JPMA Award Winners 2014
Development prize: Process
Development of a DCT synchroniser hub through laser quenching technology
Synchroniser hub for a dual clutch transmission used for automotive transmissions (Courtesy JPMA)
Sumitomo Electric Industries (SEI) received a process development prize for the production of a synchroniser hub for a Dual Clutch Transmission (DCT). The synchroniser hub is used in a newly developed 7-8 speed DCT, where the required tolerance of the inner spline diameter is very exacting compared with other hubs.
The Fe-Cr alloy material developed by SEI required an optimised sintering process in order to achieve superior hardenability. A laser quenching operation was applied to achieve local, selective hardening.
The dimensional accuracy after the sintering process has been improved by using the Fe-Cr alloy and by reducing the sintering time to only one third of that normally used with an Fe-Ni alloy. By controlling sintering conditions, such as cooling rate, a fully bainitic structure could be produced and this enabled deformation during the sizing process. The laser quenching concentrated energy on the surface, generating a very shallow quenching layer with a hardened depth of around 0.5 mm, therefore reducing thermal influences on the product dimensions.
As a result, dimensional change was reduced by half compared with induction hardening and the required accuracy was achieved. A further benefit of laser quenching is its ability to achieve the required cooling rate without coolants or oil, due to the shallow quenching layer
New powders prize
A Ni-free alloyed steel powder providing a tensile strength of 600MPa and excellent machinability
A Ni-Free Alloyed Steel Powder, providing a tensile Strength of 600MPa (Courtesy JPMA)
JFE Steel Corporation received a new powder development prize for a mixed powder without a nickel addition that is applied to iron based sintered parts and is superior in terms of strength and machinability.
Conventional iron based sintered parts with a tensile strength of 600 MPa are made from a 4% Ni alloyed steel powder that is alloyed by diffusion bonding of the alloying elements (Ni, Cu, Mo). The problems with this alloy are high cost, poor machinability and the supply restrictions for nickel. These issues have led to the development of a Ni-free alloyed mixed powder, which is lower in cost and provides the required tensile strength of 600 MPa and excellent machinability of sintered parts.
In this development, the tensile strength of 600 MPa is achieved by using a lean Mo pre-alloy (0.45 mass% Mo pre-alloy) and producing a homogeneous metallographic structure by liquid phase sintering. A high density compact is obtained by reducing the added amount of a lubricant especially developed for high density compaction. Furthermore, the uniformity of hardness distribution resulting from the use of a pre-alloy powder improves the machinability. The results of this have led to a large reduction of cost for raw materials and machining processes and have been rated highly by several sintered parts suppliers.
Development prize: Equipment
Integrated production line for shock absorber parts
Integrated production line exclusively for shock absorber parts (Courtesy JPMA)
Fine Sinter Co. Ltd received a prize for the development of an integrated production line used for manufacturing a wide variety of shock absorber parts.
The aim was to establish a system where parts can be shipped three days after the start of compaction. As low volume parts accounted for almost 40% of the total parts produced, the system concept had to work for all volumes. A production line, integrating the steps from compaction to the sizing process and ensuring a six second cycle time, 500 pieces lot size and one minute set up time, was the goal.
Fine Sinter developed down sized presses and tool sets which enabled one minute set up for both the compaction and sizing processes. A reduction of sintering time to just one third of that conventionally achieved has been delivered successfully by reviewing the heat zones. In addition, to prevent defects such as cracks, industrial robots have been arranged to perform a centralised control of the parts flow from the compaction to the sizing process.
As a result, Fine Sinter successfully developed an integrated production line with a lead time from compaction to sizing within 44 minutes, including the setup time for the tool sets. The downsizing of the compaction to sizing process line to 70% in length and 60% in installation space could be achieved.
In 2010, one production line based on this concept was established in Japan and began manufacture. Since then, two further lines based on the concept have been installed in overseas plants.
