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AAA MOULD - Plastic Injection Mould Manufacturer for custom mold design, precision processing, and plastic molding solutions.

Overmolding and 2K Molding

Overmolding and 2K Molding

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INTRODUCTION TO OVERMOLDING AND 2K MOLDING
1
Process Principles
• Overmolding: First, injection-mold the base material to form the substrate. Then, place the substrate into another cavity of the same mold or a separate mold, and inject the overmolding material so that it wraps around or covers the substrate, achieving the bonding of the two materials.

• 2K Molding: Using an injection molding machine with two injection units, sequentially inject two different materials into different cavities of the same mold or the same cavity, completing the molding and bonding of the two materials in a single injection process.

2
Mold Structure
• Overmolding: The mold typically requires complex insert installation structures or spaces to accommodate the substrate, as well as flow channels and gates for the overmolding material. If two injections are performed in the same mold, it also needs a mechanism to switch injection positions or rotate the mold.

• 2K Molding: The mold generally has two independent cavities or a switchable cavity, as well as two sets of flow channels and gate systems corresponding to the two materials, ensuring that the two materials can be accurately injected into their respective positions.

3
Material Selection
• Overmolding: The selection of substrate and overmolding materials is relatively broad, but compatibility and bonding strength between the two must be considered to ensure good overmolding effects. Typically, the substrate is a higher-hardness material such as various engineering plastics or metals, while the overmolding material is often a soft-touch, elastic, or special-performance material such as thermoplastic elastomers (TPE) or silicone.

• 2K Molding: Compatibility of the two materials must also be considered to achieve good bonding. Material selection can be more diverse, including not only plastics with different properties but also the same plastic in different colors to achieve multi-color or multi-material effects in products.

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Product Appearance and Performance
 Overmolding: In terms of product appearance, the overmolding material typically covers part or all of the substrate, forming a distinct covering layer, with relatively imprecise boundary lines between the two materials. In terms of performance, it mainly enhances specific product properties through the overmolding material, such as soft touch, anti-slip, shock absorption, etc.

◉ 2K Molding: The product appearance can achieve very precise boundary lines between the two materials, enabling more complex and detailed design effects, such as two-color or multi-color patterns or splicing of different materials. In terms of performance, two materials can be accurately selected and combined according to the functional requirements of different parts of the product to achieve optimized performance configuration.
Advantages of Overmolding and 2K Molding
 Overmolding: 

• Can unify the base material and overmolding material in a short time, reducing the time for secondary operations to connect multiple components on the assembly line;

• Makes components more robust and durable, preventing separation over time, and improving overall functionality and appearance;

• Can be used to manufacture products with special requirements such as waterproof connector cables.


◉ 2K Molding:

• Allows the use of materials with different properties in various parts of the product, such as combining rigid plastics and soft plastics, to enhance product functionality and user experience;

• Enables the integration of multiple components in a single molding process, reducing subsequent assembly steps and lowering costs;

• Creates more aesthetically pleasing products with highly precise boundary lines between the two materials, enabling seamless integration of two colors or different materials.

Application Scenarios

Overmolding finds extensive applications in fields requiring composite material performance or aesthetics:

Mobile phone cases (rigid PC substrate + soft TPE anti-slip layer), laptop foot pads (plastic base + silicone shock-absorbing pads).
Steering wheel covering (metal/plastic skeleton + PU leather or rubber grip layer), door seals (rigid support + soft sealing rubber strips).
Kitchen utensil handles (stainless steel/plastic substrate + silicone heat-insulating anti-slip layer), furniture edge rubber coating (wooden/metal edges + soft anti-collision strips).
Surgical instrument grips (metal substrate + antibacterial soft gel layer), medical catheters (rigid tubing + soft elastic connectors).
Racket handles (carbon fiber/aluminum alloy skeleton + sweat-absorbing anti-slip rubber covering), fitness equipment handles (metal rods + elastic foam layers).
Toy wheels (rigid plastic hubs + soft rubber tires), baby tableware (safety plastic + soft silicone bite mouths).
Screwdriver handles (plastic core + TPR anti-slip rubber coating), wrench anti-slip sleeves (metal tools + elastic rubber layers).
Sealing of glass bottles/metal cans (rigid lids + soft sealing rubber pads), hose nozzles (plastic tubing + aluminum sealing ends).
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Core Advantages: Achieves material complementarity (e.g., rigid support + soft functionality) through secondary injection molding, enhancing product durability, comfort, or safety, and is suitable for scenarios with high requirements for composite performance.

The application scenarios of 2K molding are extensive, covering multiple industries:

Mobile phone casings, keyboard keys (such as two-color character keys), headphone control modules, etc., achieving multi-color appearances or combinations of rigid and soft materials (e.g., rigid casings + soft anti-slip strips).
Steering wheel buttons (rigid bases + soft tactile coatings), dashboard panels (different color or texture zones), gear shift handles (rigid structures + soft grip outer layers).
Surgical instrument handles (anti-slip soft rubber + rigid support structures), medical catheter connectors (chemical-resistant materials + sealing elastic materials).
Appliance buttons (e.g., two-color function buttons for coffee machines, hair dryers), kitchen utensil handles (rigid plastics + soft heat-insulating layers).
Children's toys (multi-color splicing shapes, safe soft rubber components), stationery casings (e.g., two-color pen holders, rulers with anti-slip rubber strips).
Sports shoe soles (rigid support + soft anti-slip textures), sports protective gear (rigid frames + buffer elastic materials).
Toothbrush handles (rigid main bodies + soft rubber massage points), tableware (rigid utensils + soft heat-resistant grips).
Mechanical buttons (wear-resistant bases + indicator color layers), seals (rigid skeletons + elastic sealing materials).
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Core Advantages: Achieves multi-material/multi-color integration through one-step molding, enhancing functionality (e.g., anti-slip, shock absorption, sealing) and design flexibility for appearances, reducing assembly processes, and being suitable for mass production.

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