Methodology
Feed and Speed rates need to be determined to optimize machining time, surface finish, and tool life. Speeds and Feeds along with required horsepower can be calculated using the machinist’s handbook and a series of formulas. Information in the Machinists Handbook assumes production speeds: i.e. an average tool life of fewer than two hours.
Production speeds state the maximum production for the cost of tooling, though they are sometimes impractical for the small jobs done at the machine shop. However, calculated speed and feed rates do give a useful reference in determining what rates should be used for our purposes. The following demonstrates how to calculate Speeds and Feeds for a surface milling or slotting operation.
Input Air Turbine Spindles® governed speeds from 25,000 to 90,000RPM and you will see the scale of savings these direct drive spindles can achieve in your application.
Comparison of Cutting Speed with a 1.5mm End Mill
Standard Machine Spindle at 12,000 rpm = 2.22”/min (56.5 mm/min) advance
Air Turbine Spindles® 625 Series at constant 50,000 rpm = 9.28”/min (235.6 mm/min) advance
Your Cutting Speed is increased 4.2x with Air Turbine Spindles®!
In addition to reducing cycle time, the accuracy of the cutting tool is improved and its life extended
Cutting Speed = (D × π × Spindle Speed )/1000
Machinist Handbook Values
SFM (ft/min)
Surface Feet per Minute
Surface Feet per Minute
Also called Cutter speed. Speed of a point on the outside diameter of the tool. Value depends on the material.
FPT (in)
Feed Per Tooth
Feed Per Tooth
Also called Chip Load. Amount of stock removed by each tooth during a single revolution. Value depends on stock material, tool size, and tool material.
HPF (HP*min/in3)
Horse Power Factor
Horse Power Factor
The number used to calculate power requirement. Value depends on the material.
Other Variables
►
D (in):
Diameter of tool
►
N:
Number of teeth or flutes
►
DOC (in):
Depth Of Cut
►
RPM:
Rotations Per Minute, or Spindle Speed
►
IPM:
Inches Per Minute. Also called Feed Rate. The rate at which the workpiece is moved into the tool.
►
MRR:
(in3/min) Metal Removal Rate, Rate of volume removal
►
HP:
Horse Power, necessary power
Formulas
►
RPM:
SFM*12/(1.618*D)
►
IPM:
FPT*N*RPM
►
MRR:
IPM*DOC*D
►
HP:
MMR*HPF
Air Turbine Spindle vs Fanuc Robodrill Main Spindle Cycle Times Cut in Half
C/T Reduced by 25 Minutes with 50,000 rpm! Pocketing Brass with Air Turbine Spindles®
Application Information
►
Action: Pocketing
►
Material: Brass
►
DOC: 0.1" (5 Passes)
Robodrill Main Spindle
►
Speed:
10,000 RPM
►
Advance:
10 IPM (254mm/min)
►
Cycle Time:
51 Minutes
Air Turbine Spindles® 625 Series
►
Speed:
50,000 RPM
►
Advance:
50 IPM (1270mm/min)
►
Cycle Time:
25 Minutes
Related Videos
Restoring Antique Pocket Watches into Wrist Watches with Vortic Watches and Air Turbine Tools®
3D Surfacing at 40,000 RPM Cut Cycle Times by 4x
Testimony from Ken Stauver from KS Analytical Systems
Cycle Times Cut Dramatically! Drilling Aluminum at 50,000 rpm on Robodrill
