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Characteristics of Mass and Flow Production:a) Continuous flow of material: The flow of the material is continuous and there is no queuing at any stage of processing.b) Special purpose machines and product type layout: SPMs are used and the plant assembly stages are laid out on the basis of product layout,

the layout-by-sequence.c) Mechanized material handling: Material handling is comparatively less, firstly because the material has to move less in

between the stages, and secondly the material handling system is mostly mechanized by use of conveyors and transfer machines.

d) Low skilled labor force required.e) Short Manufacturing cycle time: The manufacturing cycle times are very short. The machine capacities are balanced by duplicating machines wherever required.f) Easy supervision: Supervision is easy as very few instructions are necessary and that too at the start of the job.

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g) Limited work-in-progress: WIP is comparatively less since the manufacturing line is balanced.h) Lesser flexibility in production schedules: Interruptions due to breakdowns and absenteeism seriously affect the production as stoppage of one machine usually disturbs the working of other machines. Systematic maintenance and provisioning of stand-by operators are, therefore two major management functions.5.Process Production: Process production is characterized by the manufacture of a single product produced and stocked in the warehouses awaiting sales. The flexibility of such plant is almost zero as only one type of product can be produced in such plants. Typical examples of such plants are sugar, cement, steel, paper, refineries, aerated drinks etc.Characteristics of process production:a) Special purpose machines with built in controls: The layout of the plant, shape and size of the buildings, location of services and storage yards, position of cranes and

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conveyors is such that the material flow is unidirectional and at the steady rate. Special purpose machinery and equipment with built-in controls to measure output and regulate the inputs are employed to suit the needs. b) Highly mechanized material handling: Material handling is highly mechanized. Conveyor system and automatic transfer machines move materials from one stage to another.c) Virtually zero manufacturing cycle time: The manufacturing cycle time is virtually zero. The whole plant is like one large machine wherein raw materials enter at one end and the emerge as the finished product at the other end.d) Low skilled labor: The labor force consists of low-skilled-workwomen and skilled technicians.e) Supervisors to be process specialist: The supervisor in process production is highly qualified and is expected to possess considerable knowledge of processes involved.

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f) Negligible work in progress: The WIP inventory is very small as the material flow is continuous.g) Limited Production planning and control functions: ● Material control function is of crucial importance. Material needs to be planned well in advance. Scientific inventory control system is a must for such plants. ● Tool control function is almost absent because of the nature of the plant. ● Process planning activity is not required since it is the plant which decides the route. ● Scheduling activity is very simple and is merely restricted to final targets. ● Progressing and expediting functions are extremely simplified and are merely limited to recording of the final production at the end of the shift.

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Selection of Manufacturing system:The five manufacturing systems referred above are the simplified versions of manufacturing systems. In practice, very few organizations use them in the pure sense.Most of the organizations combine two or more of the above systems, to producecomponents and final product. For instance, manufacturers of automobiles, domesticelectric appliances etc use batch production to produce components and flow productionfor final assembly. A production system, like a product has got life cycle. When a product is introduced,it is produced in small quantities in an inefficient manner, using project productionmethod. As output increases, due to the product being in growth phase, more and moresub processes are designed using flow production form. Finally, since the product is inmaturity phase, the product competes mostly on price and volumes are high, highlycost efficient methods are required to produce the product at low cost. In this situation,the flow type production is most suitable manufacturing system.

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Break-even-analysis is most suitable for selecting the most optimal manufacturingsystem., At the introduction phase of the product the product is produced using generalpurpose equipment, with little and no commitment on the fixed cost. Labor intensive methods are used to keep the fixed costs lower. The manufacturing system used thusis more or less the project form. As the product enters the growth phase, more generalpurpose machines are organized to have batch production. Finally, when the productenters the maturity phase, the manufacturing is organized on special purpose machinesin mass and flow production system to have lower cost per unit of output(though the fixedcosts are high).The next slide shows the least cost at any stage of life cycle.

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Date post:	21-Jul-2016
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Methods Manufacturing

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