Adhesion and Scratch Resistance Tester, Model 435 S
Purpose and Application
At first developed from the Mar Tester 435, Model
435 S has been adjusted, in cooperation with a well-
known manufacturer of – among others - scaled
indication fittings for vehicle cockpits, especially to
tests of this product group.
When used as an adhesion tester e.g. the coloured
coating applied to the dial of a speedometer in the
shape of raised numbers, points or scale lines, is
tested concerning its adhesion to the substrate, by
lateral slipping with a defined “blunt” test body
geometry, with a preselected test force.
In principle the Model 435 S is feasible for testing the
adhesion of almost all printed scales, numbers,
letters and marks “lying“ on the scale plates’ surface!
When used as a scratch resistance tester for
testing surfaces against “blunt” effects, it is
recommended for testing surfaces on which the
Hardness Test Rod 318 is still too “aggressive” –
even using the largest tip diameter of 1 mm available
for this purpose.
1. Rotating guide rolls
2. Test disc made of steel
3. Test force scale
4. Force springs
5. Allen key
6. Locking screw slider
7. Help aid for fixing the locking srew
slider
Design and Function
The main difference between the Mar Tester 435 and
the new Model 435 S is the direction in which the
test body is moved. While the test body of Model 435
(a disc with locking facility) is moved relatively fast in
longitudinal direction in order to produce a “scar”, the
test direction in which the test body of Model 435 S
is guided, is rotated by 90°.
The part of the test body relevant for the test,
corresponds in its shape exactly to that of Model 435
and is basically, for the time being, only available in
the version made of steel which is most useful within
the scope of products tested up to now.
As the diameter of the test head of Model 435 S is
considerably smaller compared with the steel disc of
Model 435, a central sector of the disc of Model 435
has been chosen as test body for reasons of space
saving. The test body is mounted on a bolt and is
preloaded by an internal helical spring to a force
adjustable from 0 to 20 N. When placing Model 435 S
with the two guide wheel perpendicularly onto the
surface, the rigidly arrested test body acts (with the
preset force) upon the surface. The test force can be
varied – as for Model 435 – by means of 3
exchangeable springs covering three different test
ranges.
Method of Operation
After checking the tight fixing of the test body at the
end of the load transmission bolt, the required force
is adjusted on the scale using the locking screw
slider. Then the Model 435 S is placed
perpendicularly onto the surface to be tested resp.
beside the applied raised coating to be tested, and is
pressed down so that the guide wheels touch the
surface. In this way the preset force acting upon the
test disc is fully effective on the test surface. The
instrument is now moved into the rolling direction the
wheels over the specimen to be tested e.g. against,
for example, scale lines.
The user selects the speed that is adequate for the
product to be tested. When testing e.g. raised
inscriptions, the test result is expressed by the test
force in Newton (N) at which the adhesion of the
coating failed.
For scratch resistance tests of surfaces against
“blunt” effects the test result is the maximum force in
Newton (N) at which the test body does not leave any
trace on the test surface.