AMS 2750 - Tell me what troubles, specifically, you have had with AMS 2750

I'm soliciting from everyone to tell me what troubles, specifically, you have had with or heard about this standard and its application?

I'd like to invite audit/auditor/interpretation/ambiguous/not practical...etc type of comments.

thank you,

GD

- if you prefer to PM me that is good too.

ggdjr said:

I'm soliciting from everyone to tell me what troubles, specifically, you have had with or heard about this standard and its application?

I'd like to invite audit/auditor/interpretation/ambiguous/not practical...etc type of comments.

thank you,

GD

- if you prefer to PM me that is good too.

Click to expand...

a common NCR is :

• Customer flowdown – or more accurately, the lack of it. It is important for suppliers to be sure of the requirements of their customer(s) and to continue this flowdown internally.

has anyone experienced this, if so specifically what happened?

thanks,

GD

At an independent metals testing laboratory, when we had our first NADCAP, we were cited for several issues related to AMS 2750 requirements.

For stress-rupture testing we were using analog temperature recorders with digital controllers. We did have proof that the temperatures were within the tolerance range. As a result, we purchased a digital, 32-channel recorder with an interface to computer data output. What we found was that our digital controllers were not holding the tolerance, so we had to make adjustments to the gain and feedback to get the temperature fluctuations within tolerance.

For our heat treating ovens, they required updated oven surveys. Again, we found too great a temperature variation between different positions in some ovens. The biggest change there was to place thermocouples on the parts.

The last issue was that some thermocouples were being used outside of the upper temperature range for the particular bimetallic joint. We had to purchase different thermocouples for particular aircraft work, and then only use them on those orders.

Although there was time and expense to these changes, it resulted in a much better temperature control and monitoring system.

Wes R.

Wesley Richardson said:

. What we found was that our digital controllers were not holding the tolerance, so we had to make adjustments to the gain and feedback to get the temperature fluctuations within tolerance.

Wes R.

Click to expand...

by gain do you mean in a PID control loop ? overshoot?

or they were not holding calibration values and were drifting?

thanks,

GD

Here are some observations from my own experiences, and those coupled with a good friend.

In short, AMS 2750 has proven to be a valid specification. In general, it seems to be fairly well written and concise. The problems encountered are NADCAP audits with AMS 2750.

Much of the problem comes from trying to integrate AMS 2750 with other industry specifications. If you were to just audit against the one specification, it would be all right. But trying to get everyone in the camp to agree on one thing is exceedingly difficult.

There becomes small differences between them; like 6 months vs. 1 year, type of process equipment, uniformity requirement, etc. Most of the auditors seem to be by-the-book, box checking auditors; with little/no process/risk-based auditing approach. Again, they check boxes and write NC's against the boxes. Instead of viewing the process as a whole and the entire myriad of specifications that heat treat facilities must deal with, it becomes a very frustrating ordeal of trying to find the most stringent requirement in print and applying it. Sometimes that is quite expensive/time consuming, and there is no process/quality/ statistical justification except "well it says it right there; you need to do it". That is not the intent of a good quality system.

In the old days, one could meet AMS 2750 and most "customers" (Bell, Boeing, McDonnell Douglas, etc.) would be fine with that, even if there were deviations from the specific company specifications.