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pcd inserts for milling of automotive cylinder block

The automobile cylinder block is the main engine component, in automotive cars, that connects the crankshaft, connecting rod, piston, and cylinder head. This engine block has an intricate design and it is made of various materials including cast iron and aluminum. Many sections of the cylinder block require high quality surface finish which can be achieved through the use of polycrystalline diamond (PCD) and cubic boron nitride (CBN) inserts. Vital parts made of aluminum such as the gasket face, datum face, parts of the top and bottom faces, require PCD inserts for efficient machining. Here are some recommended cutting conditions and examples of inserts for cylinder block milling operations.

Boss and Gasket Faces
Roughing and finishing milling operations should be done on the boss and gasket faces with standard PCD inserts on a machining center. A cutting speed of about 950 m/min, feed rate of 5,900 mm/min, and cutting depth of 2.0 to 3.0 mm, will be sufficient to provide high speed finishing. A hexagonal tipped polycrystalline diamond insert such as the WCGT 0402 has an insert clearance angle of 7 degrees which makes it suitable for both roughing and finishing operations. It has a relatively tight tolerance of 0.13mm on thickness and 0.025mm on nose height. Its chip breaker also aids the efficient removal of aluminum metal chips. With a cutting edge length of 4.3mm, this insert will offer longer tool life since it's tip length is more than 80% of the required depth of cut.

Datum Face
For datum face milling, use inserts that can cut at high speeds and provide high wear resistance without any welding. Inserts with a 90 degree corner angle are recommended for milling the right and left datum faces. To achieve an excellent surface finish, the cutting length should be less than 2.0 mm, while cutting speed can be set at 1000 m/min. A lower cutting speed may be used for engine blocks whose silicon content is greater than 12%. The standard square-shaped pcd diamond insert, SCGT 06T302, has a chip breaker with a thickness of 3.97mm and a cutting edge of 6.35 mm. It also provides the 90 degree angle required in the tool cutter for efficient milling.

Top and Bottom Faces
The aluminum material at the top and bottom faces can be milled to give a smooth and shiny surface using pcd milling inserts. With a standard roughing milling cutter, and standard polycrystalline diamond inserts, roughing operations can be performed at a speed of 1000 m/min (or less for aluminum with high silicon content). Cutting depth may be set to a value between 0.3 and 3.5 mm depending on the surface condition of the engine block but the feed rate should not exceed 0.30 mm/tooth. During the roughing operation, the SDET 1204 insert may be used. It has a wider rake angle of 20 degrees for faster removal of material and it also has a chip breaker. After roughing, the SNEW 1204 insert may be used to provide high speed precision milling to give a superior surface finish.

Conclusion
Those are some of the cutting conditions and recommended ISO standard pcd inserts used for milling automotive cylinder blocks. It is important to note that the success of the milling operation depends on adequate knowledge of the composition of the aluminum or aluminum alloy, the type of milling cutters used, setting the right cutting parameters, and the proper selection of tool inserts.

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