Bus Diesel Engine 4BD1T Isuzu Pistons In A Car , Graphite Piston With 4 Cylinder

Piston Technology

Piston roof MoS2 Spraying
The function is close to roof anodizing improving heat resistance. The MoS2 is also good at lubrication. (The bigger piston below is piston roof anodizing, the smaller one is MoS2 Spraying)

Tin Coating
Tin is coated by electro analysis or heat dipping at thickness between 0.001 and 0.003mm. Tin is characterized as soft and oil-friendly which improves running-in efficiency of piston and liner. This coating is most commonly used.

Graphite Sprayed at Piston Skirt/Graphite Printing
Graphite is characterized as good lubricating, which helps lubricant adhering to coating surface. The coating will reduce friction and scratching. The thickness is between 0.01 and 0.02 mm.

Piston roof anodizing
The piston roof is anodized by electro bath, forming thin layer of Al2O3 , This treatment will improve heat resistance (above 500), heat conductivity and anti-corrosion,  it helps prevent piston roof burn-up. The thickness is normally 0.02 to 0.05mm. If the thickness increases by 0.01mm, the heat conductivity will decrease by 25%, the roof temperature when running will be lower from 30 to 50. Anodizing technology and processing is normally complicated.

Phosphate
The phosphate is aimed to improve initial running-in performance. The phosphate layer is easy to wear off and helpful to improve running-in.

Ceramic Spraying
The treatment performance is similar to anodizing and heat insulation performance is better. The ideal thickness is 0.2 to 0.3mm. When running under high temperature, the ceramic is easy to crack and wear off. It is not commonly used due to high cost

Piston Type

ALFIN piston

ALFIN is inserted within the ring grooves when casting. ALFIN is made of special austenitic cast iron. It is tightly bonded metallically to piston body and counteracts the wear in the top ring groove. ALFIN pistons are commonly used in diesel engines.

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