Scratch pencil hardness tester, also known as hand cranked pencil hardness tester, is an important physical property of lenses and coatings, such as wear resistance, abrasion resistance, friction resistance, scratch resistance, impact resistance, coating retention effect, and ease of cleaning. Therefore, coating hardness is a necessary indicator for evaluating the performance of lenses and coatings. This instrument can conveniently measure the hardness of lenses and coatings.
Working principle of hand cranked pencil hardness tester
The hand cranked pencil hardness tester is mainly composed of a pencil holder and a test bench. The pencil holder and the column form a four-bar linkage structure, ensuring that the weight of the weight acts vertically on the intersection of the pencil lead and the test bench, and makes the pencil form a 45 ° angle with the test bench while maintaining it unchanged. The test bench can move horizontally and vertically. It is used to fix the paint sample and slide it towards the scratch direction. The pencil then marks the corresponding trajectory on the test piece. Using different pencils to make different marks can determine the hardness value of the coating.
Introduction to Parameters of Hand cranked Pencil Hardness Tester
1: Length X Width X Height 450mm x 150mm x 270mm
2: Attachment:One weight, one instruction manual, and one warranty card

Optional accessories:Chinese hardness testing special pencil, model: 6B-9H, a total of 13 types

Hand cranked pencil hardness testerexperimental procedure
Aprepare
1Prepare a 120X50X (0.2-0.3) smooth tinplate or substrate according to the requirements of GB1727-70, and prepare a coating film.
2Use a pencil sharpener to remove the wooden part from the front end of each pencil, exposing a 5-6mm cylindrical lead (be careful not to loosen or damage the lead). Hold the pencil by hand, making it always form a 90 ° angle with 400 grit sandpaper, and rub the end face of the lead on the sandpaper until a smooth and sharp edge is obtained (the edge should be free of breakage or gaps)
3Insert the sharpened pencil into the pencil holder, as shown in the attached picture. Adjust the pencil so that the working end face of the pencil lead coincides with the center of gravity of the weight (the corresponding working end face of the pencil lead is about 25mm from the pencil holder), and then tighten the screw to fix the position of the pencil.
4Loosen the clamping nut, insert the coating test piece to be measured, and then tighten the nut to secure the test piece.
5Loosen the stop screw, adjust the balance hammer to balance the working rod (even if the pencil just touches the test piece), and then tighten the stop screw to make the working surface of the pencil lead leave the coated test piece.
6Gently place the weight on the pencil holder.
Above, the preparation work is completed.
Btest
1Loosen the stop screw and gently lower the pencil lead onto the tested coating test piece.
2Rotate the handwheel to move the coating board towards the scratch direction by approximately 5mm (turn the handwheel clockwise), and pay attention to whether the surface is scratched.
3Remove the weight, replace the pencil, twist the test bench to move it longitudinally a certain distance to replace the scratch position on the test piece, repeat the preparation operation, and then perform the next test. Use pencils of each hardness type to plow out five marks at once.
4Starting from the hardest pencil, use this method. When identifying five traces, if there are two or more plowing marks on the film, switch to a higher-level pencil until a pencil with only one plowing mark on the film (or no damage) is found among the five traces. The hardness value of this level of pencil represents the hardness of the tested coating.
Hand cranked pencil hardness testersunRegular maintenance
1When using, strive for flexible rotation. After a period of use, oil should be injected into the rotating parts such as the screw and bearings.
2After using for a period of time, tighten the screws and nuts to avoid loosening.