At our facility, we have talked about gauge families with regards to capability studies. This seems to be a method to prove that the measurement system by design is repeatable, and not every single individual gauge. For example, if we use a digital caliper on the production floor to measure something that is on our control plan/inspection plan, then it has to undergo an R&R, however we dont have to do an R&R on every single caliper in the building. I am wondering if this also can go for machines that are identical. We have some plunge force bench gauges with load cells in them that check the plunging force on joints. All 3 of them are the same construction. Do you think it is feasible to combine these into a family and do 1 of them to cover the 3 gauges? Maybe we could choose a different one every cycle so you are eventually checking all of them? We had the same question about doing R&R's on gauges that are just wheels and indicators. Some of them use wheels to roll the shaft and Mitutoyo dial indicators to check the runout, while others use wheels and Solartron LVDT probes to check the runout. Could we just do the wheels/dial indicator method to cover them all, since this would likely be the one with the most influence?
Gauge families for R&R
- Thread starter Jayfaas
- Start date
There is a lot to cover in this post.
- For creating gage families (e.g., calipers) in general, see my blog on this topic. I believe that Ford has a CSR on this topic if they are a customer.
- Regarding machines, I would recommend that you treat them separately. I have many years of experience with a wide variety of processes, and in most cases, I have seen statistically significant differences between machines that are supposedly identical. This includes tooling and cavities within tooling that are supposedly identical.
- Regarding the plunge force gages, if these were made by gage supplier (e.g., Mitutoyo, Starrett, Fowler, etc.), treat them as a gage family. If they were fabricated in-house, I recommend being cautious and experimenting first.
- Can you describe the wheel/runout gage better? I am familiar with checking runout between centers or using vee-blocks but would think wheels would add the runout of the wheels to that of the part.
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The plunge gauges were made by different suppliers, but same construction, and were all 3 eventually retrofitted by the same gauge company to have all the innards upgraded. The plunge force specification for our process is 5-250N, so it's a wide open tolerance. It kind of bugs me because the plunging force is checked 100% at the component level, but when it is assembled onto something else, it is checked again. If it is bad, there are no adjustments to be made, because the plunging force relies solely on the side of the ball bearings inside the joint.\
As far as the wheel/runout gauges, they are just sets of knife roller wheels on which the welded shaft is placed. The wheels roll on the tube and the component is indicated using dial indicators or LVDTs to check the runout. Internally we call this offset, but it essentially checks the friction welding process. Because all of the wheels roll in the same places, I guess you could have runout in the wheels, but I wonder if it would be enough to justify separating them from the family to run each individual R&R. The runout specification at the very least is 0.2mm. Most of the time we fixture on the centers of the ends the best we can, but if it is something that we do not have tooling for, or the main gauge with the tooling is down and we do not have a backup, we use this method to verify that the welding process is still sufficient to run.
As far as the wheel/runout gauges, they are just sets of knife roller wheels on which the welded shaft is placed. The wheels roll on the tube and the component is indicated using dial indicators or LVDTs to check the runout. Internally we call this offset, but it essentially checks the friction welding process. Because all of the wheels roll in the same places, I guess you could have runout in the wheels, but I wonder if it would be enough to justify separating them from the family to run each individual R&R. The runout specification at the very least is 0.2mm. Most of the time we fixture on the centers of the ends the best we can, but if it is something that we do not have tooling for, or the main gauge with the tooling is down and we do not have a backup, we use this method to verify that the welding process is still sufficient to run.
This is not surprising. When you assemble components, the slightest misalignment can cause binding.
When they are checked the second time, they are assembled with grease and a cap. Its basically a check to make sure that the initial one was performed, which it is as it is automated. During the assembly process, the joint is pressed onto a shaft, which could only expand the inside if that even happens. If it expanded too much, the machine would throw an error for having too high of press force.
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