With the release of last year's revision of the ASTM E18-05 annual book of Standards, the specification now states that steel balls will be replaced by carbide balls.  This requirement affects all Rockwell Scales utilizing the 1/16", 1/8", 1/4", and 1/2" ball penetraters.  It is strongly recommended for anyone utilizing these Rockwell scales to obtain a copy of the new specification (note 2) from ASTM, for clarification of the change.
As of March 1, 2005, all Rockwell Hardness Standards and Machine Calibrations must be performed according to the new specification.  Hardness Standards and Machine Calibrations performed with steel balls will still be available, however by request only.  

Send any Rockwell Diamond indenter to Gilmore where we will inspect it visually and measure the tip geometry (cone angle and radius) for compliance with ASTM / NIST specifications.  We will use the indenter to do performance tests on NIST traceable test blocks, and then modify or repair the diamond (if necessary and / or possible) based on the results of the inspections and tests.  If no modifications are required a certificate of compliance will be issued accordingly.  After any necessary modifications we will re-inspect, retest, and certify the results to be compliant with ASTM / NIST specifications. 

WHO NEEDS THIS PROGRAM?

Organizations that are unsure of the calibration status of their diamond indenters, or have diamond indentors that read outside the tolerance of NIST traceable test blocks.  There may be some diamond indenters that had been in use for many years that could be afforded new life through this program.

THE COST

The cost of inspection, modification, verification, and certification is a fraction of the cost of a new diamond indenter.

ONE
The diamond indenter you are using to perform HRC testing must accurately reflect the performance values established by NIST SRM hardness test blocks.  If your indenter does not perform in accordance with these established hardness values, you have two choices.  You must either purchase a new, replacement indenter which has been certified to satisfy the geometrical and performance requirements set forth in ASTM E-18, or you must have your current indenter inspected, perhaps modified, and verified as compliant to ASTM E-18 specifications.  When your indenter meets the criteria it will be issued a certificate of compliance.  If you are unsure of its calibration status or your diamond indenter reads outside the tolerance of your NIST traceable test blocks, you can send your diamond to Gilmore for inspection, modification (if necessary), verification, and certification. 

TWO
The hardness test blocks in use for daily verifications on HRC scale must be calibrated and certified as traceable to NIST established values.  At the present time, NIST is proceeding with HRB scale calibrations.  HRB Standardized SRM test blocks will be available in the near future, and will also become a requirement of ASTM. 

THREE
The hardness testing machine must calibrate to within the allowable tolerances as specified in ASTM E-18.  If the machine reads out of specification while using both a certified indenter and certified NIST traceable test blocks, you should contact your calibration agency.  They can calibrate the machine properly and confirm the loading and read out systems are correct. 

FOUR
In the case of ASTM E-10 the answer is obvious.  A change in ball composition from steel to tungsten carbide must be made.  Tungsten carbide 10mm balls are available.  Carbide balls are more expensive to buy but should provide significantly more use. 

In closing, we hope that you have found this informative and helpful.  If you have further questions, concerns, or need for clarification please contact us via e-mail, phone, or fax.  We will assist you in any way possible.

      M.L. Mihalec
         President
Gilmore Diamond Tool, Inc.

This is an important development for the Rockwell hardness testing community.  Gilmore Diamond is now the only Rockwell Diamond Indentor manufacturer in the USA capable of making, testing, and certifying per ASTM E-18 with traceability to NIST.  ASTM E18 is currently in the approval cycle for a new draft revision, which aligns the US specifications with the globally adhered to ISO specification.  The new draft, among other things, creates three grades (two new grades) of Rockwell diamond indenters.  The Reference Grade  is the highest quality (new NIST SRM grade), Grade A (new calibration grade), and finally Grade B (present working grade) indenters.  All three grades share the same geometrical specifications, however the tolerance in deviation from the nominal is much tighter for the Reference Grade.  The requirements are shown in the table below.

Several years ago NIST (National Institute of Standards and Technology) initiated a National Rockwell Hardness Standards Program with the ultimate goal of providing Standard Reference Materials (SRM) to industry with traceability to the National Standard. 

The capability to consistently manufacture Reference grade diamond indenters has long been our goal at Gilmore Diamond Tools.  After several years of intensive R&D we are pleased to announce that Gilmore  is now capable of  providing  NIST, domestic and foreign industry, as well as Standardizing Agencies worldwide with a reliable source for Reference Grade, A Grade, and of course B grade diamond indenters.