What are the characteristics of rubber oil seal products processing in industrial field?

The processing of rubber oil seal products in the industrial field focuses on the four core objectives of high sealing, harsh working conditions, dimensional accuracy and batch stability, and adapts to the harsh operating environment of industrial equipment (such as motors, reducers, hydraulic systems, pumps and valves) such as high speed, high pressure and multi-media erosion. The specific features are as follows:

The selection of raw materials has strong pertinence and adapts to complex working conditions.

Accurate matching of materials and working conditions: rubber materials are selected according to equipment medium, temperature and pressure. For example, nitrile rubber (NBR) adapts to the environment of hydraulic oil and engine oil, and can withstand-40℃~120℃, which is the mainstream material of industrial oil seals; Fluorocarbon (FKM) is resistant to strong acid, alkali and high temperature (-20℃~200℃), and is used for oil seals of chemical pumps and high-temperature reducers. Silicone rubber (VMQ) has good insulation and is suitable for motor spindle oil seal; Hydrogenated nitrile rubber (HNBR) is wear-resistant and tear-resistant, and is used for oil seal of high-pressure hydraulic system.

Formula optimization to improve performance: by adjusting the proportion of curing system and reinforcing agent (such as carbon black and white carbon black), the tensile strength (≥15MPa), tear strength (≥30kN/m) and rebound rate (≥ 50%) of oil seal are improved; Adding anti-aging agent and anti-ozone agent can prolong the service life of oil seal in outdoor or highly corrosive environment.

Die design and machining accuracy are demanding.

High-precision cavity machining: the lip of the oil seal and the joint surface of the skeleton are the sealing core, and the tolerance of the mold cavity should be controlled within 0.01 ~ 0.02 mm. CNC fine carving+mirror polishing technology should be adopted to ensure that the surface roughness Ra of the cavity is ≤ 0.2 μ m, so as to avoid burr and flash after the oil seal is formed, which will affect the sealing effect.

Skeleton positioning and demoulding design: industrial oil seals are mostly skeleton oil seals (metal skeleton+rubber coating), and accurate positioning pins need to be set in the mold to ensure that the coaxiality deviation between the metal skeleton and the rubber layer is ≤±0.03mm, so as to prevent eccentric wear of the oil seal caused by skeleton deviation; The lip of the mold is designed with a demoulding inclination of 0.5 ~ 1 to avoid damaging the sealing surface of the lip when demoulding.

Accurate compensation of shrinkage: according to the shrinkage of rubber material (such as NBR shrinkage of 2%~3% and FKM shrinkage of 3%~5%), the mold allowance is reserved, and the influence of vulcanization temperature and pressure on shrinkage is considered to ensure that the size of the finished oil seal is accurately matched with the shaft hole of the equipment.

The molding process parameters are strictly controlled and the consistency of vulcanization is emphasized.

Molding vulcanization is the mainstream technology: it is molded by using a flat vulcanizer or an injection vulcanizer, and the three elements of vulcanization (temperature, pressure and time) are strictly controlled: temperature deviation ≤ 2℃ (for example, NBR vulcanization temperature is 150~160℃, FKM vulcanization temperature is 180~190℃), vulcanization pressure is 8~15MPa, and holding time is accurate to seconds, so as to avoid insufficient and excessive elasticity of oil seal caused by insufficient sulfur.

Composite technology of skeleton and rubber: the skeleton should be degreased and phosphatized first to improve the bonding strength with rubber (peeling strength ≥ 5N/mm); The injection vulcanization process can realize the seamless coating of rubber and skeleton. Compared with the traditional molding process, the production efficiency is improved by more than 30%, and the bonding is firmer.

Finishing treatment of lip: Some high-precision oil seals (such as high-speed motor oil seals) need to be finished by turning after vulcanization, so as to ensure the lip thickness tolerance of ±0.01mm, and the contact pressure between the lip and the shaft is even, so as to meet the sealing requirements when the equipment rotates at a high speed (rotation speed ≥ 3,000 r/min).

Quality inspection covers all dimensions and focuses on sealing reliability.

Dimensional accuracy detection: use image measuring instrument and CMM to detect the key dimensions of oil seal, such as outer diameter, inner diameter, lip thickness and coaxiality, and 100% check the lip position to ensure no deformation or notch.

Performance test fits the industrial scene;

Sealing test: Carry out pressure resistance and leakage resistance tests under simulated working conditions (rated speed and pressure) to ensure no oil leakage;

Medium resistance test: soak the oil seal in the corresponding medium (such as hydraulic oil and diesel oil), and after standing at high temperature for 72 hours, test the volume change rate (≤ 5%) and hardness change (≤ 5 Shore);

Aging test: Through high and low temperature cycling and ozone aging test, the performance stability of oil seal after long-term use is verified.

Batch consistency control: automatic production line is adopted to realize the automation of the whole process of feeding, vulcanization, demoulding and detection, and 10% samples are taken from each batch for full performance test to ensure that the dimensional deviation between batches is ≤ 0.03 mm.

Post-treatment and packaging pay attention to protection to avoid performance attenuation.

Deburring and cleaning: the flash of the vulcanized oil seal needs to be removed with a special tool, and then it is cleaned by ultrasonic wave to remove the residual vulcanizing agent and dust on the surface, so as to avoid impurities from affecting the sealing surface fitting.

Protective packaging: the lip of the oil seal should be coated with antirust grease and packed in PE bag separately to prevent the lip from being deformed by pressure during transportation; Customized pallets are used in batch packaging to avoid stacking and squeezing.

Storage environment requirements: Store in a cool, dry and dark warehouse (temperature 10~25℃, humidity 40%~60%), away from heat sources and organic solvents, to prevent premature aging of rubber.