To be lean, work cells must be designed and built for:

• Continuous or Single Piece Flow;
• Rapid Deployment;
• Parts Presentation & Workplace Organization;
• Reconfigurability;
• Maintainability & Ease of Access.

In addition, lean work cells need to support a key principle of lean production - adjustable output.

Continuous or Single-Piece Flow

In a continuous flow or single-piece flow line, all processes are connected into one coherent whole, and the work is moved between processes as single pieces or on small kanban trays.  The intent is to eliminate any batch processing or storage of parts or product on the line. Many lean lines are arranged into a U-shaped configuration, so that one person can work the entire process.

To achieve this, a work cell needs to utilize the minimum space required to get the job done. Any unused or wasted space increases the distance that a single operator will have to walk, and impedes ones ability to pass parts between stations manually. The unused space also invites parts to be stored in inappropriate spaces. Lean work cells need to be designed to minimize their lineal space on the assembly line.

Rapid Deployment

Many people translate lean into a call for simplicity.  Though simplicity is always a good thing, lean is about reducing waste and using the right thing quickly. Sometimes, this means using something simple, but sometimes, we advocate using something that is standard instead.

A standardized cell, even if it is tailored to the process, will always be more easily and rapidly deployed than a custom cell. Standardization makes the most sense in the control system, where a certain capacity of control can be packaged to handle a wide variety of tasks. Using other standard components can also streamline the development and deployment, all of which work to reduce the time to market and make it easier to implement changes.

Parts Presentation & Workplace Organization

In a lean work cell, the focus should be on the work, without having to worry about tools or materials. A properly designed lean work cell puts all of the tools and materials within easy grasp. It also minimizes any chance of clutter, by removing any unused horizontal work surfaces. A lean cell should have what it needs, and nothing else.

As most lean work cells are arranged in U-shaped lines, parts should be replenished from the back of the work cell. This allows the operator to work unimpeded by the resupply task, and keeps clutter and interruptions outside the overall line.

Reconfigurability

Reconfigurability is a major feature of lean work cells. The continuous improvement process cannot be sustained if a process cannot be rearranged.  Rearrangement is also necessary in some cases to adjust the output level of a process. If a process is running too quickly, but requires too many operators, reconfiguration may be needed to reduce both.

To be reconfigurable, a lean work cell needs to be easy to move, either lightweight or on wheels. It must also be easy disconnected and connected to system power. Finally, it must be easy to recalibrate, if recalibration is required.

Maintainability & Ease of Access

Maintainability and ease of access are salient features of any good automation or mechanization program.  With lean work cells, maintainability is achieved by making it easy to replace components on a work cell.  Aside from being accessible, easy replacement requires that the parts are easy to find (standard components or easily remade) and that they are easy to remove and reinstall (simple fasteners and easy realignment).

Easy access is also an important feature of a lean work cell.  To be easily accessed, consideration must be given to who needs access and when. Operator controls should be mounted where the operator can easily view and use them. Components that will need attention from maintenance should be accessed from the rear of the machine, where the maintenance function will not interrupt the rest of the line. Also, splitting access between the two sides makes the most use of the lineal line space required by a machine, which supports continuous flow more easily.