Question

8. A two-aisle automated storage retrieval system is located in an integrated factory-warehouse facility. The storage racks in each aisle are 12 m high and 55 m long. The S/R machine for each aisle travels at a horizontal speed of 2.5 m/sec and a vertical speed of 0.5 m/sec. Pick-and- deposit time of 20 seconds. The number of single-command cycles/hr is one-half the number of dual command cycles/hr and the system operated at 80% utilization. Determine the throughput rate (loads moved/hr) of the AS/RS..

Answer 1

Single command cycle time per aisle (Tomcs) Tos = 2 Max { 0.5L, 0.5H 7. The el vy Uz J Le length of aisle = lom H = Height of aisle z Rom vy - Horizontal speed of machine = 2.5 m/s VZ = vertical speed of machine = 0.5 m/s Tod s Pick and deposit time. = 15 sec Tcs = 2 Mane s 0.5X 110 , 0.5x20 + 2XIS 2-5 0.5 = 1.233 min /cycle Dual command cycle #ime per aisle (Ted) for AS/RS Ted = 2 Max { 9:151, 075 * } + 4 Tpd = 2 Max { 075310, 075.820 } + 4x15 = 2.1 min / cycle

Time spent by machine in single command and dual command cycle each hour Rcs Tcs + Red Ted = 600 where beck U = Utilization of system/hour 1.233 x Rcs + 2.14 Red = 60 x (807) = 60% (0.8) = 48 min is one half of the No. of single command cycle dual command cycle Rcs = 0.5 Red : 1.233x 0.5 Red + 2.1x Rcd = 48 Red = 17.67 cycles/ho Res z 0.5 Rad = 0.5% 17.67 = 8.84 cycles/ho Ros = 8.84 cycles/hr

- For ten aisles of the system Rt = 10 CRcs + 2 Red) = 10 (8.84 + 2x 17.67) = 441.8 fransactions /ho Rz = 441.8 transactions/ho