Overview
RONGJIDA QHY Buchholz Crowd tester is a testing instrument for measuring the coating Hardness performance of paint films. It measures the film Hardness by applying pressure to the film surface to form a Crowd, and expressing the anti-indentation test result with the reciprocal function of the Crowd length. The instrument is produced in strict accordance with GB/T9725-88, ISO1518-73, DIN53153 standards, with reliable mass and can accurately measure the Hardness performance of paint film coatings.
Features
1. Production in strict accordance with GB/T9725-88, ISO1518-73, DIN53153 standards to ensure reliable mass.
2. Accurately represent the anti-indentation of the paint film by measuring the Crowd length and calculating its reciprocal function.
3. Equipped with a 20-fold reading Microscope and a lighting system greater than 60 °, it is convenient to clearly observe the image of Cedar.
4. The Cedar device is precisely designed and consists of a rectangular metal block, a hard tool steel sharp-edged metal wheel, and two pointed feet.
5. Cedar load is accurate, 500 +/- 5g, reading accuracy can reach 0.1mm.
Principle
The instrument applies pressure on the surface of the paint film through its Cuan device (self-weight 1Kg +/- 5g, additional load 500 +/- 5g) to form Cuan. The indentation resistance of the paint film is evaluated by measuring the length of the Cuan, and the indentation resistance value is expressed as a function of the inverse of the Cuan length (100/L, L is the Cuan length). The shorter the Cang length, the higher the film Hardness, the greater the indentation resistance value. The image produced by the Cang is observed with a 20x reading microscope during measurement to accurately determine the length.
Applications
Surface measurement of pressure resistance for plastic deformation only, Clearance test for single or multi-layer films for Paints and varnishes
Standards
GB/T9725-88、ISO1518-73、DIN53153
Steps
1. Place the test plate paint film facing up on a stable test bench surface.
2. Gently place the Crowder on the test board, first make the foot of the device touch the test board, and then carefully put down the Crowder. After 30 +/- 1 seconds, lift the Crowder first, and then lift the foot of the device to leave the test board.
3. Within 35 +/- 5 seconds after removing the Crowder, use a Microscope to measure the length of the Crowder image and record the results in millimeters, accurate to 0.1mm.
4. Perform 5 tests on different parts of the same test board and calculate the arithmetic mean.
5. Amend the average value to the value in the most approximate standard table, and look up the table to obtain the anti-indentation property; or calculate the anti-indentation property by the formula 100/L (L is the length of Cedar, in mm).
Notice
• The test plate substrate should be hard, flat, no distortion and no visible bumps on the surface, and not deformed under the test load.
• During the test, the paint film should generally exhibit plastic deformation rather than resilience deformation.
• Under the load of the Crane device, the film thickness still needs to be maintained at least 10 μm.
• The paint film to be tested should be uniform, smooth and clean.
• Sampling shall be carried out in accordance with standard GB3186.
• The test board shall be made according to the requirements of Article 5 in the standard GB9275-88.
• The experiment should be carried out under the environment conditions of temperature 23 +/- 2 ℃ and relative humidity (50 +/- 5) %.
• When placing the Crowder, the action should be gentle, and when lifting, the order should be the feet of the device after the Crowder first.
• Clearance measurement must be completed within the specified time window (35 +/- 5 seconds after removing the Clearance).
• At least 5 tests should be conducted on different parts of the same test board and averaged to ensure representative results.
