How to Make A Silicone Prototype

Do you need to do some test pieces for product development? Do you know about silicone prototypes? Doing it wrong once before mass production can waste a lot of cost. Silicone prototyping can validate the design, structure, and performance in advance and reduce the production risk. In this article, we will introduce you to the complete steps to help you make faster decisions and take fewer detours.

What is a Silicone Prototype

Most of the products on the market will not be designed directly for production. Silicone prototypes are samples that help test the functionality of a product made of silicone material before high-volume production. Engineers can use it to verify whether the design structure is qualified, and to assess performance and production feasibility. If there is a problem can be found in advance, so as not to cause a lot of material waste and cost investment in mass production. This can greatly reduce the risk of mass production for enterprises, making the product more mature before flowing into the market.

Compared to plastics and resins, silicone prototypes are the closest to the final product’s performance in terms of elasticity, temperature resistance, and chemical stability. Silicone prototypes vary in structural complexity and precision requirements, and are produced in different ways. There are several types, such as rubber molding, compression molding, and liquid injection molding.

How To Make a Silicone Prototype

Step 1: Silicone Part Design

The quality of a silicone prototype is generally determined at the design stage. Proper design can lead to a higher molding success rate and also reduce the cost of later modifications. In the early stages of designing a silicone part, special attention needs to be paid to these points: wall thickness, inverted construction, tolerances, and the environment in which it will be used.

Uniform Wall Thickness

Maintaining uniform wall thickness is not just about aesthetics; it also leads to a more stable structure and more accurate dimensions. If the wall thickness is not uniform, localized deformation, shrink marks, and warping will occur. Nor is a thicker wall better. Because it will increase the heating time, vulcanization time, and cooling time, and also increase the amount of raw materials, input costs.

Avoid Complex Inverted Structures

Overly complex structures can make silicone prototypes difficult to demold. There will also be problems with mold misalignment, silicone tearing, inaccurate dimensions, and batch instability. This will increase the processing time and the investment cost of producing the molds. If any problem occurs in the middle, rework will be required, which will prolong the prototype delivery cycle.

Allow for reasonable tolerances

Silicone is an elastic material and will exhibit thermal expansion and contraction with temperature during manufacturing. Therefore, due to the material properties of silicone, there is no way to achieve no dimensional deviation even with high-precision molds. If there is no deviation, the finished product manufactured may not match with other parts and cannot be used.

Considering The Use Environment

It is very important and difficult to consider the actual use environment of the silicone prototype during the design phase. It is important to comprehensively consider the environmental factors that have an impact on the performance of silicone, such as temperature changes, humidity, water vapor, chemical exposure, UV exposure, and long-term stress. If a person does not consider them properly, the life of the silicone prototype will be shortened, affecting the normal use of the function. Evaluating these conditions in advance will help to ensure that the prototype works reliably in the real use environment.

Step 2: Choose the Right Silicone Prototyping Technology

3D Printing

3D printing is the use of raw materials to print layer by layer, so that it can be molded quickly. It can be used to print models and create master molds. This prototyping technique allows for the rapid printing of complex geometric structures without the use of additional molds. This technology is suitable for low-volume prototyping, testing of complex shapes or structures, and early design proof-of-concept. However, it is limited in available materials and is not as flexible or durable as silicone. It is also limited in surface smoothness and requires post-processing.

Silicone Casting

In this technique, a master mold is made, and then liquid silicone is introduced into the master mold and cured to form the prototype. This utilizes the biocompatibility of liquid silicone to replicate high-precision details. With a master mold, different types of silicone materials can be selected to simulate the feel and performance of the final product. However, master molds are costly to produce, the waiting time for silicone to cure is long, and the durability of the molds is limited. So it is suitable for small batch production. It is more suitable for verifying high-precision details and function testing.

Silicone Molding

This prototyping technique looks the same as Silicone Casting, which involves pouring liquid silicone into a mold, but in reality, they are significantly different in terms of production process, purpose, mold type, usage scenarios, etc. Silicone Molding is mainly used for mass production and high-precision replication. The type of molds used is durable and rigid, and can withstand multiple injections or presses so that prototypes can be produced with a high degree of dimensional consistency. However, the high cost of the molds and the long lead times make this method unsuitable for producing very small quantities of prototypes. It is suitable for small to medium volume production and manufacturing functional prototypes.

Step 3: Choose Silicone Material

If you want a prototype with greater mechanical strength, structural stability, and reduced cost investment, you can choose HTV. If your product is structurally complex or if the prototype has a high throughput, LSR would be more suitable.

High Temperature Vulcanized Rubber (HTV)

HTV is generally known as solid silicone, an elastic solid material that can be kneaded and deformed, usually in the form of flakes or granules. It is first molded or transfer molded and then heated for high-temperature vulcanization, and finally, the elastic parts are formed. The material contains a relatively high percentage of silica inside, which gives it higher mechanical strength and better resistance to tearing, abrasion, and dimensional stability.

It can maintain stable performance from -50 to 200 degrees Celsius. There is also chemical corrosion resistance and electrical insulation properties. It’s simple, low-cost mold construction makes it suitable for low to medium volume production or for “heavy duty” applications. When making ultra-thin structures with complex details, HTV can be very difficult to process, and stability cannot be guaranteed.

Liquid Silicone Rubber (LSR)

LSR is a liquid silicone rubber system made by mixing two-component fluids. It is injected into heated molds by precise dosing and mixing, and cures faster. It is more fluid than solid silicone and can be used to fill complex or ultra-thin structures and improve mechanical strength. Because it contains a large amount of silica, it makes LSR have good tear, abrasion, and dimensional stability.

Its temperature resistance ranges from -50 to 250 degrees Celsius. It has good biocompatibility, requires high mold precision and equipment automation, and the upfront investment is greater thanthat of solid silicone. It is not suitable for a small amount of prototyping; the cost is very high. However, it is suitable for large-scale production and has advantages in efficiency and stability.

Step 4: Create Silicone Prototype Mold

Designed drawings, selected materials, and production technology, but did not immediately put them into production. This important step also requires a DFM of the 3D drawings of the product. This step is mainly for engineers to verify whether the main design points are reasonable. For example, to assess whether the wallpaper is uniform, whether there are structures that are difficult to release, and whether there are deviations in size. And predict the shrinkage of silicone in molding.

Then you need to choose the right mold material, usually aluminum or steel. Aluminum molds are fast to process, cost-controlled, and suitable for practical verification or functional testing. Steel molds are durable, can be used many times, and maintain better dimensional stability at a higher cost. Next, design the parting and demolding structure appropriately. Place the parting line in a discreet position and leave sufficient space for mold release. Avoid a lot of burrs and tears. In order to avoid air bubbles and high temperatures in production, optimize the exhaust and control the temperature.

Step 5: Compound And Mix Silicone Materials

It is at this stage that the silica gel material is started to be processed. Strictly mix according to the proportion of the designed formula, fully stirring and mixing, so that the catalyst, crosslinking agent, and filler are evenly dispersed. Otherwise, the material will be partially soft, not strong enough, and have inconsistent curing, affecting the reliability of the prototype.

This mixing process will inevitably bring in air bubbles, and the need for mixing, vacuum defoaming, to improve the density and appearance of the molded aesthetic. During this period, to control the operation time, temperature, and humidity, these factors will affect the quality of the prototype. After these previous links are well controlled, you can mix and test before formal production to verify that the hardness, color, and fluidity are in line with the expected results.

Step 6: Cut And Mask Silicone Material

This step prepares the silicone before molding. The silicone material is cut to fit the mold, and the areas that need to be protected are masked in preparation for compression molding. It is also important to mask the areas that require subsequent processing to prevent contamination, which can affect the coloring and adhesion of the coating.

Step 7: Load Silicone into the Molding Tool

This step involves placing the well-mixed and cut silicone material into the mold. Take care that the mold is clean and dust-free. The two types of silicone materials mentioned earlier are LSR, which is injected into the mold by injection or by hand, and HTV, which is cut and placed directly into the mold to heat it up. The difficulty in this step is the amount of silicone material that needs to be controlled; it needs to be neither too much nor too little. If it is too much, it will overflow; if it is too little, it will not be able to be molded. This process will also produce air bubbles, exhaust processing sports needs. Generally, use the exhaust port or vacuum exhaust.

Step 8: Vulcanize Silicone Prototype

The silicone material loaded into the mold is heated, and the liquid silicone undergoes a cross-linking reaction to become an elastic and strong solid, which is called vulcanization. The prototype made by this process, its mechanical properties, size, and surface quality will be directly stereotyped by this step. So this step should strictly control the temperature, pressure, and time. Avoid problems such as deformation, air bubbles, incomplete curing, and so on.

Step 9: Demolding Silicone Prototype

The vulcanized silicone has been molded at this point, but it is still in a high-temperature state. Wait for cooling and carefully remove the silicone prototype. The force and angle when removing is delicate. If not controlled properly, the prototype may be deformed or torn. Some complex structures, or thin walls, need to be treated more carefully. Professional mold release agents can be used. After the prototype is taken out, it is necessary to immediately check whether the surface quality is acceptable, whether the size is appropriate, and whether the structure is complete. If all these checks are qualified, then trimming, surface treatment, function testing, and other subsequent work will be carried out.

Step 10: Deflash Silicone Prototype

Silicone materials are highly fluid, and during the molding process, the material will flow into the gaps of the mold and form fringes as it reacts to heating and vulcanization. After demolding, these fringes need to be removed. Cutting and trimming are required to maintain a neat appearance and dimensional accuracy. There are usually three ways to do this: hand trimming, freezing to remove the fringe, and precision punching. This is a delicate job, and it is important not to over-cut the prototype and leave it structurally incomplete, thus compromising sealing and structural strength. After trimming, you need to check the product again to see if the appearance and size are qualified.

FAQ

How long does it take to make a silicone prototype from start to finish?

It takes 3-7 days to make small or simple prototypes (3D+LSR).

Medium or complex prototypes (need to flip molds, small injections) will take 1-2 weeks

High precision or high volume prototypes will take 2 weeks to 1 month.

What is the difference between a silicone mold and a silicone prototype?

Silicone prototypes are functional samples made from silicone materials. The purpose is to verify whether the design, size, flexibility, and function are feasible and manufacturable.

A silicone mold is a tool or mold made out of silicone material. Although both are silicone products, it is a tool used to replicate the shape of other materials; it is not the product itself.

What affects the cost of making a silicone prototype?

The type of material, complexity of design, type of mold, and production requirements all affect the cost of a silicone prototype. The better the material, the more complex the structure, and the more detail, the cost increases. Metal molds can be costly. Larger sizes and more processes will also increase labor and time costs.

Is silicone prototyping suitable for functional testing or only for visual models?

The silicone material of the silicone prototype has good elasticity, temperature resistance, and durability, so the following aspects can be tested according to its own material properties: mechanical properties, weather resistance, comfort and fit, and functionality. Mechanical properties include sealing, elasticity, and tear resistance; environmental adaptability includes resistance to high and low temperatures, chemical liquids, etc.; and comfort includes wearing feelings and fit. These prototypes can be verified before mass production.

What are the applications of silicone prototyping in medical devices and healthcare?

Silicone prototypes make high-performance, precise, comfortable, and safe medical devices and accessories that meet medical industry standards. It is very biocompatible and temperature resistant, and can be suitable for prosthetics, surgical instruments, seals, medical tubing, and more.

How is silicone prototyping used in consumer electronics and wearables?

Silicone prototypes can be used in the consumer electronics industry mainly because of their comfort, durability, flexibility, and water resistance. Silicone enhances the user experience of the device and also ensures durability and functionality. It is often used to make protective cases, headphones, smart watches, buttons, seals, and other areas of use.

Can silicone prototypes be used in food-safe tools and packaging?

Can. Because silicone prototypes are chemically stable, they do not release toxic substances and are heat-resistant and durable. It is very suitable for use in food safety tools and packaging. It is widely used in baking tools, baby feeding products, food storage, kitchen tools, food packaging, etc. It can provide a safe and reliable solution.

What role does silicone prototyping play in automotive components?

Silicone prototypes have sealing, high temperature resistance, chemical resistance, and electrical protection. That’s why they are often used as seals, hoses, interior components, electronic protection, and engine compartment parts. These applications enhance the performance, comfort, and durability of automobiles and help them maintain long-term stability even under extreme conditions.

How are silicone prototypes used in custom jewelry and design?

In custom jewelry and creative design, silicone prototypes are often used in the product development phase to validate shapes and replicate fine lending, which reduces the cost of trial and error. For example, to check whether the size proportion and structure are reasonable. Whether it is comfortable to wear. If it doesn’t fit, you can then adjust it until the prototype meets the design expectations.

Are silicone prototypes suitable for DIY and low-volume production?

Silicone prototypes have a short turnaround time, making them ideal for startups and entrepreneurs. The short time from design to finished product allows for quick verification of whether the design makes sense and how well it works. You can get the ideal product before mass production. Reduces the risk of developing a product.

Final Thought

Silicone prototype is an important link to make the design landing, it can be used in product mass production experiments in all aspects, whether qualified, whether it is necessary to then adjust, and can help enterprises to find out the problem in advance, optimize the program. Reduce the cost of developing products and enhance the success rate.

What kind of prototype determines the upper limit of the product later, so it is important to choose an experienced manufacturer. Legensilicone can provide suitable material suggestions according to your design, but also with their own professionalism to help you optimize the design of the mold, and improve the overall product quality development rate. With our advanced production equipment, we can produce silicone prototypes with complex production structures and restore the details of structural design on the basis of reasonable design. If you want to make your product fast and stable and realize mass production, come and contact us.