Rockwell Hardness Tester

The N3A hardness tester has a load range of 15-187.5 kgf and covers Rockwell, HBD, HVD and Plastic testing. The N3A can easily load applications by means of 180° lever (pre and main load step).

In a Rockwell test, the residual depth of the indent made by the indenter is measured. The deeper a defined indenter penetrates at a defined test force into the surface of a specimen, the softer the tested material. The total test force is applied in two stages, this allows the impact of specimen surface roughness (grooves in the specimen) and measuring errors caused by backlash in indentation depth measurement to be eliminated.

Variable test loads
The N1A test unit with exchangeable spring sleeves is used for different loads. (Spring sleeves with different loads).

Several test loads combined
Four load adjustable test units available. Required test load selected via lever.

Dial gauge
N3A hardness tester measurement readings via analogue dial gauge. Three coloured scales printed on the clock-face. Hardness value read on corresponding scale according to chosen test method and test load.

rockwell hardness tester

Rockwell

According to ISO 6508, ASTM E18

HRA HRL HR 15-T HRB HRM HR 30-T
HRC HRP HR 45-T HRD HRR HR 15-W
HRE HRS HR 30-W HRF HRV HR 45-W
HRG HR 15-N HRH HR 30-N HRK HR 45-N

Plastic testing

According to EN ISO 2039

49.03 N 132.9 N 357.9 N 961 N

HVD, HBD

Depth measurement

HVD 30 HBT 1/30 HBT 2.5/62.5 HBT 5/62.5
HVD 100 HBT 2.5/31.5 HBT 2.5/187.5

Technical Data:

Measurement readings: Analog dial gauge
Height adjustment: Hand wheel 285 mm
Test height (N1A unit and spring sleeves): 230 mm
Test height (with load adjustable test unit):
Throat depth: 170 mm
Max. work piece weight: 20 kg
Dimensions w x h x d: 205 x 830 x 470 mm
Basic machine weight: 35 kg
Room temperature: 5 - 40°

Rockwell Procedure acc. to ISO 6508, ASTM E18

  1. Checking the repeatability of the measured values
    1. Perform five measurements with the calibrated test block.
    2. Calculate the repeatability: H5 –H1
      H1 [Rockwell-units] .. smallest hardness value
      H2 [Rockwell-units] ..... greatest hardness value

      rockwell procedure

      H [Rockwell-units] ............. range of 5 measurements
    3. Check the repeatability with the help of the table below.
    4. If the calculated repeatability is ≤ as the value in the table beside, so calculate the error (point 2). If the calculated repeatability is > than the value in the table beside, inspect the unit for possible sources of error, then repeat steps b)
    5. If value is still above value in the table contact the Kemet Service Division or your local supplier.
  2. Ascertainment of the total error
    1. Calculate the total error: H – H
      H [Rockwell-units] ............. range of 5 measurements
      H [Rockwell-units] ............. Hardness of the used plate
    2. Check the total error with the below table
    3. If the total error is > than the value in the table beside, inspect the unit for possible sources of error, then repeat checking the accuracy of the unit. If value is still above value in the table contact the Kemet Service Division or your local supplier.
Rockwell Scale Hardness range of the hardness comparative table Total Error Limit [Rockwell Units] Permissible accurancy of the hardness tester
A 20 to = 75 HRA ± 2,0 HRA = 0,02 (100 - H) or
0,8 Rockwell-unitsa
> 75 to = 88 HRA ± 1,5 HRA
B 20 to = 45 HRB ± 4,0 HRB = 0,04 (130 - H) or
1,2 Rockwell-unitsa
> 45 to = 80 HRB ± 3,0 HRB
> 80 to = 100 HRB ± 2,0 HRB
C 20 to = 70 HRC ± 1,5 HRC = 0,02 (100 - H) or
0,8 Rockwell-unitsa
D 40 to = 70 HRD ± 2,0 HRD = 0,02 (100 - H) or
0,8 Rockwell-unitsa
> 70 to = 77 HRD ± 1,5 HRD
E 70 to = 90 HRE ± 2,5 HRE = 0,04 (130 - H) or
1,2 Rockwell-unitsa
> 90 to = 100 HRE ± 2,0 HRE
F 60 to = 90 HRF ± 3,0 HRF = 0,04 (130 - H) or
1,2 Rockwell-unitsa
> 90 to = 100 HRF ± 2,0 HRF
G 30 to = 50 HRG ± 6,0 HRG = 0,04 (130 - H) or
1,2 Rockwell-unitsa
> 50 to = 75 HRG ± 4,5 HRG
> 75 to = 94 HRG ± 3,0 HRG
H 80 to = 100 HRH ± 2,0 HRH = 0,04 (130 - H) or
1,2 Rockwell-unitsa
K 40 to = 60 HRK ± 4,0 HRK = 0,04 (130 - H) or
1,2 Rockwell-unitsa
> 60 to = 80 HRK ± 3,0 HRK
> 80 to = 100 HRK ± 2,0 HRK
N ± 2,0 HRN = 0,04 (100 - H) or
1,2 Rockwell-unitsa
T ± 3,0 HRT = 0,06 (100 - H) or
2,4 Rockwell-unitsa