Hymnorq Metric M35 Cobalt Steel Extremely Heat Resistant Twist Drill Bits with Straight Shank Set of 13pcs to Cut Through Hard Metals Such as Stainless Steel and Cast Iron
Brand: HYMNORQ
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.
COBALT STEEL - Manufactured from M35 cobalt steel, with molybdenum and cobalt added to creates a hardened alloy, measuring Rockwell hardness up to 67, extremely heat resistant; for much faster cutting and extra longer life span, with up to twelve times when compared with an average HSS drill bit.
NO CENTER PUNCH NEEDED - The 135° Quick-Cut points are self-centering and penetrate quickly with less pressure. Will not "walk" or "wander". Straight shank allows for firmly holding and accurate centering, fit for standard drill chucks and regular round collet chucks. Must be used and operated at proper RPMs for maximum efficiency
13PC METRIC BITS - The set includes 13pcs of M35 cobalt steel twist drill bits: 1.5mm, 2mm, 2.5mm, 3mm, 3.2mm, 3.5mm, 4mm, 4.5mm, 4.8mm, 5mm, 5.5mm, 6mm, 6.5mm. Well organized in a plastic indexed storage case for easy transport to your worksite.
FOR METALWORKING - Particularly successful in cutting through hard metals such as stainless steel and cast iron, although they can be used for softer materials, too. Not for hardened steel / high carbon steel. Try to adjust the RPM when it fails to penetrate.
DOWNLOADABLE USER GUIDE - We've summed up some tips of drilling metals, including a RPM chart for several common metals, based on our reviews and some articles on the internet. In most cases, our customers would get a much better result with these tips. Welcome to download.