Top China overmolding company for insert molding,co-injection,2k molding

Get the Best Overmolding And Insert Molding From China in Quick Time

Overmolding are difficult to work with and all that detail work is hard on the eyes.

If you want to make your prototype, run small batches or do short runs, Topworks Overmolding is perfect for you.

We can also help you with quick deliveries and some of the best prices in the industry. Additional services like design,assembly and shipment are also available upon request. Visit our website and let us help you start your next project!

Topworks is a reliable overmolding supplier from China. We offer a wide range of high-quality overmolding and insert Molding products that can help you design and produce the perfect product. With our experienced team, we can help you create a flawless product every time.

Providing reliable and budget-friendly services of overmolding and insert molding, Topworks Plastic Mold is dedicated to offering the highest quality products at a cost-effective price.

With over ten years of experience, we offer our customers unmatched knowledge and experience in the field of designing, manufacturing, and tooling of overmolding and insert molding products at competitive prices across the globe while maintaining a commitment to quality.


The wide range of overmolding and insert molding services we offer means that we are in the unique position of being able to create overmolding and insert molding tooling and manufacture overmolding and insert molding parts from concept to reality.

The simple nature of our processes provides an extremely fast and simple injection molding process for the development and production of complex work-in-progress and prototype parts.

“I’m glad to inform you that all plastic parts are perfect!!! We are delighted, and therefore there are good chances to continue our relationship for any coming new project.”



“Steven is a very detail-oriented project manager and engineer who can solve problems creatively and also provides excellent service. It was a pleasure working with him.”



Benefits of insert molding

Using insert molding ensures that components are safe to use as the plastic formed around them prevents impact and abrasion. The aesthetic design is improved, and the components are made easier to use. Connectors, adhesives, and soldering aren’t necessary with this process.

Insert molding can derive the following benefits.

Cost reductions in assembly and labor

Insert molding can eliminate many manufacturing processes that require additional labor costs. As a result, fewer stages of product assembly are involved, fewer workers are needed, and lower labor costs.

Reduced assembly time and cost. Automated insert molding machinery reduces labor costs associated with traditional assembly processes such as fastening, gluing, bolting or welding two parts together. There is no need for separate or additional assembly equipment or tools when using insert molding to assemble parts that require adherence to strict tolerances in order to function properly with other components in a complex system. Additionally, automated insert molding machines produce parts faster than traditional assembly processes.

Minimal added cost per unit compared to other methods of assembly. Generally speaking, the cost of inserting a plastic part into another plastic part is less costly than other adhesives-based processes such as gluing or spot welding.

smaller and lighter component

Plastic resins are used to make the components tightly molded, enabling smaller, lighter components than those made with fasteners or connectors. Compact and thin components can be fabricated with it without sacrificing performance or strength.

Plastic resin is molded around components during insert molding to produce enhanced vibration and shock resistance components. This process ensures that parts are tightly molded to the plastic, preventing loosening and proper alignment. In this way, the components are guaranteed to perform exceptionally well without posing any dangers.

Better component strength and structure

The plastic resin creates a robust and structurally sound component combined with the insert piece.Overmolded components are generally stronger than their insert-molded counterparts due to better structural support.

The outer layer provides load distribution during use via compressive loading across a large area and also protects against scratches and other damage from everyday use. Additionally, overmolded parts offer more protection from heat than non-molded parts—which is especially important for resins like PBT ( a heat-resistant resin) and nylon.

Enhanced design flexibility

Insert molding is the process of joining a metal core (or insert) to a plastic part. This process can be used on any type of custom plastic part—the possibilities are endless! Since the metal core and plastic part are molded together at the time of production, you can use any kind of material for your core or your part. This opens up a world of opportunities for customizing your part and giving it unique properties.

Additionally, because you have complete control over your core and plastic material and their thicknesses, you can choose exactly what you want for your part. For example, if you’re designing a handle for a kitchen tool, you could choose to make the metal core out of a highly scratch-resistant nickel-plated brass that won’t rust over time. Then, you could choose a soft, malleable plastic (such as TPE) to form the handle itself out of so that it’s soft enough to grip but strong enough to withstand heavy usage. Then, how about adding in some soft padding around the top half inch of the handle so that it’s comfortable to rest your fingers on while still protecting them from heat? The possibilities are endless with custom insert molding—and the options are only limited by your imagination.

Variety of materials

You can combine several materials to create one piece. They are lightweight and durable, so they’re an excellent choice for various consumer goods and industrial applications.

This process also reduces waste because you don’t have leftovers from the different parts that you can’t use—all the material is used to create your finished product. Because it lets you use fewer materials, insert molding is also more efficient than other methods of producing multi-material parts. You can lower your costs while creating a better product for your customers. Plus, you can use different materials for different parts of your product. For example, if you’re making an electronic device that needs several plastic parts, you can use a different material for each part (such as ABS or TPE).

What overmolding and insert molding we supply?

As a supplier of high-class rubber and overmolding,insert molding and co-injection parts, Topworks has successfully supplied the services for single and multi-component 2K molding projects in the various fields of

  • Personal care,
  • Automotive parts,
  • Medical care,
  • Cosmetics and electronic products

and casting the technological value to more production throughout the world.

China overmolding company

Why choose us for overmolding and insert molding ?

  • Precision manufacturing at ±0.01mm
  • Implementing advanced overmolding(insert molding) product designs
  • Standardization of mold parts
  • Rapid and high precision positioning of mould components
  • Manufacturing process control from beginning to end to satisfy client’s overmolding(insert molding) demands
  • MAKINO (V99) Large multi-cavity multi-component mold size control

Overmolding Project Management

  • One to one project engineer contact
  • Plan & track overmold manufacturing process
  • Update customer’s requirements & feedback
  • Arrange delivery of trail overmodling samples
  • On site management of mold until mass production begins

Overmolding After-sales Service

  • International service capabilities
  • Rapid response support  (7×24 hrs)
  • Professional communication (English speaking engineer over 10+ yrs)

Principle of two-color injection molding

Double color mixing injection molding

It has two barrels, and the structure of each barrel are the same as those of ordinary injection molding barrels.

Each  barrel has its own passage to the nozzle, and opening and closing valves 2 and 4 are also installed in the nozzle . During molding, after the molten material is plasticized in the barrel, the opening and closing valves 2 and 4 control the sequence of molten material entering the nozzle and the proportion of discharged material.

And then the molten material is injected into the mold cavity from the nozzle. Various plastic products with different color mixing effects can be obtained.

Double Pattern Injection Molding

It also has two barrels 1 and 5, and its nozzle structure is somewhat special.

Besides the normal nozzle function, it can also be rotated by a gear 3 installed at the rear. During molding, melting materials with different colors are plasticized in the charging barrels 1 and 5 respectively, and the gear 3 drives the rotating shaft 4 to rotate, so that melting materials with different colors alternately enter the mold cavity, thus obtaining plastic products with different colors and patterns radiating from the center to the periphery.

two-color injection molding requirements

Material requirements

The 2 materials for two-color injection molding must meet two basic compatibility demands: adhesion  and compatibility.

Design of Soft and Hard material

There must be a certain melting points  temperature difference between the two materials.

Generally, the temperature difference is to be 60℃, and it is recommended to be at least 30℃. The melting temperature of the first shot material is high. Generally, the first shot material is PC or PC/ABS, and the second shot material is TPU or TPE.

PC injection molding is 0.6-0.7mm thick and software material injection is 0.4mm or more.

over-molding need widen the contact area for 2 material as much as possible, making grooves increase the adhesive force, or adopt core pulling in the first shot, inject the second material into the first shot, and rough the surface of the first shot mold should be as much as possible.

Advantages of Two-color Injection Molding

Compared with classic injection molding, two-color injection molding has the following advantages:

  1. The 2K molding main raw materials can use low viscosity material to reduce the injection pressure.
  2. The 2K molding main raw materials can use  recycled plastic, both environmental friendly and economy.
  3. Meet the special requirements of some products, make plastic parts more beautiful and colorful. For example, soft plastic is used for the surface material of the thick  product, and hard plastic or foamed plastic is used for the main body to reduce the weight.
  4. lighter or cheaper plastics can be used in unimportant parts of over-molding parts to reduce product cost.
  5. The expensive and special performance of plastic material could be used on the important and special area , such as electromagnetic interference prevention, high conductivity and other plastics
  6. Proper combination of surface material and core material can reduce residual stress of 2K plastic parts, increase mechanical strength or optimize surface performance of products.
  7. Products surface like marble texture can be obtained.

2K Injection molding is that granular or powdery plastic is fed into a heated barrel from a hopper of an injection machine, heated and melted, plasticized into a viscous fluid melt.

The material was pushed by the high pressure of a plunger or a screw of the injection machine, injected into a mold cavity at a large flow rate via nozzle and gate, maintained in the shape given by the mold cavity after pressure maintaining, cooling and shaping for a certain period of time, and then opened and molded to obtain plastic products.

the above is  an injection cycle.

The injection molding process can be abbreviated as:

feeding-plasticizing-injection-pressure maintaining-cooling-demoulding.

The details cycle:

  • The heating and pre-plasticizing barrel and screw will forward ,convey and compact the plastic from the hopper under the drive of the transmission system.

Under the mixing action of shearing and friction of the heater outside the barrel, the plastic melts inside the barrel . A certain amount of molten plastic has accumulated in the head of the barrel.

Under the pressure of the melt, the screw slowly recedes.

The retreating distance depends on the amount required for one injection by the metering device.

When the predetermined injection amount is reached, the screw stops rotating and retreating.

  • Mold clamping, the mold clamping mechanism on the injection machine pushes  the movable mold half  and the fixed mold half  to close tightly so as to ensure that sufficient clamping force.
  • The injection section moves forward. When the mold close, the entire barrel moves forward to make the nozzle of the injection machine fully fit with the sprue of the mold.
  • Injection and pressure keeping. After the mold close and nozzle completely seal the sprue on the mold, the injection hydraulic cylinder shot the high pressure oil to push the screw to move forward inside the barrel, injecting the melt accumulated in the head of the barrel into the cavity of the mold with sufficient pressure.

The plastic volume will shrink after the temperature drop.

In order to ensure the compactness, dimensional stability and mechanical properties of the plastic products, a certain pressure should be maintained on the melt in the cavity of the mold to supplement the melt.

  • Pressure Relief .When the melt at the gate of the mold freezes, the pressure can be released. At the same time, the melt is cooled and solidified in the mold cavity to make a plastic product.
  • mold opening and  products ejection .After cooling and shaping, the mold clamping mechanism opens the mold and pushes out the plastic products in the mold.