Injection Molding Services

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Plastic Injection Molding Service

Runsom is specialized in producing high-quality plastic injection molding parts and mold tools, we provide CNC machining and finishes service to make injection molding tools form various metal materials, our capacity including 50 to 100000 injection molded parts in a wide type of plastic materials. Comparing with CNC machining and 3D printing, our injection molding service can provide the most variation of materials, colors and configurations. In addition we can also satisfy your customized cosmetics, polishes and surface textures need for aesthetic needs or technical requirements.

We guarantee your injection molding tools and parts exceed your expectation with advanced material verification and quality process management. We provide multiple options of injection molds for your exception production cycles and warranty, including “in-house” and “export” injection molds as your indeed requirement.

Why not upload your production design file for a competitive injection molding quotation now.

How Injection Molding Work

Plastic injection molding is the most common way to produce high volume of plastic molded parts for all kinds commercial and industrial application. Molten resin is injected in a metal cavity under various pressure and then cooled rapidly, in order to form a solid shape. A plastic molded parts cycle just take a few seconds to minutes depending on design complexity and size.

Runsom injection molding consist the following basic steps, once we finished the plastic injection molding tool producing:

1.Prepare plastic resin with raw pellet, blended with pigments or mater batch colorants with custom requirement.
2.All pellets are poured into molding machine hopper, reciprocating screw will transport these pellets into mold.
3.All pellets will be mixed and heated into fully molten, as liquid resin form.
4.Liquid resin will be injected mold cavity under various pressure.
5.Cool the mold to inside parts solidify.
6.Open mold and eject plastic part for new cycle.


The injection molding parts arrived yesterday and it looks terrific – excellent work!The whole exterior is very well finished and looks just like the fully machined version.They all look very cleanly produced and the finish is excellent. I was slightly nervous that they might not be as good as the CNC milled prototypes but they look even better.


Tim Dane
Engineering Manager

Injection Molding Advantages

Scalability :Injection molding is perfect for custom production volume from 50 to10000 molded parts
Efficiency: Runsom provide custom molding with significant less waste than other manufacturers.
Strength: Molded parts will perform better than CNC machined with same material. Our careful selection of resin types guarantee a wide range of corrosion resistance,chemical and solvent compatibility.
Rapid turnaround: Runsom can produce top quality molded parts in as less as 7 business days.
Economic production: Runsom will provide you significant lower unit price with molding than other processes, particularly for quantities of thousands.
Precision: Our CNC machined molds are high precision and tolerance, in addition are able to produce thousands of small and intricate identical molded parts. We can provide high tolerances of +/-0.002 to +/-0.005 meters under impact of all plastic materials heat and moisture.
Excellent surface quality:In order to satisfy your aesthetic needs or technical requirements, we can offer you molds with special surface finishes.

Plastic Injection Molding Process

Injection Mold Manufacturing

Runsom has more than 10 years of experience in plastic injection molds manufacturing, our engineers can convert your 3D design files into high-quality molds at top speed. Our manufacturing services including: tools dies and molds from design to producing, aluminum and steel tooling, overmolding and insert molding, plastic blow molds. We use various kinds of steel or aluminum to make molds in reason of durability and complex injection ability, we will select the most suitable steel or aluminum types on situation and requirement. Depend on parts design, molds structure can be quite complex, in addition, we should consider shrinkage rate of plastic material in molds construction.

Plastic Injection Molding

We can provide plastic injection molding for low volume and batch parts production. Our injection molding capability range form 50 to 1000 tons clamping force, which allow us manufacture any plastic parts, such as micro parts, 0.0003m thin-walled parts and various large parts.

Insert Molding

Rusnom can provide insert molding service in your design, metal, ceramic or plastic pieces will be inserted into molten thermoplastic to form robust and functional parts as your custom requirement. Our CNC machining service can produce precision customized metal, ceramic and plastic insert to integration molded parts. Insert molding is a cost effective way than installing after molding. In addition, by integrating insert parts in molding, insert molding parts are more robust compare to staking pieces in post-molding. We need to notice that insert pieces must withstand high temperature and pressure in molding process.


Our over molding service allows multi-material injection molding in you molded parts production. Through over molding, thermoplastic elastomer can be molded onto rigid plastic. Over molding is useful for producing multi-material parts with unique properties. Basically, a previous injection molded part(substrate) will be formed by a new layer of different material(overmold). Overmolding is not as straightforward as single material injection molding, we should consider two materials chemical and thermal compatibility. Substrate material must have higher melt temperature than overmolding material, in order to avoid melt and deform in overmolding material material injection process.

Injection Molding Finishes

Pad printing: Pad printing always can add image like logos or company name onto final parts.
Silk screening:Custom color painting: No matter customer-supplied parts samples or Pantone color numbers, Runsom painting color will be 100% matching your requirement.
Laser finishing: Laser finishing can be applied to mold or final parts for company or product information.
Heat staking: Heating staking can be used for threaded insert with your complete design chart.
Texture finishing: We apply industry standard textures to mold manufacturing process, you can get mold-tech finish equivalent.

Injection Molding Application

Injection molding is widely used to produce various plastic parts with various size, complexity shapes and usage.

Plastic case as the most common production, is used widely in household appliances, consumer electronics, power tools and car dashboard. Others like computer components, containers, bottle caps, car interiors, lenses, brackets,fasteners, top and bottom covers, toys.

Injection molding is also used in medical equipment, mechanical parts.

Injection Molding Design Considerations

Runsom engineering team provides professional design guideline as following:

  1. Smallest and Constant wall thickness will be considered to avoid warping and sinking.
  2. Smooth chamfer or fillet can be used make transition for 3 times wall thickness difference.
  3. Add large radius fillet to internal and external edges.
  4. Add draft to all vertical walls design, avoid drag and make parts easy ejection

Injection Molding Materials

Almost all thermoplastic can be used for plastic injection molding production, Runsom provides flexible and rigid plastic varieties, custom resin matching available as follow:

Engineering plastics

Engineering plastics offer a range of sought after properties, including good impact strength, rigidity, thermal resistance, chemical resistance, dimensionality and color stability. The combination of strength, ductility and heat resistance make rigid plastics suitable for a range of industrial injection molding applications.


ABS PEI Nylon 6/6
Acrylic Polycarbonate PC-PBT
HDPE Polypropylene PEEK
Flexible Plastics
Rubber Plastics