HT-7
Hardness Tester

 

  • Six hardness scales plus strength of material
  • Conversion from one scale to another
  • Compensated for direction of measurement
  • Automatic error detection
  • Prints results on mPRINT
  • Measures on many materials

APPLICATION AREA:

  1. In situ Hardness measurement on dies and moulds, large and heavy work pieces, shafts, bearings, etc.
  2. Laboratory measurement on special forms.
  3. Identification of materials by measuring strength of material.

TECHNICAL DATA:

Range/ Materials - Table1
Strength of material - Table2
Accuracy - + 1HRC
Impact Device - Tungsten Carbide ball (3 dia)
Battery - 4 penlite cells (50/60 hours)
Size (mm) - 150L x 80B x 45H
Weight - 350 gms
Printer output - to mPRINT (optional)

PRINCIPLE OF OPERATION:
Energy Quotient-(LEEB's Method) An Impact body with a tungsten carbide tip is impelled by a spring onto the metal surface. The ratio of rebound velocity to the impact velocity is proportional to the hardness of the sample. The microprocessor converts this into a hardness value in various scales.

OPERATION:
The impact body is loaded into a probe. The direction of impact is selected. The probe is positioned over the sample and the impact body is released. The OPTEL HT-7 displays the hardness value giving a beep. Attachments for positioning the probe in recessed areas and on cylindrical jobs are provided.
As in the conventional hardness tester measurement, the sample surface should be bright and smoothly ground (RT< 8-10 microns). Minimum 3-5 readings should be taken and the average reading recorded. The Optel HT-7 is factory calibrated. A surface area of 10 mm sq. is sufficient for measurement. (Radius of curvature more than 30 mm).
Work pieces weighing more than 5 kgs (thickness more than 8mm) can be directly measured. Lighter work pieces can be supported firmly to a heavy back mass (or front mass) using couplant like oil, glycerin, etc. The back mass/ front mass should have matching geometry. Improperly coupled jobs will tend to vibrate resulting in inconsistent results.

DISPLAY AREA:
The special Liquid Crystal Display and the Keyboard of the HT-7 organized in various zones makes the operation simple and fast. The keyboard and other operations are confirmed by sound beeps. An elaborated Operation Manual gives further details and instructions.

RANGE & MATERIALS:
Impact device - Measuring range LD: 200-900

Table I

 
HRC
HRB
HB
HV
HSD
STEEL
18-68.5
60-99.5
93-651
83-976
32-99.5
C.W. Tool Steel
20-67
 
 
80-898
 
Cast Aluminum
 
 
30-159
 
 
Grey Cast Iron
 
 
93-334
 
 
Nodular Cast Iron
 
 
131-387
 
 
W.P. Iron
HL ONLY
BRASS
 
14-95
40-173
 
 
BRONZE
 
 
60-290
 
 
COPPER
 
 
45-315
 
 

STRENGTH OF MATERIAL:

Table 2

Code No.
Sample Material
LD
Ob (Mpa)
1
Carbon Steel
350-710
374-1670
2
Cr - steel
500-730
707-1829
3
CrV - steel
500-750
704-1980
4
CrNi - steel
500-749
763-1999
5
CrMo - steel
500-730
721-1813
6
CrNiMo - steel
540-730
844-1869
7
CrMnSi - steel
500-750
755-1993
8
Super strength steel
630-740
1180-1936
9
Stainless Steel
500-710
730-1676