Technical Guidance Troubleshooting for Milling
n Radial Chip Thinning Just as the axial rake of a cutting tool can alter the actual chip thickness, so can radial chip thinning. This occurs whenever the radial width of cut is less than 1/2 the cutter diameter. This is commonly found when making periphery cuts while end milling. Since both tool life and productivity rely on maintaining full chip thickness, it is important to compensate for this scenario. Rather than using the mathematical process to arrive at a programmed feed rate, we have included the following chart. To use this chart it is necessary to have the following information: 1) Desired feed per tooth (as taken from the end mill speed and feed section) 2) Cutter diameter 3) Radial width of cut The first step is to divide the radial width of cut by the cutter diameter and find the closest value in the first column on the left. Next find the desired feed per tooth at the top of the chart and follow that column down to the row that was found in the first step. This will be the programmed feed per tooth. Example: 1.00˝ diameter end mill Answer: Dividing 0.020˝ by 1.00˝=0.020 0.020˝ radial width of cut 0.004˝ desired feed per tooth Finding 0.020 in the first column on the left, and then the 0.004˝ desired feed per tooth at the top, we find where the two meet and obtain 0.014˝ programmed feed per tooth. This results in a large increase in the feed rate. If we use these factors for a four flute tool at 2292 RPM, we have a feed rate of 128 IPM (2292 RPM x 0.014 IPT x 4 Flutes) versus 37 IPM (2292 RPM x 0.004 IPT x 4 Flutes) that might have otherwise been programmed. As you can see from the illustration below, as radial depth increases, so does chip thickness until we reach 50% of the cutting diameter. At this point we have full, programmed chip load.
N
Radial chip thickness
n Radial Chip Thinning Compensation
Desired Feed Per Tooth (IPT)
0.004
0.005
0.006
0.007
0.008
0.009
0.010
0.011
0.012
Programmed Feed Per Tooth (IPT)
WOC/Dia. 0.005
0.0280 0.0200 0.0164 0.0140 0.0128 0.0116 0.0108 0.0100 0.0084 0.0072 0.0060 0.0052 0.0044
0.0350 0.0250 0.0205 0.0175 0.0160 0.0145 0.0135 0.0125 0.0105 0.0090 0.0075 0.0065 0.0055
0.0420 0.0300 0.0246 0.0210 0.0192 0.0174 0.0162 0.0150 0.0126 0.0108 0.0090 0.0078 0.0066
0.0490 0.0350 0.0287 0.0245 0.0224 0.0203 0.0189 0.0175 0.0147 0.0126 0.0105 0.0091 0.0077
0.0560 0.0400 0.0328 0.0280 0.0256 0.0232 0.0216 0.0200 0.0168 0.0144 0.0120 0.0104 0.0088
0.0630 0.0450 0.0369 0.0315 0.0288 0.0261 0.0243 0.0225 0.0189 0.0162 0.0135 0.0117 0.0099
0.0700 0.0770 0.0840 0.0500 0.0550 0.0600 0.0410 0.0451 0.0492 0.0350 0.0385 0.0420 0.0320 0.0352 0.0384 0.0290 0.0319 0.0348 0.0270 0.0297 0.0324 0.0250 0.0275 0.0300 0.0210 0.0231 0.0252 0.0180 0.0198 0.0216 0.0150 0.0165 0.0180 0.0130 0.0143 0.0156 0.0110 0.0121 0.0132
0.010 0.015 0.020 0.025 0.030 0.035 0.040 0.060 0.080 0.120 0.200 0.300
N58
F mark: To be replaced by a new product, made to order or discontinued (please confirm stock availability)
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