What deviations exist in precision parts processing?

2025-04-15 09:39:33

1. Dimensional deviation Reason: The wear of precision parts processing tools, the accuracy error of the machine tool, the measurement error, the thermal deformation of the process system, and the characteristics of the workpiece material may all lead to dimensional deviations. For example, the gradual wear of the tool in the cutting process will make the size of the processed parts gradually larger or smaller; the accuracy error of the screw, guide rail and other transmission parts of the machine tool will also affect the dimensional accuracy of the parts. Impact: Dimensional deviation directly affects the assembly accuracy and performance of parts. If the size of the parts is too large or too small, it may not be able to fit correctly with other parts, resulting in a decrease in the performance of the entire equipment or even failure to work normally. 2. Shape deviation Reasons: mainly include the lack of geometric accuracy of the machine tool, the installation error of the tool, the deformation of the workpiece caused by the cutting force, and the unreasonable processing technology. For example, the runout of the machine tool spindle will cause the roundness error of the machined hole or shaft; during the cutting process, the workpiece will be deformed due to uneven force, which will cause its shape to deviate from the design requirements. Impact: The shape deviation will affect the surface quality and matching performance of the parts, increase wear and friction, and reduce the service life of the parts and the stability of the equipment. For example, a shaft with out-of-tolerance cylindricity will vibrate when rotating, affecting the accuracy and reliability of the device. 3. Position deviation Reason: the positioning accuracy of the fixture is not accurate, the workpiece in the process of precision parts clamping deformation and the lack of motion accuracy of the machine coordinate axis is a common cause of position deviation. For example, the positioning pin of the fixture is worn or installed inaccurately, which will cause the workpiece to have a position offset during clamping; the coordinate axis movement of the machine tool is not accurate, which will cause the processed holes, grooves and other features to be inconsistent with the design position. Impact: Position deviation will affect the assembly relationship and relative position accuracy of parts and other components, causing assembly difficulties or affecting the function of the entire equipment. For example, if the position deviation of each hole on the engine block is too large, it will affect the installation accuracy of the piston, crankshaft and other components, thereby affecting the performance of the engine. 4. Surface roughness deviation Reason: improper selection of cutting parameters, the grinding quality of the tool, the vibration of the machine tool and the cooling and lubrication conditions in the processing process will affect the surface roughness of the parts. For example, the cutting speed is too high or the feed is too large, may lead to the cutting surface of the knife marks or chip, so that the surface roughness is poor; the cutting edge is not sharp, but also in the processing surface left obvious traces. Effect: The surface roughness deviation will affect the wear resistance, corrosion resistance and sealing of the part. Rough surface is easy to absorb impurities and moisture, accelerate the corrosion and wear of parts; in some occasions that need to be sealed, the surface roughness does not meet the requirements will lead to lax sealing, resulting in leakage and other problems.