How high is the accuracy requirement of rubber and plastic components in automobile field?

Rubber-plastic components in the automotive field require extremely high precision and have obvious differences. The core depends on the application parts, functional attributes (such as sealing, transmission and insulation) and whether they are suitable for high-precision electronic control systems. The tolerance range is usually controlled between 0.02 mm and 0.5 mm, and the precision requirements of some key components are even comparable to those of precision mechanical parts. The specific precision standards are as follows:

Core sealing components (with the highest accuracy requirement and tolerance of 0.02 mm ~ 0.1 mm)

This kind of component directly affects the waterproof, oil-proof and air-tightness of the automobile, and is the top priority of precision control.

Engine oil seal and gearbox oil seal: the thickness tolerance of lip should be ≤±0.03mm, and the fit clearance between lip and shaft should be controlled at 0.05 mm ~ 0.1 mm. If the clearance is too large, it is easy to leak oil, and if it is too small, it will aggravate wear and lead to oil seal failure; The external diameter of the oil seal should be accurately matched with the interference of the mounting seat (the interference is 0.02mm~0.08mm) to ensure that there is no looseness and eccentric wear after assembly.

Sealing ring of battery pack (new energy vehicle): As the protection core of high-voltage system, the tolerance of section size should be ≤±0.05mm, and the deviation of compression should be controlled within ±0.1mm, otherwise the protection level of IP67 will be invalid, which will lead to the risk of battery short circuit; The coaxiality error of the sealing ring is less than or equal to ≤0.08mm, so as to avoid insufficient local compression after assembly.

Fuel system gasket: the thickness tolerance is 0.02 mm ~ 0.05 mm, and the surface flatness is ≤0.03mm/m, so as to prevent fuel leakage or air tightness from reaching the standard.

Transmission and structural components (tolerance 0.05 mm ~ 0.2 mm)

Used in key links such as power transmission and chassis damping, the accuracy directly affects the running stability and driving experience.

Chassis bushing and suspension cushion: the coaxiality tolerance between the inner hole and the metal insert is ≤±0.1mm, and the matching tolerance between the outer diameter of the bushing and the mounting bracket is 0.08 mm ~ 0.15 mm; If the coaxiality deviation is too large, it will lead to abnormal noise and deviation when the vehicle is driving, and even accelerate the aging of the bushing.

Glass guide grooves and sealing strips for doors and windows: the tolerance of cross-sectional dimensions is 0.1 mm ~ 0.2 mm, and the contact pressure between lips and glass should be uniform (pressure deviation is less than or equal to 10%), otherwise, there will be problems such as glass lifting jamming, water leakage in rainy days or excessive high-speed wind noise.

Electrical and electronic components (tolerance ±0.03mm~±0.15mm)

Adapted to on-board sensors, connectors and electronic control modules, the accuracy is related to signal transmission and electrical safety.

Harness sheath and connector sealing ring: the dimension tolerance of the inner hole is 0.03 mm ~ 0.08 mm, which should be accurately matched with the harness terminal to prevent signal interruption caused by loose terminal; The tolerance of plugging and unplugging force of the sheath should be controlled within 5N to meet the plugging and unplugging life requirements of the vehicle-mounted electrical system (≥1000 times).

Sensor seals (such as tire pressure sensor and radar sealing ring): the dimensional tolerance is ±0.05mm, and the form and position tolerance (roundness and cylindricity) is ≤0.03mm, so as to ensure that there is no gap after the sensor is installed, and avoid the intrusion of external dust and water vapor from affecting the detection accuracy.

Interior and auxiliary components (tolerance 0.2 mm ~ 0.5 mm)

This kind of components have little influence on the function, but the accuracy is related to the appearance consistency and assembly fluency.

Instrument panel buckle and door panel decorative strip: the dimensional tolerance is 0.3 mm ~ 0.5 mm, and the clamping force deviation of the buckle is ≤15% to prevent looseness and abnormal sound after assembly; The splicing gap of decorative strips should be ≤0.2mm to ensure the aesthetics of the interior.

Seat adjustment rubber sleeve and armrest cushion: the tolerance range is 0.2 mm ~ 0.4 mm, which mainly meets the tactile and cushioning functions, and the accuracy requirements are relatively loose.

The core guarantee means of precision control

Mold accuracy: CNC-processed high-precision mold with cavity tolerance ≤±0.01mm ensures the consistency of molding accuracy of rubber and plastic parts.

Molding process: Through precise injection molding, vacuum molding and other processes, with constant temperature and constant pressure control system, the shrinkage deformation of rubber and plastic parts is reduced (the shrinkage rate deviation is controlled within 0.1%).

Detection means: use image measuring instrument, CMM, Shore hardness tester and other equipment to carry out 100% full inspection or sampling inspection on key dimensions.