- 产品介绍
Meets ASTM D 3363
The Model 3363 Pencil Scratch Hardness Tester is an addition to the Gardco range of surface coating test instruments. It determines the resistance of coating materials to surface scratching and is of particular use for furniture or vehicle lacquers. It is also useful in the testing of synthetic resins and other film forming materials.
The HA-3363 pictured is shown with a 200g auxiliary weight. Made in the U.S.A.
Nominal load to the substrate for the HA-3363 is 300g +/- 5%. Auxiliary weight HA-3363/W1 will add an additional 100 g +/-5% .
The Model 3363 is capable of making scratch hardness measurements in accordance with ASTM D 3363. It uses constant pressure and pencil leads having various forms of hardness. These leads, having various degrees of hardness, are moved over the surface being tested under a fixed pressure and at a fixed angle to the surface. The degree of hardness of the pencil lead, which damages the surface, is taken as a measurement of scratch hardness.
The instrument consists of a pencil lead holder carried on two rollers, the weight of which is so arranged that the pressure exerted by the flat pencil lead is approximately 300 grams. A hａnd grip is provided for pushing the instrument over the specimen. Fourteen pencil leads, in the range of grades from 6B to 6H are used. The pencil leads can be exchanged easily.
To properly position the mechanical lead holder (See Fig. 2) first extend the lead about 1/4" out of the lead holder. Then insert holder through the barrel and pass it through the accessory tube. Push holder until lead is about even with end of tube.
Tighten the set screw knob on top of the barrel. Lead holder is then permanently positioned so that pressure exerted by the flat end of the lead is approximately 300 grams.
The metal accessory tube is also used to dress the lead to a 90° angle with a fine emery board. When point of lead needs to be dressed to a smooth cylindrical shape, loosen lead holder clutch and extend lead so it slightly extends from the metal tube.
Then dress it by rotating a disc of 400 grit carborundum paper or a very fine emery board across the end surface of the lead until lead is smooth on edges (See Fig. 3).
Reference
Smith, W. T., “Standardization of the Pencil Hardness Test”, Official Digest, 28, p. 232 ff(1956).
ASTM D 3363, Method of Test for Film Hardness by Pencil Test.
Pencil Hardness Tests. Sherwin Williams Industrial Test.
NACE, TPC Publication No. 2 “Coatings and Linings for Immersion Service”, p. 22(1982).
