2-Shot molding / 2K molding

2 Shot molding(2 component molding / 2K molding / 2K injection / Overmolding) is an innovative manufacturing process used to produce complicated moulded parts in multiple materials, and can be used for a variety of product designs across all industries.

2 Shot molding(2 component molding / 2K molding / 2K injection / Overmolding) optimises the co-polymerisation of hard and soft materials to create a powerful molecular bond.

Ming-Li uses thermoplastic elastomers and plastics for the 2 Shot moulding(2 component molding / 2K molding / 2K injection / Overmolding) process as traditional thermoset compounds (such as nitriles, fluorocarbons, EPDM’s) are not suitable.

Ming-Li typically uses the following thermoplastic materials for 2 component molding(2K molding / 2K injection / Overmolding) :
 

• Styrene Block Copolymers (TPE-S)
• Thermoplastic Polyurethane Block Copolymers (TPE-U)
• Copolyesters (TPE-E)
• Copolyamides (TPE-A)
• Olefinic Thermoplastic rubbers (TPE-O)

Ming-Li typically uses the following plastic materials for 2 Shot moulding(2K molding / 2K injection / Overmolding) :
 

• Polyamide (PA/Nylon)
• Polybutylene Terephtalate (PBT)
• Polycarbonates (PC)
• Polypropylene (PP)

The 2 Shot moulding process allows us to design and manufacture complex, multiple material parts for our customers to perform a sealing function.

Additionally, the multi-shot moulding process can also be used as a cost effective method to bond materials in different colours for cosmetic purposes.

Two shot molding / 2K molding / Overmolding Design Guide

Remember that 2 Shot molding / overmolding is rarely used to cover the entire base substrate. Instead, apply 2 Shot molding / overmolding in sections. For each of these, keep in mind these useful design tips:

• Work with your manufacturing partner to ensure the compatibility between the substrate and the TPE or TPU.
• Use a TPE or TPU that has a melt temperature lower than that of the base plastic.
• Apply an overmold that is slightly thinner than the substrate which supports it.
• Design the overmold to sit just below the surface of the substrate.
• If you need more holding power, design undercuts, keyways, and other mechanical features to lock the materials together.

 

Know more for 2 Shot Overmolding

This type of plastic overmolding, sometimes called two-shot, multi-shot, or double-injection molding, adds additional material such as thermoplastic elastomer (TPE) to plastic substrates to improve the aesthetics, handling characteristics, grip, impact resistance, or environmental resistance of injection molded parts. The overmolding process is usually performed by way of multi-barrel injection molding machines, the process adding additional material shortly after the substrate is formed to create strong bonds between materials. Plastic overmolding serves to eliminate steps in the manufacturing process while creating enhanced injection molded products.

Depending on the materials selected for the substrate and overmold, materials may be bonded chemically or mechanically (via undercuts, for example). In many instances, mechanical bonding is recommended to fortify any chemical bonding that may take place. Among the many substrate materials that are suited to overmolding, polycarbonate, ABS, HDPE, and nylon are common. Overmold materials include thermoplastic elastomers like thermoplastic polyurethane (TPU), thermoplastic rubber (TPR), and thermoplastic vulcanite (TPV), as well as materials like styrene-ethylene/butylene-styrene copolymer (SEBS). Silicone overmolding is also used, especially when a softer rubber surface is needed for a plastic part. 

This is just a partial overview of 2 Shot molding(2 component molding / 2K molding / 2K injection / Overmolding). Are they the right solutions for you? Not sure how to apply them to your next project? Just contact our technical experts and we can offer helpful advice about how to get the best results from both processes.