Development prize: New materials

Matrix toughened valve seat material with improved anti-adhesive wear properties

Matrix toughened material is used in these valve seats for improved anti-adhesive wear properties. Fine Sinter Co. Ltd and Toyota Motor Corporation developed this material by distributing fine, hard particles in the matrix (Courtesy JPMA)

Fine Sinter Co. Ltd and Toyota Motor Corporation received a prize for the development of a valve seat material with improved anti-adhesive wear properties by distributing fine hard particles in the matrix. Valve seats for automobile engines are required to have high anti-wear properties and hard particles are added and distributed in the matrix to obtain a “cobblestone effect” to achieve this requirement. Also, the combustion heat from engine operation produces oxides, whose major components are Fe, on the surface of the valve seat. These oxides improve the anti-adhesive wear with the valve and this creates a synergetic effect with the conventional hard particles. However, recent improvements in engine high-efficiency technology have created difficult conditions for Fe oxide formation.

Accordingly, strengthening the valve seat against the adhesive wear by other means is required. To acquire high adhesive wear properties, the usual option is to increase hard particle content. However, this option is severely limited, as a large quantity of hard particles could cause degradations in compactability, machinability and machined surface roughness.

This development studied the method for distributing the fine hard particles in the matrix. Furthermore, hard particles have been developed with an increased austenite diffusion phase compared to conventional materials. The hard particle type developed improves adhesive properties with the matrix, solves the concerns over surface roughness after machining by detachment of hard particles and provides a 35% cost reduction compared with the conventional material.

Development prize: New materials

A VVT parts manufacturing line, which provides the simultaneous green machining of holes and grooves and the attachment of a two-dimensional barcode

Sumitomo Electric Industries Ltd’s VVT parts manufacturing-line allows the simultaneous green machining of holes and grooves (Courtesy JPMA)

Sumitomo Electric Industries Ltd. received a process development prize for a manufacturing line for Variable Valve Timing (VVT) parts, which provides the simultaneous green machining of holes and grooves and the attachment of a two-dimensional barcode to ensure high quality. Also, the line provides successful touchless manufacturing of parts, from compacting to sizing.

VVT systems control the timing of valve opening and closing by changing the phase of the rotor with oil pressure, enhancing power output and reducing fuel consumption. VVT parts are rapidly developing, with, for example, the rotor becoming unified with oil control valve, and the demand for holes and grooves, which cannot be moulded in compaction, has increased. Therefore, the increase in machining cost, including deburring after sintering, has become a problem area.

To solve this problem, Sumitomo Electric has applied green machining, enabling rapid machining without burr formation, and has sought to decrease cost. However, previous green machining processes have had concerns regarding cracks and chips. Also, the machining was not linked with compaction and sintering and therefore created problems in terms of productivity. Therefore, the company has now developed the multi-machining technology of holes and grooves in one operation and succeeded in building a consistent higher productivity line. This line can prevent the risk of cracks and chips, due to offline handling, by in-lining the green machining equipment, linking it with the compaction process, and machining with a touchless and stockless concept. In addition, traceability has been enhanced by attaching a two-dimensional barcode by laser beam to each product before sintering, enabling the tracing of product quality and manufacturing information, and the risk of cracks and chips in green machining has been decreased.

Effort prize

Development of a multistage complicated shape side plate, laser quenched on the nonconsecutive surface

A laser quenched multistage complex side plate, adapted to the high torque control system of a VVT rotor (Courtesy JPMA)

Sumitomo Electric Industries Ltd. was awarded an effort prize for the development of a laser quenched multistage complicated shape side plate adapted to the high torque phase control system of a VVT rotor.

High torque was necessary for the controlling phase of the rotor and, in the conventional model, several springs were attached to the rotor itself to control phase. However, in the developed model, a system which controls phase from outside the unit was adopted.

Therefore, a large spring, which slides with the side plate, was attached, and the replacement of the aluminium casting with a sintered iron part was demanded. Regarding the product shape, the side plate was difficult to compact, due to the many tangs required to fix the spring to the surface and the deep oil groove on the opposite surface. In order to maximise the benefits of using PM, multistage compaction was successfully designed in at an early stage. Furthermore, the side surface of each tang demanded wear resistance, due to the sliding of the spring. Though the surface was uneven, laser quenching was applied, which achieved the required hardness without decreasing accuracy by using a simple jig and program, instead of induction hardening with a complicated coil design.

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