Manufacturing Process and Common Problems of Silicone Mold

Production process

The selection of mold opening form and mold line is very important. First, it is for the convenience of mold taking. Second, the mold line should be selected in a way that does not affect the overall effect of the product. Third, it does not affect the product quality. For example, the mold line position of waterscape series products is too high, and more materials are required when sealing the mold line, which will easily lead to product cracking; The fourth is to reduce process operation procedures, such as half mold opening.

In order to prevent the silica gel from flowing around, the mold seed shall be fixed in a regular range with battens or boards. When opening the mold, the first part shall be separated with boards and putty. There shall be no gap between the putty and the mold seed, and the putty surface shall be smooth and flat.

After the preparation of the above work, the plaster mold or mold seed shall be coated with Vaseline or sprayed with mold release agent. Smooth products shall be evenly coated on the mold seed with clean cotton cloth dipped with Vaseline, and kept for 30 minutes to make the mold seed fully absorb Vaseline. Then, clean the mold seed surface with clean cotton cloth, and the surface shall be bright; For products with texture, just apply Vaseline evenly and adjust the silica gel according to the formula. The silica gel shall be mixed in an irregular direction to fully mix the curing agent and silica gel, so as to minimize the air mixing into the glue. For smooth products, it is better to draw a vacuum when applying the first layer of glue, and the vacuum degree shall be maintained for 7-8 seconds when it is required to be -0.1Mpa.

The mold shall be made in time after the silica gel is prepared. Pour the glue liquid onto the highest part of the mold in a trickle way to let it flow naturally. If the glue liquid cannot flow in place, use an oil painting brush. If it is a piece of mold silica gel, it should not only fill the whole product, but also be evenly brushed on the clay. Each product shall be brushed with at least three layers of silica gel. The thickness of each layer of silica gel is 1mm. During the brushing process, each layer shall be cured before brushing another layer. When brushing the third layer, a layer of gauze shall be added on the second layer to increase the strength of silica gel. The thickness of the silicone part of the whole mold shall be controlled within 3-4mm according to the size of the product, and the width shall not be greater than the product width of 60mm. The silica gel starts to solidify for 20 minutes.

1. Clean and dry the master mold, and make it smooth (one layer of mold release wax or one coat of mold release agent can be applied)

2. Put 500-1000g mold silicone rubber (mold silicone, mold rubber, silicone rubber, silicone rubber) into a plastic basin for standby;

3. Weigh the hardener according to the weight ratio (generally 1.5-2.5%), then add it into the container for mixing, and fully stir it evenly;



4. Add a certain amount of silica gel thinner as appropriate (especially the first layer). Until the mixture is uniform, generally 3-5 minutes.



5. After the mold silicone rubber (mold silica gel, mold rubber, silicone rubber, silica gel) is mixed with the hardener, it will react at room temperature and release low molecular alcohol. In order to make the alcohol molecules separate from the colloid, it is necessary to bubble under negative pressure for 1-3 minutes. It is also possible not to use equipment (mainly depending on the operation experience of the die maker)



6. The multi-layer coating die should be cured at the same time in the interior, middle and exterior. When the amount of curing agent is relatively small, the reaction time is longer, the reaction is sufficient, and the colloid is good. Therefore, the amount of curing agent is better to be less inside and more outside. When painting, the second layer shall be painted after the first layer (inner layer) is dry. The operation time is 30-50 minutes, and the formwork removal time is 10-15 hours. The curing time is 24 hours. Note that it is better to add mold cloth after the first and second layers are painted, which can greatly improve the service life of the mold (but glass fiber cloth is not used, otherwise it is easy to cause delamination and make the entire mold scrapped)



7. Stereo pouring mold, generally 10-15 hours of curing is better.



8. After the soft mold is made, plaster or glass fiber reinforced plastic jacket shall be made to support the silicone soft mold Note: 1. Mold line selection: select the position that will not affect the product appearance; Select the position easy to process after grouting; Select the position where the mold itself is easy to remove; Select the position where the product is not easy to deform. 2. Do not blindly increase the amount of hardener in order to catch up with the production progress, otherwise the service life of the silicone mold will be greatly reduced.

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