Production process
The choice of mold opening form and mold line is very important. First, it is convenient to take 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 waterscape series products is too high, and more materials are required when sealing the mold line, so product cracking is easy to occur; Fourth, reduce the process operation procedures, such as half mold opening.
In order to prevent the silica gel from flowing around, fix the mold seeds in a regular range with wood squares or boards. When opening the sheet mold, use boards and oil sludge to separate the first part. There is no gap between the oil sludge and the mold seeds, and the oil sludge surface is smooth and flat.
After the above work is prepared, the plaster mold or mold seed shall be coated with Vaseline or sprayed with release agent. The smooth product shall be evenly coated on the mold seed with clean cotton cloth dipped with Vaseline for 30 minutes so that the mold seed can fully absorb Vaseline, and then the surface of the mold seed shall be wiped clean with clean cotton cloth. The surface shall be bright; For products with texture, just apply Vaseline evenly and adjust the silicone according to the formula. When mixing silica gel, it shall be stirred in an irregular direction to fully mix the curing agent and silica gel, so as to minimize the air mixing into the glue. It is best to vacuum the smooth product when applying the first layer of glue, and the vacuum degree shall be maintained for 7-8 seconds when -0.1mpa.
Mold shall be made in time after silica gel is prepared. Pour the glue solution onto the highest part of the mold seed by trickling, and let it flow naturally. Where the flow is not in place, use an oil painting brush. If it is a piece mold, the silicone will not only fill the whole product, but also evenly brush 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. In the process of brushing silica gel, it is required to brush another layer after each layer is cured. When brushing the third layer, a layer of gauze shall be added to 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 requirements of different product sizes, and the width shall not be greater than 60mm of the product width. The setting time of silica gel is 20 minutes.
1. Clean and dry the master mold for smooth treatment (a layer of release wax or a layer of release agent can be applied)
2. Put 500-1000 grams of mold silicone rubber (mold silicone, mold rubber, silicone rubber, silicone) into a plastic basin for standby;
3. Weigh the hardener according to the weight ratio (generally 1.5-2.5%), add it into the container for mixing, and fully stir it evenly;
4. Add a certain amount of silica gel diluent as appropriate (especially the first layer). Until the mixture is uniform, generally 3-5 minutes.
5. after the mold silicone rubber (mold silicone, mold glue, silicone rubber and silicone) is mixed with the hardener, it will react at room temperature and release low molecular alcohol. In order to separate the alcohol molecules from the colloid, it is necessary to discharge bubbles under negative pressure for 1-3 minutes. It can also be done without the aid of equipment (mainly depending on the operation experience of the die maker)
6. For multi-layer coating sheet mold, it is advisable to follow the principle of simultaneous curing inside, inside and outside. 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 mould cloth after painting the first and second layers, which can greatly improve the service life of the mould (but do not use glass fiber cloth, otherwise it is easy to cause delamination and scrap the whole mould)
7. The three-dimensional pouring mold is generally cured in 10-15 hours.
8. After the soft mold is made, plaster or FRP jacket should be made to support the silicone soft mold. Note: 1. Mold line selection: select the position that does not affect the product appearance; Select the position easy to process after grouting; Select the position where the mold itself is easy to be removed; 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.