E-18 Hardness Testing Change – Your Input Needed

The MTI Technical Standards Committee is weighing in on rule changes by the ASTM E28.06 Indention Hardness Testing committee on E-18 specification. MTI would appreciate it if you would read the following description of the rule change and answer a one question survey at the end. This survey will be used as part of determining the argument on whether this revision should be considered.

MTI’s ASTM Task Force liaison, Steven Keckler from Thermtech in Waukesha, WI stated, “The ASTM hardness testing committees are in constant motion in making change to these specifications. Getting feedback from Members is very important so we can deliver recommendations to the ASTM committees so they understand the impact of any specification changes. MTI’s Technical Standards Committee encourages all Members to complete these short surveys.”

Indention Hardness Test Explanation

ASTM committee E28.06 (Indentation Hardness Testing) is considering taking up new business to update ASTM E18 to clearly state that Rockwell values are to be reported to the nearest integer unless required to report with a greater degree of precision. The intent of this revision would be to clarify and clearly state what is already a requirement of E18. As this would be new business to be considered by the committee no exact language has been decided at this time.

Given the limits of accuracy and precision with most Rockwell inspection today, if following ASTM E29 rounding rules, it is already required to report values to the nearest whole number. It has been asserted that this lack of clarity has contributed to a general lack of compliance with the requirement to round results when reporting Rockwell inspection per ASTM E18. ASTM E18 currently infers that Rockwell values should be reported to the nearest integer via the following: 

• Section 9.1.1 in part states “…shall be rounded in accordance with E29 (see 5.2.4 and Note 2).”
• Section 5.2.4 in part states “…rounded in accordance with E29 with a resolution no greater than the resolution of the hardness value display of the testing machine. Typically the resolution of a Rockwell hardness should not be greater than 0.1 Rockwell units.”
• Note 2 (which follows section 5.2.4) in part states “Commonly for acceptance testing, Rockwell hardness values are rounded to whole numbers following E29.”

Although not directly at hand with this revision is the consideration that when converting scales is required the converted value should only be reported as an integer due to the lack of accuracy inherent to hardness conversion.

Question

Would you consider it a positive change if E18 Section 9: Reporting were to be updated with language stating that Rockwell inspection results shall be reported to the nearest whole number unless required to do otherwise?

• I would consider this a positive change.
• I would not consider this a positive change.

CLICK HERE to submit your answer.  Thank you for your feedback.