Everything varies! But how does knowing this help us to develop changes that will lead to improvement? Many quality and cost problems in a process or product are due to variation. The same process that produces 95 percent on-time delivery or good product is the same process that produces the other 5 percent of late deliveries or bad product. Reduction of variation in such cases will improve the predictability of outcomes (may actually exceed customer expectations) and help to reduce the frequency of poor results.
There are three basic approaches to dealing with variation:
- Reduce the variation
- Compensate (deal with the variation)
- Exploit the variation
The benefits of reducing variation have been well documented during the last ten years:
A manufacturer of heat exchangers was having problems sealing tubes in their exchanger. Variation in the air pressure system contributed to most leaking tubes. The air pressure system was updated and the stability of 80 psi maintained. This resulted in a dramatic decrease of leaking tubes. This problem had previously been viewed as the fault of workers assembling the heat exchangers.
An automotive company has learned to manufacture engine and transmission parts with minimum variation. The superb fit of the parts has allowed them to reduce the normal lubrication and servicing required of most cars. The also expect to have better engine reliability and less repair and replacement warranty costs.
