Kaizen Workcells and Taki Time

Workcells are the foundation of Kaizen and Lean Manufacturing. A workcell is a small, compact arrangement that includes more than a single machine or workstation. It is a self-contained unit for manufacturing a product, or highly similar products or components. The small physical size of a workcell—typically fewer than 15 machines-- facilitates product movement and communication. Workers within a workcell are usually cross-trained so they can work in several areas within the cell.

Typically the machines in a workcell are arranged in a U-shape. It is typically self-contained, having available all of the resources needed to manufacture a product or component. Machines are arranged in the sequence needed for manufacturing the product or component, so the work-in-progress can flow smoothly from machine to machine. Communication within a workcell is simple since every worker has a common mission and is physically close to others in the workcell.

Balancing Work Flow – Takt Time

“Takt” is the German word for the baton used by an orchestra conductor to set the beat, or the speed of the music. Toyota picked up this word and used it in the Toyota Production System (TPS) as a result of German assistance to the Japanese aircraft industry during World War II. In TPS the term Takt Time is the amount of time it takes to finish one unit of production. He is an example that has been greatly simplified:

If your company makes bicycles, then the amount of time it takes to make one bicycle is the Takt time for bicycles.

Let’s say that your factory makes one bicycle every two minutes. That means the Taki time is two minutes.

Each bicycle has one seat. So the workcell that makes seats must produce one seat every two minutes. That workcell also has a Taki time of two minutes.

Each bicycle has two wheels. That means the Taki time for wheels is one minute. The wheel workcell must produce one wheel every minute.

Each wheel has 24 spokes. To match the wheel production rate the spoke workcell must produce 24 spokes per minute, giving a Taki time for spokes of 2.5 seconds.

How is the Taki Time Determined?

Taki time is set by customer demand. If you receive orders for 240 bicycles per day, that gives a Taki time of two minutes per bicycle (240 divided by 8 hours per day means 30 bicycles per hour are needed).

If demand increases to 480 bicyles per day, the Taki time is reduced to one minute per bicycle. This reduction in Taki time flows throughout the bicycle production process such that the Taki time for wheels is now 30 seconds, and the Taki time for spokes is now 1.25 seconds. Of course, your staffing and resources will need to be adjusted to match the new Taki time. The purpose of Taki time is to keep the workcells in balance, based on the need for bicycles. Thus this is a “pull” system. Each workcell produces the quanity that is required by the next workcell in the production process, based on the demand for the final product.