Monday, September 21, 2009

Pattern-Based Process Improvement

blown glass pattern Pattern-based process improvement is a practical method of making improvements where an exhaustive analysis and re-engineering exercise is prohibitive. The process consists of looking for patterns to identify key characteristics of a process that might provide valuable insight about opportunities to improve the process. A prerequisite to finding patterns is having data or information available for review.

Real world example

Objective: Improve how parts are scheduled across manufacturing work centers to reduce late orders and unnecessary expediting.

Background: A supervisor of a manufacturing facility schedules orders on a number of similar manufacturing work cells. He normally uses the following information to create the schedule based on his experience, a few rules of thumb, and some light calculations:

  • order due date
  • current schedule of orders on the work cells (capacity vs. loading)
  • change-over time (the  time it takes to change the machine to accommodate a different component part or assembly)
  • order quantity
  • estimated production time (time it takes to process the parts through the work cell)
  • physical size and shape of the part on order

Method: The supervisor uses intuition based on a large number of observations to make decisions (Bayesian statistics) when creating the schedule. The idea behind pattern-based process improvement is to begin to quantitatively blend the supervisors experiential knowledge and Bayesian intuition with the data to create standard work that improves the predictability of the scheduling process.

Start by looking at the historical data about how the work cells were scheduled in the past. This method works best when the data is in a spreadsheet or database so the data can be looked at from several angles. Sort and group the data multiple ways looking for patterns or trends – good and bad. How much you can learn from the exercise depends on how much information is available and how valuable that information is. For example:

  • Are there part sizes or size ranges that are commonly scheduled on certain work cells more than others?
  • Are there work cells that have more downtime, more change-over time, more schedule changes, or expedites?
  • Is there a pattern to size vs. quantity or quantity vs. work cell?

If you can find a desirable pattern or a trend, determine if it is possible to create a rule that would make the pattern a more consistent part of the standard scheduling process. If the pattern is associated with a negative result, determine if there is a way to detect the pattern early, or eliminate its presence completely. It is important when using pattern-based process improvement, the output of the process is monitored carefully to fully understand the effects of the change. Sometimes changes introduce new issues. This should be looked at as an iterative improvement process, not a “set it and forget it” tactic.