Surprising how much confusion exists about alignment - what it is, what to do...
We just did a webinar on this subject (as well as strain gages and some software features), and today I visited a customer to discuss it. It surprises me that there are some basic concepts that are not well understood. Let's see if I can summarize:
HOW WELL IS MY SYSTEM ALIGNED?
Simple - put in a sample that matches what you are testing and has 8 or 12 gages on it, and pull on it. ASTM E1012 tells you all about how to do it. BUT: E1012 only tells you HOW to measure, and does not require anything but a single pull. Thoroughness, however, suggests (but does not require, YET) that you reverse the alignment cell and do it AGAIN.
NOW I KNOW MY BENDING % (per E1012) - NOW WHAT?
OK. So now you know that you have X% bending. E1012 does NOT have upper and lower acceptable bounds. That's where NADCAP comes in: AC7101 (metals) and AC7122 (composites) have upper and lower acceptable bending ranges. If you are out of those, you do not meet NADCAP. Furthermore, the AC requirements include procedures that SUPERCEDE E1012 - so single pulls may not be acceptable. AC7122 requires FOUR: straight up, reverse, upside down, reverse. All have to pass, in sequence.
AC7101 requires less that 10% bending for ductile metals, static tests; AC7122 is 8% for all composites...
OK SO I DON'T PASS - NOW WHAT!?
OK. Now you need to be able to ADJUST your alignment. The old way is with shims, moving things, re-preloading the load string, and basic fiddling until your system is aligned. Modern times point to products like AlignPro.
PHEW!
Now you can adjust, re-measure, and pass your alignment requirements...
I missed a hundred details, perhaps more, but these are the basic concepts you need to know/understand: Measuring bending/alignment (ASTM E1012), meeting requirements (NADCAP AC7101, AC7122), and adjusting your test machine to meet these requirements.
Note that you do not need Instron for all of this - of course we are glad to help (for a fee, sorry!), but all this can be done on your own...
Have a great day and may your stars be Aligned.
How about them BRUINS?!
We just did a webinar on this subject (as well as strain gages and some software features), and today I visited a customer to discuss it. It surprises me that there are some basic concepts that are not well understood. Let's see if I can summarize:
HOW WELL IS MY SYSTEM ALIGNED?
Simple - put in a sample that matches what you are testing and has 8 or 12 gages on it, and pull on it. ASTM E1012 tells you all about how to do it. BUT: E1012 only tells you HOW to measure, and does not require anything but a single pull. Thoroughness, however, suggests (but does not require, YET) that you reverse the alignment cell and do it AGAIN.
NOW I KNOW MY BENDING % (per E1012) - NOW WHAT?
OK. So now you know that you have X% bending. E1012 does NOT have upper and lower acceptable bounds. That's where NADCAP comes in: AC7101 (metals) and AC7122 (composites) have upper and lower acceptable bending ranges. If you are out of those, you do not meet NADCAP. Furthermore, the AC requirements include procedures that SUPERCEDE E1012 - so single pulls may not be acceptable. AC7122 requires FOUR: straight up, reverse, upside down, reverse. All have to pass, in sequence.
AC7101 requires less that 10% bending for ductile metals, static tests; AC7122 is 8% for all composites...
OK SO I DON'T PASS - NOW WHAT!?
OK. Now you need to be able to ADJUST your alignment. The old way is with shims, moving things, re-preloading the load string, and basic fiddling until your system is aligned. Modern times point to products like AlignPro.
PHEW!
Now you can adjust, re-measure, and pass your alignment requirements...
I missed a hundred details, perhaps more, but these are the basic concepts you need to know/understand: Measuring bending/alignment (ASTM E1012), meeting requirements (NADCAP AC7101, AC7122), and adjusting your test machine to meet these requirements.
Note that you do not need Instron for all of this - of course we are glad to help (for a fee, sorry!), but all this can be done on your own...
Have a great day and may your stars be Aligned.
How about them BRUINS?!
1 comment:
Excellent summary on the issues! Thanks!
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