In recent years, more and more consumers have been attracted to silicone products due to their environmentally friendly, safe, and non-toxic characteristics, making silicone products a part of our daily life. As a result, newer customers are seeking custom development for their silicone products. Below is an introduction to the commonly used molding techniques for silicone products, the custom development process, and related considerations.
Common Molding Techniques for Custom Silicone Products
1. Solid-State Hot Press Molding
This method uses heat and pressure from a hydraulic press to shape and vulcanize silicone products. It is ideal for single-color custom silicone products but can also accommodate two-color, dual-hardness, and multi-color designs, including metal or plastic encapsulation. Encapsulated objects must withstand temperatures up to 180°C without deforming. Once molded, the silicone product can resist heat up to 230°C.
2. Liquid Injection Molding
This two-component, semi-transparent liquid silicone rubber is designed for injection molding. It is vulcanized from high-performance liquid silicone and processed using precise, stable injection molding equipment, creating an advanced manufacturing system. The process is fully automated. Simply loading the two liquid components (A and B) into the machine allows for automatic mixing and molding. This not only streamlines operations and reduces processing time but also ensures high-quality custom silicone products. The vulcanization temperature typically ranges from 110°C to 150°C, meaning embedded objects must withstand at least 150°C without deformation.
3. Extrusion Molding
Similar to pipe manufacturing, this process pushes silicone material through an extruder barrel where it is heated, shaped, and vulcanized. The die determines the final cross-sectional shape, making this method ideal for producing silicone strips, tubes, and other continuous profiles.
Silicone Product Customization Process
Step 1: Confirm Requirements
Once the customer has a complete idea for the product they are developing and provides the engineering 3D files (Stp, Step, Igs formats), we will evaluate the feasibility of silicone product customization based on these 3D files and engage in close discussions with the customer to assist with the design. To provide professional advice, especially in selecting raw materials, we must clearly understand the customer’s design concept and intended use.
For example, if the silicone product is needed for food processing, due to temperature and food safety requirements in the usage environment, food-grade silicone material needs to be selected. If it is a custom industrial silicone product, since the usage environment may involve frequent use or external impact and friction, the product needs to be elastic and wear-resistant. Therefore, we need to select raw materials that meet these characteristics for production.
Step 2: Provide a Quote
We will evaluate the production method based on the product characteristics, such as solid-state hot press molding, liquid injection molding, or extrusion molding. Evaluation points include:
- Feasibility of mold opening based on the 3D files
- Required quantity
- Required timeline
- Budget requirements
For the customized product, we will evaluate the sample mold cost, mass production mold cost, and product unit price.
Step 3: Confirm the Order
If the customer approves the quote, they will need to prepay the mold fee and deposit according to the payment terms outlined in the quotation.
Step 4: Sample Mold and Prototyping
Based on the customer’s requirements for product type, color, hardness, quality, and quantity, we will create a sample mold and prototype. After the silicone product sample is completed, the engineering team will compare it with the customer’s requirements. Once the sample meets the customer’s needs, it will be submitted for customer review. After receiving the sample, the customer will evaluate it. If the product meets the required standards, mass production can proceed. If the first batch of samples does not meet the customer’s expectations, feedback will be provided immediately, and we will revise or recreate the sample until the customer is satisfied before mass production begins. (Generally, a single-cavity mold is first created to save costs and facilitate modification after receiving the sample.)
Step 5: Mass Production Mold
Once the sample is confirmed, we proceed with creating the mass production mold. The number of cavities in the mold is chosen based on the product size and quantity. For some products, several sets of molds may be needed to simultaneously produce enough products to meet the customer’s delivery timeline. Therefore, silicone product customization pricing is not as simple as it seems; more details need to be understood to provide a better and more cost-effective solution. After the mass production mold is processed, a mold trial is conducted. The mold may need adjustments after production before it is finalized.
Step 6: Mass Production
Once the mass production mold is completed, the molding operator will begin mass-producing the silicone custom products required by the customer. The production will be done in shifts until the current order is completed before changing molds. (Supplementary: Before producing any silicone product, steps such as preparing materials, color mixing, rubber compounding, and cutting materials are required.)
Step 7: Post-Processing
After the batch production of the silicone custom products is completed, further post-processing procedures are necessary depending on the product’s manufacturing process. These may include semi-finished product processing or secondary processing, such as deburring, printing, spraying, laser engraving, labeling, surface treatment, etc. Through these post-processing steps, functionality and value can be added to the silicone finished product. For example, printing a logo to highlight the brand, laser engraving or labeling with production serial numbers for easy identification on the assembly line, and applying surface coatings for a smoother feel.
Step 8: Deburring and Quality Inspection
After removing the burrs from the silicone custom products, a quality inspection is required. A dedicated person will regularly inspect the products to ensure they meet the standard and are free from burrs, dirt, or other defects. If defects are found, the problem will be analyzed and resolved immediately to ensure all products shipped are of good quality.
Step 9: Packaging and Shipping
Once the silicone custom products are completed, they will be packaged according to the customer’s requirements. After the customer receives the silicone products, they need to inspect and store them. If any quality issues are found, please notify us for immediate resolution. Upon successful inspection and acceptance, the order will be considered completed.
Silicone Customization Size Limitations
During the silicone customization processing, different manufacturing techniques have their own product size limitations. For solid-state molding, the limitations are as follows:
- Product Size Limitations
Silicone customized products can reach a thickness of 30-70mm during the processing stage, depending on the shape of the product. If the size is long and thick, certain areas may experience improper curing. The curing time will also increase with thickness, so a general recommendation is to keep the thickness under 30mm.
The thinnest part of a silicone custom product can be between 0.3-0.5mm. Due to the stretching and elongation during the curing process, if the material is too thin, it may not stretch well. The thinnest part is typically 0.3mm, which should be determined based on the raw material properties and production parameters. - Product Size
The maximum size of silicone customized products during molding depends on the machine used. Typically, the machine size ranges from 150 tons to 500 tons and can achieve about 550-650mm. Our company has a rare 750-ton large machine that can handle oversized products. - Silicone Shrinkage Rate
Since silicone is an elastomer, there is a certain shrinkage rate between the mold and the silicone product. The general shrinkage rate for silicone custom products is between 1.022 and 1.045. Therefore, during the mold-making process, the shrinkage rate of silicone material is calculated. The mold will be made slightly larger than the 3D files. The softer the hardness, the larger the shrinkage rate. Each raw material has its own unique shrinkage rate, and even within the same batch of material, the shrinkage rate can vary. Additionally, the heating temperature and the number of cavities in the mold can cause slight differences in the finished products. - Silicone Hardness
The conventional hardness for solid-state silicone custom products ranges from 50 to 70 degrees, with larger values indicating harder products. Common silicone molding hardness is about 60 degrees, while for softer products, the hardness can be reduced to 50 or 40 degrees. Silicone hardness can be adjusted according to requirements. - Silicone Size Tolerance
Since silicone is an elastomer and multi-cavity molds are often used, there is a certain tolerance for silicone custom products. Generally, the tolerance is kept within the rubber standard tolerance.
What to Consider for Silicone Products
The properties of silicone products depend on the selected raw materials during production. The most important physical properties of silicone materials are:
- Hardness
- Elongation at Break
- Tensile Strength
- Tear Strength
- Resilience
- Compression Set
Below is a property chart for Shin-Etsu CHN-9000 series silicone materials:
1. Hardness
Hardness is the material’s ability to resist the penetration of a hard object into its surface. Silicone has a Shore hardness range from 0 to 80, giving designers the flexibility to select the required hardness for optimal functionality. By adjusting the proportion of polymer base, fillers, and additives, various intermediate hardness values can be achieved. Additionally, the curing time and temperature can also influence the hardness without damaging other physical characteristics. Silicone hardness can now range from SHOREA 0 to 90 degrees, with common hardness being 50-70 degrees. Hardness below 30 degrees is considered low, while above 70 degrees is considered high hardness silicone.
2. Elongation at Break
Elongation at break refers to the percentage increase in length relative to the original length when the sample breaks. The elongation at break for heat-cured solid silicone typically ranges from 90% to 1120%. Fluorosilicone has an elongation at break ranging from 159% to 699%. Liquid silicone typically has an elongation at break between 220% and 900%. The processing method and choice of curing agents can significantly affect elongation. Elongation is also greatly influenced by temperature. Lower hardness silicone has higher elongation at break, which can exceed 1000% in some cases. Fumed silica silicone typically has higher elongation at break than precipitated silica at the same hardness.
3. Tensile Strength
Tensile strength is the maximum tensile stress experienced by the sample during the tensile test before breaking. The tensile strength of heat-cured solid organic silicone ranges from 4.0 to 12.5 MPa. Fluorosilicone’s tensile strength ranges from 8.7 to 12.1 MPa. Liquid silicone has a tensile strength range of 3.6 to 11.0 MPa. Silicone’s tensile strength is usually below 10 MPa, reaching 11 MPa is more difficult, and 12 MPa is very hard to achieve. Generally, fumed silica silicone has higher tensile strength than precipitated silica.
4. Tear Strength
Tear strength refers to the resistance to tearing when a force is applied to a sample with a notch or cut. Even under extreme torsional stress, heat-cured solid silicone can resist tearing. The tear strength of heat-cured solid silicone ranges from 9 to 55 kN/m. Fluorosilicone has a tear strength range of 17.5 to 46.4 kN/m, and liquid silicone has a tear strength range of 11.5 to 52 kN/m.
5. Resilience
Resilience refers to the ability of a material to return to its original shape after being deformed by external force. Silicone is a highly elastic polymer material that is elastic at room temperature and can undergo significant deformation under small external forces. After the external force is removed, it can recover its original shape. Resilience is one of the important mechanical properties of silicone. High-resilience silicone can achieve a rebound value of 70 or even 80.
6. Compression Set
The compression set of silicone products relates to the elasticity and recovery of vulcanized silicone products. Elasticity and recovery are two interrelated properties. Some may think that good elasticity means fast recovery and low permanent deformation. However, this understanding is not enough. When silicone deformation is caused by the stretching of molecular chains, recovery (or the degree of permanent deformation) is mainly determined by silicone’s elasticity. If the deformation involves network destruction and relative motion of molecular chains, this part is considered irreversible and unrelated to elasticity. Therefore, all factors that affect silicone’s elasticity and recovery also influence the compression set of vulcanized silicone. The compression set rate can be as low as 5% or below, which is an important parameter for products such as silicone rollers and seals.
What Are the Advantages of Silicone Products?
1. Wide Temperature Range
Silicone has an excellent temperature resistance range from -40℃ to 230℃, with a heat resistance of up to 260℃. It can be safely used for cooking, offering good elasticity and stretchability. Whether in the oven or refrigerator, it maintains its functionality without cracking or expanding due to temperature differences. Therefore, silicone is a great choice for cooking and environments with extreme temperature conditions.
2. Safe and Non-Toxic
Silicone is made from natural minerals (silica), which is close to human skin in composition. It is non-toxic, free from heavy metals, and safe for use in microwaves and dishwashers. Silicone is also ideal for products used by infants, such as pacifiers, without the worry of toxins being released upon damage. It is suitable for skin-contact medical supplies and kitchen utensils that come into contact with food. FDA-certified food-grade silicone is commonly used in pacifiers, silicone tableware, and more.
3. Medical-Grade/Biocompatibility
Medical-grade silicone is a special type of silicone material widely used in medical devices and healthcare products. This material is known for its excellent toughness and durability, able to withstand high and low-temperature stresses. It also has good antibacterial properties and wear resistance. When silicone comes into contact with human tissue, it maintains excellent compatibility and minimal tissue reaction, offering long-term reliable performance.
4. Excellent Waterproofing
Silicone waterproof sealing materials usually have excellent sealing performance. They can effectively prevent moisture and other liquids from penetrating the surface, thus protecting objects from water damage and humidity. Different brands and models of silicone waterproof sealing materials may vary in sealing efficiency. Common silicone products include seals, O-rings, and more.
5. Durability and Long Lifespan
Silicone is a durable material that can withstand high and low-temperature stresses and has good wear resistance. The lifespan of silicone may vary depending on the brand and model, but most silicone products can provide a service life of at least 10 years.
6. Excellent Weather Resistance
Ordinary rubber degrades quickly under the effects of ozone generated by corona discharge, but silicone is not affected by ozone. Even with prolonged exposure to ultraviolet light and other weather conditions, its physical properties change only slightly. It is widely used in outdoor sealing materials.
7. Good Electrical Properties
Silicone is an insulating material with good electrical resistance. This means it can effectively prevent electrical currents from flowing through the surface of objects, protecting electronic devices from voltage damage. Silicone also has excellent resistance to high-voltage corona discharge and arc discharge, making it ideal for high-voltage insulators, TV high-voltage caps, electrical components, and more.
8. Conductivity
Silicone is an insulating material, but when conductive fillers (such as carbon black) are added, silicone becomes conductive. This makes it suitable for use in conductive contacts for keyboards, electrical heating components, anti-static components, high-voltage cable shields, and medical therapeutic conductive pads.
9. Flame Resistance
Silicone is a non-flammable material and cannot be burned. This makes it an excellent choice for protecting objects from fire hazards. When a small amount of flame retardant is added, silicone becomes flame-resistant and self-extinguishing. Since silicone does not contain organic halides, it does not emit smoke or toxic gases when burned. It is suitable for fire safety-critical applications.
10. Diverse Color Options
Silicone can be customized in various colors according to customer needs, including red, green, blue, purple, yellow, and transparent, among others. These colors can be achieved by adding pigments, allowing different brands and models of silicone to offer a variety of color choices.
Applications of Silicone Products
Silicone, made from silicon minerals refined into silica sand and then into silicon dioxide, is a highly active adsorbent material. It is insoluble in water and any solvents, non-toxic, odorless, and chemically stable, only reacting with strong alkalis and hydrofluoric acid. The structure of silicone varies depending on its manufacturing method. Its characteristics include high adsorption capacity, excellent thermal stability, stable chemical properties, and high mechanical strength. Silicone is also well-suited for industrial sealing and pressing needs due to its waterproof and insulating properties, ensuring the stability of products. In terms of temperature resistance, silicone can withstand temperatures ranging from -40℃ to 230℃, and its non-toxic nature makes it particularly suitable for use in the food industry and biomedical fields. Dafeng is a professional silicone factory focusing on custom silicone development, using food-grade silicone materials that meet the standards for food-grade products. These products are tested by SGS in Taiwan and offer professional silicone OEM services.
The list of applications are listed below:
1. Electronics Industry
The electronics and electrical industries were among the first to use silicone as an insulating material, and it remains a major field of demand. This is because high-temperature vulcanized silicone is resistant to both high and low temperatures, has excellent electrical properties, and maintains stable performance over a wide range of temperatures and electrical frequencies. Using high-temperature vulcanized silicone ensures the stable and reliable performance of electronic devices. Applications include electrical connectors, electrical sealing and shock-absorbing parts, high-temperature potentiometer seals, etc. Conductive high-temperature vulcanized silicone, which contains conductive fillers (such as carbon black, metal powder, etc.), can be used as conductive connectors (for buttons on electronic computers, remote control systems, electronic toys, telephones, and conductive connecting strips for electronic watches). Conductive silicone products are also widely used in microwave ovens, fax machines, and leadless integrated circuits. Silicone is also used extensively in televisions, with the high-voltage caps made of silicone. Insulators made from silicone are replacing ceramic products and are widely used in transmission lines, especially ultra-high-voltage circuits. Conductive silicone is used in electronic devices like computers, phones, and instruments for electrical contacts and LCD display touchpoints. Flame-retardant and radiation-resistant silicone wires and cables are widely used in nuclear power plants. Silicone heating sheets and heating tapes are used to control the working temperature of precision instruments and oil pipelines, and in medical applications, they are used in therapeutic heating blankets.
2. Automotive Industry
The use of silicone in the automotive industry is growing rapidly. Silicone (especially various types of silicone with specific properties) is resistant to fuel and lubricating oil corrosion, improving the performance of car parts and reducing maintenance costs. It is used in automotive ignition wires, spark plug protectors, heating and radiator hoses, muffler linings, battery terminals, and fuel pumps made from fluorosilicone. Rubber products near the engine and transmission, such as bushings, soft pads, belts, protectors, caps, and seals, need to withstand temperatures of 175°C, and some parts require resistance to temperatures above 300°C. In such cases, regular organic rubber is not suitable, and silicone is necessary. Silicone is also used in sealing high-temperature furnaces, low-temperature refrigeration box components, heat-treated product conveyor belts in metal processing, and heat-resistant glue radiators.
3. Food Processing Industry
Food-grade silicone uses newly imported food-grade raw materials and advanced production techniques, making it highly adaptable. It has advantages such as high transparency, odorless, non-yellowing, and no frosting. Food-grade silicone is an addition-type silicone that offers high transparency and stability, with a heat resistance of up to 230°C and no reduction in heating within sealed environments. Food-grade silicone is processed using scientific formulas and advanced techniques, offering features like flexibility and stable high-temperature performance. In today’s health-conscious world, food-grade silicone is gradually replacing food-grade plastic. Food-grade silicone products are primarily designed for items that come into contact with human food, such as silicone tubes, silicone mats, silicone sheets, and silicone woven tubes used in food processing. It is free of plasticizers and is widely used in coffee makers, water heaters, bread machines, sterilizers, water dispensers, electric kettles, steamers, deep fryers, juicers, and other kitchen appliances. Silicone is also used in food molds, such as chocolate molds, candy molds, cake molds, and silicone ice trays.
4. Mother and Baby Products
Silicone is an environmentally friendly material, and mother and baby products are made from food-grade certified silicone materials. Food-grade silicone has excellent properties, with high stability and temperature resistance from -40°C to 230°C. It is easy to clean, elastic, and flexible, so there is no need to worry about deformation, aging, or breakage. It is highly adaptable and can be used in various conditions, including oily, frozen, or high-temperature environments. Many mother and baby products are made from silicone, including silicone nipples, silicone baby bottles, baby bibs, teething rings, teething sticks, silicone spoons, silicone baby food containers, and other silicone products for babies.
5. Medical and Healthcare Applications
Silicone is non-toxic, highly biocompatible, and has good mechanical properties. It can withstand high-temperature sterilization without damage, has low biological reactivity, stable performance, and low blood coagulation. Silicone can endure high temperatures and high pressures through multiple sterilization cycles, and can be processed into various shapes such as films, sponges, and airbags. It is currently one of the most widely used materials in medicine. Silicone is used in blood transfusion tubes, various catheters, chest drainage tubes, cosmetic and reconstructive materials, artificial skin, implantable materials, drug release systems, biosensors, membranes, sponges, air sacs, and more. It can also be used to make various human organs, such as artificial larynxes, artificial lungs, retinal implants, artificial heart valves, esophagus, trachea, artificial joints, and prosthetics. When implanted in the human body, silicone can function just like the natural organ. For example, patients who have had their larynx removed can use an artificial larynx to quickly regain speech, eating, and breathing functions with no abnormal issues. Silicone applications in healthcare can be classified as: long-term implants for human organs or tissue substitutes, short-term medical devices in the human body, cosmetic surgical devices, drug release systems, and external products.
6. Wire and Cable Industry
Silicone is an ideal insulating material in the wire and cable industry. High-temperature vulcanized silicone is resistant to high temperatures, ozone, weather, and has excellent electrical properties. Even when it burns and decomposes, the silicon dioxide residue still provides insulation. It also has good thermal conductivity, efficiently dissipating heat generated by electrical loads. Its excellent arc resistance makes it suitable for high-temperature applications. Silicone-insulated wires and cables include power cables, marine cables, heating cables, ignition cables, nuclear power facility cables, and aviation wires. In high-voltage insulating cables, the addition of aluminum hydroxide filler can enhance silicone’s resistance to tracking, electrical erosion, and electrical arc damage.
7. Aerospace and Aviation
Aerospace materials need to perform in extreme conditions, ranging from -75°C to 200°C, with resistance to ozone, radiation, aging, and flame retardancy. Silicone is an indispensable high-performance material in the aerospace industry. It can withstand the extreme cold of space and the intense heat during re-entry into the atmosphere, extending the life of aircraft components, reducing maintenance costs, and preventing accidents. Silicone is primarily used in aircraft body hole seals, electrical connectors, sealing switches, dustproof and waterproof covers, gaskets, O-rings for jet engines and hydraulic devices, oxygen masks, control diaphragms, hot air ducts, and radar vibration dampeners. Burn-resistant silicone is used in rocket fuel valve covers, power source cables, and rocket launch pad coatings to protect against burns from rocket exhaust. Common silicone products used in this field include various hoses, seals, gaskets, boots, valves, shock absorbers, hot air ducts, switch covers, oxygen masks, fire-resistant partitions, instrument hoses, cushioning pads, electrical wires, cables, plugs, sockets, and switch buttons.
8. Other Applications
Silicone membranes made from high-temperature vulcanized silicone have excellent permeability, which is dozens to hundreds of times greater than that of general polymer membranes (such as polyethylene, PVC, PTFE, etc.). These silicone membranes also exhibit excellent selective permeability, allowing them to be used in various applications such as air vents for vegetables, fruits, and food preservation bags or storage rooms, and in manufacturing mixed gas separation devices. Silicone is also used in the sealing parts and gaskets for printing machines, pressure cooker seals, and other export tools.
Conclusion
Dafeng Manufacture focuses on customized silicone development, and its production processes have been certified with the international ISO9001 standard. The silicone materials provided by Dafeng Manufacture meets FDA and LFGB food-grade standards and have been tested by SGS in Taiwan. With many well-known representative clients in industries such as manufacturing, electronics, food processing, and medical equipment, Dafeng is a professional silicone factory and a leading silicone manufacturer in Taiwan, offering the best product development services for your needs.
