Dapra's high-performance 90-degree Square Shoulder cutters work best when allowed to perform within their designed operating parameters. Adhering to the following steps will ensure that you are getting the most from your investment.

  1. Refer to the Feed and Speed Chart (PDF) to find the recommended Surface Feet per Minute (SFM) and Feed per Tooth (FPT) at which to run your cutter, based on the material to be machined.
  2. Use the following formula to determine the Revolutions per Minute (RPM) for your cutting tool:
    (SFM x 3.82) / Tool Dia. = RPM
    Example: A 2" diameter tool operating at 900 SFM (900 x 3.82) / 2 = 1720 RPM
  3. Use the following formula to determine the feed in Inches per Minute (IPM) to be programmed into the machine tool:
    FPT x RPM x N (number of teeth in cutter) = Feed
    Example: A 5-flute cutter at .008" FPT (.008 x 1720) x 5 = 69 IPM
  4. If the Width of Cut (WOC) < 1/2 the cutter diameter, use the feed rate compensation chart (below) to compensate for chip thinning.

Width of Cut (WOC) (% of tool Ø) 50% or > 40% 30% 20% 10%
Feed Rate Multiplier 1 1.02 1.1 1.25 1.7

After determining the percentage of WOC for the tool diameter, multiply the desired feed rate by the corresponding factor shown in the chart. This will be the Adjusted Feed per Tooth (AFPT) resulting in a true chip thickness of the desired amount.

Example:

If using a 1" dia. end mill @ .100" WOC, the WOC = 10% of the cutter diameter. Using the chart above, the factor for the chip thickness = 1.7. If a chip thickness of .005" is desired, a feed rate of .0085" (.005 x 1.7) should be programmed into the machine tool.

or

Adjusted Feed per Tooth (AFPT) = desired chip thickness x chip thinning factor (from chart).