... , Forging, Melted Metal Squeezing.Piston StructurePiston Head, Piston Pin Bore, Piston Pin, Skirt, Ring Grooves, Ring Lands and Piston Rings.Piston TypesSolid Skirt Pistons, Shim ... Skirt, Alfin, Double Alfin, None Alfin, Steel Pieces, Drilling, Oil-cooling Channel, Three or Four Ring Grooves, Ceramic Spraying and Hard ...