General technical requirements
1. Remove the oxide scale from the parts.
2. There should be no scratches, abrasions or other defects that damage the surface of the parts on the processed surface.
3. Remove burrs and flash.
Heat treatment requirements
1. After quenching and tempering, HRC50~55.
2. The parts are subjected to high-frequency quenching, tempering at 350~370℃, HRC40~45.
3. Carburizing depth 0.3mm.
4. High-temperature aging treatment.
Tolerance requirements
1. The unfilled shape tolerance shall comply with the requirements of GB1184-80.
2. The unfilled length dimension allowable deviation is ±0.5mm.
3. The casting tolerance zone is symmetrical to the basic size configuration of the blank casting.
Part edges and corners
1. The unfilled corner radius is R5.
2. The unfilled chamfers are all 2×45°.
3. Sharp angles/pointed corners/sharp edges are blunted.
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Assembly requirements
1. Each seal must be soaked in oil before assembly.
2. When assembling rolling bearings, hot-loading with engine oil heating is allowed, and the oil temperature must not exceed 100°C.
3. After the gears are assembled, the contact spots and side clearances on the tooth surface should comply with the provisions of GB10095 and GB11365.
4. When assembling the hydraulic system, it is allowed to use sealing packing or sealant, but it should be prevented from entering the system.
5. All parts and components (including purchased parts and outsourced parts) that enter the assembly must have a certificate of conformity issued by the inspection department before they can be assembled.
6. Parts must be cleaned and cleaned before assembly, and must not have burrs, flash, oxide scale, rust, chips, oil, colorant and dust, etc.
7. The main matching dimensions of parts and components, especially the interference fit dimensions and related precision, should be reviewed before assembly.
8. Parts are not allowed to be knocked, hit, scratched or rusted during assembly.
9. When tightening screws, bolts and nuts, it is strictly forbidden to hit or use inappropriate screwdrivers and wrenches. After tightening, the screw slots, nuts and screw and bolt heads must not be damaged.
10. Fasteners with specified tightening torque requirements must be tightened with torque wrenches according to the specified tightening torque.
11. When the same part is tightened with multiple screws (bolts), each screw (bolt) must be tightened crosswise, symmetrically, step by step and evenly.
12. When assembling the conical pin, the hole should be checked for coloring, and the contact rate should not be less than 60% of the matching length and should be evenly distributed.
13. The flat key and the two sides of the keyway on the shaft should be in uniform contact, and there should be no gap between the mating surfaces.
14. The number of tooth surfaces that are in contact at the same time during spline assembly shall not be less than 2/3, and the contact rate shall not be less than 50% in the length and height direction of the key teeth. 15. After the flat key (or spline) with sliding fit is assembled, the matching parts can move freely and there should be no uneven tightness.
16. After bonding, the excess adhesive that flows out should be removed.
17. The outer ring of the bearing and the semicircular holes of the open bearing seat and the bearing cover shall not be stuck.
18. The outer ring of the bearing and the semicircular holes of the open bearing seat and the bearing cover shall have good contact. When checking with color, it should be in uniform contact with the bearing seat within the range of 120° symmetrical to the center line and the bearing cover within the range of 90° symmetrical to the center line. When checking with a feeler gauge within the above range, the 0.03mm feeler gauge shall not be inserted into 1/3 of the width of the outer ring.
19. After the bearing outer ring is assembled, it should be in uniform contact with the end face of the bearing cover at the locating end.
20. After the rolling bearing is installed, it should be flexible and stable to rotate by hand.
21. The joint surface of the upper and lower bearing shells should be tightly fitted, and a 0.05mm feeler gauge should be used to check if it cannot be inserted.
22. When fixing the bearing shell with a locating pin, the shell mouth surface and the end face should be drilled and pinned while ensuring that the opening and closing surface and end face of the relevant bearing hole are flush. The pin should not be loose after being inserted.
23. The bearing body and the bearing seat of the spherical bearing should be in uniform contact. When checked by the color coating method, the contact should not be less than 70%.
24. Alloy bearings are not allowed to be used when the surface of the lining is yellow. There should be no core separation within the specified contact angle, and the core separation area outside the contact angle should not be greater than 10% of the total area of the non-contact area.
25. The reference end face of the gear (worm wheel) and the shaft shoulder (or the end face of the locating sleeve) should fit, and a 0.05mm feeler gauge should be used to check if it cannot be inserted. And the verticality requirements of the gear reference end face and the axis should be guaranteed.
26. The joint surface of the gearbox and the cover should have good contact.
27. Strictly check and remove the sharp corners, burrs and foreign matter left during the processing of parts before assembly. Ensure that the seal is not scratched when installed.
Casting requirements
1. No cold shut, crack, shrinkage cavity and penetrating defects and serious defect defects (such as undercasting, mechanical damage, etc.) are allowed on the surface of the casting.
2. The casting should be cleaned and no burrs or flash should be allowed. The pouring riser on the non-processed surface should be cleaned and flush with the casting surface.
3. The casting characters and logos on the non-processed surface of the casting should be clearly identifiable, and the position and font should meet the requirements of the drawing.
4. The roughness of the non-processed surface of the casting, sand casting R, is not more than 50μm.
5. The casting should be clear of pouring risers, burrs, etc. The residual amount of pouring and riser on the non-machined surface must be leveled and polished to meet the surface quality requirements.
6. The mold sand, core sand and core bone on the casting should be cleaned.
7. The dimensional tolerance zone of the inclined part of the casting should be symmetrically arranged along the inclined surface.
8. The mold sand, core sand, core bone, fleshy, sticky sand, etc. on the casting should be scraped and polished flat and cleaned.
9. The right and wrong molds and boss casting deviations should be corrected to achieve a smooth transition to ensure the appearance quality.
10. The wrinkles on the non-machined surface of the casting should be less than 2mm in depth and the spacing should be greater than 100mm.
11. The non-machined surfaces of the castings of machine products must be shot peened or roller treated to meet the requirements of cleanliness Sa2 1/2 level.
12. The casting must be water-toughened.
13. The surface of the casting should be flat, and the gate, burrs, sticky sand, etc. should be cleaned.
14. Casting defects such as cold shut, cracks, holes, etc. that are detrimental to use are not allowed in the casting.
Coating requirements
1. All surfaces of steel parts that need to be painted must be free of rust, scale, grease, dust, dirt, salt and dirt before painting.
2. Before rust removal, use organic solvents, alkali solution, emulsifier, steam, etc. to remove grease and dirt on the surface of steel parts.
3. The time interval between the surface to be painted after shot blasting or manual rust removal and the primer coating shall not exceed 6 hours.
4. The surfaces of riveted parts that are in contact with each other must be coated with anti-rust paint with a thickness of 30-40μm before connection. The overlapping edges should be sealed with paint, putty or adhesive. Primers damaged by processing or welding should be repainted.
Piping requirements
1. All pipes should be free of flash, burrs and chamfers before assembly. Use compressed air or other methods to clear debris and floating rust attached to the inner wall of the pipe.
2. Before assembly, all steel pipes (including prefabricated pipes) must be degreased, pickled, neutralized, washed and rust-proofed.
3. During assembly, the parts of pipe clamps, supports, flanges and joints that are fixed with threads must be tightened to prevent loosening.
4. All welded parts of prefabricated pipes must be subjected to pressure resistance tests.
5. When piping is replaced or transported, the pipe separation port must be sealed with tape or plastic pipe plugs to prevent any debris from entering, and a label must be tied.
Requirements for repair welds
1. Defects must be thoroughly removed before welding, and the groove surface should be repaired to be smooth and round without sharp corners.
2. According to the defects of cast steel parts, defects in the welding area can be removed by shoveling, grinding, carbon arc gouging, gas cutting or mechanical processing.
3. Dirt such as sticky sand, oil, water, rust, etc. within 20mm around the welding area and groove must be thoroughly cleaned.
4. During the whole welding process, the temperature of the preheating zone of the steel casting shall not be lower than 350°C.
5. When conditions permit, welding should be performed in a horizontal position as much as possible.
6. When repairing welding, the electrode should not swing too much horizontally.
7. When welding on the surface of steel castings, the overlap between welds shall not be less than 1/3 of the weld width. The weld meat is full, and there is no burn, crack or obvious nodule on the weld surface. The weld has a beautiful appearance, without defects such as undercut, slag, pores, cracks, spatter, etc.; the weld wave is uniform.
Requirements for forgings
1. The nozzle and riser of the ingot should have sufficient removal to ensure that the forging has no shrinkage cavity and severe deflection.
2. The forging should be forged on a forging press with sufficient capacity to ensure that the forging is fully forged through.
3. Forgings are not allowed to have cracks, folds and other appearance defects that affect use that are visible to the naked eye. Local defects can be removed, but the cleaning depth shall not exceed 75% of the machining allowance. Defects on the non-machined surface of the forging shall be cleaned and smoothly transitioned.
4. White spots, internal cracks and residual shrinkage holes are not allowed on forgings.
Requirements for cutting parts
1. Parts should be inspected and accepted according to the process. They can only be transferred to the next process after the previous process is inspected and qualified.
2. Burrs are not allowed on the processed parts.
3. The finished parts shall not be placed directly on the ground, and necessary support and protection measures shall be taken. Rust and bumps, scratches and other defects that affect performance, life or appearance are not allowed on the machined surface.
4. The surface of the rolling finish shall not have peeling after rolling.
5. There should be no oxide scale on the surface of the parts after the final process heat treatment. The mating surface and tooth surface after finishing should not be annealed.
6. The processed thread surface is not allowed to have defects such as black skin, bumps, random buckles and burrs.
Post time: Apr-24-2025
