Metal Injection Molding

mim-partsMetal injection molding (MIM) is an advanced metal forming process that allows complex parts to be shaped in a single operation and in high volume—a perfect solution for creating small, complex metal components. Although metal injection molding can be utilized across a wide range of components, the best applications are typically small in overall size and less than 100 grams in weight. It is sometimes referred to as powdered injection molding (PIM).

Key MIM Differentiators

  • Costs less than CNC
  • Produces better feature detail than investment casting
  • Provides very accurate results
  • Offers more shape complexity than stampings
  • Works great for simple and complex metal parts formed to tight tolerances

mim-moldingHow Metal Injection Molding Works

Any finely-tuned operation requires strict adherence to a process. To create MIM parts, we follow 5 basic steps.

5 Steps for Producing MIM Parts

  1. Powder blending
  2. Injection mold
  3. Debinding
  4. Sintering
  5. Secondary operations
    • Coining
    • Machining
    • Heat treating
    • Plating
    • Black oxide
    • Lapping
    • Tumbling
    • Bead blast
    • Black nitride
    • Hot isostatic pressing (HIP)

This metallurgy technique involves mixing finely-powdered metal with a carefully selected and measured amount of binder material (polymer) to comprise a “feedstock.” This blending and extruding process is very tightly controlled to produce a top-quality final product. This feedstock then goes to molding presses equipped with robotic part handlers, which allows for production of a broad range of shapes and complexities using many different alloys. From there, MIM parts are transferred and immersed into water to remove approximately two-thirds of the binder. Parts are then dried to limit the amount of water present for the next step in the process—sintering, which is performed in a hydrogen/nitrogen atmosphere. The pusher furnaces provide excellent throughput and high-temperature capability. After sintering, any secondary operations are employed to create your finished metal injection part to your exact specifications. Every metal injection production run is quality monitored to ensure you receive your parts just as you ordered. The inspection process uses a multitude of techniques and equipment, including an alloy analyzer, optical comparator, Optical Gaging Products (OGP), automated inspections, and mechanical testing.

How MIM Parts Increase Your Production Efficiencies

  • High complexity shape capability
  • More efficient use of material and processes
  • Less material waste
  • Repeatability
  • Excellent mechanical properties
  • Lower overall product cost
  • Tailored solutions using unique materials
  • Materials can be brazed/joined to a variety of components for complete assembly solutions

Key Attributes

  • Metal injection molding is a repeatable process for complex components made from high-temperature alloys
  • MIM parts are near fully dense, which gives excellent mechanical, magnetic, corrosion, and hermetic sealing properties, and allows secondary operations like plating, heat treating, and machining to be easily performed
  • The shrinkage from molded parts to sintered parts is high (15-20%), but isotropic and controllable
  • Complex shapes are achieved through tooling techniques used in the plastic injection molding industry; high volumes are attained through multi-cavity tooling

Markets Served

  • Firearms
  • Medical
  • Orthodontic
  • Industrial tools
  • Security lock systems
  • Lawn & garden
  • Aerospace/Defense
  • Automotive/Heavy truck

MIM Parts Alloy Capabilities

  • Stainless steel
  • Low-alloy steel
  • Superalloys
  • Controlled expansion alloys
  • High-Density alloys
  • Soft magnetic alloys

Metal injection molding materials include all standard alloys, plus application-specific alloys upon request. As part of our MIM process, we offer low-cost prototyping, an experienced process and metallurgical team, and tool transfers from other metal injection producers. We are ISO 9001:2008 certified and support JIT and Kanban programs.

Metal injection molding is one of the many ways CSI can provide one-source solutions for you. With our years of experience and valued partners, all leaders in the high-precision component manufacturing segment, we can easily delivery the customized parts and components best suited for you. Our experienced engineering team is ready to work with you to find the best one-source solution for your needs. Contact CSI to get the conversation started.