Correct Speeds and Feeds Maximize Quality and Tool Life

Perfect milling, drilling, and tapping requires three ingredients: Skillful operators, quality tools, and correct procedures. You supply the skill. Regal Cutting Tools will supply the best tools in the market. And this article will help determine the proper cutting speeds and feed rates to achieve the most efficient operation based on the hardness and diameter of the material being manipulated.


In this context “Speed,” or surface feet per minute (SPM) refers to how often each tooth of the cutting tool engages the workpiece. This is determined by two factors:

  1. The speed at which the cutting tool and workpiece revolve – The faster the tap or mill spins, the quicker each tooth comes around to take a bite out of the steel, aluminum, alloy, or other metal.
  2. The diameter of the workpiece – Thicker pieces require more time to complete a revolution. This number will depend on how fast the tool and workpiece revolve and how many teeth the tool has per inch.

 “Feed,” expressed in inches per minute (IPM) describes the rate at which the tool advances against the workpiece, making cuts as it goes. It refers to how much of the workpiece material is cut, sheared, or milled each time it revolves or the tool passes over it.

Why They Are Important

Selecting the correct feeds and speeds can play a vital role in both the quality of the finished piece and a shop’s profitability. The goal is to maximize productivity by running the tool as fast as possible while minimizing breakage and wear by staying below critical speed. As we might expect, increasing the feed rate accelerates tool wear, as the cutting surfaces must work harder – generating more frictional heat – to remove more material with each pass.


Regal has done most of the heavy lifting when it comes to determining the ideal SFM. Our Specs and Engineering Data page contains all the charts you need for selecting the right speed, based on the tool and workpiece material. You simply need to measure the diameter of your workpiece. Consult the chart to find the ideal SFM for the tool you are using and the material you are working. The charts have done the math, but if you want to try it yourself, use the following formula:

SFM = RPM x Workpiece Diameter x .262

The charts also reveal the perfect feed rate expressed in inches per minute, or IPM. Feed rate is a function of the number of cutting teeth on the tool and how fast the tool introduces each tooth to the workpiece. The product of this combination (T x IPT) where T = number of teeth and IPT = inches per tooth is inches per revolution, IPR, sometimes referred to as feed per revolution. Multiply IPR and RPM to arrive at the proper feed rate for the tool and work material:


Regal’s taps, end mills, and drills are engineered and manufactured to deliver precise cuts and long life when operated at the feeds and speeds our experts have calculated and posted on our Specifications and Data webpage. Refer to these sheets to find the recommended rates for specific tools and workpiece hardness.

Contact our customer service professionals for help selecting the proper tools for your application or for assistance in applying the recommended feeds and speeds,