Plastic Injection Molding Manufacturers


Advanced Plastic Injection Molding & Assembly

KS Group has built a reputation for excellence in plastic injection molding and assembly. By combining highly specialized engineering and manufacturing knowledge, cutting-edge materials, and state-of-the-art technologies, we can deliver exceptional tooling value and injection molds tailored to our customer’s unique needs and demands.

One of the advantages of working with KS Group is that we build, repair, and maintain our molds in all three of our North American facilities. As a result, we can provide our customers with the best options for delivery and price. We also operate advanced injection molding facilities in Silicon Valley for the demanding manufacturing requirements of high-precision medical devices, life science, and tech industries. 

Whether molds are built here, or in our near-shore facility, we offer seamless service with our experienced professionals and hands-on oversight throughout the entire process.

Learn how we can bring your products to life

What is Injection Molding?

Pump housing thats is used in commercial and personal pool systems - Plastic Injection Molding

Injection molding is a manufacturing process for producing parts by injecting molten material into a mold. The process consists of the high-pressure injection of the raw material into a mold, which shapes the polymer into the desired form. Injection molding can be performed with various materials, including metals, glasses, elastomers, confections, and, most commonly, thermoplastic and thermosetting polymers. Injection Molding is widely used for manufacturing a variety of parts, from the smallest component to entire body panels of cars. Injection Molding is also used in manufacturing medical devices, toys, and many other products.


Benefits of Injection Molding

The benefits of injection molding can include:

  • Cost-effectiveness: Injection molding is cost-effective for high-volume production runs. Once the molds are created, the process is fast and efficient.
  • Versatility: Injection molding can be used to create parts with a wide range of material properties, including plastics and metals.
  • Precision: Injection molding is a precise process that can produce parts with high accuracy and consistency.
  • Efficiency: Injection molding is an efficient process that can quickly produce large quantities of parts.

Plastic Injection Molding vs. 3D Printing

While both 3D printing and injection molding are manufacturing processes that have their own advantages and disadvantages, they are quite different in their approach. Injection molding is cheaper for bigger products, whereas 3D printing is more expensive but allows you to make changes at any stage of production.

While injection molding delivers uniform quality and high volume, 3D printing provides high fidelity in low volume.

3D printing offers more design flexibility than injection molding.

Plastic Injection Molding vs. Die Casting

Die casting, and plastics molding are two popular manufacturing processes used to produce parts with complex geometries. The primary difference between the two is the material used. Die casting uses metal, while injection molding uses plastic or polymers. Die casting is ideal for producing parts that require high strength and durability, while injection molding is better suited for producing parts that require intricate designs and tight tolerances.

Thinking Outside the Box

Our job is to question the traditional way of doing things in terms of design, tooling, molding, materials, process, or packaging. Many of our customers first came to us because they were confident that we could deliver quality end products, no matter how unique their requirements were.

We offer a variety of molding techniques to optimize your product’s performance, aesthetics, and manufacturability and deliver many manufacturing advantages:

Standard Plastic Injection Molding

Injection molding is a process that heats up a thermoplastic polymer above its melting point, and then forces this heated plastic into a custom shaped mold.  After a short cooling period, the mold is opened and the finished part is ejected from the press or removed by an operator.

The main pieces of equipment typically used in this process are the injection molding machine, the mold, water heater, material dryer, and occasionally side arm robotics;

High And Low-Volume Molding Production 

Low Volume: generally, a low production run consists of smaller batches of 10 to 10s of thousands of parts. These are typically for larger parts, or parts that are going through developmental molding runs. 

High volume: high production runs are projects that run batches of hundreds of thousands to millions of parts per run. These are for projects that run continuously for hours if not days on end. 

White Room Injection Molding Environment

A white room is a designated space where airborne particulates are removed, and the environment is tightly controlled to provide the ideal conditions for manufacturing sensitive components. White rooms manage air quality in a room, including parameters such as temperature and humidity.

Clean Room Injection Molding Environment

A clean room is a controlled environment that filters pollutants like dust, airborne microbes, and aerosol particles to provide the cleanest manufacturing area possible. Most controlled environments protect the production of products like electronic devices, pharmaceuticals, and medical equipment.

clean room class 10,000 iso class 7

Broad Range of Engineered Grade Materials To Mold

Engineering grade resins are a group of tough resins with different properties destined for professional, usually engineering-based applications with a hefty price tag in tow. Some popular variants include tough resins similar to ABS-like, flexible resins, strong and rigid resins with high thermal and chemical resistance, and reinforced resins.

Some Examples of Engineering-Grade Resin Types Include:

  • Acrylonitrile Butadiene Styrene (ABS) —Chemically resistant, has excellent ductility and has high impact strength. However, it has poor solvent resistance and poor weather ability.
  • Polyethylene terephthalate (PET) —High water resistance, strength, and shatterproof.
  • Polycarbonate (PC) —High impact resistance, lightweight, and useful in applications requiring transparency.

Some Other Types of Engineering Plastic Resins Include:

  • Epoxy Resin
  • Uv Resin
  • Polyester Resin
  • Polyurethane Resin
  • Phenolic Resins
  • Alkyd Resins

Our MOS Plastics Division Also Offers High-Precision Capabilities That Include:

High-Precision Plastic Injection Molding


Precision Products are ones that require highly accurate components and are made into a workable parts from complex subassemblies.  At MOS Plastics we utilize high technology processes that are used in the production of complex device assemblies, and are able to get precision measurements to +/- .0001 of customer specifications.

Overmolding Process

The overmolding process is used to manufacture plastic parts with two or more materials. You can quickly create products with different materials or colors using this method.

Insert Molding

A specialty of our MOS Plastics division is our insert molding capabilities. Using a state-of-the-art vision system, allows us the insert very small plastic components and needles with precision, ensuring the tool isn’t damaged. We overmold millions of parts at the highest quality standards

plastics injection molding process

Two Shot Molding

Two-shot injection molding is a dual-step manufacturing process that enables the rapid production of complex parts from different materials in an efficient way. The first step of the two-shot injection molding process is similar to traditional injection molding: heated resin is injected into a properly warmed mold. The second step involves injecting a second material into the same mold. It creates multilayer, multicolor, or multi-material parts in a single molding process. This process is sometimes called 2K, multilayer, or multi-shot injection molding. 

Presses Ranging From 28 to 500 tons

MOS Plastics has 32 presses in the San Jose Facility of MOS Plastics. They range from 28 to 500 tons, and 14 of these presses are within a class 7 cleanroom. We offer class 7 and 8 cleanroom molding and assembly. 

Industries KSPlastics Works With

As a whole, The KS group aggregates many industries with its Plastic injection molding and contract manufacturing services. From automotive parts to life-saving medical devices, the KS Group is your vertically integrated supplier for the United States West Coast. 

Through our MOS Plastics division, we primarily focus on manufacturing and assembling all portions of the healthcare sector. Our specific strengths in this category are Medical devices, Diagnostics, Lifescience, Biotechnology, and Pharmaceutical Markets. We currently work with several of the largest OEMs in the space, including Theromofisher, Abbott, Medtronic, Allergan, and Cepheid. 

We are focused on servicing the Commercial, Automotive, Consumer, and Gaming markets through our San Leandro and Tijuana facilities. Our specific strengths in this category include Electric Vehicles, Batteries, pool pump systems, and Gaming machines. We work closely with Fluidra, Jandy, IGT, Tesla, and Camelbak in these industries.

Through our commercial divisions, we utilize certain biodegradable resins that are used in the production of plastic toys; these toys are made from recycled plastic waste and this special blend of biodegradable materials.

KS Manufacturing has 90 injection molding machines across 3 facilities and 2 continents. Of those 90, 8 are vertical presses specific to medical device molding. They are particularly suited for insert molding applications due to their design and use of gravity while molding.

Top Grade Inspections and Finishing Alternatives for Custom Plastic Molded Parts

Quality inspection is a process that involves measuring, examining, testing, or gauging various characteristics of a product and comparing those results with specified requirements to determine whether there is conformity.

There are several QA techniques:

  • Statistical process control (SPC): SPC is a method of quality control that uses statistical methods to monitor and control an injection molding process.
  • Failure mode and effects analysis (FMEA): FMEA is a method of quality assurance that identifies potential failures in a product or process and then determines the effects of those failures.
  • DFM

Contact KSPlastics Today for Your Plastic Parts Injection Molding Needs

MOS Plastics is an ISO 13485-certified contract manufacturer servicing the Healthcare market.

We offer full clean room molding, assembly, kitting, and packaging within our 50,000-square-foot San Jose, California facility. We offer 32 injection molding machines ranging from 28 to 500 tons, 8 of which are vertical presses for specialized medical device manufacturing. MOS Plastics is an industry leader when it comes to our insert molding capabilities. 

Have a project you would like to discuss? Send us an email at or give us a call at 408-994-9407 and dial extension 111.



High-precision molding is our specialty, and our turnkey services enable our customers to get their products to market quickly, with confidence.

Let’s talk about your project