HOW TO DRILL STAINLESS STEEL
…FOLLOW THE “SLOW SPEED, HARD FEED” RULE

Stainless steel has a reputation for being a difficult material that requires the use of Cobalt drill bits or specialty tooling to be cut or drilled successfully. By following a few simple rules, stainless steel can be worked with a quality HSS Drill bit, using either a hand-held drill motor or a drill press.

Contrary to popular belief, stainless does not have a high surface hardness in its normal state. The problems experienced drilling stainless are due to its tendency to “work-harden” when exposed to the extreme frictional heat caused by the drill bit tip turning on the surface of the stainless steel. Improper drilling methods will cause stainless steel to work harden, creating a material that may be nearly as hard as the drill itself and turning a simple task into an impossible one. To avoid work hardening and to successfully drill stainless steel, while preserving your drill bits and tools, follow this simple rule: Slow speed, hard feed, and...use plenty of cutting fluid too.

HOW TO DRILL STAINLESS STEEL LIKE A PRO

1. Start with a sharp, good quality HSS drill bit and have it turning as slowly (lowest RPM’s) as your hand-held drill or stationary drill press will allow. This is the “slow speed” part of the rule for drilling stainless steel.
2. Now, the “hard feed” rule must be followed! Exert a lot of pressure on the drill bit, as much as you think it can safely take without breaking. An indication that you are drilling stainless correctly using the slow speed, hard feed rule will be that a continuous spiral of material is coming off the drill bit while drilling. That spiral of debris tells you that you are consistently cutting and removing the stainless and applying enough feed pressure to avoid work hardening the material. The “slow speed” reduces heat buildup and the “hard feed” ensures you are consistently cutting and removing fresh material with every revolution of the bit.
3. Don’t start yet though!...The importance of using a cutting fluid or cutting oil cannot be overstated. Cutting lubricant cools both the drill bit and the stainless. It also reduces cutting friction to extend tool life. When drilling by hand, without the benefit of an automated coolant system, the best practice is to stop drilling in intervals and apply more fluid to the bit and to the work surface. A true cutting fluid is always preferred, but any available lubricant or oil is much better than using nothing at all.

SAFETY FIRST

Always wear ANSI/CSA approved protective eyewear when using any tool. The high feed pressure needed to successfully drill stainless can lead to bit breakage/snapping, particularly on small diameter bits. Consider using a shorter than standard drill bit to reduce the possibility of breakage due to high feed pressure. Our Ultra-Bor Screw Machine (Stubby) Bits are a good choice. And finally, always secure the work surface. Smaller parts can spin violently as the drill tip begins to cut through the last bit of metal at the bottom of the hole. To avoid possible injury always clamp or restrain the item being drilled.

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