What are the post-treatment processes of rubber oil seal products?

After vulcanization molding of rubber oil seal products, a series of post-treatment processes are needed to eliminate production defects, improve dimensional accuracy and sealing performance, and meet the requirements of actual working conditions. The core post-treatment processes and operation points are as follows:

Trimming treatment

This is the core process of oil seal post-treatment, and its purpose is to remove flash, burr and glue overflow during vulcanization, so as to ensure smooth lip and accurate size of oil seal.

Mechanical trimming: It adopts a special trimming machine, which is polished by rotating cutter or grinding wheel. It is suitable for large-scale oil seals with simple structure, with high efficiency, but it is necessary to control the cutter precision to avoid scratching the lips.

Freeze trimming: put the oil seal in a low temperature environment (usually liquid nitrogen, the temperature is-100℃~-150℃) to embrittle the flash, and then spray the bullet at high speed to impact the embrittled flash and make it fall off. This process is suitable for complex special-shaped oil seals and lip thin-walled oil seals, with high trimming quality and no damage to the oil seal body.

Manual trimming: For small batch and high-precision oil seals, manual trimming with blades or scissors is suitable for products with insufficient mold precision or special structure, but it is inefficient and requires high skills of operators.

Cleaning and drying

After trimming, impurities such as crumbs, oil stains and release agents will remain on the surface of the oil seal, which need to be cleaned and removed to avoid affecting the subsequent assembly and sealing effect.

Cleaning method: ultrasonic cleaning machine with special cleaning agent (neutral or weakly alkaline) is used to peel off surface impurities by ultrasonic vibration; High pressure spray cleaning can also be used, which is suitable for mass production.

Drying treatment: after cleaning, the oil seal should be put into a drying box (temperature 40℃~60℃) to dry at low temperature, or naturally air-dried, so as to avoid rubber aging caused by high temperature, and at the same time ensure that there is no water residue on the surface of the oil seal to prevent mildew during storage.

Detection and sorting

Conduct a comprehensive quality inspection of oil seals, screen out qualified products and eliminate defective products.

Dimension detection: use calipers, micrometers, plug gauges and other tools to detect the key dimensions of oil seal, such as inner diameter, outer diameter, thickness and lip width, to ensure that it meets the tolerance requirements of drawings (usually the tolerance is 0.01 mm ~ 0.05 mm).

Visual inspection: Visually check whether there are cracks, bubbles, lack of glue, scratches and other defects on the surface of the oil seal, and whether the lip is smooth and notch-free.

Performance sampling inspection: each batch of samples shall be tested for hardness (Shore hardness tester), tensile strength and oil immersion resistance to verify whether the physical properties of the oil seal meet the standard.

Surface treatment (optional)

According to the requirements of special working conditions, some oil seals need surface treatment to improve their performance.

Coating lubricating coating: coating graphite, molybdenum disulfide or special grease on the lip of oil seal to reduce friction resistance during assembly, prevent lip wear during installation and improve initial sealing effect.

Anti-static treatment: the oil seal used in electronic equipment and inflammable and explosive environment shall be coated with anti-static coating to avoid electrostatic accumulation and dust adsorption.

Medium-resistant coating: coating with fluorine resin and other coatings can enhance the ability of oil seal to resist acid, alkali and organic solvents, and expand the scope of application.

Aging treatment (optional)

Also known as "aging treatment", the oil seal is stored in a dry environment at normal temperature for 7~15 days, so that the rubber molecular chain can be fully relaxed, the internal stress of vulcanization can be eliminated, and the dimensional deformation and sealing failure of the oil seal caused by stress release during use can be avoided. This process is especially suitable for high-precision and large-size oil seals.

Packaging and storage

Qualified oil seals should be packaged in a standardized way to prevent damage during transportation and storage.

Packaging: Anti-static plastic bags and cartons are used for independent packaging to avoid rubbing and scratching between oil seals; Batch packaging should be separated by layers, and batch identification should be done well.

Storage requirements: stored at normal temperature (0℃~25℃), in a dry and ventilated environment, away from direct sunlight, heat sources, oil stains and chemical solvents to prevent rubber from aging, hardening and deformation; The storage period is generally less than 6 months, and the principle of "first in, first out" should be followed.