The winners of the Japan Powder Metallurgy Association (JPMA) 2012 Powder Metallurgy Awards highlight the capabilities of PM and demonstrate the continuing advances of Japan’s PM industry. Many of the winners are evidence of the continuing potential for PM applications in the automotive industry.
Development Prize: New Design
Variable valve timing parts on the exhaust side for eco-friendly car
Diamet Corporation received an award for the development of a rotor and housing for the variable valve timing system of an eco-friendly car.
The design required high precision components offering weight savings and cost reductions.
The combination of the rotor and the housing was designed to avoid drilling holes for setting springs. Tight tolerances between the rotor and the housing were achieved, resulting in a sealant free system. Blind holes on the rotor were formed by compaction, which resulted from improved powder flow and optimised tool design and material.
Sintered bearings for the poppet valves in an exhaust gas recirculation system
Diamet Corporation also received an award for the development of sintered bearings for the poppet valves in an exhaust gas recirculation (EGR) system.
The original bearing was made from graphite in order to endure high temperature (250°C) tribological properties and was machined out for the inner asymmetric shape to inhibit valve rotation.
Diamet has developed a new PM material to replace the graphite bearings. The Cu-Sn-C material has a high carbon content of more than 6mass% to satisfy the high temperature tribological properties. The microstructures of the material consist of Cu-Sn matrix and uniformly dispersed graphite phase. The graphite phase also seals pores, which results in preventing oxidation.
Powder Metallurgy offers a machining free production process, with the guide part of the asymmetric inner hole shaped by sizing.
Torque converter utilising CNC compacting techniques
Sumitomo Electric Industries, Ltd.
Sumitomo Electric Industries received an award for the development of a turbine hub used for a torque converter of an automatic transmission.
CVT production has been increasing for small vehicle applications, offering better transmission efficiency at a low speed range. However, for large vehicles requiring a larger output, automatic transmissions are preferred. The use of forged turbine hubs in automatic transmissions become the main choice due to the need for high strength, large, complicated shapes.
This sintered turbine hub, developed by Sumitomo Electric Industries, utilises CNC compacting technology and sizing techniques. The product has a complex shape incorporating a large, thin, flange with 24 rivet holes and inner spline with step.
The turbine hub, successfully produced by the Powder Metallurgy process, offers a lower cost alternative to that produced by forging.
Sintered coupling for the balancer in a clean diesel engine
Diamet Corporation received an award for the development of this coupling for the balancer in a clean diesel engine. The high strength, wear resistance part works as a connection between crankshaft and balancer, where high precision is required for assembly.
In order to obtain a cost advantage to wrought steels the part is produced without machining. High precision is achieved by optimum tool design and material based on FEM analysis, and by optimisation of compacting conditions for the improvement on the density distribution. A Fe-Mo-C system steel was selected for the material of the part.
The Powder Metallurgy process allows for the net shape mass production of this high precision component.
Parking shift support parts in a CVT system
Hitachi Chemical Co., Ltd
The design eliminates the need for certain existing parts, allowing for a more compact unit
The prevention of cracks during compaction was managed by improvement in tooling rigidity. Heat treatment was optimised in order to secure the dimensional accuracy.
The PM process allows for a design that reduces the total number of parts used in the unit, offering weight and cost savings.
Component of a lightweight centrifugal clutch
Hitachi Chemical Co., Ltd.
Hitachi Chemical also received an award for the development of a centrifugal clutch part for automatic motorcycles.
The component required a high level of accuracy and wear resistance, whilst being lightweight for improved fuel economy and offering a reduction in cost.
A high dimensional accuracy resulted from suppressing the variation in density distribution, analysing the filling method of material powder, feeder and compacting conditions, optimizing sintering and sizing conditions and applying a steam treatment instead of normal carburizing.
The final design allows for mass-production of the lightweight centrifugal clutch parts, whilst meeting the customer’s accuracy, wear resistance, and cost reduction requirements.
Development Prize: New Materials
Low noise oil impregnated bearing for fan motors in super-slim laptops
The material developed by Porite Corporation is used for producing low noise bearings for the fan motors in super-slim laptop computers.
As the laptop becomes thinner and lighter so does the fan motor in it. The thinner motor means shorter length and higher loads per unit area of the bearing supporting the shaft. As a result the oil film strength of the bearing becomes insufficient and can cause increased noise levels.
To prevent high frequency noise caused by iron in the material, Porite developed a bronze based powder with a reduced tin addition.
The resulting material allows for low noise and low cost oil impregnated sintered bearings to be produced. In the future, Porite expect that this bearing material can also be applied to the cooling fan of home LED lamps.
Development Prize: New Powder
Segregation-free mixed powder to achieve a sintered material with excellent drilling performance
JFE Steel Corporation
JFE have developed this segregation-free mixed powder in order to improve drilling performance of iron-based sintered parts.
Conventionally a sulfurization treatment is applied to the part which has many holes, such as a shock absorber piston. However, carbon disulfide used in the sulfurization treatment is a substance subject to Pollutant Release and Transfer Register (PRTR) regulations, and as such an alternative method of sulfurization treatment is desired.
The material from JFE, which has a newly developed machinability aid, achieved excellent drilling performance with reduced cutting forces by decreasing the shear strength in shear deformation of chips.
As a result, not only is it possible to replace the sulfurization treated material with this new product, it also offers significantly improved tool life.
Precision cam sprocket with sensors for an idle reduction system
Sumitomo Electric Industries, Ltd.
Sumitomo Electric Industries received an Effort Prize for this cam sprocket with sensors used in a vehicles idle reduction system.
The introduction of the idle reduction system into vehicles is expanding rapidly due to the need for improved fuel economy.
Three sensors were formed on the face of the large size sprocket and weight reduction was achieved by adding holes and adding grooves in the opposite face.
The newly developed sintered sprocket has successfully started mass production.
Valve seat material with higher wear resistance
Fine Sinter Co., Ltd.
Fine Sinter received an Effort Prize for development of this material for manufacturing valve seats used in modern high performance automotive engines.
A valve seat material offering higher wear resistance is required for use in the latest high performance automotive engines. There are two approaches to obtain high wear resistance: one is adding and scattering hard particles in the material, and the other is generating oxide on the material surface to prevent the adhesive wear originating from the contacts with the valve material.
The approach of adding hard particles, however, has become disadvantageous to oxide formation due to its higher costs and incompatibility with the high performance engines working in non oxidizing environments.
Fine Sinter achieved high wear resistance by adding a small amount of rare earth metal to the existing Mo-Co wear resistant hard particles to disperse the stabilized rare earth oxide in the particles.
This technology produced higher wear resistance than that of previous materials and enabled a reduction in costs as well as the amount of added wear resistant hard particles.
Sintered brake lining for high-speed trains on Japan’s regional rail network
Fine Sinter Co., Ltd.
A further Effort Prize was presented to Fine Sinter for the development of a material used in the brake linings of high-speed trains.
Synthetic resin is conventionally used for brake linings on high-speed trains running on Japan’s regional rail network. However, as the maximum speed of these vehicles is further increased, this material will reach the limit of its performance. Thus it has been necessary to adopt sintered brake linings, similar to those used in Japan’s bullet trains.
However, the requirements of trains on the regional rail network differ from that of the Bullet Train system. The braking distance is shorter than bullet trains and requires the lining to be pressed against the brake with a larger force, but the maximum speed of the regional trains is lower.
To address this, Fine Sinter applied Cu-Sn-Ni-based material instead of the conventional Cu-Sn-based material to ensure strength at the temperature reached when braking. In addition, they optimised the amount of lubricant added in order to obtain a stable coefficient of friction at the beginning of brake application and immediately before stopping. This was achieved by increasing the amount of lubricant.
The resulting sintered friction material, offering a stable friction coefficient, has now been adopted as the brake lining for high-speed trains running on Japan’s regional rail network.