How To Produce High-Quality PCD Tools

The PCD tool is made by welding a PCD composite sheet to a carbide or steel body. 

Since the PCD composite sheet combines the high hardness, wear resistance, the low friction coefficient of the single crystal diamond and the high bending strength of the tungsten carbide cemented carbide, the PCD composite sheet not only increases the bending strength, but also the cemented carbide layer. Easy to solder, making it easy to make finished tools.

In recent years, with the large-scale use of lightweight materials in the automotive industry, such as aluminum alloys and composite materials, the application of PCD tools has also increased significantly.

For example, in the process of some parts of the transmission housing, the original carbide boring tool is changed into a diamond tool, and the tool life can be increased to tens of thousands of pieces, and the economic benefit is very obvious. 

When machining aluminum alloy with PCD tool, the hardness of the diamond is high, the surface and metal affinity are small; and the rake face of the tool is polished into a mirror surface, which is not easy to produce built-up edge; the dimensional stability and surface quality are very good.t Ra0.02~0.32i. Under the condition of zm, 5 to 7 levels of precision can be obtained. The PCD tool is used to process various specifications of aluminum alloy parts with the surface

roughness Ra≤0. I m, tool life of thousands to tens of thousands of pieces, especially suitable for mass production of automotive parts.In the Chinese automobile manufacturing industry, PCD tools are mainly used to cut aluminum alloy engine blocks, cylinder heads, transmission housings, valve bodies, tanks, side covers, and other parts. 

Due to the increasing use of PCD tools, the research on the preparation process of PCD tools is becoming more and more important. This paper mainly introduces the key processes of welding, wire cutting and grinding of PCD tools.

1 Key processes for preparing PCD tools

 1.1 Classification of PCD tools

The PCD tool is mainly divided into a monolithic PCD tool and a welded PCD blade.  In recent years, welded shank PCD tools have developed rapidly in the automotive and parts industry.There are mainly PCD milling cutters, PCD boring tools, PCD reamer or a combination of two or more of the above tools. The shank forms are mainly cylindrical shank, BT shank (BT40 and BT50),  SK shank (SK40 and SK50). , HSK handles (HSK63 and HSK100), etc.

1.2 The key process of preparing PCD tools

For PCD tools, especially for the preparation of non-standard combined PCD tools with high precision (up to 21x dimensional tolerances), the welding, cutting and grinding (outer and chamfering) processes of PCD tools are the most critical.

1.2.1 Welding of PCD tools

For PCD tools, the welding of PCD composite sheets with cemented carbide or steel substrate is very important. The welding methods for PCD are mainly as follows:

Laser welding, vacuum diffusion welding, vacuum brazing, high-frequency induction brazing, etc. The brazing process of PCD composite sheets is one of the key technologies that restrict the application of PCD tools.

1.2.2 Cutting of PCD cutters

For PCD tools, especially the cutting of various high-precision non-standard combination PCD tools, CNC five-axis linkage slow wire cutting machine is required for machining. This type of machine is represented by the QWD series of machines from VOLLMER, Germany.

For PCD tools, especially the cutting of various high-precision non-standard combination PCD tools, CNC five-axis linkage slow wire cutting machine is required for machining.

This type of machine is represented by the QWD series of machines from VOLLMER, Germany.

The machine uses PCS tools for wire EDM. Thanks to the advanced CNC system, the multi-edge tool can be controlled to 0.001 inln and the tool surface roughness can reach Ra 0.4 m.  It is especially suitable for the processing of multi-edge tools such as shank step drills, milling cutters and saw blades.

The geometry of the stepper tool, the edge of the curved tool, the back, and the inner fold line can be cut out with one input program, and the degree of automation and machining accuracy are high.  The downside is that the surface roughness of the cut surface is not as good as that of the ground surface.

1.2.3 Grinding of PCD tools

The grinding of PCD tools is divided into external grinding and chamfer grinding. The grinding machines are cylindrical grinding machines and multi-axis manual tool grinding machines.

The cylindrical grinding machine is represented by the Swiss STUDER series grinding machine. The multi-axis manual tool grinding machine is represented by the RS series grinding machine of EWAG of Switzerland, and the ceramic bond diamond grinding wheel is used. The ceramic bond diamond grinding wheel is more efficient than the resin bond and the metal bond diamond wheel in grinding PCD tools with high grinding efficiency, high durability and low processing cost.

The particle size, concentration, and bonding agent of the diamond grinding wheel have a great influence on the sharpening quality and efficiency of the PCD tool. The fine-grained grinding wheel can obtain a lower grinding surface roughness. The influence of the grinding wheel speed on the surface roughness is that the roughness values at high speed and low speed are both large and the intermediate level is good. That is to say, under the test conditions, there is an optimal value.