Hymnorq 13-Piece Cobalt Drill Bit Set with Index Case – M35 Grade (5% Cobalt) Steel, 1.5mm to 6.5mm, Dual Twist Flute, 135° Split Point, Ideal for Hard Metals Like Stainless Steel and Cast Iron;

M35 Grade Cobalt Steel

Cobalt drill bits are not made of pure cobalt, but rather a steel alloy with certain percent cobalt. The 5-percent alloy is known as M35 grade. The cobalt increases the strength of the steel and makes it more heat-resistant.

135 Degree Split Point

The flater the drill, the smaller the chip width. This means less force required to remove metal, compared with lower angles like 90° and 118°. This is important on hard stuff, because your power requirements are already more than mild steel, so making the chip load less helps. It also reduces heat since less surface area is generating the cut.

Lowest Cost Per Hole Drilled

Cobalt drill bits are more expensive than other drill bits, but if you regularly drill through metal, they are a good investment since they tend to last longer. With an extended tool life, Migiwata cobalt drill bits will give you the lowest cost per hole drilled.

For Drilling Stainless Steel

This set of Migiwata M35 cobalt steel drill bits are particularly successful in cutting through hard metals such as stainless steel and cast iron, although they can be used for softer materials, too.

Tests shows that the M35 cobalt steel drill bits can penetrate a 5mm-thick 304 stainless steel plate in 5 seconds.

Not for Hardened Steel

M35 grade cobalt drill bits are NOT suitable for hardened steel, high carbon steel and heat-treated steel. Please buy carbide drill bits to drill these materials.

Cooling Liquid Required

Please use with cooling liquid to prolong the working life of the drill bits and to avoid overheating and breakage.

About Breakage

It's a common sense that harder stuffs are more brittle. While the 5% cobalt makes the bits much more durable as well as giving them an abrasive quality, it also makes them more brittle than ordinary HSS bits.