3
EN
1. OPERATION
The Impressor is intended for handheld testing of hardness for aluminum and aluminum alloys,
soft metals, plastics, fiberglass, rubber and leather. Harder materials cannot be tested with the
Impressor. For information on the available models, refer to the current revision of our product
guide.
To test a surface, place the indenter point and the leg of the impressor on the same plane of the
surface. To insure reading accuracy, make certain that no indentations from previous use are
within 1/16th of an inch of the present indenter point position. Readings should not be taken
on both sides of the 1/32nd inch-thick test disks. Readings taken on top of old indentations will
adversely affect the accuracy of the reading. An ample supply of appropriate test disks should be
maintained for these reasons.
Press down firmly, but carefully, on the impressor handle. Observe the indicator, noting the peak
reading. For softer materials there will be some falling-off of the reading from the peak value. This
is normal and is due to the nature of the materials being tested.
As a general rule, you should increase the number of readings taken as the softness of the
materials being tested increases. Refer to the table below for recommended minimal numbers of
readings for various materials using the Model GYZJ 934-1. Though specific numbers for Models
GYZJ 935 and GYZJ 936 are not included due to correlation difficulties with softer materials, the
numbers suggested for reinforced plastics serve as a starting point for softer materials.
Recommended Numbers of Reading for Model 934-1
GYZJ-934-1
For an Average
Recommended
Reading Range
Variance of
Number of Readings
Homogeneous
80
0.28
3
Material:
70
0.28
4
60
0.28
5
50
0.28
6
40
0.28
7
30
0.28
8
20
0.28
9
Reinforced Plastics:
70
0.72
5
60
0.78
10
50
0.75
16
40
0.78
22
30
0.77
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