Handbook of Metal Injection Molding

Donald F. Heaney

• Publisher: Woodhead Publishing
• Year: 2012
• ISBN:
  9780857096234
• Topic: Technology & Engineering
• Subtopic: Mining Engineering
• Index: Technology & Engineering

Metal injection molding combines the most useful characteristics of powder metallurgy and plastic injection molding to facilitate the production of small, complex-shaped metal components with outstanding mechanical properties. The Handbook of metal injection molding provides an authoritative guide to this important technology and its applications.Part one discusses the fundamentals of the metal injection molding process with chapters on topics such as component design, important powder characteristics, compound manufacture, tooling design, molding optimization, debinding, and sintering. Part two provides a detailed review of quality issues, including feedstock characterisation, modeling and simulation, methods to qualify a MIM process, common defects and carbon content control. Special metal injection molding processes are the focus of part three, which provides comprehensive coverage of micro components, two material/two color structures, and porous metal techniques. Finally, part four explores metal injection molding of particular materials, including stainless steels, titanium and titanium alloys, thermal management alloys, high speed tool steels, heavy alloys, refractory metals, hard metals and soft magnetic alloys.With its distinguished editor and expert team of international contributors, the Handbook of metal injection molding is an essential guide for all those involved in the high-volume manufacture of small precision parts, across a wide range of high-tech industries such as microelectronics, biomedical and aerospace engineering.

• Provides an authoritative guide to metal injection molding and its applications
• Discusses the fundamentals of the metal injection molding processes and covers topics such as component design, important powder characteristics, compound manufacture, tooling design, molding optimization, debinding, and sintering
• Comprehensively examines quality issues such as feedstock characterization, modeling and simulation, common defects and carbon content control

1

Metal powder injection molding (MIM): key trends and markets

R.M. German, San Diego State University, USA

Abstract:

Metal powder injection molding (MIM) has been in production since the 1970s. During that time the market has expanded enormously to include a broad array of applications; the initial successes were in dental orthodontic brackets, watch cases, and firearms, but recently the technology has moved into higher performance, life-critical applications in dental implants, artificial joints, heart pacemakers, and aerospace jet engines. This chapter provides a statistical overview of MIM, its applications, growth, financial performance, and growth prospects.

Key words

markets

productivity

sales

applications

production statistics

capacity

financial

1.1 Introduction and background

Powder injection molding (PIM) has a main subdivision, metal powder injection molding (MIM), that has penetrated many fields. This chapter captures the status of the MIM field and provides a basis for evaluating different operations, markets, and regions. Like powder metallurgy, MIM relies on shaping metal particles and subsequently sintering those particles. The final product is nearly full density, unlike press-sinter powder metallurgy. Hence MIM products are competitive with most other metal component fabrication routes, and especially are successful in delivering higher strength compared with die casting, improved tolerances compared with investment or sand casting, and more shape complexity compared with most other forming routes. Injection molding enables shape complexity, high production quantities, excellent performance, and often is lower in cost with respect to the competition. Its origin traces to first demonstrations in the 1930s. In the metallic variant, most of the growth has been after 1990, when profitable operations began to emerge following several years of incubation.

Sintered materials technologies (cemented carbides, refractory ceramics, powder metallurgy, white wares, sintered abrasives, refractory metals, and electronic ceramics) add up to a very large value, with final products reaching $100 billion per year on a global basis. About 25% of that global activity is in North America. The production of metal powders alone in North America is annually valued at $4 billion (including paint pigments, metallic inks, welding electrodes, and other uses, besides sintered bodies). Sintered carbide and metal parts production in North America is valued at near $8 billion, where metal-bonded diamond cutting tools, sintered magnets, and semi-metal products contribute significantly to industry heavily focused on automotive and consumer products.

The powder metallurgy industry consists of about 4700 production sites around the world involved in variants of powder or component production. Most popular is the press-sinter variant that relies on hard tooling, uniaxial compaction, and high-temperature sintering. Based on tonnage, about 70% of the press-sinter products are for the automotive industry. However, on a value basis the story is dramatically different; metal cutting and refractory metal industries generate the largest value. Here the products include tantalum capacitors, tungsten light bulb filaments, tungsten carbide metal cutting inserts, diamond-coated oil and gas well drilling tips, highperformance tool steels, and molybdenum diode heat sinks. Compared to the other powder technologies, the MIM variant is still relatively new and small, but it is growing at 14% per year. In 2011 MIM products were globally valued at approximately $1 billion. This sales activity is spread over about 300 actors. Thus, the average sales would be just $3 million per year for a MIM firm.

1.2 History of success

Powder injection molding followed behind the first developments in plastic injection molding. Early polymers were thermosetting compounds; Bakelite, the first man-made polymer, was invented about 1909. Subsequently, as thermoplastic such as polyethylene and polypropylene emerged, forming machines appeared to facilitate the shaping of these polymers a few years later. The first demonstrations of PIM were nearly coincidental with the emergence of plastic injection molding. Simultaneously in the USA and Germany during the 1930s, this was applied to the production of ceramic spark plug bodies. This was followed by the use of PIM for forming tableware in the early 1960s. Generally these were components with wide allowed dimensional variation. The MIM variant reached production in the 1970s. The time delay between early demonstration and commercialization was due to a lack of sophistication in the process equipment. The manufacturing infrastructure improved dramatically with the advent of microprocessor-controlled processing equipment, such as molders and sintering furnaces, which enabled repeatable and defect-free cycles with tighter tolerances.

About 80% of the PIM production capacity is devoted to metals, recognized as MIM, but this generally does not include other metal molding technologies such as die casting, thixomolding, and rheocasting. The first MIM patent was by Ron Rivers (Rivers), using a cellulose–water–glycerin binder that proved unsuccessful. Subsequent efforts with thermoplastic, wax-based binders did reach production at several sites.

Major attention was attracted when MIM won two design awards in 1979. One award was for a screw seal used on a Boeing jetliner. The second award was for a niobium alloy thrust-chamber and injector for a liquid-propellant rocket engine developed under an Air Force contract for Rocketdyne. Several patents emerged, and one of the most useful was issued in 1980 to Ray Wiech. From this beginning, a host of other patents, applications, and firms arose, with special activity in California. By the middle 1980s the technology landscape showed multiple actors. Many companies set up at this time without a license, simply by hiring former employees from the early firms who brought with them insight into the technology.

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Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Contributor contact details
• Preface
• Chapter 1: Metal powder injection molding (MIM): key trends and markets
• Part I: Processing
• Part II: Quality issues
• Part III: Special metal injection molding processes
• Part IV: Special metal injection molding processes
• Index