What is Cutting Speed, Feed, Depth Of Cut in Machine tools
After reading this article you will learn about the concept of cutting speed, feed and depth of cut.
Cutting Speed :
Cutting speed is defined as the speed at which the work moves concerning the tool (usually measured in feet per minute).
The cutting speed, expressed in FPM, must not be confused with the spindle speed of the lathe which is expressed in RPM. To obtain uniform cutting speed, the lathe spindle must be revolved faster for workplaces of small diameter and slower for workplaces of large diameter.
The proper cutting speed for a given job depends upon the hardness of the material being machined, the material of the tool bit, and how much feed and depth of cut is required. Cutting speeds for metal are usually expressed in surface feet per minute, measured on the circumference of the work
Cutting Speed Calculation :
Cutting Speed is the speed at which the metal is removed by the cutting tool from the workpiece. In the case of lathe machine cutting speed is the peripheral speed of the work past the cutting tool. It is expressed in meter/min. or mm/min.
Cutting speed (V) = π DN/60 × 1000 mm/min
Where D = diameter of the workpiece (mm)
N = rpm of the work
Cutting speed depends upon the following factors:
i. Tool material.
ii. Work material.
iii. Depth of cut.
iv. Tool geometry.
v. Type of machine tool.
vi. Surface quality required.
Feed rate :
Feed rate is defined as the distance the tool travels during one revolution of the part. Cutting speed and feed determines the surface finish, power requirements, and material removal rate. The primary factor in choosing feed and speed is the material to be cut. However, one should also consider the material of the tool, rigidity of the workpiece, size and condition of the lathe, and depth of cut. For most Aluminum alloys, on a roughing cut (.010 to .020 inches depth of cut) run at 600 fpm. On a finishing cut (.002 to .010 depth of cut) run at 1000 fpm. To calculate the proper spindle speed, divide the desired cutting speed by the circumference of the work. Experiment with feed rates to achieve the desired finish. In considering the depth of cut, it’s important to remember that for each thousandth depth of cut, the working diameter is reduced by two thousandths.
Depth of Cut
The depth of cut is the distance that the tool bit moves into the work. usually measured in thousandths of an inch or millimeters. General machine practice is to use a depth of cut up to five times the rate of feed, such as rough cutting stainless steel using a feed of 0.020 inches per revolution and a depth of cut of 0.100 inch. which would reduce the diameter by 0.200 inch. If chatter marks or machine noise develops, reduce the depth of cut.
It is the total amount of metal removed per pass of the cutting tool. It is expressed in mm. It can vary and depend upon the type of tool and work material. Mathematically, it is half of the difference of diameters.
Sachin is a B-TECH graduate in Mechanical Engineering from a reputed Engineering college. Currently, he is working in the sheet metal industry as a designer. Additionally, he has interested in Product Design, Animation, and Project design. He also likes to write articles related to the mechanical engineering field and tries to motivate other mechanical engineering students by his innovative project ideas, design, models and videos.