The Most Common Problems And Solutions Of Rubber Molded Products: Lack Of Materials

The lack of material is one of the common problems in the production of rubber molded products, which is manifested in the fact that the rubber products are not filled, and there are problems such as holes, incomplete edges, or insufficient thickness. This phenomenon significantly impacts the product's quality and functionality, especially in rubber products that require high precision and functional integrity, and the lack of material can lead to scrap or unusable products. The following is a detailed explanation of the causes and solutions of the material shortage phenomenon.

The manifestation and impact of material shortage

Expression

Holes or collapses in the surface or edges of rubber products.

The thickness of rubber products is uneven, and the local area is thin.

Rubber products are not fully formed, and the structure or appearance is missing.

Impact

Functional failure: A lack of materials can lead to seal failure, air leakage, liquid leakage, and other problems for functional rubber products such as seals; for mechanical parts, the lack of material can affect strength and reliability.

Cosmetic defects: Incomplete holes and edges in rubber products can reduce their aesthetics, especially in applications with high aesthetic requirements.

Insufficient dimensional accuracy: A lack of material can lead to dimensional deviations in the product, which cannot meet assembly requirements.

Waste of raw materials and man-hours: Lack of materials often necessitates reproduction, increasing scrap rates and production costs.

The main reason for the shortage of materials

The air between the mold and the rubber cannot be discharged

During the molding process, if the air in the mold cavity cannot be discharged in time, it will hinder the flow of the compound. Air trapped in the mold cavity, especially at the edges or in areas with complex shapes, can cause these areas to be underfilled, resulting in material shortages.

Not enough weighing

The insufficient amount of rubber is one of the direct causes of material shortage. If the compound weight does not meet the cavity design requirements, the material distribution in the cavity will be insufficient, resulting in edges or thin-walled sections not being filled.

Lack of stress

Insufficient or uneven pressure distribution in the molding equipment can prevent the compound from flowing to all areas of the mold cavity, especially away from the center of pressure, resulting in material shortages.

The fluidity of the rubber compound is too poor

Improper formulation design of the compound may lead to insufficient flowability. The compound is not evenly distributed to every corner of the cavity during molding, especially in complex structures or thin-walled parts.

The mold temperature is too high, and the rubber is scorched

Too high a mold temperature can cause the compound to scorch or harden prematurely, losing fluidity and not being able to fill the mold cavity adequately. Scorch affects flowability and can lead to localized quality problems in rubber products.

Early scorching of rubber (dead material)

Improper formulation design or processing may lead to partial scorching of the compound before entering the mold cavity, limited flowability, and eventually incomplete mold cavity filling.

The thickness of the rubber compound is insufficient

If the thickness of the compound is insufficient during preparation, it will not provide enough material to fill the entire cavity, especially the edges and thin-walled areas.

A way to solve the phenomenon of material shortage

Given the different causes of material shortage, the following solutions are taken:

Add an exhaust slot

When designing the mold, add exhaust grooves or optimize the layout of existing exhaust grooves so that the air in the mold cavity can be quickly discharged.

For rubber products with complex shapes or thin edges, more venting points can be added in critical areas.

Exhaust multiple times

In the molding process, increase the number of exhausts, and then pressurize after each exhaust to ensure that the compound flows smoothly and there is no residual air in the mold cavity.

It is especially suitable for cases where the mold cavity is complex or the fluidity of the compound is poor.

Increase the molding pressure

Check whether the pressure setting of the molding equipment meets the requirements, and increase the pressure appropriately to enhance the fluidity and filling capacity of the compound.

Make sure the pressure is evenly distributed to avoid underfilling or uneven pressure that may result in some areas not being filled.

Optimize the compound formulation and improve the flowability

Plasticizers are added to compound formulations to reduce the proportion of fillers to improve the flow of compounds.

Use rubber raw materials with better performance or add accelerators to improve the filling capacity of the compound in the mold cavity.

 Extend the scorch time

Adjust the ratio of the vulcanizing agent in the formulation to extend the scorch time of the compound and ensure that it has sufficient flow time in the mold cavity.

Avoid early scorching of the compound before the cavity is filled.

Increase the thickness of the compound

During the compound preparation phase, make sure that the compound is thick enough to provide sufficient material to fill the mold cavity.

For complex cavities, the initial thickness of the compound can be increased appropriately to avoid material shortages on the edges and thin-walled sections.

Optimize mold design

When designing the mold, arrange the position and number of inlets to ensure that the compound can be quickly and evenly distributed to each area of the mold cavity.

For thin walls and edges, add local material flow channels to ensure complete filling.

Adjust the mold temperature

Check the mold temperature control system to ensure that the mold temperature is kept within a reasonable range. If the mold temperature is too high, it should be appropriately reduced to avoid scorching of the rubber material.

For complex rubber products, try zoning temperature control to ensure consistent flow and curing of the compound in different areas.