Silicone mold making process

Silicone mold production process and common problems

Production process

The choice of the mold opening form and the mold line are very important. First, it is for the convenience of taking the mold. Second, the mold line should be selected so as not to affect the overall effect of the product. Third, it does not affect the product quality. For example, the position of the mold line of the waterscape series products is too high. If the mold sealing line requires too much material, cracking of the product will easily occur; the fourth is to reduce process operations, such as opening half the mold.

In order to prevent the silica gel from flowing around, fix the mold in a regular range with wooden squares or wooden boards. When opening the mold, use wooden boards and sludge to separate the first part to be opened. It is required that there is no gap between the sludge and the mold, and the surface of the sludge is smooth and flat.

After the above preparations are completed, apply Vaseline or spray release agent on the plaster mold or mold. For smooth products, use a clean cotton cloth dipped in Vaseline and apply it evenly on the mold, and keep it for 30 minutes to soften the mold. Fully absorb Vaseline, and then wipe the surface of the mold with a clean cotton cloth. The surface is required to be bright. For products with texture, just apply Vaseline evenly. Adjust the silicone according to the formula. When mixing silicone gel, stir in irregular directions to fully mix the curing agent and silicone gel, and minimize the mixing of air into the glue. For smooth products, it is best to vacuum once when applying the first layer of glue, and the vacuum degree is required to be maintained at -0.1Mpa. 7-8 seconds.

After the silicone is prepared, the mold should be made in time. Pour the glue into the highest part of the mold in a dripping manner and let it flow naturally. Use an oil brush to brush the areas where the flow is not in place. If it is a sheet mold, the silicone not only fills the entire product but also the glue must be evenly brushed. Each product should be brushed with at least three layers of silica gel. The thickness of each layer of silica gel is 1mm. During the process of brushing silica gel, each layer is required to be cured before another layer can be brushed. When brushing the third layer, add a layer on top of the second layer. layer of gauze to increase the strength of the silicone. The thickness of the silicone part of the entire mold is controlled at 3-4mm depending on the size of the product, and the width is no larger than the product width of 60mm. The silicone gel begins to solidify in 20 minutes.

1. Wash and dry the master mold and make it smooth (you can apply a layer of release wax or apply a release agent)

2. Put 500-1000 grams of mold silicone rubber (mold silicone, mold glue, silicone rubber, silicone) into a plastic basin and set aside;

3. Weigh the hardener according to the weight ratio (usually 1.5-2.5%) and add it to the container for mixing, and stir thoroughly;

4. Add a certain amount of silica gel diluent depending on the situation (especially the first layer). Mix until evenly mixed, usually 3-5 minutes.

5. After the mold silicone rubber (mold silicone, mold glue, silicone rubber, silica gel) is mixed with the hardener, it reacts at room temperature and releases low molecular alcohol. In order to separate the alcohol molecules from the colloid, it needs to be bubbled under negative pressure for 1-3 minute. You don’t need to use equipment (mainly depends on the mold engineer’s operating experience)

6. For multi-layer painted sheet molds, it is advisable to solidify the inside, middle and outside at the same time. When the amount of curing agent is relatively small, the reaction time is lengthened, the reaction is sufficient, and the colloid is good. Therefore, it is best to use less curing agent on the inside and more on the outside. When applying, wait for the first layer (inner layer) to dry before applying the second layer. The operation time is 30-50 minutes, and the mold removal time is 10-15 hours. Maintenance time is 24 hours. Note that it is best to add mold cloth after painting the first and second layers, which can greatly increase the service life of the mold (but do not use glass fiber cloth, otherwise it will easily cause delamination and make the entire mold scrapped)

7. Three-dimensional injection molding generally takes 10-15 hours to cure.

8. After the soft mold is made, a plaster or fiberglass jacket must be made to support the silicone soft mold. Note: 1. Mold line selection: choose a position that does not affect the appearance of the product; choose a position that is easy to process after grouting; choose the mold itself that is easy to disassemble. The position of the mold; choose a position where the product is not easily deformed. 2. Do not blindly increase the amount of hardener to meet the production schedule, otherwise the service life of the silicone mold will be greatly reduced.