How to use a pencil hardness tester
The pencil hardness tester (small model) is designed and manufactured according to the national GB/T6739-1996 standard and with reference to foreign similar products. It uses the hardness of the pencil to determine the hardness of the film. It has the advantages of small size and light weight, which is convenient for the hardness measurement in the laboratory and construction site. Here's how to use the pencil hardness tester:
1. Scope of application
The method stipulates that the relative hardness of the coating surface can be determined by using a pencil of known hardness, and can be operated by manual operation and instrument, and the arbitration test is operated by an instrument.
2, the sample
The sample should be flat, free from oil and damage.
3. Sample disposal and test environment
Before the test, the sample to be tested should be placed in the environment of 23 ± 2 ° C for at least 24 h, and the test should also be carried out in the same environment. The arbitration test shall be placed and tested in an environment with a temperature of 23 ± 2 ° C and a relative humidity of 50% ± 5%.
4, instruments and materials
a set of advanced drawing pencils in accordance with GB 149, pencil labels are 6H, 5H, 4H, 3H, 2H, H, F, HB, B, 2B, 3B, 4B, 5B, 6B, of which 6H is the hardest and softest , the hardness decreases from 6H to 6B. It is recommended to use Zhonghua Advanced Drawing Pencil, or you can agree to use other grades of pencils by both the supplier and the buyer;
b. Pencil sharpener;
c. coated film pencil scratch hardness tester;
d. 400# sandpaper.
5, the test steps
5.1 Use a pencil sharpener to cut the pencil to expose the 4-6mm cylindrical refill (do not loose or scratch the refill), hold the pencil perpendicular to the 400# sandpaper surface, and grind it on the sandpaper until the end surface is flat. The edge of the sharp edge of the pen (the edge must not be broken or notched), the pencil should be rotated 180° after use, and then used or regrind.
5.2 Manual operation procedures
Fix the specimen on the surface of the water platform, hold the sharpened pencil at an angle of 45° to the coating, and push forward at a speed of about 1 mm/s to force the edge of the pencil to break or plow the coating. It is appropriate. Starting with the hardest pencil, use each pencil to draw 5 times. If you can plow the coating twice in 5 times, use a softer pencil until you find at least 4 of 5 times. Until the coated pencil, the hardness of the pencil is the pencil hardness of the coating being tested.
5.3 Instrument operating procedures
The sharpened pencil is placed in the instrument fixture, and the test surface to be tested is fixed upward on the sample stage of the instrument. Adjust the horizontal weight so that the pencil has zero surface load on the sample and then add a weight of 1 ± 0.05 kg. The specimen was moved 3 mm in reverse with the pencil and the moving speed was about 0.5 mm/s. Turn the pencil to make the edge of the lead-free lead contact the coating, and change the test position, plow 5 times in turn, start the test from the hardest pencil, if it can plow the coating twice in 5 times, change it to softer. One pencil, until the pencil that can not plow the coating is found at least 4 times out of 5 times, the hardness of the pencil is the pencil hardness of the tested coating. Use a softer pencil until you find a pencil that cannot plow the coating at least 4 times out of 5 times. The hardness of the pencil is the pencil hardness of the coating being tested.
The above is an introduction to how to use the pencil hardness tester, I hope to help everyone!
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