Physical Vapour Deposition

Until today, electroplating of gold (more popularly called as wetplating of gold) is still the usual way of obtaining a thin layer of gold for decorative applications such as for artificial jewellery, watch cases and straps, spectacle frames etc. The disadvantage of the above process is that gold being extremely soft, gets rapidly eroded; also the process is very expensive due to the high costs of gold as a large thickness is required to obtain a minimum guaranteed lifetime. It is also very difficult to electroplate stainless steel with gold.

A solution to the above problem is a configuration involving the combination of a TiN layer and a gold layer. A very thin layer of gold (about 0.1 micron thick) is deposited with a thicker underlayer of TiN thus combining the advantages of the hardness of TiN with the colour of gold providing longer life guarantee with considerable lower consumption of gold. This configuration is being successfully used in India by several watch companies as Titan (Hosur, Tamil Nadu) and Timex (Noida, U.P.)

The above coatings have successfully passed the various standard tests recommended for decorative coatings such as:

1. Porosity test
2. Salt spray test
3. Synthetic perspiration test.

Broadly classified, there are three types of coatings:

1. 
   Decorative coatings: These are used for watches, jewellery, bathroom / kitchen door hardware, writing instruments, spectacle frames, cutlery and leatherware accessories.
2. Tool coatings: These are used for drills, cutters, punches and saw blades as well as used for tools used in bending, rolling, pressing, forming and in the plastic processing industry.
3. Functional coatings: These are used in applications such as piston rings, connecting rods, fuel injection pumps and gears where high wear and friction are involved.
4. Special coatings: Very often the customers’ requirements are too highly specific to be met by our standard systems.

For tools:

Low adhesive & abrasive wear Low coefficient of friction Heat resistivity

- Extended lifetime of the tool - Improved surface quality of workpiece - Low heat generation - Higher operational speeds - Less heat transfer to tool substrate

The above factors lead to reduced operation cycle times, less rejects and a longer uninterrupted machine operation providing a large increase in productivity. Additional advantages are a lower tool consumption and lesser resharpening.

Low adhesive & abrasive wear Low coefficient of friction

- Extended lifetime - Reduced power consumption - Higher operational speeds - Reduced heat generation - Reduced noise levels