In the real world of offset printing, ink density variation is inevitable. effectively applying TPM and process control techniques can tighten the variation.
VSM
The press process data box includes quality rate (total production minus spoilage). Improved ink density control and roller maintenance could increase the quality rate.
In the real world of offset printing, ink density variation is inevitable. effectively applying TPM and process control techniques can tighten the variation.
VSM
The press process data box includes quality rate (total production minus spoilage). Improved ink density control and roller maintenance could increase the quality rate.
Ink density variation is not inevitable and is caused by a specific problem in the process. If it was inevitable or inherent, it would be the same for all press designs and that is not the case.
The tightness of variation can be designed into the process. How much variation would one want?
Predictability is obtainable when the variation is designed out. Of course there is variation in everything but for practical purposes, SID variation can be designed out of the offset process.
Since there is so much doubt that the process can become very consistent and predictable, let us just consider the hypothetical question.
"If one would have a press that could be preset to the density targets and run consistently at those targets for the whole run with tight control, without the need of the operator or a closed loop system making any adjustments, would that not be a benefit to the Lean effort?"
Last edited by Erik Nikkanen; 03-16-2009 at 11:06 AM.
Ink densities will vary. As important as it is to know how much they vary is to know that they do. Having a grasp on the variation on press will help the opreator to refrain from tampering and chasing the density: adjusting a stable press makes things worse. Control charts will provide a guide.
It's interesting that Lean does not get into much statistical process control. There is a way of thinking, a notion, that variation is waste and sloppiness, which needs to be cleaned up and eliminated. That works for me. Ink density variation, then, is waste, it's messy, and it ought to be eliminated to keep the process tidy. Total Production Maintenance is aimed at the causes of that variation; prevention is the wise way of keeping the process clean and tidy.
I read a wise article that said the choice of method ought to depend on the culture of the organization. Most printing companies - and all that I've worked in - are command and control structured. The open sort of culture that Lean requires would be a stretch in printing. Management would have to learn about systems and systems thinking for Lean to take hold. Management would have to change, and the command and control structures be eliminated. For this reason, a structured approach like Six Sigma is a good cultural fit. Six Sigma is, like printing, rigidly hierarchical.
The wise Quality Manager will work with the system he/she has, and choose one program and stick with it. It matters not which one, in the end, for they all take an organization to the same place. It matters that one not waver and that one not quit.
It matters not which one, in the end, for they all take an organization to the same place. It matters that one not waver and that one not quit.
I must, respectfully, disagree. While a student of Deming, practical application has shown that no single process identifies all problems, solves all issues, removes all waste, or increases all profit centers. In short, what works for one, may not work for all.
After nearly 24 years working and managing production environments I have learned to mix and match best practices. Picking what works for a given situation and adapting the processes to create a workable, affordable, timely solution. If my first selection doesn't fit the bill, I modify it (just as you will modify the process being observed) in order to create the desired outcome.
This, of course, means that I have to be knowledgeable and fluent in more than one process improvement methodology in order to apply their theories and processes effectively and also flexible enough to know when the road I've chosen isn't working and be able to shift accordingly.
Linear Mode
