Specialists in Plastic Injection Molding and Insert Molding

事業内容 Business

Our Technology Our Technology

Expertise in Large-Scale Insert Molding

We manufacture a wide range of insert-molded products, including air filters, serving diverse industries such as home appliances, automotive, and housing equipment.
By combining large-scale vertical injection molding machines of up to 300 tons with the expertise of certified injection molding technicians, we deliver large insert molding solutions with reliable quality—capabilities that are difficult to achieve elsewhere.
In addition, we carefully select molds and resin materials based on product applications and durability requirements, enabling us to provide molding solutions tailored to our customers’ specific needs and expectations.

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About Insert Molding About Insert Molding

Insert molding is a manufacturing process in which components made of materials such as metal, glass, or resin are placed inside an injection mold, and molten plastic is injected around them to create a single integrated product.
By combining plastic with components made from different materials, insert molding eliminates the need for separate assembly processes while enhancing product strength, functionality, and overall performance.

Insert Molding Illustration
  • 1

    Selection of Insert Components

    Insert materials such as filters, metal components, and glass are selected based on the intended application.
    Image of the insert flow
  • 2

    Placement of Insert Components

    Insert materials are positioned inside the mold.
    Image of the insert flow
  • 3

    Resin Injection & Integrated Molding

    Resin is injected to form a single integrated component with the insert material.
    Image of the insert flow
  • 4

    Mold Opening & Part Removal

    The molded part is removed and inspected for appearance, dimensions, warpage, and strength.
    Image of the insert flow
Insert-Molded Products
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Benefits of Insert Molding Benefits of Insert Molding

Eliminate Secondary Processing with Insert Molding!
Boosting Efficiency and Cost Effectiveness

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    Significant Reduction in Component Count

    By molding resin together with components made from different materials, insert molding reduces the need for assembly processes and multiple individual parts. This simplifies product structures while contributing to weight reduction and greater design flexibility.

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    Reduction in Total Costs

    Because assembly is completed within the mold itself, secondary processes such as bonding and crimping are no longer required.
    By shortening the production process, insert molding improves manufacturing efficiency while helping to reduce labor costs and overall production management costs.

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    Enhanced Safety, Strength, and Durability Through Integrated Molding

    By securely integrating components made from different materials with resin, insert molding enhances product strength and durability.This enables reliable, long-lasting performance in demanding applications, including home appliances and automotive components, where durability and consistent quality are essential.

Mitsumikoma’s Strengths Mitsumikoma’s Strengths

Strengths01

Proven Expertise Backed by the Production of 3.5 Million Units Annually

We manufacture more than 3.5 million insert-molded products annually, including air filters. By utilizing vertical, horizontal, and small-scale molding machines according to product requirements, we are able to handle everything from large-scale insert molding to ultra-thin insert molding as thin as 0.05 mm and ultra-precision molding.
Drawing on the expertise gained through our extensive manufacturing experience, we provide support from the earliest stages of product development, including specification review, design assistance, and manufacturing process proposals.
We approach every challenge with innovative thinking, delivering molding solutions that go beyond conventional ideas and make our customers say, “We never thought of that.”
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Strengths02

Supporting Large-Scale Insert Molding with 300-Ton-Class Production Capabilities

We operate multiple 300-ton-class vertical injection molding machines capable of producing large molded parts up to 800 mm × 700 mm, giving us a strong advantage in large-scale insert molding. We can also evaluate and manufacture large insert-molded products using specialty resin materials.Through the expertise of certified injection molding technicians, combined with optimized molding conditions and rigorous design and production management, we achieve stable, high-quality results even for large insert-molded products that are prone to deformation and warpage.
Vertical Insert Molding Machines

Strengths03

100% Material Sourcing Capability. Delivering Solutions from the Material Level

One of our key strengths is the ability to source and optimize a wide range of materials, including filter fibers, metals, and resins.
In particular, filter fiber materials can be finely customized to meet specific performance requirements. This capability is supported by our close collaboration with the Tamurakoma Group, a leading textile trading company and our parent organization.Leveraging our extensive sourcing network and expertise in diverse materials, we optimize everything from material selection to molding conditions. This integrated approach enables us to maintain stable mass production while minimizing defects and ensuring consistent product quality.
Insert-molded parts

Manufacturing Process Manufacturing Process

At Mitsumikoma, we provide a one-stop manufacturing solution covering every stage of production, from design and molding to secondary processing, inspection, and shipping.
Our integrated production system ensures a smooth transition from prototyping to mass production. By maintaining strict quality control throughout every process, we deliver reliable products and a manufacturing environment that our customers can trust with confidence.

  • 01

    Planning, Design & Mold Manufacturing

    Planning, Design & Mold Manufacturing

    We carefully assess our customers’ requirements, operating environments, and durability expectations to propose the most suitable resin materials and mold specifications.We also provide design support with consideration for manufacturability, including molding-friendly product designs and production methods. By taking mass production requirements into account from the early stages of development, we help ensure a smooth and efficient path from concept to production.

  • 02

    Mold Installation and Machine Setup

    Mold Installation and Machine Setup

    The completed mold is installed on the injection molding machine in preparation for production.
    Depending on the product size, complexity, and material requirements, we select the most suitable molding equipment, ranging from 300-ton-class vertical injection molding machines to compact horizontal machines, ensuring efficient and stable production.

  • 03

    Insert Component Loading

    Insert Component Loading

    Insert materials such as filters, metal components, and glass are precisely positioned within the mold before the molding process begins.
    Because even a slight misalignment can directly affect product quality, this is a critical step that requires a high level of accuracy and attention to detail.

  • 04

    Resin Injection and Integrated Molding

    Resin Injection and Integrated Molding

    The resin selected for the application is injected into the mold, where it is integrated with the insert components to form a single molded product.
    After the mold is filled, pressure and cooling conditions are carefully controlled to minimize warpage and sink marks, ensuring dimensional stability and consistent product quality.

  • 05

    Part Removal and Inspection

    Part Removal and Inspection

  • 06

    Post-Processing, Assembly & Shipping

    Post-Processing, Assembly & Shipping

    Excess material is removed from the molded products, and finishing processes are carried out to achieve the required shape and appearance. When necessary, we also provide assembly services before carefully packaging and delivering products that meet our high quality standards.
    By maintaining a fully integrated production system, we ensure consistent quality throughout every stage of the manufacturing process, enabling us to deliver reliable products to our customers time after time.