Surface Modification And Passivation Technology Of Diamond Cutting Tools

Technological requirements of surface modification

1. Selection of Diamond blanks materials: natural crystal; CVD and HPHT monocrystal

❉  The color of natural crystal and pureness are not necessary to be good, the worst dark puce blanks can be selected.

❉   At present, the man made noncrystalline have to reach some standards, cutting tools made welded with the transparent CVD, after the surface modification, is work life can be prolonged.

2.The selection of crystalline surface: no matter choose which crystal blanks for cutting tools, there must be a 110 facet for the tool face.

❉  This cutting face crystal direction selection, after the surface modification, the work life is roughly the same. However, the rake angle -35°±10°, and the tool face is close to 110 crystal face, performance will be better. 

❉  The domestic 100 facet and 100 sides yellow crystalline blanks for the cutting tools should be cut apart diagonally. And then design the 110 crystal face to be the rake face and the flank face or make the cutting tool face among the 110 side. 

3.Surface modification technical principals:

❉ processing residual stress relieving     

❉ damaged layer of cutting surface repairing    

❉ cutting tool surface hardness improving  

4.Surface modification technical effect: 

             Depth of indentation             Depth of indentation 

The surface hardness of natural crystalline/CVD crystalline cutting tools will improve 1 grade, and the service life will be twice long as the purely pressed cutting tool.

Prolong the cutting tool service life without changing any parameters. Tool surface with 110 crystal surface, can be applied to any diamond cutting tool. 

5. Cases of the surface modification of our customers:

Organic glass and optical turning inserts, its rake face uses the natural 110 crystalline face. Through the surface modification, we can use the product close to the corresponding type of Contour. If you choose improve the machinery pressing and grinding technology further, cutting tool after the surface modification is comparable to the imported products. (after the pressing and grinding)

The sharp-tipped carving tools, the angled cutting face adopt the natural diamond with 110 crystalline face. Through the surface modification, the service life for single use changes from 40~50h to over 140h, and the best 380h. The processed product quality is not inferior, and even superior to the imported products. (after the expressing and grinding, then take the pre-bond)  

6. Edge passivating technology of diamond cutting tool 

Edge passivating principles:

1) the process is the same to conventional metal cutting tools by rounding a removal of tens of nanometers ;  

2) as for the edge passivating, at present, we can accurately control the sharpness from 20mm to 50mm.

3) the rounding of the tool face can eliminate and relief the machine pressing and grinding chipping or cracks.

4) different from the surface modification technology, the edge passivating technology is not concerning the tool face crystalline selection.

5) Currently, the edge passivating of one cutting tool need 2h, and the service life is under assessment

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