Does the gold on the Alpha Gold Series Drill Bits wear off? This is a commonly asked question, and the short answer is yes, eventually it does. However, there is a longer story.
The gold on drills is a Titanium Nitride (TiN) coating that is applied using an advanced process called Physical Vapour Deposition (PVD) in a vacuum heat treatment plant.
This process involves putting the cleaned drills into a vacuum heat treatment chamber and creating a thin film coating using a low-voltage electron beam with arc and magnetron sputtering.
The coating is extremely hard – approximately 85 Rockwell compared to about 55-60 Rockwell for the hardness of a drill and has a very low friction coefficient. The coating also has excellent rust resistance.
Coatings can be applied in different thicknesses. Thin coatings are applied for rust resistance and appearance and slightly thicker coatings are applied to industrial cutting tools such as jobber drills to significantly increase their life and durability.
The secret to cutting tool life in any jobber drill lies in the quality of the raw materials used, the hardness
and tempering process used on the HSS material, and finally the design and grinding of the cutting edges. TiN coating on a high-quality tool is like an “icing on the cake” that increases tool performance, cutting durability and wear.
Once the coating is worn off, the underlying qualities of the drills are unchanged, and tools can still be reground or resharpened to extend life.
Drills supplied by leading brands such as the Sutton Tools TiNite and Alpha Gold Series drills use an industrial thickness coating which significantly increases the life of the drill.
While the coating does wear off, the extra microhardness on the thin film and the lubricity created by the low coefficient of friction significantly increases the wear life and cutting performance of these drills.
Extensive independent testing has demonstrated that these drills provide over 30% more life and cutting durability than uncoated drills.