LEAN PRODUCTION

A presentation by

Marcelo Augusto A. Cosgayon

DEFINITIONLean manufacturing or lean production, often simply "lean", is a systematic method for the elimination of waste ("Muda") within a manufacturing system. Lean also takes into account waste created through overburden ("Muri") and waste created through unevenness in work loads ("Mura").

WASTE (MUDA)Anything other than the minimum amount of equipment, materials, parts, space, and time that are absolutely essential to add value to the product.

KINDS OF WASTE (TIMWOOD)1.Transporting2.Inventory3.Movement4.Waiting5.Overproduction6.Over Processing7.Defects

TRANSPORTING

Moving products that are not actually required to perform the processing

INVENTORY

all components, work in process, and finished products not being processed

MOVEMENT

people or equipment moving or walking more than is required to perform the processing

WAITING

waiting for the next production step, interruptions of production during shift change

OVERPRODUCTION

production ahead of demand

OVER PROCESSING

resulting from poor tool or product design creating activity

DEFECT

the effort involved in inspecting for and fixing defects

ELEMENTS 1. Flexible resources2. Cellular layouts 3. Pull system4. Kanbans5. Small lots 6. Quick setups7. Uniform production levels8. Quality at the source

9. Total productive maintenance

10.Supplier networks

FLEXIBLE RESOURCES

•Multifunctional Workers – instead of specialized workers performing a single task, workers are trained to be able to perform multiple tasks•General Purpose Machines – machines capable of performing several basic functions•Takt Time – from the German word for “baton”, this refers to the pace at which production should take place to match the rate of customer demand

ELEM

ENTS

CELLULAR LAYOUTS

Manufacturing Cells – dissimilar machines grouped together to manufacture a family of parts with similar shapes or processing requirements, resembling a small assembly line.These use smaller multipurpose machines operated by a single worker to produce several parts before passing them on to another cell.Because cells produce similar items, setup time requirements are low and lot sizes can be reduced.Movement of output from the cells to subassembly or assembly lines occurs in small lots and is controlled by kanbans

ELEM

ENTS

PULL SYSTEM

Pull System – relies on demand instead of supply to provide a continuous flow of materials and parts in the production process.This eliminates the need for high inventory of materials and parts to avoid stockouts and a stoppage of work. It also prevents overproduction and underproduction because workers only produce what is needed and no more and no less.

ELEM

ENTS

ELEMENTS

Kanban - a card that corresponds to a standard quantity of production. These cards contain basic information such as part number, brief description, type of container, unit load (i.e., quantity per container), preceding station (where it came from), and subsequent station (where it goes to).Kanbans are essential for the push system to work by determining when work should be done

KANB

ANS

SMALL LOTS

Products are manufactured in small lots at a time. This improves quality and reduces lead time because processes can be physically moved closer together and transportation between stations can be simplified. Quality problems can also be easily detected.These allow for remedial measures to be undertaken more quickly

ELEM

ENTS

QUICK SETUPS

Setup times can be reduced by:1. Separate internal setup from external setup2. Convert internal setup to external setup3. Streamline all aspects of setup4. Perform setup activities in parallel or

eliminate them entirelyELEM

ENTS

UNIFORM PRODUCTION LEVELS

Lean production systems require a uniform production level in order to maintain the flow of production created by the pull system, kanbans, small lots, and quick setups.This is done by smoothing the production requirements on the final assembly line by making accurate forecasts of demand.EL

EMEN

TS

QUALITY AT THE SOURCE

Extremely high quality parts are essential for lean systems to work. There is no extra inventory to act as a buffer against defective units and producing poor quality items that need to be reworked or rejected later on is a waste that must be eliminatedEL

EMEN

TS

TOTAL PRODUCTIVE MAINTENANCE

Periodic preventive maintenance is required to prevent breakdown of machines that will cause work stoppages and an interruption in the production process.Total Productive Maintenance combines the practice of preventive maintenance with the concepts of total quality: employee involvement, decisions based on data, zero defects, and a strategic focus

ELEM

ENTS

SUPPLIER NETWORKS

Reliability of suppliers and the synchronization of their production to the needs of the customer are essential to the success of lean production.This can be done by

ELEM

ENTS

1. Long-term supplier contracts 2. Synchronized production3. Supplier certification4. Mixed loads and frequent

deliveries

5. Precise delivery schedules6. Standardized, sequenced

delivery7. Locating in close proximity to

the customer

BENEFITS1. Reduced inventory2. Improved quality3. Lower costs4. Reduced space

requirements5. Shorter lead time6. Increased productivity7. Greater flexibility

8. Better relations with suppliers

9. Simplified scheduling and control activities

10.Increased capacity11.Better use of human

resources12.More product variety

DRAWBACKS1. Requires steady demand to maintain production

flow2. Requires discipline3. Not applicable to production of high volume

repetitive items4. Vulnerable to unexpected changes in demand or

supply