molde de silicona
- 2024-10-29
Los moldes de silicona son moldes especializados para la elaboración de artesanías. Las materias primas para herramientas de caucho se pueden dividir en silicona ordinaria y silicona meteorológica según sus propiedades. La silicona se caracteriza por su resistencia a altas temperaturas, resistencia a la corrosión, fuerte resistencia al desgarro y alta precisión de simulación, lo que la convierte en un molde para realizar diversas artesanías.
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Materias primas para moldes de silicona.
La silicona es cada vez más popular debido a su excelente desempeño medioambiental. Para comprender el conocimiento de los moldes de silicona, hay que comenzar con las materias primas de silicona.
1. Gel de silicona común, también conocido como gel de silicona precipitado.
Color: Translúcido, blanco lechoso, amarillo claro, gris, etc.
Dureza: 30°, 40°, 50°, 60°, 70°, etc., comúnmente entre 40°-70°.
Densidad: 1,1-1,12 g/cm³
Tasa de elongación: 400%
Uso: comúnmente utilizado en productos de silicona de gama baja, como botones de teléfonos móviles, artículos diversos, adhesivo conductor, etc.
Adhesivo meteorológico, también conocido como gel de silicona pura.
Color: Transparente.
Dureza: 30°, 40°, 50°, 60°, 70°, 80°, etc., comúnmente entre 40° y 60°.
Densidad: 1,1-1,12 g/c㎡
Tasa de alargamiento: 600% -700%
Características: Debido a su buena transparencia y fuerte resistencia a la tracción. Alto costo
Uso: Tubos de silicona, cubiertas protectoras y otros productos de alta gama que requieren alta elasticidad.
2. Las materias primas de silicona se pueden dividir en silicona sólida y silicona líquida según sus propiedades físicas.
La silicona sólida se utiliza principalmente para productos moldeados. Por ejemplo, fundas de silicona, vajillas de silicona, moldes de silicona, botones de silicona, etc. La silicona líquida se utiliza principalmente para productos extruidos como tetinas de silicona, tubos de silicona, etc.
Almohadilla de silicona con aislamiento térmico, excelente resistencia a altas temperaturas. La silicona (silicona de calidad alimentaria) puede soportar altas temperaturas de hasta 200 ℃ y puede utilizarse durante mucho tiempo. Los materiales de producción de este producto cumplen con los estándares de calidad alimentaria y han pasado las pruebas de calidad alimentaria de la FDA. Es inodoro y no tóxico. El fabricante produce según el molde y el color y la forma se pueden personalizar.
The choice of mold opening form and mold line is very important. Firstly, it is for the convenience of taking the mold. Secondly, the mold line should be selected so as not to affect the overall effect of the product. Thirdly, it should not affect the product quality. For example, the mold line position of the water feature series products is too high, and a lot of material is required for sealing the mold line, which can easily lead to product cracking; The fourth is to reduce the number of process operations, such as cutting half of the mold.
To prevent the silicone from flowing around, fix the mold seeds in a regular range with wooden blocks or boards. When opening the mold, separate the first part with wooden boards and oil sludge. It is required that there is no gap between the oil sludge and the mold seeds, and the surface of the oil sludge is smooth and flat. After the preparation of the above work, apply Vaseline or spray release agent on the gypsum mold or mold seed. Smooth products require a clean cotton cloth dipped in Vaseline and evenly coated on the mold seed. Keep it for 30 minutes to allow the mold seed to fully absorb Vaseline, and then wipe the surface of the mold seed clean with a clean cotton cloth. The surface should be shiny; For textured products, simply apply Vaseline evenly and adjust the silicone according to the formula. When mixing silicone gel, it should be stirred in an irregular direction to ensure that the curing agent and silicone gel are thoroughly mixed, minimizing the mixing of air into the gel. For smooth products, it is best to vacuum once when applying the first layer of gel, and the vacuum degree should be maintained at -0.1Mpa for 7-8 seconds.
After the silicone is prepared, it should be molded in a timely manner. Pour the adhesive solution onto the highest part of the mold using a drip flow method, allowing it to flow naturally. If the flow is not in place, use an oil painting brush to brush it in place. If it is a sheet mold silicone, not only should it fill the entire product, but it should also be evenly brushed on the adhesive. Each product should be coated with at least three layers of silicone, each with a thickness of 1mm. During the silicone coating process, it is required that each layer is cured before applying the other layer. When applying the third layer, a layer of gauze should be added on top of the second layer to increase the strength of the silicone. The thickness of the silicone part of the entire mold is controlled within 3-4mm according to the different requirements of the product size, and the width is not greater than 60mm of the product width. The starting time for silicone gel to solidify is 20 minutes.
1. Wash and dry the master mold, and smooth it out (you can apply a layer of release wax or brush it with release agent)
2. Put 500-1000 grams of mold silicone rubber (mold silicone, mold adhesive, silicone rubber, silicone) in a plastic basin for later use;
3. Weigh the hardener in a weight ratio (usually 1.5-2.5%) and add it to the container for mixing, stirring thoroughly and evenly;
4. Add a certain amount of silicone diluent depending on the situation (especially for the first layer). Until the mixture is evenly mixed, usually 3-5 minutes.
5. After mixing the mold silicone rubber (mold silicone, mold rubber, silicone rubber, silicone) with the hardener, the reaction occurs at room temperature and releases low molecular weight alcohols. To remove the alcohol molecules from the colloid, it is necessary to evacuate under negative pressure for 1-3 minutes. It is also possible to avoid using equipment (depending on the experience of the mold maker)
6. Multi layer coating film molds should follow the principle of simultaneous curing of the inner, middle, and outer layers. When the amount of curing agent is relatively small, the reaction time is prolonged, the reaction is complete, and the colloid is good. Therefore, it is best to use less curing agent inside and more outside. When brushing, wait for the first layer (inner layer) to dry before brushing the second layer. The operation time is 30-50 minutes, and the demoulding time is 10-15 hours. The maintenance time is 24 hours. It is best to add mold cloth after brushing the first and second layers, which can greatly improve the service life of the mold (but glass fiber cloth should not be used, otherwise it may cause delamination and render the entire mold useless)
7. Stereoscopic infusion molds are generally cured within 10-15 hours.
8. After the completion of the soft mold production, gypsum or fiberglass jacket should 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 location that is easy to process after grouting; Choose a location where the mold itself is easy to disassemble; Choose a position where the product is not easily deformed. 2. Do not blindly increase the amount of hardener to catch up with the production schedule, otherwise it will greatly reduce the service life of the silicone mold.
Why do silicone molds have fewer flipping times?
Too much silicone oil was added during the mold making process, which damaged the molecular weight of the silicone oil. As a result, the mold may have fewer flips and become less durable. If we use high hardness silicone to mold small products with complex patterns, there will be fewer mold flips because the silicone will be brittle and prone to breakage when it is hard for a long time. On the contrary, if silicone with low hardness is used to make molds for building products, the result will also be unsatisfactory. Because silicone is too soft, its tensile and tear strength will decrease, and the resulting mold will deform, resulting in a decrease in the number of mold flips. The quality of the mold adhesive itself is very good, and there is no distinction between good and bad silicone, only suitability and unsuitability. We need to use silicone that is suitable for the hardness of the product to make the mold, so that this situation will not occur.
Why does silicone mold burn out?
Due to the addition of peroxide curing agents to unsaturated resins and resin products, a large amount of heat is generated when the resin reacts. Generally, the resin curing time is 3 minutes, so it is necessary to demold as soon as possible after 3 minutes to prevent the silicone mold from burning out.
3. Methods for making silicone injection molds and slicing molds:
Splitting mold or sheet mold operation method: Apply the evacuated silicone by brushing or pouring. If you are making sheet molds or dividing molds and use brushing method, before brushing, apply a layer of release agent or isolation agent to the product or model you want to replicate, and then brush the silicone on the product (note: be sure to brush evenly). Wait for 30 minutes, then stick a layer of gauze or fiberglass cloth on the surface to increase strength, and then apply a second layer of silicone. After the silicone dries, make the outer mold. The outer mold can be made of materials such as gypsum or resin.
The operation method of injection molding or pouring mold: Injection molding or pouring mold is used for relatively smooth or simple products. It is to enclose the product or model you want to replicate with a rubber plate or glass plate, and pour the evacuated silicone directly onto the product. After the silicone is dried and formed, the product is taken out, and the mold is formed (note: injection mold generally uses silicone with relatively soft hardness to make the mold, which makes demolding easier and will not damage the products inside the silicone mold). The above is the entire process of using and operating the silicone mold.
Why does the silicone mold appear to be dry on the surface but not dry on the inside?
Mold silicone belongs to the condensation type silicone gel, which solidifies by absorbing moisture from the air. During the production process of silicone gel, the moisture is evaporated without adding an appropriate amount of moisture, resulting in this phenomenon. Solution: This phenomenon is not a product quality issue, but rather due to the failure to control moisture and improve the storage life of silicone. The phenomenon only occurs when the shelf life is long. As long as 0.05% moisture is added appropriately and stirred evenly when using silicone, some problems can be solved.
5. Why does the silicone mold have a difference in tensile strength?
Because in the process of making molds, customers add a large amount of silicone oil to the silicone in order to reduce its viscosity and make it easier to operate. This makes the silicone very soft, resulting in poor tensile strength, reduced tear strength, and decreased pulling force. As a result, the mold is not durable, has a short service life, and has fewer flipping cycles.
Why does the mold have oil leakage?
Mold silicone itself does not emit oil, and the occurrence of oil emission is due to the addition of composite silicone oil (a compound of silicone oil and white mineral oil) during the operation process, because white mineral oil is a petrochemical product, not silicone oil.
7. Why do molds have the phenomenon of not being resistant to acid and alkali, and not being resistant to aging?
In the process of making silicone molds, we recommend that customers do not add any silicone oil. If necessary, the maximum amount of silicone oil added should not exceed 5% to 10%. Due to the excessive addition of silicone oil, the molecular weight of the silicone gel will be damaged, resulting in molds that are not resistant to acid, alkali, and aging.
Why do molds made of silicone have surface marks, stripes, and roughness?
This phenomenon occurs because the product or model to be replicated has not been polished or polished. Because the actual model or product itself is not smooth or perfect enough, if the product or model to be replicated is not polished or polished, even the best silicone mold will not be aesthetically pleasing or smooth enough. Another situation is that when applying the release agent, not applying it evenly can also cause the mold to be uneven.
Do you know the wonderful uses of mold silicone??
Mold silicone is mainly used in the toy and gift industry, craft gift industry, furniture decoration industry, character reproduction, building decoration industry, resin craft industry, unsaturated resin craft industry, candle craft industry? The plastic toy industry,? The gift and stationery industry?, The gypsum craft gift industry, what,? The mold manufacturing industry,? Boli Industrial Products?, Product replication and mold making for various industries such as simulated animal and plant sculptures, Buddha carvings, and handicrafts.
Mainly used for toys, gifts, and products with fine patterns, for packaging and injection molding products, for glass crafts, lighting fixtures, candles, and character replication production molds, for large products, split molds, reliefs, Buddha statues, and craft gift production molds, shoe sole models, injection molds, and sand casting.
The various uses and specific operations of mold silicone are also different, and to achieve certain requirements, specific operations must be carried out according to different parameters.
We usually use sandblasting to clean production molds. First, we select a suitable mold cleaning sand (according to the shape of the silicone product mold), then introduce the mold cleaning sand into the sandblasting machine. Then, we also place the silicone product production mold into the sandblasting machine, align the sandblasting head with the mold cavity of the silicone product production mold, and gradually perform sandblasting treatment in the order of the mold cavity arrangement.
(s50c) is commonly referred to as 50 # steel in our industry, and its numbering varies depending on the standards of different countries (American standard number: AISI 1050~1055; Japanese standard number: S50C~S55C; German standard number: 1.1730). Some people in China also refer to it as medium carbon steel or 45 # steel, while in Hong Kong it is called ace steel. This steel has a hardness of HB170~HB220, is cheap, easy to process, has low cold deformation plasticity, poor welding performance and hardenability, but has no temper brittleness and decent cutting performance. Generally used under normalizing, quenching, and tempering, it is used for manufacturing with low wear resistance requirements. This steel is commonly used in ordinary silicone rubber molds.
(P20) This is what we often call p20 steel. Because of different standards in different countries, its number is also different (American, Japanese, Singapore, Chinese Mainland and Hong Kong standard number: AISI P20. German and other European countries number: DIN: 1.2311, 1.2378, 1.2312) P20 steel is a model of die welding material, which can be directly used for die making and processing with pre hardening treatment up to 285-330HB (30-36HRC), and has the characteristics of good dimensional stability. Only the pre hardened steel can meet the needs of general use, and the die life can reach 50W dies. If subjected to nitriding and hardening treatment, a high hardness surface structure can be obtained. The surface hardness after nitriding reaches 650-700HV (57-60HRC), and the mold life can reach more than 1 million times. The nitriding layer has the characteristics of dense and smooth structure, and the mold's demolding performance and resistance to humid air and alkaline corrosion are improved.
(S718) 718 mold steel is an improved steel grade developed on the basis of P20. 718 only adds 5HRC hardness to P20 steel, which greatly improves its quality and fills the gap of P20 mold steel, meeting the requirements of situations where P20 mold steel cannot meet the requirements. Steel specialties: polishing, electro etching, good weldability and machinability. Factory condition: hardened and tempered to HB290-330. Vacuum degassing refining process for pure steel, suitable for hot pressing molds that require polishing or etching processing. Pre hardened state supply, can be directly used for mold processing without heat treatment, shortening the construction period. After forging and rolling processing, the structure is dense, 100% ultrasonic inspection, and there are no porosity or needle hole defects. S136 steel is used in a quenched and tempered state (hardness 48-54HRC). In order to meet the long-term work or service life requirements of more than 1 million parts, a more suitable method of use is to achieve a hardness of 48HRC or above after quenching and low-temperature tempering treatment, which has better polishing properties and better corrosion resistance. Currently, it is the most widely used universal plastic and a typical steel grade for silicone rubber mold steel. It is commonly referred to as "advanced" hot pressed mold steel.
With the continuous improvement of quality in the hot forming mold market, there is a greater demand for the perfect combination of toughness, corrosion resistance, and overall hardness of mold steel. S136 has been proven to meet these requirements. Its factory hardness can reach HB250, and even after being priced at 200 degrees, its surface hardness can still reach HB220. It has excellent polishing and optical properties, excellent wear resistance, excellent machinability, and excellent stability during quenching. Therefore, after long-term use, the surface of the mold cavity still maintains its original smooth state. The mold does not require special protection when stored in a humid environment after operation. Greatly reducing production costs, due to the fact that the cooling water channel of the mold is not affected by corrosion (unlike ordinary mold steel), the heat conduction characteristics and cooling efficiency remain stable throughout the life of the mold, ensuring a constant forming time for the mold. Due to its special properties, it is more suitable for the needs of special environments. Excellent corrosion resistance and rusting properties make it more suitable for injection molding materials such as corrosive materials, acetates, or molds that must work and be stored in humid environments. Strong wear resistance, when using injection molding materials with high wear (including thermosetting injection molding molds) or requiring molds to have a long working time, such as electronic components, disposable cutlery, utensils, etc. High smoothness surfaces are used to produce optical products such as cameras, sunglasses, chemical instruments, and plastic products.
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