Many rubber products are molded, and after molding, vulcanization to obtain products with qualified physical properties, the appearance of the product does not have major defects, but the conventional trimming method can not repair the appearance requirements of the product, there are small burrs can not be removed, manual repair or scrapping causes a lot of economic waste.

At this time, the structural design of the mold clamping line of the product is particularly important, how to design the lip, overflow line and overflow groove, etc., will not be explained here, you can refer to the "Rubber Mold Design Manual".

The focus of this article is to explain from the formula and process, because the mold is often designed can not often modify or scrap the mold (economic waste), often find a formula engineer to modify the formula or change the process to achieve easy tearing.

Here, it is not recommended to repair the formula frequently, because formula modification often involves whether many physical and chemical indicators inside meet the application requirements of rubber products, without further ado, directly on the solution:

1. Due to the high process temperature (mixing, smelting, parking), the slight scorching caused by (sometimes the rheometer looks at the vulcanization history chart ML, TS1 and other initial fluidity and fluctuations), resulting in difficulty in trimming.

Solution: increase the flow rate of the mixer cooling water system or use a cold mold temperature machine (regularly clean the calcium scale of the pipeline); The mill can drill the roller to increase the flow of cooling water in the roller to reduce the temperature (the mixer method is also practical); Parking as quickly as possible to reduce the temperature to room temperature, it is not recommended to stack in large quantities, which can easily cause high intermediate temperature and cause scorching.

2. The dispersion of the rubber material is uneven, and it is difficult to tear the edge caused by the high local material.

Solution: Reasonably arrange the order and time of material delivery, material dispersion and melting meet the process requirements, and rubber dispersion additives can be appropriately added in the formula design.

3. The vulcanization temperature is too high, resulting in brittle edges.

Solution: choose the vulcanization temperature with a reasonable product structure, can not blindly pursue production capacity, damage the entropy of rubber and the degree of vulcanization local structure is different.

4. The vulcanized rubber edge is uneven in thickness and the mold lip error is large.

Solution: Modify the mold to meet the design error requirements and meet the production needs.

5. The Mooney of the rubber material is large, and the "Green strength" of the rubber material is large.

Solution: It can be plasticized, reduce plasticity, and improve the fluidity of rubber; The formulation considers the Mooney viscosity and Mooney scorching of the compound.

6. The fluidity of the rubber material is poor.

Solution: When designing the formula, consider the fluidity, add flow additives, dispersants, softeners and resins, etc., to improve the fluidity of the rubber material, but the overall combination should meet the product design parameters and production process requirements.

7. The overflowing edge of the rubber material is thick and cannot be torn.

Solution: increase the pressure of the vulcanization mold; Mold modification to meet production requirements; Reduce the Mooney (stiffness) of the compound, so that the rubber has better "softness" and fluidity.

8. The formula design is unreasonable.

Solution: Because the formula is considered in many aspects, to meet the production needs, product design parameters and qualification rate, etc. Specific designs can be found in our studio to develop cost-effective and factory-friendly practical formulations.

9. Other reasons: unreasonable storage, failure or agglomeration of materials; The scorching period of raw rubber selection is unstable; The blending glue cannot meet the requirements of "liquid phase mixing"; vulcanization system; Accelerator matching; filler particle size distribution; Resin melting and so on.