Preface: We make electronic hardware that converts 12 volts direct current (car battery) @ 100 amps into 120 volts alternating current (wall socket) @ 10 amps. I am attempting to finalize an APQP and a PPAP package for our customer. The control plan, gage R&R and the MSA for this have me stumped since this is not a caliper checked camshaft or casting, it's electronics! We check 3 areas of this product:
1) During PFMEA we determined that 80% of our reliability issues are related to loose hardware, specifically the nuts and bolts that hold down heavy transformers and large busbar connections that carry high amperage current. We have included torque specifications in our assembly instructions for each critical nut and bolt. These specs are ~25% greater than "tight" and ~25% of the torque required to break the hardware. So, while we want to know we've "tightened" the nut, it is not critical torque as in an engine head application. We use a your basic $40 torque wrench, a small window shows the torque value as you twist the handle to set it.
2) The product has a 4 bolt mounting pattern. We plan to use a go-nogo platform to make sure the mounting holes line up. The holes are much wider than the width of the recommended mounting bolt and are U shaped. Once again, the acceptable variation is huge.
3) Finally, we functionally test all of the operational features of the product on every unit. This is required 100% because the units are "calibrated" at this point. This term is used loosely since we are setting a potentiometer to adjust the output to 120VAC at a specific load. The output of inverters varies in relation to the amount of load (current demand) applied. The output spec is very wide for this reason and the kind of equipment that gets plugged in will operate from 110-130 VAC so the acceptable variation is huge here as well. We measure the inputs, outputs, and loads with HP and Fluke equipment that is +/-0.05% accurate.
Questions:
1) Units are tested 100% to specifications in the test procedure that are based on the customer's requirements and all of the functions are checked/set. Is that the control plan?
2) What exactly do I need to show in gage R&R? A measurement systems analysis seems to be overkill. All of this equipment is overkill for what we are measuring. Unless you are blind, it is impossible to misread the equipment enough to make any significant impact. Is that a MSA?
3) We have three identical HP/Fluke test sets, calibrated annually. The wrenches are off-the-shelf. Unless the whole plant disappears, the line can't shut down for equipment failure. So what do I say about maintenance?
1) During PFMEA we determined that 80% of our reliability issues are related to loose hardware, specifically the nuts and bolts that hold down heavy transformers and large busbar connections that carry high amperage current. We have included torque specifications in our assembly instructions for each critical nut and bolt. These specs are ~25% greater than "tight" and ~25% of the torque required to break the hardware. So, while we want to know we've "tightened" the nut, it is not critical torque as in an engine head application. We use a your basic $40 torque wrench, a small window shows the torque value as you twist the handle to set it.
2) The product has a 4 bolt mounting pattern. We plan to use a go-nogo platform to make sure the mounting holes line up. The holes are much wider than the width of the recommended mounting bolt and are U shaped. Once again, the acceptable variation is huge.
3) Finally, we functionally test all of the operational features of the product on every unit. This is required 100% because the units are "calibrated" at this point. This term is used loosely since we are setting a potentiometer to adjust the output to 120VAC at a specific load. The output of inverters varies in relation to the amount of load (current demand) applied. The output spec is very wide for this reason and the kind of equipment that gets plugged in will operate from 110-130 VAC so the acceptable variation is huge here as well. We measure the inputs, outputs, and loads with HP and Fluke equipment that is +/-0.05% accurate.
Questions:
1) Units are tested 100% to specifications in the test procedure that are based on the customer's requirements and all of the functions are checked/set. Is that the control plan?
2) What exactly do I need to show in gage R&R? A measurement systems analysis seems to be overkill. All of this equipment is overkill for what we are measuring. Unless you are blind, it is impossible to misread the equipment enough to make any significant impact. Is that a MSA?
3) We have three identical HP/Fluke test sets, calibrated annually. The wrenches are off-the-shelf. Unless the whole plant disappears, the line can't shut down for equipment failure. So what do I say about maintenance?