Hoeganaes Corporation will present three technical papers at Euro PM2015, which takes place in Reims, France, from 4–7 October.
Ferrous PM Opportunities and Challenges with High Temperature Sintering, Bruce Lindsley
High temperature sintering (>1200 C) of ferrous PM components enables a number of potential benefits. Particle bonding is improved, density can be driven to higher levels, mechanical properties increase, especially those of hybrid alloy systems as a result of enhanced diffusion of alloying elements, and alloying elements with higher affinity for oxygen can be effectively processed. Use of Cr, Mn, Si and V allows greater flexibility in alloy design and can reduce the dependence on the traditional Mo, Ni and Cu alloying elements. Given these possible benefits, there are barriers to the wide spread use of high temperature sintering. Equipment is the largest challenge, but looking beyond this barrier, other issues include dimensional control, carbon control and melt-related defects. Part distortion results from non-uniform green density and/or friction with sintering trays, carbon reacts with hydrogen at a greater rate to produce a decarburized condition, and non-uniform distribution of alloying elements and other contaminates can result in localized melting. The presentation will explore both the benefits and address several of the challenges associated with high temperature sintering.
Sensitivity Analysis of Machining Parameters in Fe-Cu-C Mixes Containing Machining Enhancers, Cecilia Borgonovo and Bruce Lindsley
The paper addresses the need of improving machining behavior of PM components. Parts manufactured by means of powder metallurgy are characterized by a very heterogeneous microstructure, not only as far as phases in the material itself, but most of all for the presence of voids. As a result, the machining tool is subjected to very high thermal and mechanical stresses due to these diverse structures that the tool comes into contact at every pass. The addition of MnS to premixes has traditionally given enhanced machinability and lowered tool wear; despite this, MnS is a sub-optimal solution in that it tends to accelerate rusting under atmospheric conditions. This makes machining operations time-sensitive and difficult to control. In the present work, we investigate the response to drilling of the Fe-Cu-C system with addition of novel machining additives. Specifically, the dependency to feeds, speeds, coolant and drill bit material will be analyzed. The variables that will be accounted for in the study are number of holes drilled, torque, and variation in hole size. The wear mechanism for different test conditions will also be explored and ultimately the optimum machining variables per condition will be selected.
Industrial Performance of a New Lubricant for Manufacturing PM Gears, Peter Sokolowski, Andreas Milbrath, Davide Vitti, and Stefano Fontana
Admixed lubricants used in powder metallurgy (PM) have been effective at meeting the needs of the industry to manufacture traditional PM parts. With increasing demand to improve upon part tolerances, surface finish, density distribution, weight consistency, and reduced environmental impact; parts makers desire to replace traditional lubricants such as Acrawax and Kenolube. In an effort to do so, Ancorlube has been developed as an engineered lubricant system to enable robust part manufacturing. This work compares the production characteristics, based on lubricant type, for a water pump gear pressed to a density of 6.80 g/cm3. The weight consistency was evaluated during serial production of more than 5,000 gears, each weighing approximately 191 grams. A standard deviation of 0.6 grams was measured, indicating that a stable process was achieved with a premix containing Ancorlube. Metallographic inspection of surface quality and density distribution was evaluated and compared against parts made with Kenolube. In addition, laboratory studies show improved ejection characteristics are obtained at typical press operating temperatures approaching 60°C (140°F).
This story is reprinted from material from Hoeganaes, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
