Many manufacturers in silicone mold production will find some low-hardness silicone products produced after some cracking phenomenon; the solution is also very simple. Usually, silicone products exhaust difficulty and shrink the edge of the cracking reason, then encounter these situations; how do we solve it?
Cause silicone cracking that there are mainly 4 reasons caused by:
1. The vulcanizing agent content in the rubber material is too large (that is, the vulcanizing agent added more).
2. Vulcanization time is too long.
3. The vulcanization temperature is too high.
4. The vulcanization pressure of vulcanizing instrument is too large.
Cracking of silicone products is related to the problem of difficult exhaust:
1. The exhaust distance is too large or too short, which should be strictly controlled between 1 – 5cm.
2. One exhaust is not exhausted, and the second exhaust can be carried out to solve the problem.
3. Not to the vulcanization time.
4. The rubber material has problems; moisture / vulcanizing agent dispersion is not uniform / rubber mixing is not uniform.
Solution:
1. lower the molding mold temperature if there is a package wind (bubble) and white spots bad to extend the vulcanization time. Molding temperature must be fierce until the silicone products do not burst the edge, do not think that a drop of four or five degrees of mold temperature can be solved.
2. exhaust stroke and the number of times must be controlled; exhaust as few times as possible; if possible, exhaust stroke will also try to shorten.
3. Reducing the amount of vulcanizing agent added can be appropriate.
Silicone products molding mold since the dismantling of the knife is too sharp, or there are burrs. Generally speaking, silica gel with a hardness of about 20 degrees is suitable for small products and products with fine patterns. Usually, the size of these products is below 1 meter because this type of silica gel has: small viscosity, good fluidity, good operation, easy to-drain bubbles, good tensile strength, and is easy to fill. The hardness of the mold silicone is relatively large for large products, usually above 1 meter in size.
Low hardness (about 30 degrees) of the rubber in the molding is easy to appear package wind (bubble) and other bad; if the silicone body color or translucent color is also easy to see many small white dots inside the silicone products. The method of raising the mold temperature, the molding mold temperature will be properly increased.
In summary, although in the process of silicone production, when will encounter many problems, but master the process of silicone products and temperature vulcanization and other issues, these problems can be solved.
