What Are The Precautions For Processing Machine Parts?
In order to ensure that precision parts are not corroded by sweat, air, and other components, keep them in the factory state and increase their service life, we should pay attention to the following matters in the processing of machine parts.
Contour processing of parts
Shape Tolerance: The unmarked shape tolerance should meet the requirements of GB1184-80.
Length Dimension Deviation: The allowable deviation of the unmarked length dimension is ±0.5mm.
Corner Radius: Unfilled corner radius should be R5.
Chamfers: All unfilled chamfers should be C2.
Sharp Angles: Sharp angles should be obtuse.
Edge Treatment: Sharp edges should be dull, and burrs and flash must be removed.
Surface Treatment of Parts
Surface Quality: No scratches, abrasions, or defects damaging the surface are allowed on the processing surface of the parts.
Thread Surface: Processed thread surface should be free from defects like black skin, bumps, random buckles, and burrs. Steel parts requiring painting must be free from rust, oxide scale, grease, dust, soil, and salt.
Surface Cleaning: Before rust removal, use organic solvents, lye, emulsifier, steam, etc., to remove grease and dirt on steel parts’ surfaces.
Riveting Parts: Surfaces in contact should be painted with anti-rust paint (30-40μm thickness) before connecting. Lap edges should be sealed, and damaged primer must be repainted.
Coating Timing: The time interval between shot blasting or manual derusting and primer coating should not exceed 6 hours.
Technical Requirements After Precision Machining
Placement: Finished parts should not be placed directly on the ground; necessary support and protection measures should be taken.
Surface Quality: Machined surfaces should be free from defects affecting performance, life, or appearance, such as rust, bumps, and scratches.
Rolling Process: Surfaces processed by rolling should not peel off after rolling.
Heat Treatment Residue: No oxide scale should be present on the parts’ surface after the final heat treatment. Finished mating and tooth surfaces should not be annealed.
Thermal Processing of Parts
Quenching and Tempering: After quenching and tempering treatment, the hardness (HRC) should be between 50 and 55.
Medium Carbon Steel: For medium carbon steel (e.g., 45 or 40Cr), high-frequency quenching, tempering at 350-370℃, and HRC40-45.
Carburizing Depth: The carburizing depth should be 0.3mm.
High-Temperature Aging: High-temperature aging treatment should be carried out.
Sealing of Machine Parts
Seal Preparation: All seals must be soaked in oil before assembly.
Assembly Check: Check and remove sharp corners, burrs, and foreign objects before assembly to ensure the seal is not scratched.
Adhesive Removal: After bonding, remove excess adhesive flowing out.
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