Problems in the Process of Silicone Rubber Mold Making

1. Reasonable choice and proper opening of the exhaust channel. The correct opening of the exhaust channel on the silicone mold has a great effect on ensuring the quality of the silicone prototypes. The exhaust position should be selected at the highest point of the mold cavity and ensure that the passage is open to prevent the exhaust passage from being clogged with the silicone so that the product can not be formed or has pores defect. As the elasticity of silica gel is very good, when gas needle pricks exhaust hole and we pull out the air needle, the airway will shrink to be smaller. In the product copy, you can insert fine-pored plastic pipe in the hole avoid silicone being clogged.

2. Correct control of the knife path. When cutting the mold with a knife, the walking path of the knife is a straight line with a knife nose, and curve with the tail, so the silicone rubber mold is irregular, so as to ensure accurate positioning of the upper and lower mold clamping molds and avoid dislocation caused by error.

3. Ensure that the material is mixed evenly. When the curing agent and silica gel mixed, due to the intense reaction, the mixture will produce a large number of bubbles and the volume becomes larger. At this moment, we should immediately enter air into the vacuum chamber, reduce the bubble, and continue to repeat this process to ensure that the curing agent and silica gel mix evenly.

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RIM molding is a kind of molding process that mixes two or more high-active raw materials under pressure, impinge-mix through the mixing head and inject into the mold to produce prototypes along with the chemical reaction. RIM molding can be used to produce fender, body panels and other large parts.

RRIM (enhanced reaction injection) molding is a kind of RIM moulding that adds fiber or filler in the liquid raw material components. RRIM moulding can produce good impact of the car shells, such as car door panels.

SRIM (structural reaction injection) molding produces roof frame, shell, trunk lid, bumper and so on. The glass fiber reinforced SRIM bumper produced by KAIAO for one of the top car manufacture in China, weighs about 3.45kg (7. 6lb) and it perfectly replaces the original steel bumper which is about 7kg. That is 50% of weight reduction and impact resistance also improves. KAIAO’s RRIM Polyurethane products have been used as a rear panel for the German Volkswagen.

Gas Assisted Injection Molding: the Basic Principles and Basic Processes

The basic principle of Air Mould is: put a certain amount of melt into the cavity, then the compressed air into the melt center, and then the melt will fill with cavity under the action of compressed air.

The basic process of GA IM mainly includes the following stages:

(1) Melt injection: the polymer melt is put into the mold cavity, the process is the same as with the traditional injection molding, the melt is generally filled with 60% to 97% of cavity, which varies by products;

(2) Gas injection: high-pressure nitrogen is put into the melt core, the melt flow is driven by high-pressure gas to move forward until the full cavity;

(3) Gas pressure: the workpiece is cooled while maintaining gas pressure; in the cooling process, the gas from the inside out pressure to ensure that the outer surface of the product close to the mold wall, and the internal supplement melt shrinkage caused by melt cooling through the secondary gas through;

(4) Gas pressure relief and recycling;

(5) Cavity open, remove the parts