The winners of the Japan Powder Metallurgy Association’s (JPMA) 2015 Powder Metallurgy Awards showcase the continuing developments being made to further expand the range of applications for Powder Metallurgy. The demands of the automotive industry for ever more efficient engines continues to require improved mechanical properties and flexibility of design, both of which PM can offer.
The winning components in this years awards recognise innovations in new materials, manufacturing processes and component design, not just in the automotive sector, but in a number of other important industries.
Development prize: New design
Enhanced cost effectiveness through the reduction of wear resistant material on the valve seat
Fine Sinter Co. Ltd. received an award for a modified design concept for valve seats. This valve seat provided an improvement in cost effectiveness by minimising the amount of highly wear resistant material used through the reviewing of the layer boundary angle. The valve seat has expensive, highly wear-resistant material (seat material) on the seat surface where the valve impacts, because impacting the valve wears the seat. Therefore, in order to improve cost effectiveness, the developed valve seat has two layers with a cheaper material (base material) on the cylinder head side because wear resistance is not required on this part of the component.
This development improved the layer boundary angle to 45 degrees, which is parallel to the valve-impacting surface angle. The amount of expensive material is therefore reduced. Furthermore, a drastic cost reduction is achieved by locating the highly wear-resistant material on the valve seat without waste because wear progresses parallel to the valve-impacting surface. Moreover, the valve seat needs to have heat conduction performance since the interior temperature of the engine is becoming higher with the trend towards higher efficiency engines, but the use of highly wear resistant material as the seat material reduces heat conductivity because of the hard layer that includes carbide.
Decreasing the proportion of highly wear resistant material improves total heat conductivity and provides a heat reduction effect. This effect contributes to the control of knocking that is caused by the higher temperature of the engine. In addition, machinability of the outer diameter is improved because of the reduction of the area of the highly wear resistant material on the outer diameter, which requires heavy machining.
Development of a soft magnetic composite core for high-power output and rectangular-shaped ignition coil
Sumitomo Electric Industries Ltd. received an award for the development of a soft magnetic composite core for a rectangular-shaped ignition coil, possessing superior ignitable stability resulting in high ignition energy output. Due to increasing environmental concerns and a consequent significant focus on fuel economy in the automotive market, there is a growing demand for engines with higher thermal efficiency and lower emissions.
The use of technologies such as direct-injection lean burn (thin fuel) and EGR (exhaust gas recirculation) is being more widely adopted, due to their improvement of thermal efficiency and suppression of nitrous oxide formation. However, the applications for these technologies are limited because their utilisation can degrade ignitable stability.
Therefore, there is a demand for the development of an ignition coil with superior ignitable stability. The key points in this development were:
- Improvement of the magnetic saturation-resistance that is the characteristic of soft magnetic composites.
- Improvement of volumetric efficiency. This was achieved via a circular re-design of the cross-sectional shape taking advantage of the shape flexibility of the soft magnetic composite core. This type of circular design is difficult to achieve using conventional electromagnetic steel sheet.
- Achievement of high productivity and cost competitiveness through an automated process from compacting to packing, which is unprecedented in the manufacture of sintered parts.
Through these improvements, the company has succeeded in developing a soft magnetic composite core for the rectangular-shaped ignition coil possessing superior ignitable stability and resulting in high ignition energy output.
Development of a bearing for a linear vibration actuator to be used in a wearable device
Porite Corporation received an award for the development of a sintered bearing which is used for the linear vibration actuator in a wearable device. The vibration motor has been mounted on the Pocket Bell since around 1990 and its use has increased in number with the spread of the use of the mobile telephone. Mobile telephones in the world market are transforming into smart phones from feature phones. Also, small, high performance and health-conscious wearable devices with vibration features have entered the market. These wearable devices are thin and curved so that a thin, flat-shape linear actuator is required, rather than the cylinder and coin type actuator which has been the mainstream to date.
The company has developed a sintered bearing, which has satisfied the characteristics for a linear vibration actuator (vibration characteristic, low noise, shock resistance). This product required different characteristics from the rotating vibration motor. The radius shape on the inner diameter was formed by special tooling in order to remove a fine burr. Low noise material with a high oil film strength, provided by fine porosity and the use of a high viscosity oil specialised for linear sliding motion, were the keys to success in this development.
The customer was initially considering the full- machining of a stone bearing, such as Ruby and Sapphire. However, as a result of this development, Porite were able to enter this new market.
A set of sintered joints for the motor used in a valve lift actuator
Diamet Corporation received an award for the development of a set of sintered joints for the motor used in the valve lift actuator of an SOHC engine.
One of the components has projections and the other has grooves. In combining the projections and grooves, the width between the projections is a critical issue. The compaction tool and the compaction conditions were optimised to minimise the distortion caused by springback. The sintering method and conditions were also optimised to improve the scatter of dimensional changes.
As a result, the company has succeeded in developing the set of sintered joints for the motor used in the valve lift actuator and the sizing process has been eliminated. These developments have contributed to the practical use of the new mechanism, improving fuel economy and environmental performance and contributing to the potential for downsizing.