2.810 Energy Analysis – CNC Machining Worksheet By Terry Gaige [email protected] 2006.11.03 CNC Mill - Bridgeport Torq-cut TC3 #D2597913 Travel dimensions 30” x 16” x 20” Spindle speeds, variable 80 - 8000 RPM Motor 9.5 HP Power requirements 230V, 3 phase, 60hz The CNC mill uses electric grid power for its spindle, axis drives, computer, and coolant pump. Current usage ranges from 1.34A with only the computer running to a full spindle and drive stall at 22A. In this analysis we will assume a typical machining cycle, which incorporates a machine warm-up period and idle time for fixture set-ups: For a part with a 10 minute operation time as estimated by the g-code there are approximately 40 other minutes of machine idle time. For the above cycle we found an average of 766 W, or, separated into averages: for idle: 2.4A x 220V = 528W for operation” 6.0A x 220V = 1320W Additional elements: - Stock preparation with horizontal or vertical band saw: typically small in comparison to milling because operation time is short. If used a lot, find energy usage by time on machine: _________ x 220V x 2.1A = _______ - Coolant: TRIM E206 from Master Chemical Corp has an evaporation rate of 1 compared to that of water 0.3, according to the MSDS, and contains 14.29% volatiles by volume. The coolant is replaced approximately once a year, mainly because of evaporation. Ignore because not enough information. - Chips: Generally the chips are of mixed materials and are thrown away. Assume 100% chip loss. Add energy cost of lost chips to total CNC energy usage.Current measurements: Horizontal Band Saw Idle Coolant Cutting Current (A) X 1.84 X X 1.94 X X X 2.05 CNC Torq-cut 3 - Idle Computer Drives Coolant Spindle* x-axis y-axis z-axis Current (A) X 1.34 X X 1.8 X X X 2.63 X X X X 3.64 X X X 3.5 X X X 3.7 X X X 4.8 * 1800rpm CNC Torq-cut 3 - Operation Tool Depth (in) Feed (in/min) Current (A) 3" shell mill 0.1 41 15 3" shell mill 0.2 41 22 3/4" end mill 0.1 41 6.25 3/4" end mill 0.1 32 5.1 3/4" end mill 0.2 32 7.25 Environmental impact estimation procedure for class: Idle time on CNC machine: ________(s) x 220V x 2.4A = _____(J) Operating time on machine: ________(s) x 220V x 6.0A = _____(J) (MasterCam estimate is fine) ______(kg) _______(kg) ______(J/kg) = _____(J) (Mass of stock - mass of part and scraps) * material energy req. Total energy used =
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