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Silicone mold is a special mold for making handicrafts. The raw materials of glue can be divided into ordinary silicone rubber and meteorological silicone rubber according to their performance. The characteristics of silicone rubber are high temperature resistance, corrosion resistance, strong tear resistance, and high simulation precision. ‘s mold.
Raw materials for silicone molds
Silicone is more and more popular because of its good environmental performance. To understand the knowledge of silicone molds, you must start with silicone raw materials.
- Ordinary silicone rubber, also known as precipitated silicone rubber
Color: translucent, milky white, light yellow, gray, etc.
Hardness: 30°, 40°, 50°, 60°, 70°, etc., commonly used between 40°-70°.
Density: 1.1-1.12g/cm³
Elongation: 400%
Uses: It is mostly used in low-grade silicone products such as mobile phone buttons, miscellaneous parts, and conductive glue.
Meteorological glue, also known as pure silicone rubber
Color: Transparent.
Hardness: 30°, 40°, 50°, 60°, 70°, 80°, etc., commonly used between 40°-60°.
Density: 1.1-1.12g/c㎡
Elongation: 600%-700%
Features: Due to the good transparency and strong tensile strength of this material. high cost
Uses: Silicone tubes, protective sleeves and other high-end products that require high elasticity.
- silicone rubber raw materials can be divided into solid silicone rubber and liquid silicone rubber according to their physical properties.
Solid silicone rubber is mainly used for molded products. For example: silicone sleeves, silicone tableware, silicone molds, silicone buttons, etc. Liquid silicone is mainly used for extrusion molding products, such as silicone pacifiers, silicone tubes, etc.
Insulation silicone pad, excellent high temperature resistance, silicone rubber (food grade silicone rubber) can withstand high temperature of 200 ℃ and can be used for a long time. Production, color and shape can be customized.
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Production process:
The selection of the mold opening form and the selection of the mold line are very important. First, it is for the convenience of mold taking. Second, the mold line should be selected so that it does not affect the overall effect of the product. Third, it does not affect the quality of the product. High, the mold sealing line requires a lot of material, and the product cracks easily; the fourth is to reduce the process operation process, such as opening half of the mold.
In order to prevent the silicone from flowing around, the mold seed is fixed in a regular range with a wooden square or a wooden board. When opening the mold, the board and the sludge are used to separate the part that was opened first. It is required that there is no gap between the sludge and the mold seed, and the surface of the sludge is smooth and flat. After the above preparations are completed, then apply Vaseline or spray mold release agent on the plaster mold or mold seed. For smooth products, use a clean cotton cloth dipped in Vaseline to spread evenly on the mold seed, and keep it for 30 minutes to make the mold It is necessary to fully absorb Vaseline, and then use a clean cotton cloth to wipe the surface of the mold seed, and the surface is required to be bright; and for products with texture, just apply Vaseline evenly and adjust the silicone according to the formula. When the silicone is prepared, it should be stirred in an irregular direction, so that the curing agent and the silicone are fully mixed, and the air is mixed into the glue as much as possible. For smooth products, it is best to vacuum once when the first layer of glue is applied. 7-8 seconds.
After the silicone is prepared, it should be molded in time. Pour the glue on the highest part of the mold by dripping and let it flow naturally. Use an oil paintbrush to brush in place where the flow is not in place. If it is a piece of mold, the silicone will not only fill the entire product but also brush evenly on the glue. Each product should be brushed with at least three layers of silicone rubber. The thickness of each layer of silicone rubber is 1mm. In the process of brushing silicone rubber, it is required to brush another layer after each layer is cured. When brushing the third layer, add another layer on top of the second layer. Layers of gauze to increase the strength of the silicone. The thickness of the silicone part of the whole mold is controlled at 3-4mm according to the size of the product, and the width is not greater than 60mm of the product width. The time for the silicone rubber to start to solidify is 20 minutes.
Wash and dry the master mold and make it smooth (you can apply a layer of mold release wax or apply a mold release agent)
Put 500-1000 grams of mold silicone rubber (mold silicone, mold glue, silicone rubber, silicone) into a plastic basin for later use;
Weigh the hardener according to the weight ratio (usually 1.5-2.5%) and add it to the container for mixing, and stir well;
Add a certain amount of silicone rubber diluent depending on the situation (especially the first layer). Until the mixture is uniform, usually 3-5 minutes.
After the mold silicone rubber (mold silicone, mold glue, silicone rubber, silicone rubber) is mixed with the hardener, it will react at room temperature and release low-molecular-weight alcohol. minute. It is also possible to use no equipment (mainly depending on the operating experience of the molder)
For multi-layer brushing die, it is advisable to follow the inner, middle and outer curing at the same time. When the amount of curing agent is relatively small, the reaction time is prolonged, the reaction is sufficient, and the colloid is good. Therefore, the amount of curing agent is preferably less inside and more outside. When painting, wait for the first layer (inner layer) to dry before applying the second layer. The operation time is 30-50 minutes, and the demolding 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 improve the service life of the mold (but do not use glass fiber cloth, otherwise it will easily cause delamination and the entire mold will be scrapped)
The three-dimensional perfusion mold is generally cured for 10-15 hours.
After the soft mold is made, a plaster or glass fiber reinforced plastic jacket should be made to support the silicone soft mold
Note: 1. Die 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 a position where the mold itself is easy to demold; choose a position where the product is not easily deformed Blindly increase the amount of hardener, otherwise it will greatly reduce the service life of the silicone mold.
