Lean Manufacturing and Workcells: What You Need to Know

Lean Manufacturing Workcells - What you need to know
Lean Manufacturing Workcells - What you need to know
Lean Manufacturing Workcells - What you need to know

Lean Manufacturing and Workcells: What You Need to Know

Lean Manufacturing is designed to improve quality and eliminate waste ultimately improving the end-user’s experience. The workcell is one of Lean’s key strategies.

What is a Workcell?

A workcell is the particular, consolidated arrangement of resources and processes, most often a combination of people, equipment, and materials, designed to improve the quality and speed of a particular output. Efficient workcells ensure a continuous process flow while removing various types of waste. Workcells are at the heart of lean manufacturing and must be designed so that all elements of the process function smoothly. Workcells are also designed for minimal wasted motion. This refers to any unnecessary time or effort required to assemble a product.

A simple example would be a desk in an office. When a desk has upper shelves, the worker has to reach above for office supplies instead of walking over to a supply closet to get necessary items. Imagine how much time and effort is spared by doing this? It may only take a minute or two to get necessary supplies but when multiplied by several times a day, a week, or a month, it is easy to see how much motion is wasted. Having all necessary materials within arm’s reach saves both time and effort; one of the main tenets of Lean.

In his book, The Toyota Way, Jeffrey Liker explains that the goal of cellular manufacturing is to move as quickly as possible, make a wide variety of similar products, while making as little waste as possible. He further explains,

“Cellular manufacturing involves the use of multiple "cells" in an assembly line fashion.”

Each of these cells is composed of one or multiple different machines which accomplish a certain task. The product moves from one cell to the next, each station completing part of the manufacturing process. The most frequently used machines in a cell include lathes, milling machines, and drill presses.

Often the cells are arranged in a U-shape design because this allows for the overseer to move less and better watch over the entire process. One of the biggest advantages of cellular manufacturing is the amount of flexibility built into the process. Since most of the machines are automatic, simple changes can be made rapidly.

This allows for a variety of scaling for a product, minor changes to the overall design, and in extreme cases, entirely changing the overall design. These changes, although tedious, can be accomplished extremely quickly and precisely.

Lean consultants from Strategos, Inc describe workcells as a work unit larger than an individual machine or workstation but smaller than the usual department. “Typically, a workcell has 3-12 people and 5-15 workstations in a compact arrangement around a product or a narrow range of similar products. Once processing begins, they move directly from process to process (or sit in mini-queues). The result is very fast throughput. Communication is easy since every operator is close to the others. This improves quality and coordination. Proximity and a common mission enhance teamwork.”

Benefits of a Workcell

As with other Lean tools, workcells offer improvements quickly. Here are some benefits:

  • Reductions in work-in process, finished goods, lead time, late orders, scrap, direct labor and workspace

  • Enhanced production and quality control

  • Quality parameters and control procedures can be dovetailed to the particular requirements of the parts or workpieces specific to a certain cell. By focusing quality control activity on a particular production unit or part type, the cell can quickly master the necessary quality requirements. Control is always enhanced when productive units are kept at a minimum operating scale, which is what cellular manufacturing provides.

Designing a Workcell

Executives who implement lean manufacturing successfully put time, thought, and planning into designing a particular workcell. The three resources that comprise the flow of any workcell are people, equipment, and materials. Six Sigma Materials clarifies that regardless of the workcell one uses (straight cells, U-shaped cells etc.) the goals are to “reduce floor space, improve throughput of smaller batches, provide more predictable production, and improve cross-training.” Here are questions Six Sigma Materials recommends you ask when designing a workcell:

  • What equipment should go into the workcell?

  • Is cross-training needed?

  • What risks are being added?

  • Can these risks be avoided, prevented, or reduced?

  • What items or processes should be produced in workcells?

  • How should people operate the workcell?

  • Which design is optimal for the workcell?

  • Is there access for maintenance?

  • What type of manning methods should be employed?

  • Do I understand the takt time?

  • What is the capability (loading)?

  • Do I have a suitable product family?

  • How should the product family be determined?

  • Is there space to perform changeovers?

  • Access for direct and indirect materials?

  • What can and cannot be placed at the point-of-use?

  • Can the equipment run independently if needed?

  • Which direction should the workcell be designed?

Understanding the theory and application of Lean, and how to design effective workcells to turn raw materials into finished goods, creates efficiencies and an increase in overall manufacturing performance.

Jeffrey Liker, in The Toyota Way, sums up this idea. “Once implemented, cellular manufacturing has been said to reliably create massive gains in productivity and quality while simultaneously reducing the amount of inventory, space and lead time required to create a product. It is for this reason that the one-piece-flow cell has been called the ultimate in lean production."