AMT | Specifications, Standards, and Testing Procedures in Powder Injection Molding

Date：2025-06-06   Views：1019

Table of Contents

Quality Standards

Material Standards

Product Standards

Testing Standards

Testing Objectives

Resources for Additional Information

Quality Standards

The final phase of Powder Injection Molding (PIM) production is inspection. Quality efforts in PIM are consistent with those across all manufacturing enterprises. Leading PIM producers are certified by international systems such as ISO, Total Quality Assurance, GMP, or Automotive Industry QS criteria. The ISO 9000 standards differentiate between companies with design responsibilities and those that are fabricators. ISO 14000 focuses on environmental compliance.

At the core of the quality system are inspection, documentation, and assurance that the shipped product meets customer and internal standards. Key concerns include production set-up and actual production. During first-article manufacturing, various tests may be required, including visual examinations, weight checks, ultrasonic examination, X-ray radiographs, optical profiling, and resistivity, magnetic, or dimensional checks. Dimensional and weight uniformity are of paramount importance.

During production, periodic samples are measured based on a planned sampling frequency. Common inspection tasks include visual examination for defects, density and weight determinations, measurement of final dimensions, and verification of impurity levels using hardness or chemistry tests. Calibration and acceptance criteria are largely set by customers and suppliers on an ad hoc basis due to the lack of PIM reference materials.

Material Standards

Most PIM compositions are treated at two levels: nominal composition and specific ingredient specifications. Nominal composition is generally expressed by designations such as 316L or 98% alumina. Specifications allow for reasonable composition and property variation. For example, 316L stainless steel allows for a range of ±1 to 2% on major alloying ingredients. Specific ingredient specifications detail impurity limits and important composition relations.

There is no industry-accepted set of material standards. Producers have formed some material standards through regional trade associations. More rigorous standards often come from users in industries such as automotive, medical, and microelectronics. However, most material standards are derived from military specifications, ASTM, or other recognized efforts.

Product Standards

PIM lacks process, material, and geographic specificity in its governing bodies. Many PIM operations have joined regional or material-based trade associations. Fragmentation inhibits sharing trade data across geographic and material boundaries, leading to regional data for specific materials. This has resulted in the need for a global PIM materials trade association to improve standards and industry statistics.

Testing Standards

Despite challenges with material standards, progress has been made in developing testing standards for PIM. Nomenclature is standardized, and publications from organizations like the National Institute for Standards and Technology define the language for various tests. Most PIM firms have their own tests for raw materials and products. Industry standards promoted by organizations such as the European Powder Metallurgy Association and the Metal Powder Industries Federation provide useful procedures for powders and products.

Common engineering tests for PIM products include mechanical property tests, surface finish measurements, magnetic response, corrosion resistance, and microstructure examination. These tests are often adopted from ISO or ASTM standards.

Testing Objectives

Testing in PIM production aims to prevent or eliminate defects early to ensure conformance to specifications and quality standards. Dimensional control is crucial, and testing helps minimize dimensional scatter. Weight control of molded components helps reduce dimensional variation. Process control technology can achieve weight variation of ±0.1%, but dimensional scatter can grow at each processing stage, making sintering unable to correct variations in the molded product.

Resources for Additional Information

For more detailed information on specifications, standards, and testing procedures in PIM, refer to the following resources:

• Materials Standards for Metal Injection Molded Parts, Metal Powder Industries Federation

• Standard Test Methods for Metal Powders and Powder Metallurgy Products, Metal Powder Industries Federation

• The Business of Injection Molding, Injection Molding Magazine Book Club

• Guide to Rheological Nomenclature: Measurements in Ceramic Particulate Systems, National Institute of Standards and Technology