Drill Bits – General Information
Drill bits are not all the same. High-Speed Steel untreated drill bits will cut through soft materials such as wood and plastic products. M2 TiN or Black Oxide drill bits will cut through steel, wood & plastics while M35 drill bits containing a percentage of carbon will cut through metals such as stainless steel and cast iron. They can also be used to cut through softer materials too so it makes sense when loading up your tools, buy a good quality M35 drill bit set. You should find your M35 drill bit set will have a dull gold colour due to how the drill bits are baked during the production process.
M35 Cobalt Drill Bit Set
An M35 drill bit set is a steel alloy that contains 5% cobalt. The 5% alloy is what is known as M35 grade with the added cobalt increasing the strength of the steel, making the product more heat resistant. This is an important factor in drilling hard materials as the added friction of metal against metal produces high temperatures that can damage the material or the drill bit. Some M35 drill bits can withstand temperatures greater than 500 degrees Celcius. The colour is not a plating or paint but directly related to the cobalt alloy. M35 drill bits can be sharpened easily with cutting fluid and will retain their strength and durability, although the gold colouring may become less prominent.
The expense of cobalt drill bits versus M2 or HSS needs to be tempered with how often you might use them against what you are actually drilling. If commonly drilling into hard metal, it is likely M35 will meet your requirements most times, however, where you are just after a general-purpose drill bit for various materials, the expense of M35 might not be worthwhile.