CPMT Logo

Issued Project Reports

Full reports are available to members in the Members' Only section of this website. CPMT has issued reports for the following projects:

Strain-Based Fatigue for Powder Metallurgy Materials

The majority of fatigue data generated from PM laboratory test specimens have utilized the traditional stress-based approach. This approach is based on nominal (average) stresses within a component that is being analyzed. While most engineered components are designed such that nominal stresses remain elastic during service loads, local areas of stress concentration can cause plastic strains. The strain-based approach to fatigue involves detailed analysis of localized plastic deformation (yielding) that may occur in areas of stress concentration and is used as a basis for calculating fatigue life.

A long-term fatigue program is being conducted by CPMT in collaboration with the Metal Powder Industries Federation (MPIF) Standards Committee to determine the strain-based fatigue properties of sintered materials. To date, reports have included ferrous alloys FN-0205, FLN2-4405, FL- 4405, FLN2-4405, FL-5305, FC-0208, FLC-4208, FLNC4408, FLC-4608, and PM aluminum alloy AC-2104.

Powder Metallurgy Lubrication Study: Lubricant Practice and Tool Coating Effects

The ability to compact components to higher densities for improved properties is a common goal of the powder metallurgy industry. Reducing admixed additions such as lubricants to iron powder premixes is one of the most effective means of attaining higher pore-free density in as-pressed parts. Based on this premise, a multi-year study to determine the lowest level of lubricant admixed in ferrous powder premixes that provides acceptable compaction and part ejection forces, and also provides acceptable die tool wear. Additional technologies were evaluated in concert with trials using lower lubricant premixes. These technologies included tool coatings, premium steel tooling material and die wall lubrication.

Single Press to Full Density: Traditional Warm Compaction and Sintering Methods

Warm compaction technologies were employed for single press/single sinter at both conventional and high temperatures to produce a gear design used in testing by the Gear Research Institute, Penn State University, a single level, 3.34 inch diameter spur gear with 24 teeth. Results suggested that a practical upper limit to green density is 7.35 - 7.45 g/cm³. This limitation is based on the pore free density (PFD) of the premix and rationalization that only 98% PFD is practical. The amount of density increase via sintering was minimal, even with high temperature sintering at 1285°C (2350°F). Coordinate measurements of gear geometry produced by this technology resulted in values similar with gears produced by other PM process technologies, or correctable with die design modifications.

Effect of Drilling or Turning and Tooling Parameters on the Machinability of Select PM Materials

This two-part, multi-year machinability study conducted by CPMT, evaluated drilling and turning machinability of a baseline steel, AISI/SAE 1045 wrought compared to four popular powder metallurgical sintered steels, three iron or low alloy structural grades and one stainless steel, 409 grade. Two reports document drill and turning (plunge) tests with the relative measure of machinability determined by the response variables, cutting force and tool life, i.e. number of plunge holes or cuts. Powder metallurgical material and secondary process parameters investigated include composition, carbon content, density, hardness and two types of machinability enhancers, manganese sulfide additions to the powder mix and post-process resin impregnation.