1. Hardness
1) All heat treated parts should undergo hardness inspection or spot check according to the requirements of the drawing and process regulations.
2) Calibrate the hardness tester with a standard block and confirm before testing the hardness.
3) Before inspecting the hardness, the surface of the part should be cleaned to remove oxide skin, decarburization layer, and burrs, and there should be no obvious mechanical machining marks on the surface. The temperature of the tested part should be based on room temperature, or slightly higher than room temperature, but only if it can be stably grasped by human hands.
4) The hardness testing location should be determined according to the process documents or by inspection and process personnel. The hardness of the quenched parts should be checked at least 1 point, with each point at least 3 points, and the unevenness should be within the required range. The diameter of the tested part is less than Φ Correction should be made at 38mm.
5) Ordinary normalized, annealed and tempered parts shall be inspected with Brinell hardness hardness tester; For larger sizes, hammer hardness testing can be used, and quenched parts can be tested using a Rockwell hardness tester; For larger sizes, it is allowed to use a Shore hardness tester instead; Parts with thin carburized or hardened layers shall be inspected using a Vickers hardness tester; When using a file to inspect the hardness of parts, attention must be paid to the location of the file marks, which should not affect the final hardness of the parts. The inspection of non-ferrous metals should be based on Brinell and HRB hardness. When selecting the loading load, the specific requirements of the part, the size and thickness of the tested part, etc. should be taken as the selection basis, and the conversion accuracy should be high and accurate.
2. Deformation
1) Use a feeler gauge to check the unevenness of thin plate parts on the inspection platform.
2) Shaft parts are supported at both ends with tips or V-shaped blocks, and their radial circular runout is measured with a dial gauge. Small shaft parts can be inspected on the platform using a feeler gauge.
3) For sleeve and circular ring parts, use a dial gauge, vernier caliper, feeler gauge, inner diameter dial gauge, thread feeler gauge, ring gauge, etc. to inspect the dimensions of the outer circle, inner hole, thread, etc. of the parts.
Non standard tested threads are provided with specialized testing tools by the user.
4) The deformation inspection of special parts, such as gears, cams, etc., should be carried out with the cooperation of the user.
3. Appearance
After heat treatment, general mechanical parts should be observed with the naked eye or a low-power magnifying glass for any cracks, burns, bumps, pitting, rust, etc. on their surface.
For important parts or parts that are prone to cracks, inspection should be carried out using methods such as flaw detection or kerosene immersion sandblasting.
4. Metallography (performed under the following circumstances, but subject to billing)
1) According to customer requirements.
2) Important parts in machinery according to process regulations.
3) When the inspector suspects this batch of parts.
4) When it is deemed necessary to change the process for the first batch or trial production of parts after batch or mass production.
5) When analyzing the cause of waste.
6) Materials (should be charged separately).
When there is doubt about the material, it can be sent to the physical and chemical laboratory to check whether the material conforms to the specifications of the drawing using a spectroscope (spectrometer) or by grinding sparks. The inspection of raw materials shall be carried out in accordance with relevant regulations.
5. Mechanical properties (should be charged separately)
For parts with special requirements for mechanical properties or at the request of customers, relevant technical requirements should be followed