Design Lean Cells for Flexibility - How To Guides

Becoming lean means more than putting together a few U-shaped work cells. It's a philosophy that drives you to reduce waste. To implement lean, you need to consider how materials, people and information flow through your manufacturing process.

Optimizing the Flow
The first step is to segment the assembly process into time-balanced increments of work.

To do this, perform time and motion studies with a stopwatch. Then, pare the assembly process down to value-added processes only. Optimize these and eliminate everything else.

Creating time-balanced segments doesn't mean that each operation should take the same amount of time. It means laying out the cell so the work can be divided into time-balanced increments for one, two or three operators-shifting resources into and out of the cell to match demand and remove waste.

One-piece Flow: Optimizing Material and People
The key to optimizing material and people flow is to insist on one-piece flow: Making one complete part at a time or passing completed work to the next operator only when that operator is ready for it.

In a poorly balanced cell, work-in-process (WIP) stacks up between each station. This is waste. And quality re-work means you have to find the error and re-make lots of inventory. With one-piece flow, you find errors immediately and can fix the problem.

Proper Work Cell Design
Cells designed to eliminate waste help optimize material, people and information flow. U, J, or L-shaped cells, with stations interlinked by manual roller conveyors, eliminate wasted space so operators can move swiftly from station to station with no wasted steps or energy.

Ergonomic principles can minimize reach distances and times and help eliminate worker fatigue. Parts should be provided from the rear of the cell via parts "stores" with bins on wheeled racks. This simplifies replenishment and any line changeovers.

A Word on Information Flow
Finally, one glance into a well-designed work cell will tell you everything: which product is being produced, whether line-side parts stores are low, and whether any trouble spots exist. Good visual indicators make for good information flow and continuous process improvement. Even the best cells can be improved.