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The demands on valve seat insert materials, in terms of providing greater wear-resistance at higher temperatures, enhanced machinability and using non-environmentally hazardous materials at a reasonably low cost have intensified in recent years. Due therefore to these strong demands in the market, research was made into the possibility of producing a new valve seat insert material. As a result a high speed steel based new improved material was developed, which satisfies the necessary required demands and the evaluation trials, using actual gasoline engine endurance tests, were found to be very successful.

Generally, cobalt-contained sintered materials have mainly been applied for exhaust valve seat inserts (VSI). However, there is a trend to restrict the use of cobalt as well as lead environmental law, and cobalt is expensive. To solve these problems, a new exhaust VSI on the assumption of being cobalt and lead free, applicable for conventional engines, having good machinability, and with a reduced cost was developed. The new exhaust VSI is a material dispersed with two types of hard particles, Fe-Cr-C and Fe-Mo-Si, in the matrix of an Fe-3.5mass%Mo at the ratio of 15 mass % and 10 mass % respectively.

The demands on valve seat inserts are that they should have enhanced wear resistance and machinability using non-environmentally hazardous materials at a reasonably low cost. Research into the possibility of producing a new valve seat insert material which fulfills such demands was therefore made. As a result Hitachi Powdered Metals (HPM) has developed a new material which uses dispersed die steel hard particles in the production of intake valve seat inserts.

A new sintered material has been developed which shows high performance as a internal combustion engine valve guide. This material, consisting of Fe-Cu-Sn-P-C-Graphite alloy, includes free graphite, Fe-P-C hard phase and pores in it, and offers both of good durability and machinability.

The key-points in the diffusion bonding technique of green compacts during sintering, are the material compositions, which should be chosen according to their dimensional change during sintering, and the fitting clearance, which should be maintained in the range of press fit. Applying this technique, we have developed sinter-diffusion bonded idler sprockets for automotive engines by comfirming the bonding strength and torsional fatigue strength. And we also have developed a nondestructive analysis method for assuring the joint strength of idler sprockets in the mass production.

Recently the demands on automobile engines have greatly increased, these demands include better performance and improved energy efficiency and more environmentally friendly materials. As a result of these demands, the requirements on valve guides in the valve train have increased, not only in regards to greater wear resistance but also in regards to better machinability. In particular, the valve guide tool is now expected to have a longer life, a shorter machining time and a reduction in the revolving energy of the tool. We, at Hitachi Powdered Metals, in order to answer to these new requirements have improved the machinability sintering valve guide material where, up until now, it has been difficult to improve the machinability and the wear resistance at the same time.

Sintered materials have been applied widely for Valve Seat Inserts (VSI) due to their high flexibility of material design. Hard particle dispersion type materials, which have specific microstructures in sintered material, are popular for VSIs. The load - temperature, combustion pressure, etc. - on the VSI has become severer along with increasing demands for better engine performance. (1) Especially, there is increasing tendency of the amount of wear on VSIs when used in heavy-duty engines such as diesel/gas (LPG, CNG) engines because of their dry environments.(2) In this paper, two new developed high performance VSI materials for heavy-duty engines are introduced. These materials adopt new hard particles and a new method of distribution of the solid lubricant to increase wear resistance. Hard Particles: The new developed hard particle has superior wear resistance due to increasing the amount of intermetallic compounds.

The LogiX tooth profile making up for some demerits of Involute tooth profile excelled in surface durability and wear-abrasion resistance because of many points on the tooth profile having being zero relative curvature and specific sliding. The usage of this tooth profile can expand the application fields of P/M gears which have been limited in the past due to their lower surface durability and wear-abrasion resistance. Furthermore, it makes possible to use conventional material in exchange for expensive high strength material and to eliminate the heat treatment process. This report will show a characteristic of “LogiX” tooth profile, basic properties and the application on it to oil pump gears. This Profile is now under the application in mass production for the diesel engine oil pump gears.