One of the major challenges a CNC programmer faces every day is identifying critical metal machining parameters such as depth of cut, spindle speed, and feed rate. Traditionally, the starting point for this has been either a machining data handbook or the experience of senior machinists on the floor.

SFMforstainless steeldrilling

Feed rate is the velocity at which the cutter is fed or advanced against the work piece. It is expressed in units of distance per revolution for turning and boring (typically inches per revolution[ipr] or mm per revolution).

Different formulas are needed for the different types of tool being used within the CNC machine. Here we will go over the formulas for milling.

The best practice for establishing the best feeds and speeds for the material to be machined is to use a feeds & speeds calculator. By utilizing a materials database and knowing the very specific specification for each CNC machine, optimal feeds and speeds can be calculated that provide the three goals identified above.

Stainless Steelspeeds and feeds calculator

It can be expressed thus for milling also, but it is often expressed in units of distance per time for milling (typically inches per minute [ipm] or millimeters per minute), with considerations of how many teeth (or flutes) the cutter has then determining what that means for each tooth.

Stainless Steel SFMchart

SFPM is a unit of velocity that describes how fast the cutting edge of the cutting tool travels, or in other words, it’s the speed at which the material moves past the cutting edge (outside diameter) of the tool in feet per minute.

There is a wide variety of cutting fluids available today. Many new coolants have been developed to meet the needs of new materials, new cutting tools, and new coatings on cutting tools.

Cutting speed forstainless Steelwith carbide

The actual values for cutting speeds and feeds are a good reference point to start and should be verified by experiment depending on the job.

Getting the best possible results from a CNC machine covers a lot of ground. To begin with, there are several goals the operator might be trying to optimize for:

SFMforstainless steelturning

The primary function of cutting fluids is to cool the tool, workpiece, and chip, reduce friction at the sliding contacts, and prevent or reduce the welding or adhesion on the contact edges that causes a built-up edge on the cutting tool or insert. Cutting fluids also help prevent rust and corrosion and flush chips away.

Did you find this blog helpful? Do you have any questions on how to improve finish through speeds and feeds for metal machining? Leave a comment below, we'd be delighted to hear from you!

In machining, almost all of the energy expended in cutting is transformed into heat. The deformation of the metal to create chips and the friction of the chip sliding across the cutting tool produce heat.

The goal of metal machining operations must be to improve productivity and reduce costs. This is accomplished by machining at the highest practical speed while maintaining practical tool life, reducing scrap, and producing parts with the desired surface quality. Proper selection and use of cutting fluids can help achieve all of these goals.

A common consideration for establishing cutting speed is the time it takes to dull a tool. It may be more profitable to run faster for higher production and replace the tools more often. The other way might be to run the tools more slowly for endurance and machine unattended. There is a big variation here so, after selecting a starting speed, tune it up for the work to be done and the desired productivity.