Since the mission of this blog is to offer ideas for how to align the strengths of both Lean Manufacturing and Six Sigma I wanted discuss a topic I firmly believe all continuous improvement practitioners should practice. This topic is standard work.
There are three components of standard work:
- Takt Time
- Work Sequence
- Standard Work in Process (SWIP)
Formally defined, Takt Time is the rate at which your customer buys a product. It is often called the heart beat of production since once Takt Time is calculated all processes should operate at, or preferably a bit below, Takt Time.
A common mistake is when people think they can measure Takt Time with a stop watch. This is incorrect as Takt Time must be calculated as follows: Takt Time = Net Available Time per Day / Customer Demand per Day.
American football helps me remember this formula. By remembering TD for touchdown I get T (time) / D (demand). Typically we note Takt Time in “seconds per piece.”
Takt Time is the law of the land and once it is understood all processes must work to this pace. Toyota, for example, operates at a Takt Time of around 50~60 seconds. How amazing is that?
Next up is Work Sequence which is simply the order in which an operator performs manual operations (including walking and waiting). It is extremely important to determine the best and most efficient way for operators to perform their work. It helps ensure your process maintains consistency and stability. Whenever possible our aim should be to limit wasted motion, reaching, or any other non value added action.
Finally, we must discuss Standard Work in Process (SWIP). SWIP is calculated as follows:Standard WIP = (Manual Time + Auto Time) / Takt TimeWhen a process is operating at, or slightly less than, Takt Time SWIP will usually be 1 piece.
An exception to this rule would be if two sequential processes summed cycle time was less than Takt Time. In this case you may only have one piece of SWIP for these two processes. If a process has a cycle time greater than Takt Time SWIP will be at least 2 pieces, possibly more depending on how the formula works out.
This evening I have introduced the basics of Standard Work. There is much more to Standard Work including things such as the cycle time / Takt Time bar chart and the standard work combination sheet.
But if you understand the basics outlined in this article you will be well on your way to a better and more efficient process no matter if your title is black belt or lean specialist.
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