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7. Advanced settings
The most frequently used advanced functionalities of the Equotip 3 indicating device are de-
scribed below. A more comprehensive operating manual for the Equotip 3 indicating device
can be downloaded from the Proceq website www.proceq.com.
7.1. Custom conversion curves
7.1.1. Minimizing conversion errors
Provided the material group is selected correctly, conversion errors will not normally exceed ±2
HR for Rockwell scales and ±10 % for HB and HV. In most cases, the conversion error is sig-
nificantly lower. If higher accuracy is required or if the alloy under test is not covered by one of
the built-in conversions, the Equotip 3 provides a variety of methods to define material-specific
conversions. These custom conversion curves can be set up through "Config" – "Customer
Conversions", and used through the "hardness scales" dialog, see section 6.3. "Hardness
scales".
7.1.2. Methods for setting up custom conversions
The Equotip 3 provides 3 methods to accomplish custom conversions (example HLD →
HRC):
• One-point method: The Leeb hardness HLD and the hardness in the desired scale HRC
are determined for a reference work piece. A standard conversion function HLD-HRC is
then adapted through vertical offset until the measured reference data pair lies on the
shifted curve.
• Two-point method: Two reference samples are tested, one as soft and one as hard as
possible to find two data pairs HLD / HRC. A standard conversion function HLD-HRC is
then adapted through adding a straight line until both of the measured reference data pairs
lie on the tilted curve.
• Conversion polynomial: If a custom conversion needs to be applied throughout a wide
hardness range, several reference samples shall be tested to find a stable basis for inter
polation. Up to 5
th
device by defining the polynomial coefficients A
A
·HLD
+ A
·HLD
3
4
3
4
7.1.3. Example of a custom curve
• The data pairs (640 HLD / 41.5 HRC) and (770 HLD / 54.5 HRC) were measured on two
reference samples made from "special steel".
• To measure "special steel" in future using an adapted HLD-HRC conversion, the original
HLD-HRC conversion curve for "1 Steel and cast steel" is tilted using the two data points.
In this example, the special conversion is defined as valid for the range 41 to 55 HRC.
• Once this curve has been created, it can be selected via material group "Customer
defined" – "Special steel", using the hardness scale "HRC Rockwell C".
© 2012 by Proceq SA
order polynomials can be programmed into the Equotip 3 indicating
+ A
·HLD
.
5
5
in HRC(HLD) = A
+ A
i
0
·HLD + A
·HLD
+
2
1
2
22
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