Silicone molding parts have become an adaptable plastic fabrication technique. From toy making to shaping custom silicon internal auto car prototypes, silicon molding parts plays a significant role. It yields parts with high dimensional accuracy and tolerances to +/- 0.005x. Before going into in-depth details, it is important to understand some basic concepts related to designing and molding silicon parts. There are a few basic concepts for designing silicon molds that one must need to understand. Let’s discuss these briefly;

What is Silicone Molding?

It is the use of silicone to shape products that can be used. Silicone molding uses diverse methods to get a final product. They include using the block method which is the simplest. It is mixed with other products like liquid soap to get a finer design.

Silicone molding creates flexible materials. It casts a number of items such as polyester, polyurethane wax, plaster, and concrete. Other materials include epoxy resins and polyurethane foam. It makes the materials stronger and chemical resistant. This gives the materials a longer life span.

Design Steps For Silicone molding parts

Step 1: Adjust the Gate Location

Ideally, gates should be located on a silicone part’s hidden and insignificant faces. Since LSR is a flexible material, several gate types are available, and the two most common types are direct gating and sub-gating. Direct gating channels the silicone directly into the mold cavity through the runner system, while sub-gating directs the silicone under the mold cavity to a particular area on the lower part of the component.

Step 2: Parting Lines

Before proceeding with the creation of the mold, it is necessary to decide on the position of the parting line, which is the area where the two halves of the mold are connected and where the silicone part will be located. Typically, the flashing area is found at the parting line of a molded part. Therefore, parting lines should be placed on second and third-level surfaces that are not as noticeable inside the molds.

Step 3: Part Shrinkage

Some of the difficulties that are expected to be observed when molding silicone parts include shrinkage, which ranges between 2-4% of the molded silicone parts.   If a higher quality fabrication is required, then additional steps may be required, and the use of these parts should be taken into account. However, some of them may decrease by an extra 1% from their designed sizes after the molding process.

If a higher quality fabrication is desired, then more steps may be needed, and the application of these parts should be considered.  Nevertheless, certain parts may shrink by an additional 1% from their designed dimensions after molding. Medical component molding can be divided into several types depending on the type of material, size, volume, and molding technology used, among other factors. This article specifically discusses silicone injection molding from a depth perspective.

High Consistency Rubber (HCR) Silicon

HCR has a high viscosity and resembles peanut butter. Usually, It can be catalyzed with either platinum or peroxide. For compounding, a two-roll mill is used with the base material. HCR can be injection molded using two main methods: Compression molding and transfer molding are two of the most important types.

Compression Molding

As the name implies, the material is compressed between the two heated plates in compression moulding. These plates are then compressed, and the material that has been extruded between the two halves is squeezed out along the parting line. However, compression molding is an older technology to mold silicon parts. Despite this, it’s still one of the most affordable ways of fabricating custom molded silicone parts

in small volumes.

Transfer Molding

Transfer molding is somewhat similar to compression molding where high pressure (approximately 1500 to 2000 psi) is used to force the material into a mold cavity. However, it differs in that it employs a runner, sprue and gate system to transfer the material. This method is especially important when it comes to manufacturing silicone parts at low to medium production volume per year.

Overmolding

Afterwards, the silicone material is laminated to the substrate, which gives the final product the characteristics of both materials. This process often employs LSR molding equipment and specific tooling to enhance productivity in the production line. However, some difficulties can be encountered; for example, the insert may be misplaced, which can harm the tooling.

Two-Shot Silicone-Thermoplastic Molding

Like in overmolding, two-shot molding also involves the use of silicone and thermoplastic materials.  First, the first part is injection molded into one half of the mold; then the second part is overmolded silicone onto the thermoplastic molded in the second half of the mold.  Once the mold is opened, the silicone molded parts are released, and the thermoplastic parts are transferred to the silicone overmold side of the mold.  This technology is quite different and involves the use of high temperature resistant tools, self-bonding grade LSR material and skilled personnel to fabricate the required parts.

Difference Between Rubber & Silicon Molding Parts

Rubber molding and silicone molding are two processes with unique features and use. Rubber molding involves high temperature and pressure, whereas silicone molding is carried out at room temperature. This is one of the main differences between the two methods, as the temperature requirements differ significantly.

In rubber molding, a release agent is always needed to prevent the material from sticking to the mold. On the other hand, silicone injection molding usually does not require a release agent, which is beneficial. Moreover, rubber molding is not always accurate and may produce intricate shapes and designs with slight deviations from the original form. Silicone molding, however, is easier to perform and gives shapes that are closest to the mold or the casting material.

Rubber molding mainly generates hard and rigid products, while silicone molding mainly generates products with high chemical resistance. In addition, rubber molding products have low shrinkage rates, meaning they can be stored and used for long periods. On the other hand, silicone products are known to shrink a lot, which poses a problem in storage.

Therefore, rubber molding and silicone molding create numerous designs and shapes; however, they differ in the final products and materials. Rubber molding is particularly useful for producing sturdy and durable parts, while silicone molding produces parts with good chemical resistance. All these methods are important and have their specific roles to play in the manufacturing process.

How does LSR Injection molding work?

Liquid silicone injection molding begins with the CNC machining of the molding tool. This tool is important because it must endure high temperatures during the process. Once the tool is fabricated, it can be sanded to various surface finishes depending on the desired outcome.

The tool is then placed into an LSR-molding machine to start the process. These machines’ presses are designed to have a high level of precision in shot size to enable the production of rigorous quality molding silicone parts. T. LSR is a type of thermosetting polymer, and once it is molded, it cannot be remelted like other thermoplastics resins.

 

After the LSR parts have been injection molded, they are ejected from the mold and can be used as prototype parts production. Injection molded silicone rubber is a flexible material that can be used in various applications across different sectors, such as the medical, lighting, and automotive industries.

Uses of Molding Silicon Parts

LSR injection molding has a wide range of applications and benefits. It uses pellets made from plastic to mold, making it easier to produce parts and components efficiently. LSR molding has several benefits, including high durability, which makes it ideal for applications that demand the use of parts that can withstand great stress. Also, LSR has a broad range of hardness that can be used to produce products with different hardness levels or elasticity to suit a certain purpose.

 

LSR molding is mainly used to create gaskets, flanges, and cushioning pads in portable communication equipment and ruggedized electronic products. Its durability and ability to perform in extreme conditions suit these and many different applications. LSR injection molding is flexible in terms of molding and designing products, and therefore, it can be used in various product designs and uses. Some characteristics of the material include its high degree of hardness, the ability to reach a wide range of hardness levels, flexibility, and the capacity to meet a wide variety of high-performance requirements in numerous industries.

Design Guide For LSR Injection Molding Parts Fabrication

Several aspects need to be considered when designing for LSR injection molding to increase the effectiveness of the molded parts.

Undercuts add to the complexity and cost of the tool ejection mechanisms, so they should be used sparingly. Another way to minimize the use of undercuts is to integrate pass-thru coring into the design. Undercuts ensure that the parts are ejected from the mold correctly. Therefore, these parts must be designed at minimum draft angles of 0. 5° and up to 5° to facilitate ease of demolding after a shot.

The thickness of the wall is also an important factor that affects the quality of the final product. It also ensures no problems, such as wall sinks and voids in the structure’s wall. Thinner walls are also beneficial in terms of cutting down the cycle time and the total cost of production.

Ribs and gussets are structural elements that should be designed very carefully. The rib’s thickness should be 40-60% of the outer walls while maintaining the necessary draft. This helps provide adequate support to the mold design without exerting excessive pressure.

Hole bosses should be drilled to 30% of the wall thickness. While the edge groove should be 30%. The bosses should best be secured to side walls or ribs to enhance structural behaviour. This design consideration makes the part strong and durable to withstand the test of time and usage.

By following these guidelines, designers can obtain the best LSR injection molding practices, which will help them produce high-quality and relatively cheaper parts at an affordable budget.

Contact Sincere Tech For High Standard Quality Molding Silicone Rubber Parts

Sincere Tech is a professional company that provides custom silicone molded parts services. We have gained the trust and confidence by providing our customers  Rubber Molding Parts & Silicone Molding Parts at competitive prices. Our skilled professionals manufacture this product using advanced technology and quality material to ensure durability and high tensile strength. Moreover, with its superior stability, it is a naturally preferred elastomer for diverse applications, as much as in diverse environments.

We use advanced technology and assure our clients about the optimum performance. Further, we put great emphasis on continuous improvement of the product to ensure it has superior performance to save more labor costs for customers. We are involved in manufacturing and supplying a quality range of  csutom Silicone Molded Parts which is produced using high-grade raw material that is sourced from our respected vendor base, having years of experience in the market.

In addition, these are extruded to manufacture products that can be obtained in both solid and sponge characteristics on multiple extrusion lines. We provide these products with different gradations in size and specifications customizable as per the clients’ exact needs. Our range is in high demand by our client spread across the international market and can be availed at industry leading prices.

Molding can be done using two different materials. It can be rubber or silicone which are both unique. To mold the products, you need a number of items for each of them. Rubber molding and silicone molded parts have the same end result. However, there are distinct differences between the two. Our products include rubber and silicone molding parts, which are good quality and cheap.

• We use appropriate tools and quality materials to ensure the parts’ structures are strong and durable.
• Our products guarantee optimum performance and ongoing improvement to reduce the cost of manpower.
• Our products come in solid and sponge characteristics, and flexibility can be offered to suit the client.
• Our portfolio products satisfy international demands, and stringent ISO and FDA standards and are reasonably priced in the market.
• At Sincere Tech, our team of engineers and advanced silicone production equipment ensure that we meet all your silicone mold rubber requirements.
• Rubber molding and silicone molding are two of the most common types; each has benefits and uses.

Conclusion

In conclusion, LSR injection molding has several advantages: durability, hardness range, and versatility. It can also employ pellets of plastics to ensure its production lines are precise and effective. From gaskets to cushioning pads in electronics, LSR molding is a reliable approach to producing stiff yet elastic parts. This type of injection molding is suitable for various industries and can create intricate designs, which is why it is preferred by companies that aim to produce durable and high-quality products.