Chapter 15 - Lean operations and JIT

‘The key principle of lean operations is relatively straightforward to understand: it means moving towards the elimination of all waste in order to develop an operation that is faster and more dependable, produces higher quality products and services and, above all, operates at low cost.’

Synonyms

continuous flow manufacture high value-added manufacture stockless production low-inventory production fast-throughput manufacturing lean manufacturing Toyota production system short cycle time manufacturing

JIT Material Flow

JIT and capacity utilization

JIT definitionsJIT aims to meet demand instantly, with perfect quality and no waste

More fully:

Improved overall productivity and elimination of waste Cost-effective production and delivery of only the necessary quantity of parts at the right

quality, at the right time and place, while using a minimum amount of facilities, equipment, materials and human resources

JIT is dependent on the balance between the supplier’s flexibility and the user’s flexibility JIT is accomplished through the application of elements that require total employee

involvement and teamwork A key philosophy of JIT is simplification

The lean philosophy of operations is the basis for JIT techniques that include JIT methods of planning and control

The 5 S’sSort (Seiri): Eliminate what is not needed and keep what is needed.

Straighten (Seiton): Position things in such a way that they can be easily reached whenever they are needed.

Shine (Seiso): Keep things clean and tidy; no refuse or dirt in the work area.

Standardize (Seiketsu): Maintain cleanliness and order – perpetual neatness.

Sustain (Shitsuke): Develop a commitment and pride in keeping to standards.

Delivering smaller quantities more often can reduce inventory levels

Waste (muda)Which of these symbols signify non-value- adding activities?

The problem with inventory

Types of waste:

over-production waiting time transport process inventory motion defective goods

influencing the throughput efficiency

Small machinesThe conventional Western approach is to purchase large machines to get ‘economies of scale’.

These often have long, complex set-ups, and make big batches, quickly creating ‘waste’.

Using several small machines rather than one large one allows simultaneous processing, is more robustand is more flexible

JIT small machines approach:

Visible, enforced improvement‘Traditional’ production systems often accept waste and use the insurance of all types of inventory

In JIT systems:

gradual reduction of inventory identify exposed problems eliminate these problems repeat the cycle

Emphasis: continuous improvement insmall steps, to expose waste and eliminate it

JIT, MRP, or both?

easy to move layout quick set up flexible scheduling cheaper tooling planned maintenance fewer set-ups needed

Emphasis: Flexibility Economies of Scope

Key Terms Test

Just-in-time (JIT)

A method of planning and control and an operations philosophy that aims to meet demand instantaneously with perfect quality and no waste.

Kaizen

Japanese term for continuous improvement.

Set-up reduction

The process of reducing the time taken to change over a process from one activity to the next; also called single minute exchange of dies (SMED) after its origins in the metal pressing industry.

Single minute exchange of dies (SMED)

Alternative term for set-up reduction.

Andon

A light above a workstation that indicates its state: whether working, waiting for work, broken down, etc. Andon lights may be used to stop the whole line when one station stops.

Kanban

Japanese term for card or signal; it is a simple controlling device that is used to authorize the release of materials in pull control systems such as those used in JIT.

Levelled scheduling (Heijunka)

The idea that the mix and volume of activity should even out over time so as to make output routine and regular, sometimes known by the Japanese term ‘heijunka’.