3-D shape soft magnetic composite parts can be formed by general compaction method of powder metallurgy. In this study, the results on the high density nanostructured Fe-Si/Fe composite prepared by a warm compaction method were presented. Ball-milled Fe-25 wt.%Si powder, pure Fe powder and Si-polymer were mixed and then the powder mixture was compacted at various temperatures and pressures. Pore free density of samples up to 95% theoretical value has been obtained. The warm compacted sample prepared at 650 MPa and 240℃ had highest compaction properties in comparison with other compacts prepared at 300, 400 MPa and room temperature and 120℃. The magnetic properties such as core loss, magnetization saturation and coercivity were measured by B-H curve analyzer and vibration sample magnetometer.

In recent years, a rapid increase in demands for the soft magnetic composite parts has been created and it has been tried to improve their properties by various processing methods, alloying elements and compaction parameters. Warm compaction method has been used for the reduction of residual stress, the improvement of magnetic properties and the higher densities. In this work, the effects of warm compaction and polymer binder on magnetic properties of Fe powder core were investigated. The sintering powder, Fe oxide, was ball-milled for 30n hours. And then ball-milled Fe oxide powder was reduced through hydrogen reduction process. The hydrogen reduced Fe powder and polymer binder were mixed by 3-D turbular mixer. And then the mixed powder was warm-compacted. The magnetic properties such as core loss and permeability were measured by B-H curve analyzer.

Various approaches have been proposed to increase the green density. Warm compaction method has been used for the reduction of residual stress, the improvement of magnetic properties and the higher densities. In this work, the effect of warm compaction on green density of Fe powder was investigated. After ball-milling of Fe oxide powder for 30 hours, Fe oxide powder was reduced through the hydrogen reduction process. The pure Fe powder and polymer binder were mixed by 3-D tubular mixer. And then the mixed powder was warm-compacted with various compaction pressure and binder contents. The green density of specimen was added polyvinyl binder was higher than any other specimens.

Warm compaction powder metallurgy was used to produce a Ti3SiC2 particulate reinforced Cu matrix composite. Fabrication parameters and warm compaction behaviors of Cu powder were studied. Based on the optimized fabrication parameters a Cu-based electrical contact material was prepared. Results showed that in expend of some electrical conductivity, addition of Ti3SiC2 particulate increased the hardness, wear resistivity and anti-friction ability of the sintered Cu-base material.

Recently warm compaction techniques are focused on and commercialization of one high-density compaction process in the P/M industry. Another development is a new SEGLESS using a developed lubricant that reduces ejection force at room temperature compaction. It is possible to achieve high-density by reducing lubricant amount. In this paper we confirmed that green density was 7.35 g/cm3 at 686MPa of compaction pressure when the new SEGLESS was applied to relatively lower temperature warm compaction process, such as 80℃.

The processes of P/M affect the properties of sintered gears. The different techniques of P/M lead to the different properties of sintered gears. This paper summarizes new progress in powder metallurgy for sintered gears. These progresses include warm compaction, high velocity compaction, sinter hardening, high temperature sintering, infiltration, CNC powder press and surface densification etc.

We investigated the mechanism how the high green density can be provided during die lubricated warm compaction (WD). We observed and analyzed the densification processes of iron powders including different contents of an inner lubricant, and measured the lateral pressure at the die wall during WD in comparison with conventional compaction and warm compaction. As a result, the high density in WD was due to not only the particles-deformation enhanced by warming powders but also the particles-rearrangement promoted by reducing an amount of the inner lubricant rather than the die lubrication.

There is an increasing demand for PM-processes with the capability to produce parts of higher complexity than with conventional press and sinter technology in high production numbers. Warm-flow-compaction (WFC) makes use of improved flowability of powders when blended in an appropriate ratio with fine powder fractions and lubricating binders. Here the process is shown with examples of PM-Steels. General features possible with the process like pressing of undercuts and threaded bores are shown.

An apparatus measuring changes of various forces directly and continuously was developed by a way of direct touch between powders and transmitting force component, which can be used to study forces state of powders during warm compaction. Using the apparatus, warm compaction processes of iron-based powder materials containing different lubricants at different temperatures were studied. Results show that densification of the iron-based powder materials can be divided into four stages, in which powder movement changes from robustness to weakness, while its degree of plastic deformation changes from weakness to robustness.

PM recent developments focus on increasing this technology's competitiveness when compared to wrought materials. Warm compaction allows the replacement of a double press double sinter process with a single warm press and sintering step, thus allowing cost and time savings. Moreover there are added benefits to consider such as reducing work in process and lessening part's logistics cost. This paper presents a successful industrial trial to replace a double press-double sinter process with a warm die compaction and sintering process. The part chosen was a high performance gear containing 0,9% wt. carbon. Sintering was conducted in a belt furnace at in a nitrogen rich atmosphere with rapid cooling process in order to obtain a quasi fully martensitic structure with a minimum of 700HV0,1 and 450HV10 after annealing. The balance between properties and cost is favoured by the use of a singular lubricant developed in a Eureka frame project together with POMETON S.A. and die warm compaction. Warm compaction is only needed to be effective on the gear teeth, in order to achieve the required properties. Therefore only the die is actually heated. This simplified system avoids flow rate problems typically involved when using more elaborate warm compaction equipments.

The high pressure compaction without internal lubricant and the high green density even with the pore free density were achieved by the newly developed die wall lubricant for warm compaction. This developed die wall lubricated warm compaction followed by high temperature sintering resulted in not only the superior mechanical property but also the low dimensional change. In this paper, the effects of increasing the green density on the sintered density, the dimensional change and the mechanical property are mainly discussed

In recent years, demands for sintered ferrous material with higher strength are increasing. To satisfy these demands, studies and commercial use of the die wall lubrication method, the warm compaction method and the combination of both methods are widely carried out to achieve high density. The die wall lubrication warm compaction method makes it possible to achieve high density by reducing internal lubricant through die wall lubrication, although the method involves several issues such as prolonged cycle time due to lubricant spraying and difficulty in spraying lubricant in the case of compacting with complicated geometry. Meanwhile, the conventional warm compaction method requiring no die wall lubricant application cannot achieve such a high density as in the case of die wall lubrication warm compaction due to higher volume of internal lubricant. However, this report discloses our study result in which the possibility of improving density is exhibited by using a lubricant type with superior dynamic ejection property that can reduce volume of lubricant additive.

The deformation under radial pressure of rectangular dies for metal powder compaction has been investigated by FEM. The explored variables have been: aspect ratio of die profile, ratio between diagonal of the profile and die height, insert and ring thickness, radius at die corners, interference, different insert materials, i. e. conventional HSS, HSS from powders, cemented carbide (10% Co). The analyses have ascertained the unwanted appearance of tensile normal stress on brittle materials, also "at rest", and even some dramatic changes of stress patterns as the die height increases with respect to the rectangular profile dimensions. Different materials behave differently, mainly due to difference of thermal expansion coefficients. Profile changes occur when the dies are heated up to the temperature required for warm compaction. The deformation patterns depend on compaction temperature and thermal expansion coefficients.

With the onging trend of weight saving in automobiles, the application of light alloys is increasing. Recently, aluminum powder metallurgy has been the subject of renewed attention due to the combination of lightweight of aluminium and the efficient material utilisation of the powder metallurgical process, which offer attractive benefits to potential end-users. This study is to explore the use of warm compaction process to aluminium powder metallurgy. This paper presents a detailed study of the effect of warm compression and sintering conditions on the resultant microstructures and mechanical properties of Al-Cu-Mg-Si PM blend.

Densificationbehavior of conventional austenitic stainless steel powder compacts was studied by comparing the relative density of sintered compact(Ds)with that of green compacts(Dg)prepared with various catbon contents and P/M process. Dg of 304and 316 powders by warm compaction under pressure of 686 MPa at heating temperature of powder(553K) and dies (573K) were 80% and 81%, repectively, whichwere 2 and 3% higher than those of conventional green compacts at the same pressure. Ds of 304 compacts sintered at 1373K in H2 gas has the same value of 84% max. regardless of compacting temperature, and Ds of 316 compacts at the same sintering conditions were 80% by conventional compaction and 83% by warm compaction. Oxygen contents of 304 and 316 sintered compacts were increased 1.43∼2.94% and 0.010∼0.921% higher than those of raw powders and warm green compacts, respectively. In other case, Ds of 316 compacts sintered at 1573K in vacuum had the same value of 86%max. And Ds of 316 compacts at the same sintering conditions were 83% and 86% by conventional and warm compaction, respectively. Oxygen contents of 304 sintered compacts were 0.321% and 0.360%, and in case of 316, they were 0.419% and 0.182% by the respective compating condition. With carbon additions in the range 0.1∼0.6% Ds increased to the extent of 86∼89% in 304 sintered compacts, and to 82∼84% and 85∼87% in 316 according to different two compacting peocesses compared to those of sintered compacts without carbon addition.