CPMT is presently involved in the following projects:
This project will investigate of strain-controlled, low-cycle axial fatigue response of steel and aluminum PM steel materials and process conditions. The building of data for use with comprehensive design tools for fatigue performance is expected to continue for several years.
A variety of high performance mixes will be prepared using acoustical mixing technology. Samples will be evaluated and compared with traditional mixing techniques. Compacted test specimens will be evaluated in the green and sintered condition for improved microstructural uniformity and mechanical properties.
Different sintering tray/plate materials will be evaluated to compare microstructure and dimensional stability of PM parts during the sinter hardening process. The plate materials will be ceramic vs. carbon/carbon fiber. Dependent upon outcome, a second test program to review resulting microstructures may be considered.
Investigation of shot peening (normal and micro-peening) on the gear performance of high density PM gears will include effects on residual stress, microstructure, density, dimensions and surface finish, and gear test performance.
This project will investigate the advances in die-wall lubrication techniques for warm-tooling compaction. Compaction behavior, including ejection forces, compaction forces, processing rate and any wear of damage on the tools will be investigated. Parts will be evaluated for dimensional consistency, green density, density gradients, green strength and staining.
Full reports are available to members in the Members' Only section of this website. CPMT has issued reports for the following projects:
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 FC-0205, FC-0208, FN-0200, FN-0205, FL-4405, FL-5305, FLN2-4400, FLN2-4405, FLN2-4408, FLNC-4408, FLC-4208, FLC-4608 and PM aluminum alloy AC-2014.
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.
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.
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.