What is the processing technology flow of cylinder head?
2 Answers
The top surface, bottom surface, and intake/exhaust surfaces of the cylinder head are all large-area planes, which require relatively high geometric accuracy of the machining center and adjustment accuracy of the tools. The focus of inspection should be on the geometric tolerance that affects the workpiece processing. The rough datum for surface processing is generally selected as the bottom surface of the cylinder head. Based on this datum, the top surface, sand holes, and airway plane positions are checked. The cover surface is matched with the camshaft cover that serves as dustproof and noise prevention, with a cylinder gasket in between. The two side surfaces mainly install some controllers and covers and other devices.
I worked in a machine shop at a factory for several years, and machining cylinder heads is no easy task. First, there's the casting process—pouring molten aluminum into molds to create rough blanks. The biggest concern here is avoiding air pockets and sand holes. Then comes the rough machining stage, where CNC milling machines are used to flatten all six surfaces. The flatness of the cylinder head's bottom surface is especially critical, as any imperfection can lead to oil leaks when mounted on the engine block. Next, we drill and tap holes, with particularly high precision required for spark plug holes and bolt holes, so we use specialized fixtures to secure the parts. The finish machining is the most labor-intensive step, involving the machining of combustion chamber recesses and intake/exhaust ports, which requires switching between several different cutting tools. After machining, key dimensions must be checked with a coordinate measuring machine. Finally, the parts are cleaned, dried, and any burrs are manually removed. The entire process involves at least a dozen steps, each requiring careful handling—after all, if a cylinder head leaks, the entire engine is ruined.
