Polycrystalline diamond (PCD) tool for automotive piston

In order to improve the performance of the engine, the piston material is changed from low silicon aluminum alloy to medium silicon aluminum alloy, and even high silicon aluminum alloy.And the PCD tools with excellent characteristics, it widely used in processing aluminum alloy, especially for high silicon aluminum alloy.

The hardness and wear resistance of high silicon aluminum alloy are higher than other aluminum alloys. When normal cutting tools alternately cut soft aluminum and hard silicon particles, the tool is also easy to produce debris, so the processing accuracy and surface roughness will deteriorate.

In order to avoid chip deposition and hardening, the blade must be sharp and the blade surface must be smooth, and the PCD cutter meets these requirements.

Below picture 1, shows the comparison of the wear on the rear surface of PCD tool and CBN tool in processing al-si alloy (V=170m/min, f = 011mm/ r, ap= 015mm).

As can be seen from the figure, the wear resistance and service life of the PCD tool is relatively high than CBN tool. After a long time of cutting, the wear of the pcd tool behind the cutting surface is still small. Results is PCD tool is suitable for al-si piston.

Using:

1. Although PCD tools has extremely high hardness, its toughness is not as good as that of cemented carbide and much lower than that of high-speed steel, so the main failure form of PCD tools is cutting edge.

Cutting edge collapse is usually caused by vibration in machining. It is helpful to reduce vibration to reduce tool overhang and improve rigidity of machine tool. High rigidity machine tool is necessary condition for PCD tool, most using on CNC machine for fine processing of silicon aluminum piston.

2.Higher cutting speed can also protect the cutting edge of PCD tools. PCD turning tool  speed should be 2 ~ 3 times higher than that of carbide tool, otherwise it is difficult to obtain satisfactory machining results.

3.PCD tools can for surface machining, hole machining, ring groove machining. For surface machining or boring of aluminum piston with PCD tool, coolant is usually not required, while for semi-closed machining with ring groove, smooth chip removal and cooling and lubrication of cutting edge are required.