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Zhongde, a reputable plastic and rubber injection molding company in China, provides insert molding service and overmolding services and produces unique multi-material parts.

 

Both over-molding and rubber insert molding injection processes by Zhongde, a reliable injection molding supplier, involve putting two types of materials together to make one part. And the inserts can be threaded metal inserts. China overmolding is a two steps process that one to create the substrate and one for the oversold that goes on top of it. China insert molding is a slightly faster process as it takes only one step that the two materials are molded at the same time.

 

What Materials are Used in Injection Moulding

 

In addition to the general materials listed below, Zhongde, a reliable custom overmolding factories, can also modify the materials according to the special needs of customers. Our professional engineers will adjust the raw material formula to meet the unique conditions of use. Our production materials of custom over-molding and custom insert molding range from thermoplastic to elastomer-rubber, as well as metal and silicone. We've broken down the differences and similarities between the two processes. Let us help you decide which process is right for your project.

 

Overmolding and insert molding

 

Overmolding is a process where a single part is created using two or more different materials in combination. Traditonally, overmolding starts with injection molding a hard plastic resin that has a higher melting point. Once that part is cooled, another material is injection molded over the first part, resulting in a single, finished product.

 

Insert molding combines metal and plastic injection molding service into one single part. It allows plastic to bond to insert pieces, mostly brass or stainless steel metal component, which go inside a mold cavity. There are many options for insert that can be placed into the mold. A few of examples are warming labels, threaded bushings, wires, batteries, etc.

 

 

Insert and Overmolded Plastic Injection

ABS | Acrylonitrile Butadiene Styrene

 

PA 6 | Polyamide 6, Nylon 6

 

PA 6/6 | Polyamide 6/6, Nylon 6/6

 

POM | Acetal Polyoxymethylene, Delrin

 

PP | Polypropylene

 

PE | Polyethylene

 

LDPE | Low-Density Polyethylene

 

HDPE | High-Density Polyethylene

 

UHMWPE |Ultrahigh Molecular Weight Polyethylene

 

PTFE  | Polytetrafluoroethylene

 

PEEK | Polyether Ether Ketone

 

PC | Polycarbonate

 

PMMA | Polymethyl Methacrylate, Acrylic

 

PS | Polystyrene

 

PVC | Polyvinyl Chloride (Shore D)

 

PU | Polyurethane

 

Rubber Overmolding & Insert Molding

NR | Natural Rubber

 

NBR | Nitrile Rubber

 

SBR | Styrene-butadiene Rubber

 

HNBR | Hydrogenated Nitrile

 

CR | Neoprene Rubber

 

VMQ | Silicone

 

LSR | Liquid Silicone Rubber

 

FVMQ | Fluorosilicone

 

FKM | Fluorocarbon

 

FFKM | Perfluorocarbon Rubber

 

EPDM | Ethylene-Propylene Diene Monomer Rubber

 

IR | Polyisoprene Rubber

 

IIR | Butyl Rubber

 

Metal Overmolding and Injection Molding with Metal Inserts

Aluminum

 

Stainless Steel

 

Carbon Steel

 

Copper

Size of Molding Over & Insert Injection Molding

 

 

Below table shows the size of Overmolding & Insert Molding parts we usually make. If you need a larger size, we can also help you achieve it.

 

Size	Metric	Inch
Length	2500	98.4
Width	2000	78.7
Height	1500	59

Additives of Overmolding & Insert Molding Injection

Name	Description
UV absorbers	Absorb UV radiation, slowing down the degradation of the material when used outdoors.
Flame retardants	Prevent ignition and inhibits spread of fire.
Plasticizers	Increase flexibility and promotes plasticity, reducing brittleness of the material.
Colorants	Used to color plastics.
Carbon fibers	Increase strength, toughness, and rigidity of the material at the expense of making the material more brittle.
Glass fibers	Increase strength, toughness, and rigidity of the material at the expense of making the material more brittle. It is more flexible than carbon fibers.

 

Surface Finishing of Overmolding & Inserts Injection Molding

 

For product designers and engineers, surface finish on molded parts is an important design consideraton. Most polish and texture is appled directly to the mold itself and trasferred to the parts during the injection molding process. Following are serveral surface finish options for molded parts.

Name	Description
Glossy	The mold is smoothed and then polished with a diamond buff, resulting in parts with a mirror-like finish.
Semi-gloss	The mold is smoothed with fine grit sandpaper, resulting in parts with a fine surface finish.
Matte	The mold is smoothed using fine stone powder, removing all machining marks.
Textured finish	The mold is first smoothed with fine stone powder and then sandblasted, resulting in a textured surface.
As-machined finish	The mold is finished to the machinist's discretion. Tool marks may be visible.

 

As a reputable custom injection molding company in China, Zhongde supplies china metal parts machining, automotive injection molding, custom rubber prototype and etc. Contact us to know more.