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9.13 Slotting

Micky R. Jennings

A hand holds a rectangular part that has a finished slot cut on one end.

Figure 9.164. A hand holds a rectangular part that has a finished slot cut on one end. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0Slottingis the process of using an end mill to create a slot or groove in a part. A precision slot is generally performed in multiple passes, allowing the operator to adjust the machine for position and size. Attempting a slot in a single pass may result in an oversized and out-of-position slot that has a poor surface finish.

Step by step process slotting:

  1. Load material into a vise.
  2. Apply layout dye to the top of the part.
  3. Using odd legged calipers, scribe lines on the top of the part to indicate the position of the slot.
  4. Load an end mill for roughing, one size smaller than the slot, into the milling machine.
  5. Calculate the spindle speed and feed rate for the cut.
  6. Turn the spindle on and adjust the machine to the calculated speed.
  7. Position the machine so that the tool is visually in the center of the slot.
  8. Zero and lock the table handwheel.
  9. Touch the tool off to the top of the work.
  10. Set the graduated collar of the knee to zero.
  11. Move the saddle so the tool is off the work.
  12. Move the knee up the desired depth of cut, minus .015″.
  13. Lube the tool and the work.
  14. Make the initial cut through the length of the slot at the calculated feed rate.
  15. Take a measurement to determine the amount needed to be removed in one direction.
  16. Conventional cut the remaining material, leaving material on walls for finishing.
  17. Load a separate finishing tool if needed.
  18. Make a test cut just skimming the bottom and the side of the slot.
  19. Zero the table and knee handwheels.
  20. Accurately measure the part.
  21. Set the knee to the full depth of the slot.
  22. Adjust the machine and make successive cuts in order to finish one side.
  23. Make a skim cut on the other side of the slot.
  24. Zero the table handwheel.
  25. Measure the slot and calculate the material needed to be removed to finish the slot.
  26. Adjust the machine and make successive cuts in order to finish the slot.

Step 4: Load an end mill for roughing, one size smaller than the slot, into the milling machine.

A roughing end mill is loaded into the milling spindle.
Figure 9.165. A roughing end mill is loaded into the milling spindle. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0

Step 7: Position the machine so that the tool is visually in the center of the slot.

A roughing end mill has been centered on the slot layout lines that are scribed on the part. The part is held firmly in the jaws of the vise with enough clearance for the tools to cut the full depth of the slot.
Figure 9.166. A roughing end mill has been centered on the slot layout lines that are scribed on the part. The part is held firmly in the jaws of the vise with enough clearance for the tools to cut the full depth of the slot. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0

Step 9: Touch the tool off to the top of the work.

Step 12: Move the knee up the desired depth of cut, minus .015″.

The knee has been moved so the tool is positioned at the proper depth for the roughing cut.
Figure 9.167. The knee has been moved so the tool is positioned at the proper depth for the roughing cut. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0

Step 13: Lube the tool and the work.

A brush applies cutting oil to the tool and the work before the cutting operation begins.
Figure 9.168. A brush applies cutting oil to the tool and the work before the cutting operation begins. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0

Step 13: Lube the tool and the work.

Step 14: Make the initial cut through the length of the slot at the calculated feed rate.

Step 14: Make the initial cut through the length of the slot at the calculated feed rate.

A roughing end mill has made a slotting cut through the part at nearly full depth. Small broken chips lay in piles on the vise and the work.
Figure 9.169. A roughing end mill has made a slotting cut through the part at nearly full depth. Small broken chips lay in piles on the vise and the work. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0

Step 14: Make the initial cut through the length of the slot at the calculated feed rate.

A roughing end mill has made a slotting cut through the part at nearly full depth. Most of the chips have been swept away to expose the clear path cut between the scribe marks.
Figure 9.170. A roughing end mill has made a slotting cut through the part at nearly full depth. Most of the chips have been swept away to expose the clear path cut between the scribe marks. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0

Step 15: Take a measurement to determine the amount needed to be removed in one direction.

A hand uses a pair of calipers to measure the wall thickness on the left hand side of the slot.
Figure 9.171. A hand uses a pair of calipers to measure the wall thickness on the left hand side of the slot. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0

Step 16: Conventional cut the remaining material, leaving material on walls for finishing.

Step 16: Conventional cut the remaining material, leaving material on walls for finishing.

A roughing end mill has conventional milled the material on the left side of the slot, leaving an allowance for a finishing cut.
Figure 9.172. A roughing end mill has conventional milled the material on the left side of the slot, leaving an allowance for a finishing cut. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0

Step 16: Conventional cut the remaining material, leaving material on walls for finishing.

A roughing end mill has conventional milled the material on the right side of the slot, leaving an allowance for a finishing cut.
Figure 9.173. A roughing end mill has conventional milled the material on the right side of the slot, leaving an allowance for a finishing cut. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0

Step 18: Make a test cut just skimming the bottom and the side of the slot.

Step 20: Accurately measure the part.

A hand uses a depth mic to measure the depth of the bottom of the slot after a finish end mill has made its initial cut.
Figure 9.174. A hand uses a depth mic to measure the depth of the bottom of the slot after a finish end mill has made its initial cut. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0

Step 20: Accurately measure the part.

A hand uses a pair of calipers to measure the wall thickness on the left hand side of the slot before finishing cuts.
Figure 9.175. A hand uses a pair of calipers to measure the wall thickness on the left-hand side of the slot before finishing cuts. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0

Step 22: Adjust the machine and make successive cuts in order to finish one side.

Step 22: Adjust the machine and make successive cuts in order to finish one side.

A hand uses a pair of calipers to measure the wall thickness on the left hand side of the slot before finishing cuts.
Figure 9.176. A hand uses a pair of calipers to measure the wall thickness on the left hand side of the slot before finishing cuts. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0

Step 23: Make a skim cut on the other side of the slot.

Step 25: Measure the slot and calculate the material needed to be removed to finish the slot.

A pair of calipers are used to measure the width of the slot before finishing cuts.
Figure 9.177. A pair of calipers are used to measure the width of the slot before finishing cuts. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0

Step 26: Adjust the machine and make successive cuts in order to finish the slot.

Step 26: Adjust the machine and make successive cuts in order to finish the slot.

Step 26: Adjust the machine and make successive cuts in order to finish the slot.

A pair of calipers are used to measure the width of the slot after finishing cuts.
Figure 9.178. A pair of calipers are used to measure the width of the slot after finishing cuts. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0

Step 26: Adjust the machine and make successive cuts in order to finish the slot.

A hand holds a rectangular part that has a finished slot cut on one end.
Figure 9.179. A hand holds a rectangular part that has a finished slot cut on one end. / Image Credit: Micky R. Jennings, courtesy of Wenatchee Valley College, CC BY 4.0

Attributions

  1. Figure 9.164: Finished slot by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  2. Figure 9.165: Load a roughing end mill by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  3. Figure 9.166: Positioning the roughing cut by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  4. Video 9.43: Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  5. Figure 9.167: Setting the depth of cut by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  6. Figure 9.168: Lube the tool and the work by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  7. Video 9.44: Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  8. Video 9.45: Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  9. Figure 9.169: Rough cut the slot by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  10. Figure 9.170: Finished roughing cut by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  11. Figure 9.171: Measuring left side of slot by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  12. Video 9.46: Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  13. Figure 9.172: Roughing left side of slot by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  14. Figure 9.173: Roughing right side of slot by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  15. Video 9.47: Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  16. Figure 9.174: Measuring the bottom of the slot by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  17. Figure 9.175: Measuring left side of slot by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  18. Video 9.48: Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  19. Figure 9.176: Measuring finished left side of slot by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  20. Video 9.49: Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  21. Figure 9.177: Measuring width of slot by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  22. Video 9.50: Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  23. Video 9.51: Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  24. Figure 9.178: Measuring width of slot 2 by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
  25. Figure 9.179: Finished slot by Micky R. Jennings, courtesy of Wenatchee Valley College, for WA Open ProfTech, © SBCTC, CC BY 4.0
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Introduction to Machining Copyright © by SBCTC is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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