Speeds & Feeds for Knurling

For convenience, Knurling is often performed at the same speeds used for turning operations when using high speed steel tool bits. But to prevent seizing of the rolls on the pin, we recommend a maximum surface speed of about 150 SFPM (Feet/Min) or 50 m/min. You may find you get longer knurl life and improved appearance by slowing down the spindle to about 50 SFPM (15 m/min) for harder steels and stainless. Carbide knurl pins are strongly recommended for all high speed knurl applications. Dowel pins with a plus tolerance SHOULD NOT be used because of the possibility of the knurls seizing up and breaking.

For Bump knurling with a Single Tool Holder from the cross-slide, the infeed would normally be .001-.004"/rev (.025 - .1mm) to roll the part complete 5/20 revolutions. When knurling stainless steels, it is important not to roll any longer than necessary as this material work hardens as it is formed. The total amount the tool penetrates into the workpiece is approximately 50% of the tooth depth of the wheel (which is shown in TABLE 1 - APPROXIMATE INCREASE IN KNURLED DIAMETERS). You may have to travel more than this amount to allow for the flexing of the part or holder due to rolling pressure. Some trial and error will be required.

If you are using a two die Straddle Holder, the infeed rate should be 5 or 10 times faster because the wheels are coming in tangentially instead of head on. Before knurling, the holder should be set so that the distance between the two wheels is smaller than the workpiece diameter by approximately the depth of the knurl tooth. Then to knurl, move the holder so that the two wheels are as close to the centerline as possible to minimize the knurling pressure on work spindle and cross slide. To initially find the centerline using a two die straddle holder, you may use this method:
Bring the preset holder and knurls towards the workpiece up to just touch a flat plate of any thickness inserted between the knurls and workpiece.

Remove the plate and advance the holder the thickness of the plate + 50% of the diameter of the knurl wheels + 50% of the diameter of the workpiece. The two knurls should then be over and under the centerline of the workpiece.

If you will also be axial feeding to produce a knurling pattern that is wider than the knurling wheels, chamfers should be on the edges of the wheels. If the knurling doesn't go up close to a shoulder, the use of our Convex axial feed wheels is strongly recommended to further reduce the knurling forces, extend tool life and improve the cosmetic appearance of the workpiece. The normal axial feed rates would be from about .004-.020"/rev. (.1 - .5 mm/rev). The slower feed for stainless steels and tough or semi-hardened steels and faster for mild steels, brass or aluminum. When using Convex axial feed wheels, even faster feeds may be used.

END KNURLING from the turret (axial feeding only) is usually done at .005/.030"/rev (.1-.7 mm/rev), using the slower range for coarser Knurling on high-alloy steels, faster for finer pitches and on brass, aluminum or mild alloy steels. Normally the dies are fed off the work about twice as fast.

CUT TYPE KNURLING is done at similar speeds and feeds as pressure knurling, but the method of initial contact is critical if clean knurling is to be produced.

Please click below for recommended speeds and feeds.
Speeds and Feeds for Cut Knurling

IMPORTANT: If you are having problems with double or mis-tracking, it usually can be solved by increasing the infeed on bump or cut knurling. For end-knurling from the turret, increase the axial feed rate. The deeper and wider the penetration of the knurling wheel into the workpiece on the first revolution, the more likely it will fall into step the next time around.

An estimated best workpiece or knurling wheel diameter can be calculated, but it may not always work the first try. Variations in the material hardness, sharpness of the crest of the knurling wheel teeth, width of knurling, initial in-feed rate, or spindle speed all affect the initial tracking.

Another common way to correct a mis-tracking problem is to grind or stone a small flat of up to .004" (.1mm) or slightly more on the crest of the knurl wheel teeth. This also may actually improve tool life because the wheel is less likely to chip out. Usually, the flat in the root of the rolled workpiece is not noticeable.

APPROXIMATE INCREASE IN KNURLED DIAMETERS Using ACCU TRAK Circular or Diametral Pitch Knurls
TPI	Pitch mm	Tooth Angle	Straight In. / mm	Diagonal In. / mm	Diamond (ON PART)
					Male	Female
12	2.12	90°	.034" / .86mm	.034" / .86mm	.038" / .97mm	.023" / .58mm
16	1.59	90°	.025" / .64mm	.025" / .64mm	.029" / .74mm	.017" /.43mm
20	1.22	90°	.020" / .51mm	.020" / .51mm	.023" / .58mm	.014" / .36mm
25	1.02	90°	.016" / .41mm	.016" / .41mm	.018" / .46mm	.011" / .28mm
30	0.85	90°	.013" / .33mm	.013" / .33mm	.015" / .38mm	.009" / .23mm
35	0.73	90°	.011" / .28mm	.011" / .28mm	.013" / .33mm	.007" / .18mm
40	0.64	90°	.009" / .23mm	.009" / .23mm	.010" / .25mm	.006" / .15mm
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35	0.73	70°	.014" / .36mm	.014" / .36mm	.016" / .36mm	.009" / .23mm
40	0.64	70°	.012" / .34mm	.012" / .34mm	.013" / .33mm	.008" / .20mm
50	0.51	70°	.009" / .23mm	.009" / .23mm	.010" / .25mm	.006" / .15mm
60	0.42	70°	.007" / .18mm	.007" / .18mm	.008" / .20mm	.005" / .11mm
70	0.36	70°	.006" / .15mm	.006" / .15mm	.007" / .17mm	.004" / .10mm
80	0.32	70°	.005" / .13mm	.005" / .13mm	.006" / .15mm	.004" / .10mm
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DP	Pitch mm	Tooth Angle	Straight In. / mm	Diagonal In. / mm	Diamond (ON PART)
					Male	Female
64	1.25	80°	.024" / .61mm	.021" / .53mm	.024" / .61mm	.015" / .38mm
96	0.83	80°	.016" / .41mm	.014" / .36mm	.016" / .41mm	.010" / .25mm
128	0.62	80°	.012" / .30mm	.010" / .25mm	.012" / .30mm	.007" / .18mm
160	0.50	80°	.009" / .23mm	.008" / .20mm	.009" / .23mm	.005" / .13mm