D
DuaneG
What are the standards as far as where a rockwell hardness tester must be placed, and temp, humidity etc. Is it ok to be on the machining shop floor, does it need to be in the QA Lab. It is an older wilson model.
thanks
thanks
K
Kevin H
Hi Duane, my experience with the older Wilson model Rockwell hardness testers is that they are capable of operating accurately in very wide environmental ranges. We stationed Rockwell testers near productuion units in the steel mill I worked for out in the normal mill environment - temperture range of about 40 to 110 degrees F, humidity range from relatively low to fairly high (western PA, just north of Pittsburgh). Of more concern was isolation from vibration - we need to place them on rubberized mats to minimize vibration affects. An important part of keeping them operational/accurate was regular service by a Wilson technician, plus we (the mechanical testing lab) verified them monthly.
These machines were used for in process checks by production personnel. The mechanical testing lab used newer automated units made by Rockwell that were operated in a more controlled environment - air conditioned in the summer & heated in the winter, plus more vibration free. Temperature was normally between 60 and 80 degrees F, no specific controls on humidity. All test results that were sent to the customer were generated by the lab. We verified the testers at the beginning of each turn and when we changed Rockwell testing scales with Rockwell hardness blocks traceable to NIST.
If you're using your tester to produce test results that go to your customer, I might verify more often, to ensure you'll catch any possible nonconforming/questionable materials.
Per ASTM E18, section 7.2, "The test is normally carried out at ambient temperature within the limits of 50 to 95 degrees F. However, because temperature variation may affect the results, users of the Rockwell test may choose to control the temperature within a tighter range."
Note - Both speed of applying the major load and the dwell time of the major load may affect Rockwell hardness results. With the older manual Wilson machines, these are operator controlled. If you don't have a copy of the most recent revision of ASTM E18, you should get it - it is the mini-bible (22 pages) for the use, calibration and control of Rockwell Hardness.
These machines were used for in process checks by production personnel. The mechanical testing lab used newer automated units made by Rockwell that were operated in a more controlled environment - air conditioned in the summer & heated in the winter, plus more vibration free. Temperature was normally between 60 and 80 degrees F, no specific controls on humidity. All test results that were sent to the customer were generated by the lab. We verified the testers at the beginning of each turn and when we changed Rockwell testing scales with Rockwell hardness blocks traceable to NIST.
If you're using your tester to produce test results that go to your customer, I might verify more often, to ensure you'll catch any possible nonconforming/questionable materials.
Per ASTM E18, section 7.2, "The test is normally carried out at ambient temperature within the limits of 50 to 95 degrees F. However, because temperature variation may affect the results, users of the Rockwell test may choose to control the temperature within a tighter range."
Note - Both speed of applying the major load and the dwell time of the major load may affect Rockwell hardness results. With the older manual Wilson machines, these are operator controlled. If you don't have a copy of the most recent revision of ASTM E18, you should get it - it is the mini-bible (22 pages) for the use, calibration and control of Rockwell Hardness.
Last edited by a moderator:
S
SteelWoman
We went through this fairly recently - we bowed to the manufacturer's standards as stated with the instrument - each instrument (rockwell, tensile, whatever) specifies an "optimum operating temperature range." In looking at all our instruments - the ones used in our lab as well as the ones used on the production floor - we found the operating temp ranges were such that if the environment surrounding the instrument was outside of these ranges we wouldn't be operating the MACHINEs either! The ranges were so wide that temperatures outside those ranges were either so low or so high that they'd be too uncomfortable for people to be working in at all, not to mention performing a rockwell test.
But look at the data that came with your instrument - or if it isn't available contact the manufacturer OR utilize their web site to get the info. Then write your procedures according to what you discover from that search.
But look at the data that came with your instrument - or if it isn't available contact the manufacturer OR utilize their web site to get the info. Then write your procedures according to what you discover from that search.
Similar threads
