May 19, 2010

Changeovers and art

My friend Mike Thelen fielded a question recently that he agreed to share on Lean Reflections, so here it is...


Q:  I have conducted two changeover events in the last month and in both cases, we were able to pull out the obvious waste but in the internal change, the tasks that the operators went through were highly technical and required lots of adjustments (Art). I know we teach to 'remove as much adjustment as possible' but I am stuck! We are setting a thread rolling machine to make high precision screws for aerospace. Tolerances are very close. One of the operators suggested that the way to improve the set-up was to get a new machine! Thoughts


A.  I, too, have been working with Lean - for about 9 years now. Currently, I'm in a machining setting using similar equipment (thread rollers, thread grinders, lathes, mills, etc). Even with tolerances of +.005/-.000, it is a challenge. Inspection becomes critical and, although a true waste, is very hard to eliminate.

Why? Simply because if operation "A" has that tolerance, and the machine naturally drifts in the tolerance due to variations in material (not just piece to piece, but within the piece being machined itself - thus causing inconsistent tool/insert wear daily), it makes operation "B" (thread rolling or grinding) EXTREMELY difficult to set up without 1st piece and in-process inspection. Since the variation is inherent to the product and the processes, and the whole is run as a jobshop with different specifications and sizes running continuously through a machine, with different operators on each shift, as well as parts from different machines funneling through a single machine, you are left with testing/inspection as a standard part of your process. Would a new machine help? Maybe. Ours tend to be old, bought used, and run into the ground without a good TPM process. But, how would buying a new machine help when those practices aren't corrected?

I suggest - start by simplifying the inspection. Create standard work on the process of setup and inspection. Strive to build inspection processes that ALL operators can do within a timeframe (I guarantee one operator is very good and very quick, while some aren't good or quick!) You can make some reasonable setup reduction gains in the inspection process here.

Then build a strong TPM program. Why buy new machines when the operators and maintenance staff are just going to run them into the ground. This will also require educating the scheduling folks on the importance of routine maintenance.

Have the design folks work on the BEST specification (+anything / -0 is a STUPID design spec).

RETRAIN ALL operators to work toward the exact, not allowing +/- to get out of control - yes a little SPC. Again, I guarantee some work to hold the bottom of the tolerance, some work to the top.

Most importantly - remember this is NOT an overnight fix - no matter what your plant manager or GM thinks. EVEN WITH FULL SUPPORT - financially and culturally this will likely take years to complete. I've never worked in a facility that had full support both financially and culturally. When machines and processes are beaten down, $200.00 can't fix them...

2 comments:

Joe said...

Excellent post, Karen, it speaks directly to an issue I'm dealing with even this afternoon!!

Karen Wilhelm said...

Glad it hit at the right time!

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