The Myths and Truths of Lean Transformations by Raymond Kelly

Author:Raymond Kelly
Language: eng
Format: epub
ISBN: 9781351584975
Publisher: Taylor & Francis (CAM)

  Figure 3.2 Little’s Law.

– the less inventory, the smoother and faster the flow;

■ Motion: Eliminate unnecessary movements and ensure the principles of motion are adhered to.

■ Wait: Eliminate waiting through:

– workload balancing of operators and equipment;

– Standard Work – minimize variations that lead to delays;

– visual controls – proactively highlight delays.

■ Overproduction: Do not overproduce. Refer to Little’s Law: inventory decreases your throughput velocity:

– utilize Standard Work-in-Process (SWIP) to control amount of inventory allowed on the production line/cell and the amount of inventory allowed within the production area/workspace.

■ Over-processing: Simple over-processing steps can disrupt flow; e.g. too many approvals/signatures, too many hand-offs, excessive inspections, any just-in-case activities, etc.:

– if it’s not adding value to the customer, then eliminate it.

■ Defects: As previously discussed, long processing times contribute to the creation of defects and to deferred detection of real-time quality issues;

■ Muri: Don’t overburden your people, equipment, or manufacturing cells:

– overburdening disrupts flow: overburdening of associates may lead or contribute to increased fatigue or absenteeism; overburdening of equipment may lead to increased minor stoppages or increased downtime; overburdening of equipment can lead to a reduction of equipment performance.

■ Mura: Unevenness is the enemy of flow:

– eliminate unevenness by balancing the manufacturing cells;

– remove production unevenness with the aid of SWIP;

– decouple operations with large differences in process lead times and/or cycle times using supermarkets;

■ utilize manufacturing run strategies and load-leveling methodologies (e.g. heijunka boards, kanbans, etc.) to smooth production.

The objective of flow production is to create continuous (non-stop) flow. Continuous flow is producing and moving one item at a time (or a small consistent batch of items) through a series of processing steps as continuously as possible, with each step making only what is requested by the next step.

Continuous flow can be realized in numerous ways:

■ one-piece or single-piece flow (remember a small lot or batch of items can be considered “one-piece”);

■ moving assembly lines (automatically paced lines, motorized conveyors, etc.);

■ push-assembly lines (slide-lines); e.g. make one, move one.

Figure 3.3 shows an example of a continuous-flow assembly line (note: no inventory between units being assembled).

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