b'Deflection of a boring bar depends on the mechanical properties of the shank material, the length of the overhang and the cutting conditions.Boring Bar None mm/min.: 1,00060 = 60,000.d is DOC, mm.f is a feed rate, mm/min.Thenumber396,000isex- Kis a power constant, kW/cm 3 /ppressed through: min.A unit of power equal to 550 ft.- C is the feed rate factor for the lbs./sec.: 550. power constant adjustment.A unit of power equal to 550 ft.- Example of calculating the cut-lbs./min.: 55060 = 33,000. ting force (F)A unit of power equal to 550 in.- Given:lbs./min.: 33,00012 = 396,000. The workpiece is AISI 4140 chro-d is DOC, in. mium-molybdenum steel, 220 to f is a feed rate, ipm. 240 HB.Kis a power constant, hp/in. 3 / DOC, d = 2.03mm.pmin. Feed rate, f = 0.2mm/rev.C is the feed rate factor for thePower constant, K p= 0.0346kW/power constant adjustment. cm 3 /min.Example of calculating the cut- Feed factor, C = 1.08.ting force (F) Adjusted power constant, K pa= Given: K p C = 0.03461.08 = 0.0374.The workpiece is AISI 4140 chro- Calculating:mium-molybdenum steel, 220 toF = 60,000dfK pa= 60,000 240 HB.2.030.20.0374 = 911.1 NDOC, d = 0.08". Comparing the data of the cut-Feed rate, f = 0.008 ipr. ting forces, we can say that for-Power constant, K p= 0.76 hp/ mulas (2) and (3) provide sufficient in. 3 /min. accuracy.Feed factor, C = 1.08. By converting the cutting force Adjusted power constant, K pa=of 207.8 lbf (customary U.S. units of K p C = 0.761.08 = 0.82. measure) into metric units of mea-Calculating: sure, we get:F = 396,000dfK pa=F = 207.84.448 = 924.3 N (com-396,0000.080.0080.82 =pare with 911.1 N)207.8 lbf The difference is:Cutting force (F) expressed in924.3 N - 911.1 N = 13.2 N, or 1.4%metric units of measure, calculatedBy converting the cutting force by formula (3). of 911.1 N (metric units of measure) F = 60,000dfK p C (3) into customary U.S. units of mea-Where sure, we get:The number 60,000 is expressedF = 911.1 N0.2248 = 204.8 lbf through: (compare with 207.8 lbf)A unit of power equal to 1kW The difference is:m/sec.: 1. 207.8 lbf - 204.8 lbf = 3 lbf, or 1.4%A unit of power equal to 1kWm/min.: 160 = 60. Moduli of ElasticityA unit of power equal to 1kW Boring bar shanks are made of 70JULY 2019 Boring.indd 70 6/17/19 10:14 AM'