Cylinder Head

Since the cylinder head and cylinder block are assembled to form the engine, the flatness of their large mating surface is subject to stringent requirements. This surface is typically finished using a face milling cutter equipped with PCD (polycrystalline diamond) indexable inserts,  which ensures high productivity and stable cutting performance. In addition, an aluminum alloy cutter body is adopted to reduce weight, thereby meeting the demands of high‑speed milling.

The intake and exhaust valve seats in the combustion chamber are both located on the cylinder head. They are made of powder metallurgy (PM) material, which offers high wear resistance, and are typically machined with PCBN (polycrystalline cubic boron nitride) tools in industrial practice. Currently, there are two processes for machining the sealing conical surfaces of the cylinder head valve seats:

Countersinking using a PCBN formed conical countersink tool (its specifications and dimensions are given below);

Boring the conical surface with PCBN inserts.

After machining the intake and exhaust valve seats, a pressure tightness test under a specified pressure is carried out to check the sealing performance. Typical combined superhard tools and cutting parameters for cylinder head seat machining are shown in the figure.