This sintered stainless pulley is used for high output 4-stroke outboard engine.
Recently, outboard engine is required for good fuel consumption and clean emission, so 4-stroke engine has been replacing 2-stroke engine. At the early stage of the designing, sintered stainless pulley competed with aluminum die-casting. Because of better strength and anti-erosion characteristic, development of Sintered stainless pulley was preferred.
At stainless compacting, stainless powder was easy to stick to tooling surface. Also at sizing, scratches on the part surface happened frequently.
To resolve compacting problem, large amount of lubricant is added. To prevent segregation of lubricant, liquid binder is mixed first and coat powder surface, latter lubricant is mixed. Lubricant is extracted at vacuum, and heating pattern is optimized. To prevent sizing scratches, special oil has been developed.
As a result, we achieved designing of uniquely large stainless parts and increased the outboard engine application that is the new field of powder metallurgy.