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Ultra-high flow materials for Powder Injection Molding (PIM) powder injection molding (PIM)

Summary

  • Powder injection molding (PIM) is a technique for manufacturing miniature high-precision metallic or ceramic components. In PIM, a metallic or ceramic powder is first blended with a binder, then injection molded, processed to remove binder components, and sintered.
  • Asahi Kasei recommends our TENAC™ -C FF520 ultra-high-flow polyacetal copolymer as a PIM binder resin.

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What is powder injection molding (PIM)?

PIM is a technique for manufacturing miniature high-precision metallic or ceramic components. In PIM, a metallic or ceramic powder is first blended with a binder, then injection molded, processed to remove binder components, and sintered.

 

PIM was developed in the U.S. during the 1970s as an advanced approach to powder metallurgy for manufacturing metal components; the technique combined conventional methods of powder metallurgy with injection-molding techniques for plastics. The traditional approach to powder metallurgy, known as press molding, involved inserting metal powders into molds and could only produce components with relatively simple shapes. In contrast, PIM fabricates metal components according to the same principles used in injection molding, allowing mass production of complex-shaped components.

powder injection molding

PIM encompasses both metal injection molding (MIM), based on metallic powders, and ceramic injection molding (CIM), based on ceramic powders; the both processes are nearly identical in practice.

The PIM Process

A typical PIM process, here assuming the use of a metallic powder (MIM) as an example, proceeds as follows.

 

First, the metallic powder is blended with a binder (plastic + wax) to yield a uniform mixture, which is compounded into feed-stock pellets with good formability properties. These pellets are then molded by an injection-molding machine, just like typical plastics. The resulting molding parts are heated and treated with solvents, catalysts, and other agents to remove binders, then finally sintered in a furnace to yield high-precision metal components. The molding parts obtained immediately following injection molding contain some concentration of binder resins, but these components are eliminated by the binder-removal and sintering steps, ultimately producing metallic bodies with complicated three-dimensional shapes.

Powder Injection Molding

Features of PIM

PIM is a processing technique capable of addressing a broad and expanding range of needs, including production of precision instruments, electrical and communication devices, automotive components, and medical devices. PIM essentially forms metallic components via the same procedure used to manufacture plastics, and has the following key features.

Features of PIM

  • Capable of manufacturing high-precision components with complicated shapes
  • Allows high flexibility in the choice of metallic materials
  • Excellent for mass production with minimal variation in quality
  • No need to remove shavings, or for other post-processing steps
  • Restricted in practice to fabrication of small components due to difficulties in handling larger bodies

Resins used as PIM binders

Resins used as PIM binders must satisfy several practical requirements.

Key requirements for PIM binder resins

  • Resins must blend with metal or ceramic powders to yield uniform mixtures (for feed stocks).
  • Feed stocks must have good processing and formability properties.
  • Resins must exhibit minimal loss of strength at higher temperatures.

Among the various types of resin used as PIM binders, polyacetal (also known as polyoxymethylene or POM) has a number of particularly valuable properties: it is easily processed, offers high dimensional stability and high mechanical strength, and exists as a crystalline resin with many physical properties that remain stable over a range of temperatures extending up to the melting point. These properties of POM make it the primary choice for injection modeling of precision resin components such as gears—and carry over directly to the PIM domain when POM is used as a binder.

Asahi Kasei’s Recommended Solutions

TENAC™-C FF520 polyacetal copolymer

Asahi Kasei recommends our TENAC™-C FF520 ultra-high-flow polyacetal copolymer as a PIM binder resin.

TENAC™-C FF520 is an ultra-high-flow polyacetal copolymer developed as a binder resin for powder injection molding (PIM).

 

Polyacetal (POM) is commonly used as a resin constituent of PIM binders due to the high strength of POM itself and its ability to decompose with no residue under application of acid or heat. TENAC™-C FF520 combines the superior mechanical properties of POM with the advantage of ultra-high flow.

Comparison of TENAC-C FF520 properties vs. reference values for other resins used as PIM binders.

Comparison of TENAC-C FF520 properties vs. reference values for other resins used as PIM binders.

Sintered ISO2740 dumbbell fabricated using TENACTM-C FF520

Sintered ISO2740 dumbbell fabricated using TENAC™-C FF520.

For more information, please download slides

We hope you will consider Asahi Kasei’s TENAC-C FF520 as an ideal match for your design needs. For more information, please refer to the slides available from the download link below.

  • Download TENACTM-C FF520 slides here.

We would like to talk to you about Asahi Kasei’s TENAC™ -C FF520 for PIM binder resins. Please contact us to ask any questions, discuss any concerns, and request samples.

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