How would the Taguchi Loss Function (TLF) help an SPC deployment in a real situation?
Steven Ouellette
August, 2007
The ROI Alliance
http://www.roi-ally.com/
Trane is a global market leading manufacturer of heaters, air conditioners, and ventilation systems.. In 2006, Trane implemented an integrated SPC system using WinSPC software in 26 plants across the globe.
Randy DeGier, Trane's Global Operations Quality Element Leader, says of the implementation, "Leadership doesn't spend that amount of money unless you provide them with a payback, so we naturally had to provide that to them to get the purchase justified. We conservatively estimated the cost savings at $400,000 over five years."
DeGier continues, "Now we are getting into it and getting questions about how we are measuring the benefits of SPC." DeGier's first attempt at quantifying savings was a Costs of Poor Quality (COPQ) model that "rolled up direct and indirect costs out of operations." He planned on using this to determine the cost benefit of SPC.
"The problem is that while measuring direct costs are easy, you get into arguments about what project or process generated the savings. We tried to get WinSPC administrators at each plant to measure COPQ, but we still had the same issues."
DeGier identified a different way to quantify the cost benefit of SPC implementation using the Taguchi Loss Function equation to estimate the costs saved due to reducing and controlling the variability.
"We are going to take an example process in the plant where we are going to do improvements anyway and use the TLF to establish the (loss) curve. On the longer term, it would be useful to the owner of the process for justifying process improvements."
"We are devoting more effort to design for reliability. We have always tried to do this, but never had a way to measure it." Using the TLF, Trane will be able to quantify the loss due to variation from the target. "The closer you are to target, the longer the life of the product."
Using SPC to track their process will allow Trane to detect when a process is subject to unusual sources of variability, so that they can correct it before it becomes a larger problem. As they improve their processes, Trane can use the TLF to measure the improvements in terms of dollars, and their customers will in turn see an improvement in quality and reliability.
<< Back to article
|
