Rockwell Testing rounding criteria
Rockwell Testing rounding criteria
(OP)
Rockwell Hardness Testing to ASTM E18 :2014
Clause 5.2.4 states:
Rockwell hardness measurements shall be rounded in accordance with Practice E29 with a resolution no greater than the hardness values display of the testing machine.
we have recently upgraded our machine and the display resolution is to 1 decimal place. Technically we report to this level and have now been questioned from one customer who is requesting this rounded to the nearest whole integer. he is citing Note 2 of the standard which states that common practice for acceptance testing is to round to the nearest whole number, as we are a commercial testing facility we are not performing acceptance testing ( which I believe is related to production facilities )
my question is - if our Rockwell testing machine displays to 1 decimal place can we round to the nearest whole number and still be compliant with ASTM E18:14
thanks
Clause 5.2.4 states:
Rockwell hardness measurements shall be rounded in accordance with Practice E29 with a resolution no greater than the hardness values display of the testing machine.
we have recently upgraded our machine and the display resolution is to 1 decimal place. Technically we report to this level and have now been questioned from one customer who is requesting this rounded to the nearest whole integer. he is citing Note 2 of the standard which states that common practice for acceptance testing is to round to the nearest whole number, as we are a commercial testing facility we are not performing acceptance testing ( which I believe is related to production facilities )
my question is - if our Rockwell testing machine displays to 1 decimal place can we round to the nearest whole number and still be compliant with ASTM E18:14
thanks





RE: Rockwell Testing rounding criteria
RE: Rockwell Testing rounding criteria
RE: Rockwell Testing rounding criteria
my only concern is that the clause 5.2.4 clearly states the resolution of the machine is to be used , rounded to E29
the Note related to this clause does reference the rounding to whole number for acceptance testing , we as a commercial test house do not do acceptance testing , I believe this is essentially production testing.
Liam
RE: Rockwell Testing rounding criteria
The wording in 5.2.4 states "with a resolution no greater than the hardness values display", it certainly can be less.
This is becoming more common, as more and more third party inspectors who have little specific knowledge are reviewing the test results. A standard states a hardness range of, say, 24-28 HRC. The hardness test report states 28.1 HRC. Is this acceptable or does it represent an out-of-tolerance condition? How about if the other testing is acceptable (tensile, impact, etc...)? Obviously, if the other tests are not acceptable, the hardness value is irrelevant. The controlling document is the material standard. If it required 24.0-28.0, then the value is not acceptable. However, if it states the requirement as 24-28, then it should be acceptable to round per E29 prior to determining acceptance, which is what it sounds like your client is asking.
rp
RE: Rockwell Testing rounding criteria
I also wanted to use Redpicker's example in another way: Suppose your average hardness measures 23.9 for hardness specified as 24 - 28? That would still be acceptable because the precision of the hardness specification dictates the precision used in E29 rounding. (This is true for other physical properties, like tensile requirements). I usually explain why the test is acceptable even if the number in that situation is less than minimum.