What Is Silicone Extrusion Molding?
Silicone extrusion molding is a process used to create long, continuous shapes made from silicone materials unlike other types of molding, such as injection molding, extrusion molding is typically used to produce shapes that have a consistent cross-sectional profile, like tubes, rods, cords, seals, gaskets, strips, sheets, and custom profiles. This process involves feeding raw silicone into an extruder, which applies heat and pressure to soften the material. The softened silicone is then forced through a die, giving it its final shape. After the silicone is extruded and shaped, it is cured or vulcanized, causing it to harden and take on its final properties. The key features of extruded silicone include its excellent thermal stability, resistance to UV and ozone, flexibility, and biocompatibility. These properties make extruded silicone suitable for a wide range of applications in various industries, including medical, food and beverage, aerospace, electronics, automotive, and more.
Silicone Extrusion Molding
The Process of Silicone Extrusion Molding
Step 1: Preparation of the Silicone Material:
The raw silicone material, typically in the form of a silicone gum or high-consistency rubber (HCR), is prepared by mixing it with the required additives like colorants or catalysts to achieve the desired properties in the finished product.
Step 2: Feeding into the Extruder:
The prepared silicone material is then fed into an extruder, a machine that applies heat and pressure to the material to make it pliable. The extruder has a rotating screw inside a heated barrel, which pushes the material forward.
Step 3: Shaping the Material:
The pliable silicone material is forced out through a die at the end of the extruder. The die is a specially designed tool that gives the extruded silicone its specific shape.
Step 4: Curing the Extruded Silicone:
After being shaped, the silicone is then cured or vulcanized. This process involves exposing the silicone to heat, typically in a hot-air or steam oven, which causes it to harden and take on its final properties.
Step 5: Cooling and Cutting:
The cured silicone is then cooled and cut into the desired lengths, completing the manufacturing process.
Silicone extrusion molding is widely used due to silicone’s excellent properties, such as high thermal stability, flexibility at low temperatures, resistance to UV and ozone degradation, and biocompatibility. These properties make silicone extrusions suitable for various applications in industries like medical, food and beverage, aerospace, electronics, and automotive.
Silicone Extrusion Shapes
Silicone extrusion molding can be used to create a wide variety of shapes with consistent cross-sectional profiles. Here are a few examples of common silicone extrusion shapes:
(1) Tubes and Pipes: Silicone tubes and pipes are widely used in medical and food processing applications due to their resistance to temperature, chemicals, and UV radiation. They come in a variety of diameters and wall thicknesses.
(2) Rods and Cords: Solid or hollow silicone rods and cords are used in many applications, including sealing, vibration dampening, and insulation.
(3) Profiles: This is a general term that can encompass a wide variety of custom shapes, including U-channels, H-channels, D-shapes, P-shapes, E-shapes, L-shapes, T-shapes, etc. These profiles can be used for edge protection, sealing, guiding, or other applications.
(4) Seals and Gaskets: These are used to prevent leakage of fluids or gases in various applications, ranging from appliances to automotive to industrial machinery.
(5) Strips: Silicone strips are versatile and can be used in a variety of applications, including as weatherstripping for doors and windows.
(6) Sheets and Films: Silicone sheets and films are used in a variety of applications, including as gaskets, seals, insulators, and barrier layers.
It’s worth noting that the specifics of the shapes (like the size, thickness, and precise geometry) can usually be customized to fit the needs of the particular application. The silicone extrusion process is highly adaptable, and by changing the design of the die, manufacturers can produce a vast array of different shapes and profiles.
Typical Properties Of Extruded Silicone
Extruded silicone, also known as silicone rubber, has various properties that make it suitable for use in a wide range of applications. Here are some of the typical properties of extruded silicone:
(1) Thermal Stability: Silicone rubber can withstand extreme temperatures, typically ranging from -60°C to 200°C (-76°F to 392°F) and even up to 300°C (572°F) for unique formulations.
(2) Resistance to UV and Ozone: Silicone has excellent resistance to UV radiation and ozone, which can degrade many other types of rubber. This makes silicone ideal for outdoor applications where it will be exposed to sunlight and weather.
(3) Biocompatibility: Certain grades of silicone rubber are biocompatible, meaning they are safe for contact with human tissue. This makes them ideal for medical applications.
(4) Electrical Insulation: Silicone rubber has excellent electrical insulating properties, which make it useful for applications such as insulation for wiring and components in electronics.
(5) Chemical Resistance: Silicone rubber is resistant to many chemicals, including water, many types of acids and bases, and various solvents. However, it can be broken down by strong acids or bases and certain solvents.
(6) Flexibility and Elongation: Silicone rubber is flexible and can be stretched significantly without deformation. It also maintains its flexibility at both high and low temperatures.
(7) Low Toxicity and Odor: Silicone rubber is low in toxicity and does not emit harmful fumes or odors. This makes it suitable for food and beverage applications, as well as other sensitive uses.
(8) Low Compression Set: Silicone maintains its shape well after being compressed, meaning it is an excellent material for seals and gaskets.
(9) Resistance to Fungi and Bacteria: Silicone is inherently resistant to the growth of fungi and bacteria, making it suitable for applications that require high standards of hygiene.
Keep in mind, though, that the specific properties of a particular silicone extrusion can be tailored by altering the formulation of the silicone rubber, including the addition of fillers, catalysts, and other additives. As such, the actual properties of a given piece of extruded silicone can vary based on its specific formulation.
Applications of Extruded Silicone Profiles
Extruded silicone profiles are utilized across a wide range of industries and applications due to silicone’s excellent properties, like high thermal stability, resistance to UV and ozone degradation, biocompatibility, and flexibility. Here are some common applications of extruded silicone profiles:
(1) Medical Industry: In the medical field, silicone profiles are used in a variety of equipment. This includes silicone tubing for fluid transfer, seals and gaskets in medical devices, and strips for sealing sterilization trays. Silicone is biocompatible and can be sterilized, making it suitable for these applications.
(2) Food and Beverage Industry: Silicone’s resistance to temperature extremes and its FDA-approved status for food contact make it ideal for use in the food and beverage industry. Extruded silicone profiles can be found in oven seals, gaskets, tubing for fluid transfer, and sealing strips for food storage containers.
(3) Automotive Industry: Silicone’s heat resistance and durability make it useful in various automotive applications. This includes seals and gaskets for engine components, door and window seals, and tubing for various fluids.
(4) Aerospace and Aviation: The aerospace industry uses extruded silicone profiles for a variety of purposes, including seals for cabin doors and windows, gaskets for fuel tanks and engines, and insulation for wiring.
(5) Electronics and Electrical: Silicone’s excellent electrical insulating properties make it suitable for use in electronics and electrical applications. Extruded profiles are used as protective sheaths for wiring and cables, as well as seals and gaskets for electronic enclosures.
(6) Construction: Silicone extrusions are commonly used in construction for window and door seals, as well as seals for prefabricated elements, HVAC applications, and more.
(7) Industrial Machinery: Extruded silicone profiles are used as seals, gaskets, and tubing in a variety of industrial machinery, where they help prevent leaks, dampen vibrations, and insulate against heat and electricity.
These are just a few examples of the wide range of applications for extruded silicone profiles. The versatility and durability of silicone make it a popular choice for many other industries as well.
Custom Silicone Extrusion Molding
Mitour Custom Silicone Products specializes in silicone extrusion molding, which creates continuous shapes with consistent cross-sections. Mitour Custom Silicone Products, an expert in this field, can provide these products to meet various needs, catering to specifications required by different industries. With our expertise, you can expect high-quality, custom-designed silicone extrusions that meet your requirements. Reach out to us to discover more about molding process knowledge, such as Silicone Compression Molding, LSR Injection Molding, Silicone Overmolding or Silicone Dripping Molding and order bespoke, multicolored silicone rubber items today.