Silicone rubber components

Silicone rubber which is originated from silicon is basically a synthetic polymer. Silicone rubber bears good durability and is also non reactive in nature. These characteristics make it suitable to be utilized in kitchen utensils and medical devices. The question about the safety of silicone rubber started a comprehensive scientific research. The results of the extensive research indicated that silicone rubber is biocompatible and non toxic in nature.

These properties are considered vital when applications include food industry and medical sector. The regulations and safety standards devised by regulatory bodies are implemented and followed to ensure safety. However, there are environmental concerns which need to be addressed when production and disposal of silicone rubber is carried out. Silicone rubber proved to be safe for utilization in numerous applications which eliminates the concerns about its leaching and stability.

Is Silicone safe

Fundamentals of Silicone Rubber

Primarily silicone rubber is composed of following atoms.

  • Silicon
  • Carbon
  • Oxygen
  • Hydrogen

Silicone rubber is basically synthetic elastomers and is produced through polymerization processes. These processes involve the combination of silicones with different additives to acquire the required properties. These properties then depicts in the form of chemical resistance, flexibility and heat resistance. Silicon and oxygen bond exists in the molecular structure of silicone rubber. This bond provides the following two important properties.

  • Elasticity
  • Flexibility

These properties are the basic reason of its utilization in household items, kitchenware items, automotive seals and medical devices.

Understanding the Chemistry and composition of Silicone Rubber (Basics)

The composition and chemistry of silicone rubber varies from the following traditional rubber materials.

  • Styrene butadiene rubber
  • Natural rubber.

The characteristics and properties of silicone rubber are governed by its molecular structure.

Silicone rubber composition

There are three major portions which form the composition of silicone rubber.

  1. Silicone backbone

In silicone backbone a polymeric chain is formed by the alternating silicon and oxygen atoms. This backbone bears the following characteristics.

  • Highly stable
  • Resistant to chemical attack
  • Provide silicone rubber durability
  1. Organic group

There are organic groups in the composition of silicone rubber which defines and impart the properties and characteristics to the silicone rubber. These groups include methyl groups and phenyl groups. These groups are attached to the silicon atoms in the atomic structure of silicone rubber. Each group offers particular capabilities as follows.

  • Phenyl group increase the resistance to the oxidation and thermal stability
  • Methyl group improves low temperature performance of silicone rubber and its flexibility
  1. Cross linking

Cross linking is a very important phenomenon in silicone rubber which is achieved during the curing process. So in silicone rubber individual polymer chains are interconnected by chemical bonding. The process of cross linking enhances the following aspects.

  • Strength
  • Elasticity
  • Resistance to deformation when stress is applied

There are certain curing agents which are utilized to treat silicones during the curing process.

  • Peroxides for peroxide cure silicones
  • Platinum catalysts for addition cure silicones

Synthesis Process of Silicone Rubber

The synthesis process of silicone rubber involves following four steps.

  1. Raw materials

Silica sand is basic raw material which provides silicon dioxide. After that a chain of chemical reactions involve to retrieve silicon from silicon dioxide. This silicon is then further processed to produce siloxane units. Then ultimately the backbone of silicone polymers is formed by these siloxane units.

  1. Polymerization Process

In this process raw materials are transformed into polymers having long chains and cross linked structure. The oxygen atoms combine with silicone atoms to produce siloxane units. The phenyl or methyl organic groups which are attached with silicon atoms are used to carry out the modification in siloxane units. After that these siloxane units are polymerized to produce long chains which are in the form of network.

  1. Additives

The additives are added to get the required properties. However, carbon black and silica which are utilized as reinforcing filler provides following.

  • Stabilizers for heat
  • Resistance to ultra violet radiations
  • To enhance mechanical strength
  • Pigments for color
  1. Curing Stage

After the formulation of silicone rubber is completed the curing process is carried out. The curing process is performed to acquire the final elastomeric form of silicone rubber. There are two types of curing methods which are generally adopted.

  • Heat curing method (Heat is applied on silicone mixture and as a result of that curing agents are activated)
  • Room temperature vulcanization curing method (moisture of the air starts curing process).

Silicone rubber

Significant and Important Properties of Silicone Rubber

Silicone rubber offers very unique characteristics and properties. These properties make it very suitable to be utilized in numerous applications. Followings are the main properties of silicone rubber.

  • Exhibits excellent resistance to chemical
  • Non toxic and biocompatibility
  • Excellent heat and temperature resistance
  • Good resistance to weathering, ozone and ultraviolet radiations
  • Highly elastic and flexible
  • Excellent Electrical Insulator
  • Excellent durability and high tear resistance
  • Non sticking property because of low surface energy
  • Ease of processing to form complex and intricate products
  • Ability to be formulated to become transparent

Doubts about the Safety of Silicone Rubber- Is silicone safe?

Although silicone rubber is popular for its versatile characteristics including there are some concerns related to its safe usage. These doubts and concerns are associate with the followings.

Impurities and additives

There are certain additives and impurities which are added to achieve specific formulation of silicone rubber. This typical formulation is formed to enhance performance and to get the required properties. However, on the other hand these additives can be the reason of toxicity and adverse environmental impact. So it is important to ensure that safety regulations and standards are being followed by the manufacturers while handling these additives. The limits devised for the safe usage of these additives by the regulatory authority must be adhered. Generally following additives are used.

  • Pigments
  • Catalysts
  • Plasticizers
  • Stabilizers
  • Fillers

Release of organic compounds

It is important to note that certain compounds are released during the curing process. These compounds are organic and volatile in nature. These include the followings.

  • Solvents
  • By products of curing reactions
  • Residuals of chemicals from manufacturing process

The release of these compounds during the manufacturing process can pose various risks to human health due to prolong exposure including the followings.

  • Respiratory irritation
  • Exacerbation of asthma
  • Various potential long-term health effects

Extractables and Leachables

Silicone rubber is utilized to produce the items for food industry and medical sector. It is pertinent to mention that silicone rubber can release small quantity of the following substances into the surrounding environment.

  • Un-reacted monomers
  • Additives
  • Impurities

These substances are termed as leachables or extractables.The safety of these substances is based on these two parameters.

  • The chemical nature of released substances
  • The level of exposure

Keeping in view the usage of silicone rubber in food and medical sector it is important to ensure that the exposure limits set by the regulatory authorities for these released substances are being followed.

Applicability as a biomaterial

Silicone rubber is biocompatible but still there are certain concerns regarding the usage of silicone rubber as a biomaterial as mentioned below.

  • Potential for inflammation
  • Potential for tissue reaction
  • Immune response of the body to the silicone materials

In order to address the above mentioned doubts and concerns, medical grade silicone is subjected to series of testing and certifications are obtained to ensure the safe utilization of silicone rubber in biomaterial applications.

Impact on the Environmental

Generally, silicone rubber is considered non toxic and inert in nature but there are certain concerns which are related to its impact on environment. The major issue regarding this is the persistence of the wastage of the silicone in the environment because of the followings.

  • Silicone rubber is stable
  • Silicone rubber shows resistance to biodegradability

These adverse impacts on the environment can be prevented or minimized by ensuring the below mentioned steps.

  • Optimizing the effective disposal practices
  • Improving the recycling processes

Compliance of standards and regulations

This is the basic and most important concern which plays a vital role in the safe utilization of silicone rubber. The strict quality control of the silicone rubber products is necessary throughout the manufacturing process to make sure that required safety is being acquired. The standards and regulations devised by the regulatory authority need to be strictly implemented and followed. This is mandatory to ensure the followings.

  • Impurities are not above the specified level
  • Additive are not above specified quantity
  • Emissions are not above the specified values

 Safe Applications of Silicone Rubber

Silicone rubber provides safe utilization in many renowned sectors because of its unique characteristics. Major applications of silicone rubber are mentioned below.

Medical Sector

Silicone rubber is considered very suitable to be utilized in medical and healthcare sector because of its biocompatibility properties. There are two basic reasons behind this utilization.

  • Human body tolerate silicone rubber well
  • Immune response is not provoked

The utilization of silicone rubber in medical implants and medical devices is mentioned below.

  • Joint replacements
  • Pacemaker insulation
  • Soft tissue implants such as breast implants
  • Ocular implants such as intraocular lenses
  • Catheters
  • Tubing such as respiratory tubing
  • Feeding tubes
  • Wound drains
  • Respiratory masks (Because of the properties of resistance to bacterial growth, flexibility and durability which silicone rubber provides)

Food industry and cooking sector

There are regulatory bodies such as FDA which has approved the silicone rubber to be utilized in applications which involve contact with food. This kind of authentic approvals has provided the base of silicone rubber usage in food related products and kitchenware.

Followings are the main applications of silicone rubber in cooking utensils, food storage and bake wares.

  • Silicone spatulas
  • whisks, baking molds
  • Cooking brushes (Because they provide heat resistance, non-stick properties, and ease of cleaning as well)
  • Silicone baking mats
  • Cupcake liners
  • Ice cube trays
  • Food storage containers (They commonly used in households and commercial kitchens)

Consumer Products

Silicone rubber also finds its utilization in consumer goods because it offers durability along with safety. It is mainly used in personal care products, skin care items and baby products as mentioned below.

  • Silicone baby bottle nipples
  • Pacifiers
  • Teething toys (They are selected for their safety because silicone is hypoallergenic and completely free from harmful and dangerous chemicals like BPA and phthalates)
  • Facial cleansing brushes
  • Makeup applicators (a variety of products)
  • Hair care tools (Because it offers gentle touch and ease of cleaning)

Silicone rubber parts

Engineering and industrial applications

Silicone rubber bears excellent mechanical properties and is utilized in numerous industrial and engineering applications. Keeping in view the reliability and safety that silicone rubber offers, it is mainly utilized in following applications of automotive, insulation and sealing areas.

  • Seals and gaskets
  • O-rings
  • Spark plug boots (because silicone rubber provide resistance to automotive fluids along with durability)
  • Hoses
  • Insulation for electrical components (Because silicone offers resilience to extreme temperatures, UV exposure, and weathering)

Conclusion

Silicone rubber is has certain critical and important properties and characteristics which enable it to be considered safe for many applications. These properties include durability, biocompatibility, ease of maintenance and resistance to the chemicals. The applications range of silicone rubber covers many sectors such as medical, food and automotives. Regulatory bodies ensure the safety of silicone rubber by implementation of safety standards and regulations in all stages. The proper formulation and compliance to the devised standards and guidelines result in the production of safe silicone rubber.

Final answer for the question “is silicone safe“, the answer is Yes, the silicone is safety materials, go to silicone molding parts page to know more.

silicone parts

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.

Silicone molding parts

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.

molded silicone parts

molded silicone parts

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.

silicone cookare molds

silicone cookare molds

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.