Six Sigma – Importance of “Head Room”

When in the quest for six sigma performance it never hurts to have a little “head room” in the process. In simple terms, this means that the equipment used should not be “maxed out” to achieve the desired result. I’m sure that none of us would be comfortable if we had to keep the accelerator pedal on our car “floored” to keep up with traffic flow or had to turn our radio to full volume to be able to hear the music at all. Similarly, in a cleaning system, operating in a “maxed out” condition is seldom a sustainable operating mode and opens the door for failure. The occasional need for getting a little “extra” from the system should be anticipated and accommodated.

An example – – I have always been an advocate of the use of laboratory testing to verify process prior to equipment specification. However, laboratory testing is usually conducted under ideal conditions and, in effect, gives results indicating what will happen if everything is exactly right. It seldom anticipates a clogged filter, a missing or mis-directed spray nozzle, a part that is more contaminated than normal, a dirty rinse and a host of other real-life variables. In anticipation of these aberrations, the process engineer should always be confident that the system will perform even under extreme circumstances.

Insurance –

There are many ways to assure that six sigma results will be achieved in a given cleaning system. Some may be as simple as adding slightly more heat or pump capacity. Maybe a spray bar in the rinse of an immersion system or an “extra” spray bar in a spray system. Duplicate sensors where appropriate are another way to increase confidence. Realizing that extra features such as these will increase system cost, the benefits and cost of these added features must be weighed against the cost of producing bad product.

Although I don’t advocate hunting mice with an elephant gun, there are times when the addition of some relatively major system features may make sense. One such example is the addition of a pre-clean or an additional cleaning step. The price of such additions is relatively low in the initial build of a system as compared to that of retrofitting the same feature once the system has been placed in operation. Adding ultrasonics to an immersion cleaning system or as an added step in a spray system, although relatively expensive in some systems can make the difference between a system that has to run “balls out” to achieve six sigma results and one that easily achieves the required goal with a little “extra” in reserve.

Anticipating the requirements for a system capable of six sigma performance is important but the real goal is to monitor and analyze real-time data to determine and maintain the “health” of the process. In the next blog, I’ll explore some of the variables that can be measured which, in conjunction with a thorough Process Failure Mode Effects Analysis can provide six sigma results.

– FJF –

Leave a Reply