As a precision measuring instrument, Vickers hardness tester may malfunction due to improper operation, component wear, or environmental factors during long-term use. The following is a systematic analysis and solution for common faults, covering core modules such as mechanical, optical, electrical, etc.:

1、 Loading system malfunction: the main cause of hardness value deviation

1. Unable to load or unable to load

Fault manifestation: After pressing the load button, the weight does not fall and the hardness value displays abnormally.

Possible reasons:

The weight suspension system is stuck: the weight guide rail is rusted or foreign objects are stuck, causing gravity to be unable to transmit;

Loading motor fault: The stepper motor drive circuit is damaged, or the motor gear is worn and slipping;

Deformation of lever mechanism: Long term overload use leads to bending of the loading lever and failure of force transmission.

resolvent:

Clean the weight guide rail and apply a small amount of lubricating oil (such as clock oil) to remove foreign objects;

Use a multimeter to measure the resistance of the motor coil (normally around 50-100 Ω), and replace it with a motor of the same model if it is damaged;

Calibrate the levelness of the lever and replace the lever component if necessary (using a level with an accuracy of 0.01mm).

2. Overloading or abnormal speed

Fault manifestation: There is a noticeable impact sound during the loading moment, and the repeatability of the hardness value is poor (as if the measurement difference of the same specimen is greater than 5HV).

Possible reasons:

Buffer failure: damping oil leakage or damping hole blockage, unable to buffer loading impact;

Loose loading speed adjustment knob: hydraulic system flow out of control, resulting in excessive loading;

Weight imbalance: The weight is worn or the weight block falls off, and the actual load does not match the nominal value (such as a 10kg weight measuring only 9.5kg).

resolvent:

Replace the buffer damping oil (recommended viscosity 30-50cSt silicone oil), unclog the damping hole (diameter 0.5mm needs to be cleaned with a fine needle);

Adjust the flow valve to the standard loading time (2-3 seconds) and secure it with a locking nut;

Use an electronic balance to calibrate the weight (with an accuracy of 0.1g), and replace it with a new weight when the wear exceeds 0.5%.

2、 Optical system malfunction: the root cause of indentation measurement deviation

1. Blurred or ghosted field of view

Fault manifestation: The edge of the indentation in the eyepiece is unclear, or there is a double image, making it impossible to accurately measure the diagonal.

Possible reasons:

Objective lens contamination: dust or oil stains (such as fingerprint residue) adhering to the surface of the objective lens, abnormal optical refraction;

Optical path offset: The objective lens converter is loose, or the angle of the reflector is offset (normal angle is 45 °);

Eyepiece focal length not calibrated: The eyepiece focusing knob is not turned to the clear position of the measured object.

resolvent:

Wipe the objective lens clockwise with degreased cotton dipped in anhydrous ethanol (purity ≥ 99.5%), and do not use paper towels or hard objects for scraping;

Tighten the fixing screws of the converter and correct the light path by adjusting the screws of the reflector bracket (the light source can be observed at the center of the field of view);

First, turn the coarse focusing knob until the indentation is blurred and visible, then fine tune the fine focusing knob until the edge is sharp (with an accuracy of 0.01mm).

2. The scale of the measuring microscope is inaccurate

Fault manifestation: When measuring the diagonal of the indentation, the scale value does not match the actual length (such as 105 μ m measured on a 100 μ m scale).

Possible reasons:

Wear of micrometer drum scale: Long term rotation causes the scale line to blur, and the reading error value is greater than 0.5 μ m;

Objective magnification error: Misuse of low magnification objective lens (such as 10x) instead of standard objective lens (20x or 40x);

Screw pitch error: The measuring mechanism's screw is worn, and the pitch deviation exceeds 0.002mm/turn.

resolvent:

Calibrate the drum with a standard glass scale (accuracy ± 0.5 μ m). If the error is greater than 1%, replace the drum component;

Confirm the objective lens identification (such as the "40 ×/0.65" engraved on the outer ring of the objective lens), and replace it with the correct magnification objective lens;

Disassemble the screw assembly, check the pitch (standard pitch 0.5mm), and replace the high-precision screw (accuracy level ≥ T7) when worn.