ME 486 - Materials Handling Fall, 2007(open book)
Name______Solution______
(20) 1.Check whether the statement is best true or false:
a. In the EAAL conveyor lab one or more sensors were placed on the
crossover track.T_X_ F___
b. In the hospital video clip, an AGV moved a bed with a person around.T___ F_X_
c. Non-powered conveyors always depend on human force to work.T___ F_X_
d. An AS/RS is always used to provide a building’s support structure.T___ F_X_
e. AIDC is used to represent the term automatic integration and
data capture.T___ F_X_
f. This bar code is width modulated:T___ F_X_
g. Laser guidance is the least expensive AGV guidance method.T___ F_X_
h. Standardization means less variety and more customization in the methods
and equipment employed.T___ F_X_
i. Ergonomics is a science of human interaction with physical and mental tasks.T_X_ F___
j. WIP stands for Work Integrating Process.T___ F_X_
(40) 2.An automated guided vehicle system is being planned for a warehouse complex. The AGV’S will be a driverless train system, and each train will consist of the towing vehicle plus four carts. Speed of the trains will be 160 ft/min. Only the pulled carts carry loads. The average loaded travel distance per delivery cycle is 2000 ft and empty travel distance is the same. Anticipated travel factor = 0.95. Assume reliability = 1.0. The load handling time per train per delivery is expected to be 10 min. If the requirements on the AGV’S are 25 cart loads per hour, determine the number of trains required.
Solution:
Tc = 10 + = 35.0 min/delivery cycle
Rdv = = 1.629 deliveries/hr per vehicle (train)
Rf = = 6.25 trainloads/hr = 6.25 train deliveries/hr
nc = 6.25/1.629 = 3.84 Use nc = 4 AGV trains.
Grading:
Delivery cycle time10 pts
Delivery rate per vehicle10 pts
Flow rate (del/hr)10 pts
Number of trains10 pts
(40) 3.A unit load AS/RS must be designed to hold an average of 600 pallets. An allowance of 15% additional storage compartments is to be designed into the storage system for peak use periods and flexibility. The unit load has dimensions (x = horizontal, y = vertical): x= 40 in., y = 36 in., and depth into storage rack of 48 in. It has been determined that the AS/RS will consist of 3 aisles with one S/R machine per aisle. Assume that storage compartments are designed into both sides of the aisle. The height cannot exceed 30 ft. Now determine the height and length of each aisle that will satisfy the design specs.
Solution:
np = (600)(1.15) = 690 pallets
Thus, there are 690/3 = 230 compartments per aisle, or 115 compartments each side.
Letx = length dimension = 40 in.
y = vertical dimension = 36 in.
Don’t need to worry about width in this problem.
H = structural height = ny (y + 10) = ny (36 + 10) = 46 ny
L = structural length = nx (x + 8) = nx (40 + 10) = 50 nx
But H 30 ft; thus 46 ny = 30(12) which gives
ny = 360/46 = 7.83 or 7 compartments high (can’t exceed 30 ft)
But nx ny = 115. Solve to get ny = 115/7 = 16.43. Must round up to nx = 17 compartments
Thus there are (7)(17) = 119 total compartment on one side of the aisle. The final dimensions are
Height = (7)(46) = 322 in. = 26.83 ft
Length = (17)(50) = 850 in. = 70.83 ft
Grading:
Total number of pallets required10 pts
Add in structural dimensions (10, 8)10 pts
Num of vertical and length compartments10 pts
Final dimensions10 pts