Suzhou Vickers hardness tester maintenance technicians provide on-site service

Repair and common troubleshooting solutions for Vickers hardness tester

1、 Human error:

1. Insufficient technical proficiency, poor practical experience, and improper operation of operators should be led by personnel familiar with operating hardness testers

Use;

2. If the loading is too fast, the holding time is short, and the hardness of the low hardness parts is high, while if the loading is too slow, the holding time is long, and the hardness is low, it should be added during operation

The load should be flat and maintained for a certain amount of time.

2、 Factors affecting the tested parts:

1. Different surface smoothness has different effects on Rockwell hardness testing. The lower the surface smoothness, the higher the hardness during high hardness testing

The higher the hardness, the lower the hardness. For rough surfaces with knife marks, rapid cooling is the first step during quenching, or for very hard surfaces, the hardness value is higher. On the contrary

During high-temperature tempering of quenched and tempered parts, the surface structure with knife marks transforms first, resulting in lower resistance to tempering and lower hardness values. Test surface smoothness below Δ 7

When producing parts, it is necessary to use a waste grinding wheel for precision grinding, then use a file to smooth them out, or use a fine hand grinding wheel to polish them, and then wipe them clean.

2. The surface of heat-treated parts contains salt, sand, and other substances. When loaded, the parts will slip. If there is grease present, the diamond head will press in

Plays a lubricating role, reduces friction, and increases pressure depth. These two reasons result in a lower hardness value being measured. The parts being tested have thin and hard oxide skin and pine layer

The degree value decreases, and the hardness value of the dense layer of oxide skin increases. The parts to be tested for hardness must have their oxide skin removed, wiped clean, and free of dirt.

3. The error in hardness testing for inclined, spherical, and cylindrical parts is greater than that for flat parts. When the pressure head is pressed into the surface of this component, the area around the pressing point

The resistance is smaller than that of a flat surface, and there may even be deviations and slippage, resulting in an increase in compression depth and a decrease in hardness. The smaller the curvature radius, the greater the slope, and the higher the hardness value

The more significant the decrease. Diamond indenters are also prone to damage. Design a workbench for these types of parts so that the workbench is concentric with the indenter.

3、 The influence of hardness tester indenter:

1. If the diamond indenter does not meet the technical requirements or has worn out after a period of use, and the operator cannot judge the quality of the diamond, it can be calculated

Testing institutions conduct calibration.

2. The strength and hardness of the steel ball indenter are insufficient, which can easily cause deformation. The steel ball is flattened and deformed to form an ellipse, with the short axis perpendicular to the parts list

When faced, the indentation is shallow and the indication is high; When the long axis is perpendicular to the surface of the part, the indentation deepens, the indication decreases, and the allowable deviation of the steel ball is 0.002mm.

4、 In terms of load:

1. Initial load: Friction occurs between the spring and spindle, lever and dial gauge, causing an increase or decrease of 100N. Adjust the looseness and adjustment of screws

Move, improper position of the top pole. There is a difference in the starting line, which causes the initial load to be incorrect. If the initial load is not correct, adjust the spring, spindle, lever, and hundred

Coordination in areas such as tables. After adjusting the position of the block appropriately, tighten the adjustment screws and also tighten the position of the top rod. The allowable deviation of the initial load should be less than ± 2%.

2. Main load: The leverage ratio is incorrect, and there is an error in the balance between the suspension rod and the weight; The deviation of the spindle, lever, and weight will cause the main load to be generated

Error. The leverage ratio is incorrect and should be adjusted. The blade should be repaired or replaced if there is wear, and the spindle deformation should be straightened. Spindle, lever, and weight deviation

Tilt should be straightened. The allowable deviation of the main load of various scales is less than ± 0.5%.

5、 The hardness tester is not properly positioned. The hardness tester is not in a horizontal position, and its value is low when testing hardness. Measure the levelness with a spirit level, and then

Flatten hardness tester.

6、 Poor contact between the surface of a certain testing part of the component and the workbench, or unstable support points, will result in phenomena such as sliding, rolling, and lifting

This not only makes the results inaccurate, but also damages the instrument. Suitable workbenches should be designed based on the geometric shape of the parts.

7、 The influence of the surrounding environment. Hardness testers used in factory production are often affected by vibrations in the surrounding environment, resulting in loose instrument structures and readings

instable. The hardness tester should be installed in a place without vibration or far away from the seismic source.

8、 Inaccurate hardness value: There are two situations that can lead to inaccurate hardness testing. If the indenter used is a diamond indenter, first use a nail gauge

Gently rub the surface against the top of the indenter once or twice, and observe if there are any deep marks on the nails. If there are deep marks, it indicates that the indenter is damaged, otherwise it is a good indenter

The second situation is that the instrument's fine adjustment is not properly adjusted. Open the top cover of the hardness tester, use a Phillips screwdriver to loosen the two screws on the top pin, and then adjust the fine adjustment

Adjust the iron block forward to increase the hardness value, and vice versa.