SPC for machining processes

[Peter2906]

Dear Elsmar Forum Users,

In my plant we have 15 CNC machinees and produce 130 types of alu body for hydraulic pumps. Each machine has for 4 to 8 fastenings for alu body to be prepared before machining start. After operations each alu body has several holes in different diameters. Total ca 30-40 special characteristics are monitored per part.
Standard set up procedure is a follow:
1. Operator chose correct NC program No for part number he want to produce.
2. He starts machine and after machining measure first parts.
Problem is that for set up he use all available tolerance according technical specification.
If he use 75% tolerance to achieve min 1,33 Cpk the set up time will go up and deteriorate OEE.
How to correct set up of machining process to achieve required Cpk 1,33 level without OEE deterioration? How to correct set up machine if fastenings are not in line and you can adjust all fastenings at the same time but not individually.

Thanks in advance for you advice and support.

 

[Bev D]

You’re barking up the wrong tree. OEE is a sub metric to on time delivery of quality parts at a profitable cost. Perhaps a better question is why do you have to meet a Cpk of 1.33? (That’s a trick question by the way). Perhaps you should be looking elsewhere for cycle time improvements?