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Overmolding is a molding technology widely used in the manufacturing field. It coats one material on the surface of another material to enhance the functionality, aesthetics and added value of the product. This article aims to comprehensively analyze the main material types involved in overmolding technology, as well as their unique advantages and limitations in different application scenarios.

What is overmolding？

Overmolding is a production processthat focuses on combining soft thermoplastic elastomers or similar materials with rigid plastic or other substrate materials through injection molding or wrapping to create a composite structure with specific functional properties and aesthetic appearance. This process is widely used to improve the feel, anti-slip effect, visual beauty of products, and enhance product durability and ergonomic design.

What Materials Are Used in overmolding？

Overmolding is a commonly used manufacturing process that involves a wide variety of materials. Today, we will focus on four types of materials in this section, including thermoplastics, elastomers, metal materials, and composites.

1. Thermoplastics

(1) Polyethylene (PE)

• Characteristics:Tough and resistant to chemicals and temperature changes, with good electrical insulation.
• Application:Widely used in the manufacture of plastic bags, plastic wrap, foam boxes and other packaging materials, as well as construction insulation materials, pipes, mulch films, etc. In the electrical aspect, it is used as a cable sheath material. In addition, it is also used in the manufacture of medical equipment, surgical utensils, etc.

(2) Polypropylene (PP)

• Characteristics:white granules, tasteless, non-toxic, low density, high melting point, good electrical insulation and impact strength. It is easy to process and can be molded by injection molding, extrusion, blow molding and other methods. Corrosion-resistant, chemically resistant, can be used in food contact materials.
• Application:Used in the manufacture of auto parts (such as bumpers, wheel shells, etc.), household appliance parts (such as refrigerator parts, washing machine troughs, etc.), packaging materials (such as food and beverage containers, packaging films, etc.), construction pipes, pipe fittings, etc. In addition, it is also used in the manufacture of daily necessities (such as edible tableware, basins, baskets, etc.) and medical devices (such as medical syringes and containers, infusion tubes, etc.).

(3) Polystyrene (PS)

• Characteristics:According to the different formulas and processes, it can be made into general-purpose polystyrene (GPPS), high-impact polystyrene (HIPS), expandable polystyrene (EPS) and other types. It has good processability and electrical insulation.
• Application:Widely used in the manufacture of disposable tableware, CD and DVD cases, etc. EPS is also used in the field of building insulation and packaging. GPPS is used in electronic appliances, optical display and other fields.

(4) Polycarbonate (PC)

• Characteristics:high transparency (up to 90%), stiffness and toughness, high impact strength, high dimensional stability and a wide range of operating temperatures (can be used for a long time between -100°C~130°C). In addition, it has good electrical insulation properties, heat resistance and non-toxicity.
• Application:used in the manufacture of large lampshades, protective glass, eyepiece tubes for optical instruments and other optical lighting materials; insulated connectors, coil frames, etc. in electronic appliances; gears, racks and other parts in mechanical equipment; and cups, tubes, bottles, etc. in medical equipment. In addition, it is also used for hollow reinforced double-walled panels on buildings, greenhouse glass, etc.

2. Elastomer

(1)Silicone

• Characteristics:Silicone elastomer particles are used as modification additives for cosmetics, coatings, inks, etc., and are particularly preferably used as internal stress relievers for thermosetting organic resins or surface lubricants for organic resin films.
• Application:Specific application areas include high-functional organic resins (such as resin substrates for semiconductors), functional organic resin films, and resin coatings for these.

(2)TPE (thermoplastic elastomer)

• Characteristics:It has the dual characteristics of rubber and plastic, as well as excellent performance advantages, such as good weather resistance, not easy to age, comfortable and dry touch, etc.
• Application:Widely used in medical supplies (such as tourniquets, infusion tubes, etc.), sports equipment (such as tension tubes, grip rings, etc.), kitchen supplies (such as chopping boards, kitchen knife handles, etc.), toy products (such as toy dolls, elastic balls, etc.) and automotive interior products (such as automotive floor mats, automotive seals, etc.).

(3) TPU (thermoplastic polyurethane)

• Characteristics:It has the characteristics of abrasion resistance, scratch resistance, softness and comfort, and has good waterproof performance, ultraviolet resistance and impact resistance.
  
• Application:In the footwear industry, it is used for the production of shoe soles, uppers and other parts; In the garment industry, it is used to make raincoats, waterproof clothing and other functional clothing; used in sports equipment to make skateboards, bicycle seats, etc.; In addition, it is also used in packaging materials (such as plastic bags, sealed bags, etc.), automotive parts (such as bumpers, headlamp covers, etc.), electronic product accessories (such as protective covers, housings, etc.), and in the medical field (such as artificial heart assist devices, etc.).

3.Metal

(1)Aluminium

• Characteristics:light weight, corrosion resistance, easy processing and molding, and has good electrical and thermal conductivity.
  
• Application:Widely used in construction, transportation, packaging, electronics and other fields, aluminum cladding materials are often used to make doors and windows, furniture, decorative materials, etc.
  

(2)Steel

• Characteristics:high strength, good toughness, wear resistance, and good weldability and processability.
  
• Application:Widely used in automobiles, construction, machinery and other fields, steel cladding materials are often used to make structural parts, connectors, etc.

(3)Stainless steel

• Characteristics:Excellent corrosion and high temperature resistance, and easy to clean and maintain.
  
• Application:Widely used in medical, food, chemical and other fields, stainless steel cladding materials are often used to make medical equipment, tableware, containers, etc.

(4)Copper

• Characteristics:It has good electrical and thermal conductivity, and has certain antibacterial properties.
  
• Application:Widely used in electrical, construction, plumbing and other fields, copper cladding materials are often used to make wires and cables, pipes, etc.
  

(5)Titanium alloy

• Characteristics:high strength, low density, good corrosion resistance, and good biocompatibility.
  
• Application:Widely used in aerospace, medical and other fields, titanium alloy coating materials are often used in the production of aircraft engine parts, medical equipment, etc.

4.Composite materials

• Overview:Composite materials are materials with two or more different properties, through physical or chemical methods, macroscopically composed of materials with new properties.
  
• Applications:Composite materials have a wide range of applications in aerospace, automotive, construction, electronic appliances and other fields. For example, in the aerospace sector, it is used in the manufacture of aircraft structural parts and engine components; In the automotive field, it is used in the manufacture of body and chassis components, etc.

What are the specific applications and materials of overmolding?

Overmolding technology has a wide range of applications in a variety of fields, and the materials used are also diverse. Choosing the right materials and processes is critical to ensuring the performance and quality of your products.

A. Silicone overmolding

Application:

1. Medical Devices: The biocompatibility of silicone makes it ideal for manufacturing medical devices such as catheters, pacemaker housings, etc.
   
2. Food-grade containers: Silicone is safe for contact with food, so it is often used in the manufacture of baby products, kitchen utensils, etc.
   
3. Consumer goods: Silicone's soft-touch and heat resistance make it widely used in kitchenware, stationery, toys and other fields.
   
4. Electronics: Silicone is used to make electronic product shells, buttons, and other parts to provide a soft feel and durability.
   

Reasons for use:

1. Biocompatible: harmless to humans and suitable for medical applications.
   
2. Heat resistance: Able to withstand high temperatures, suitable for occasions that require high temperature treatment.
   
3. Soft touch: Provides a comfortable touch experience.

B. Rubber overmolding

Application:

1. Hand tools: Rubber handles provide non-slip and comfortable grip.
2. Handle: Used in various equipment, such as power tools, gym equipment, etc., to improve comfort and control while using.
   
3. Power tools: reduce vibration and protect the user from injury.
   
4. Auto parts: such as anti-slip mats, seals, etc.
   
5. Electronic products: such as remote control buttons, gamepads, etc., to provide non-slip and comfortable grip.

Reasons for use:

1. Anti-slip: Materials such as TPR (thermoplastic rubber) and TPU (thermoplastic polyurethane) have excellent anti-slip properties.
   
2. Ergonomic Grip: Ergonomic design for increased comfort and control during use.
   
3. Shock absorption function: reduce vibration and shock, protect users and equipment.

C. Plastic overmolding

Application:

1. Consumer electronics: such as mobile phone cases, remote control cases, etc., providing aesthetically pleasing appearance and durability.
   
2. Auto parts: such as interior parts, exterior parts, etc., to improve the aesthetics and durability of the vehicle.
   
3. Household items: such as electrical shells, furniture accessories, etc., available in a variety of colors and designs.

Reasons for use:

1. Multiple colors and design aesthetics: Plastic overmolding can provide a wide range of color and design options to meet different aesthetic needs.
   
2. Increased strength and durability: With overmolding, a stronger layer of material can be added to the plastic substrate, improving overall strength and durability.

D. Polycarbonate (PC) or ABS overmolding

Application:

1. Auto parts: such as bumpers, body shells, etc., providing impact resistance and toughness.
   
2. Electronics: such as laptop shells, mobile phone back covers, etc., to provide stability and aesthetics.
   
3. Tools: such as hammers, pliers, etc., to increase durability and impact resistance.

Reasons for use:

1. Impact resistance: Both PC and ABS have excellent impact resistance and are able to resist external shocks and collisions.
2. Toughness: Both of these materials have good toughness and are not easy to break or deform.
   
3. Stability: Stable performance under a wide range of environmental conditions.

What are the applications of overmolding?

Overmolding technology has a wide range of applications, the following are some of the main application examples:

Aerospace field

Overmolding technology plays an important role in the aerospace sector. Because carbon fiber composites have excellent properties such as high strength and high modulus, and their strength is more than five times that of steel, they have been widely used in the aerospace field. By using overmolding technology, it is possible to precisely wrap a reinforcing material such as carbon fiber inside a matrix material such as resin to form a composite material with excellent mechanical properties. These composite materials are widely used in key parts of the aircraft, such as the main load-bearing components, wings, and fuselage, making the aircraft stronger and stronger, and improving the flight safety performance.

Medical industry

Overmolding is widely used in the medical industry. Different medical products, such as device housings and surgical equipment, are manufactured by overmolding to create ready-to-use finished parts. Some examples include syringes, patient monitors, needles, catheters, dilators, soft-touch buttons, and many more.

Everyday necessities

Overmolding technology is also widely used in the manufacture of everyday items such as toothbrushes, razors, power tools, cameras, and kitchen utensils. These products need to be pleasant to the touch and non-slip properties, and overmolding technology is able to meet these requirements and offer a wide range of color, texture, and haptic options.

Automotive industry

Overmolding technology is also widely used in automobile manufacturing. With the continuous development of the automotive industry, the requirements for automotive materials are also getting higher and higher. Overmolding technology plays an increasingly important role in automobile manufacturing due to its excellent properties such as light weight, high strength and impact resistance. For example, long-fiber reinforced thermoplastic composites prepared by overmolding technology can replace traditional short-fiber reinforced materials and are used to manufacture automotive bumpers, spare tires, dashboards and other components, which not only improves the performance of components, but also reduces manufacturing costs.

Electronics

In the field of electronics, overmolding technology can be used to prepare high-performance circuit boards, electronic packaging materials, etc., to improve the performance and reliability of electronic products. With the continuous miniaturization and integration of electronic products, the requirements for materials are also increasing. Overmolding technology is able to meet these requirements and provide high-performance packaging materials and circuit boards for electronic products.

FAQs

1.What material is used for moulding?

The materials used during molding depend on the specific molding process and product requirements. In insert molding and overmolding, commonly used materials include plastic, rubber, metal, etc. Plastics: such as thermoplastics (TPE, TPU, ABS, PC, PP, PE, etc.) and thermosetting plastics (such as epoxy resin, phenolic resin, etc.). Rubber: such as natural rubber, synthetic rubber (such as silicone rubber, nitrile rubber, etc.). Metal: such as copper, aluminum, steel, etc.

2.What materials are used in insert molding?

Insert moldingtypically uses a part made of metal or other suitable material as an insert, and then injects plastic into or around the insert. Commonly used insert materials include: Metal inserts: such as copper, aluminum, steel, stainless steel, etc. These materials have high strength, high hardness and good electrical conductivity, and are often used in parts that need to bear large loads or need to conduct electricity. Plastic Inserts: In some cases, plastic can also be used as the insert material. This is usually to reduce weight, reduce cost or achieve specific functional requirements.

3.What are the materials used in mold tooling?

The materials used in mold processing mainly depend on the purpose of the mold, working environment and cost requirements. Commonly used mold materials include: Mold steel: It has good hardness and wear resistance and is often used to make molds that need to withstand greater pressure and friction. Aluminum alloy: has good thermal conductivity and lightweight properties, and is often used to make molds that require rapid heating and cooling. Copper alloy: has excellent thermal and electrical conductivity and is often used to manufacture molds that require efficient heat dissipation.

4.What is the best plastic for overmolding?

The plastic best suited for overmolding often depends on the specific needs of the product and the nature of the substrate. Here are some commonly usedovermolding plasticsand their characteristics: TPE (Thermoplastic Elastomer): TPE is an excellent overmolding material with good elasticity, wear resistance, weather resistance and easy processability. TPU (Thermoplastic Polyurethane): TPU has excellent elasticity, wear resistance and chemical resistance, and is often used to manufacture parts that need to withstand large stress and friction. Silicone: Silicone has excellent high and low temperature resistance, chemical corrosion resistance and biocompatibility. It is often used in parts that require direct contact with the human body or food in the medical, food and other industries.

Summary

Overmolding materialsare selected based on specific application needs. Materials like rubber, silicone, plastic, and polyurethane are commonly used depending on the product's intended function, performance requirements, and aesthetic preferences. Proper material compatibility is crucial for ensuring durability, performance, and adhesion during theovermolding process

Disclaimer

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LS Team

This article was written by multiple LS contributors. LS is a leading resource in the manufacturing sector, withCNC machining,sheet metal fabrication,3D printing,injection molding,metal stamping, and more.