313 Каталог INGERSOLL 2011 Режущий инструмент и инструментальная оснастка Стр.315

Каталог INGERSOLL 2011 Инструмент и оснастка Стр. 315 0313 Lab2u

BALL NOSE MILLING Fig. 2: Axial Chip Thinning Step-Over (WOC) First Pass Second Pass Cusp Height To calculate the proper feed rate first multiply the ACTF by the RCTF. This result is the Feed Correction Factor (FCF): FCF RCTF x ACTF Divide the desired chip thickness by the FCF. This result is the desired APT to maintain proper chip thickness: APT FCF Finally to arrive at the feed rate in Inches Per Minute (IPM) multiply the APT by the number of effective flutes and the RPM: IPM RPM x (No. of Flutes) Overall performance would also improve since the cutter would be taking a true "bite at the new feed rate. At the lower feed rate the carbide may rub rather than cut. Example Figure 1 shows a 2.000 diameter ball nose end mill running at .125 DOC and a .125 radial DOC (step over). the effective diameter at this DOC is .968 (see chart on page M463). If the desired SFM is 500 the RpM would normally be set at 955 RPM for a 2.000 diameter cutter. However since the effective .010 .021 APT .48 The feed rate would be: 1973 RPM x .021 41.4 IPM Fig. 3: Radial Chip Thinning at Effective Diameter In the same manner the radial DOC (step over) has the same effect on feed rate. The radial DOC on a ball nose end mill is the same as the radial WOC on an end mill or face mill. In this example the radial DOC of .125 has an RCTF of .67 (see chart on page M463). To achieve the desired chip thickness of .010 multiply the ACTF by the RCTF resulting in the FCF. .48 ACTF x .67 RCTF .32 FCF The APT is: .010 .32 .021 APT diameter is .968 the RPM should be set at 1973 to achieve 500 SFM. This is an increase of more than 100 percent. The DOC also affects the feed rate due to axial chip thinning. At .125 DOC a 2.000 diameter has a chip thinning factor of .48 (see chart on M463). If the desired chip thickness is .010 the feed rate will need to be increased more than 100 percent. Without chip thinning the feed rate would be set at 19.7 IPM (1973 x .010). However at this DOC the ACT would be only .0048 (.010 x .48). To achieve the proper chip thickness (APT or ACT) divide the desired chip thickness by the chip thinning factor. Productivity in this example is three times greater by using the correct chip thinning factors. On a single flute one-effective tool using this example the feed rate should be set at: 1973 RPM x .031 APT 61.3 IPM At this feed rate productivity is increased over 200 percent by using the proper chip thinning factors. Ingersoll Cutting Tool Company provides speed and feed selectors which are designed to help obtain optimum speed feed and ACT multipliers. Ask your Ingersoll sales engineer for a complimentary selector. Second Revolution First Revolution 315