For this exercise we will calculate the turning speed, feed rate and cut time for a part that is similar to the pen base that you modelled in CAD previously.
For this sample part the workpiece material is aluminium, measures 12mm in diameter and the depth of cut is 3mm.
The cut length (on this model) is 30mm.
Step 1: Firstly, to use the tool above we will have to start by converting our metric measurements into imperial measurements.
Step 2: Calculate the spindle speed using the simplified metric formula of workpiece diameter x π.
Step 3: Find the suggested cutting speed for our aluminium stock (using HSS cutter).
Step 4: Enter all values into the calculator above to find the fastest possible cut time.
All answers below:
Depth of cut is 3mm or 0.118 inches
Cut diameter is 6mm or 0.236 inches
Cut length is 30mm or 1.181 inches
This equal to 3.14 x 12mm = 37.68 RPM
What is Feed Rate (IPR)?
IPR - Also called, feedrate, or called simply feed, is the relative velocity at which the cutter is advanced along the workpiece. The units are almost always distance per spindle revolution (inches per revolution [in/rev or IPR] or millimeters per revolution [mm/rev]).
Suggested Speeds Roughing Cut (IPR):
Mild Steel: .005 - .020 inches
Aluminium: .005 - .020 inches
Brass: .005 - .020 inches
Suggested Speeds Finishing Cut (IPR):
Mild Steel: .002 - .004 inches
Aluminium: .002 - .004 inches
Brass: .002 - .004 inches
Spindle Speed: 37.68 (RPM)
Cutting feed: 0.020 (IPR)
Feed rate: 0.754 (IPM)
Cut Length: 1.181 (in)
Cut Time: 1.566 (mins)
Cutting feed - The distance that the cutting tool or workpiece advances during one revolution of the spindle, measured in inches per revolution (IPR). In some operations the tool feeds into the workpiece and in others the workpiece feeds into the tool. For a multi-point tool, the cutting feed is also equal to the feed per tooth, measured in inches per tooth (IPT), multiplied by the number of teeth on the cutting tool.
Cutting speed - The speed of the workpiece surface relative to the edge of the cutting tool during a cut, measured in surface feet per minute (SFM).
Spindle speed - The rotational speed of the spindle and the workpiece in revolutions per minute (RPM). The spindle speed is equal to the cutting speed divided by the circumference of the workpiece where the cut is being made. In order to maintain a constant cutting speed, the spindle speed must vary based on the diameter of the cut. If the spindle speed is held constant, then the cutting speed will vary.
Feed rate - The speed of the cutting tool's movement relative to the workpiece as the tool makes a cut. The feed rate is measured in inches per minute (IPM) and is the product of the cutting feed (IPR) and the spindle speed (RPM).
Axial depth of cut - The depth of the tool along the axis of the workpiece as it makes a cut, as in a facing operation. A large axial depth of cut will require a low feed rate, or else it will result in a high load on the tool and reduce the tool life. Therefore, a feature is typically machined in several passes as the tool moves to the specified axial depth of cut for each pass.
Radial depth of cut - The depth of the tool along the radius of the workpiece as it makes a cut, as in a turning or boring operation. A large radial depth of cut will require a low feed rate, or else it will result in a high load on the tool and reduce the tool life. Therefore, a feature is often machined in several steps as the tool moves over at the radial depth of cut.
www.destinytool.com/speeds-feeds.html
www.micro-machine-shop.com/SFM_Formulae_Chart_2.pdf