Surface finish requirement—Lower feed rate gives good surface finish. So if operation is rough cut then a higher value can be considered. For example, for rough turning a feed rate of 0.1 – 0.3mm/rev can be taken; whereas, for finishing pass, 0.01 – 0.05mm/rev can be considered.

Feed rateformula for milling

Need additional assistance selecting the right drill bit for your workpiece material or application? Contact our tech team!

A good quality High Speed Steel (HSS) drill bit is suitable for use on mild steels, but if you need to get a lot of use from them, go with M35 cobalt drills, or even the aforementioned M42 cobalt drills.

We believe the Right Tool Is Everything™, and we strive to share our experience and expertise in an effort to ensure you select the right tool for your application, follow best practices, and can push your productivity further.

Feed rate definitionsteel

Permissible feed rate—Machine tools have a maximum and minimum limit of feed rate, beyond which, selection is not permitted. Again, conventional machine tools may have only few feed rate options within that range.

Productivity requirement—In case of higher productivity requirement, feed rate can be increased, if surface quality can be sacrificed. Otherwise, cutting speed (rpm) can be increased maintaining feed rate unchanged.

What isfeed ratein machining

Machining is basically one material removal process where excess material is gradually removed from the workpiece in the form of chip by feeding the cutting tool against the workpiece. In order to smoothly remove material, three relative motions between tool and workpiece are to be provided. Such motions are cutting velocity (or cutting speed), feed rate and depth of cut. Since these three parameters are inherent to any conventional machining process, so they are also called cutting parameters.

Prior to machining, selection of optimum feed rate is crucial as a number of factors are affected by the process parameter. An optimization can help finding out suitable range for feed rate for machining a particular material under specific conditions and cutting environment. However, considering all possible factors is sometime difficult and thus, in machine shop, its value is commonly selected from practical experience. The following table displays the impacts on machining performance if feed rate is improper.

Feed rateunit

There exist a large number of factors which should be considered for selecting an optimum value of feed rate, as discussed below. Note that the following list is just few of such factors that need consideration while choosing feed rate value.

Cutting speed vsfeed rate

Stainless steel can actually ‘work harden’ as it heats up—so keep your cool, take your time, and make sure the tool and work area stay well lubricated.

Feed rate is one of the cutting parameters, which is provided for moving the tool against the workpiece for covering the entire surface to be machined. Usually it is imparted in a direction perpendicular to cutting velocity; however, the angle between cutting velocity vector and feed vector may also deviate from 90º. The following schematic diagram for straight turning operation shows the feed direction in conjunction with speed and depth of cut.

Value of feed rate affects machining performance and economy, so an optimum value is always desirable. Typical values for feed rate in several conventional machining operations are provided below.

When drilling hardened or stainless steel, select a drill point of at least 135° or higher. This spreads the workload out over a larger cutting surface. Since hardened steel and stainless steel are both quite difficult to drill into, using a drill press or a milling machine should provide the best results.

Feed rate definitioncnc machine

Feed rateformula

Since feed rate is one of the three cutting parameters so its value has to be selected carefully prior to the actual machining operation. Improper feed rate can lead to inaccuracy in machining and thus production of rejected parts. Feed rate affects machining performance in many ways—surface finish to tool life, as discussed below. For detail, you may also read effects of feed rate on machining performance.

Machine capability—Higher feed rate causes high cutting force and vibration. Depending on the capability of machine tool to absorb and transmit such forces and vibrations, feed rate should be chosen.

Cuttingfeed definition

Cutting tool geometry—Beside feed rate, tool geometry also affects surface quality. So, if geometry permits, then a higher value can be selected.

Check out our latest video, and learn how to select the right drill bit to use for the job. Take the guesswork out of drilling holes in metal, as Kurt Repsher walks you through our recommendations for drilling hardened or stainless steels, mild or carbon steels, and aluminum. Subscribe to our channel to see more exclusive how to videos and tips from the pros.

Cobalt drill bits are best suited for use on hard to machine metals, including hardened or stainless steel. Cobalt is blended in with High Speed Steel to make the drill bits harder and more wear resistant. As each cobalt drill bit consists of High Speed Steel with a small percentage of cobalt, the higher the percentage of cobalt, the more heat-resistant and durable the drill bit is.

Try to avoid the cheapest drill bits, or you could likely end up spending more in the long run. Always use cutting oil or coolant for any drilling operation.

Topics: Aluminum, Video, Metalworking and Machining, Holemaking, Drilling, Rushmore USA, TTC, Viking, Precision Twist Drill, Carbon Steel, Stainless Steel

Various machining operation use different unit in order to express feed rate in the most suitable way particularly for that process. The below list displays the common unit of feed rate used in various machining operations. Irrespective of the unit, the purpose of the feed rate remains unaltered as discussed earlier.

Aluminum is very easy to machine, but it’s abrasive, so cutting tools will tend to wear quickly. The best drill bits for aluminum are solid carbide because solid carbide is very hard and stays sharp much longer than other materials, providing extended tool life. If you’re only poking a few holes, high speed steel (HSS) is fine. Using a cobalt drill bit isn’t worth the extra cost because on aluminum, its performance level is about the same as that of high speed steel. Skip the coatings on these drills —there’s no need to increase the already high cost. Especially avoid any coating with “Al” in the ingredients (AlTiN, TiAlN, etc.). A drill bit with a  bright finish is ideal.