ISE 312 Material Handling & Facility Design Spring_2017
Homework #1 Due: Wednesday 3/08/2017
1. Economic analysis is needed in evaluating material-handling equipment requirements. One piece of equipment under consideration is a forklift truck that has a purchase price of
$24,960 & a 10-year life expectancy. The fuel cost has been calculated at $32 per 8 hours of operation. A cost review indicates maintenance cost is $2.00 per hour. If the truck has to travel an average of 12,000 feet per day, what is the cost per foot for operating this forklift? (Assume that the truck operates 312 days per year & that the operator is paid $20.00 per hour including fringe benefits). (8 hour-days) (9)
2. A company delivers finished products in batches to its warehouse daily. The demand between manufacturing and the warehouse changes on the product mix of five items A, B, C, D, and E. The company has found that trucks respond to the capacity change much more readily than conveyor systems; so, the company is considering purchasing two different types of fork-lift trucks (#1 or #2) for transporting packaged products to its warehouse and loading tractor-trailers for shipping. Equipment specifications for each type of truck are listed below. Pertinent sizes and costs for items A through E are listed below in material characteristics. The loading and unloading cost includes not only cost for loading and unloading for one trip, but also the cost for making the return trip to pick up another load. Determine the least expensive type of forklift truck for transporting the products. Make sure to compare Total Costs for each option. Shipments from the warehouse are made once per week. (Assume
5-day work week & each item has shipping orientation listed below LxWxH). (10)
Equipment Specifications:
Maximum Loading & Unloading Cost per
Equipment Volume (L x W x H) (in) Cost ($) Foot ($)
Type #1 48 x 60 x 44 1.20 / trip 0.032
Type #2 36 x 42 x 40 1.22 / trip 0.018
Material Characteristics:
Volume Distance from Distance to Units Units Shipped
Items (L x W x H) (in) Mfg. (ft.) Shipping (ft.) Received /Day per Week
A 6 x 6 x 6 400 200 100 500
B 22 x 26 x 18 312 310 100 500
C 12 x 12 x 10 450 350 50 250
D 14 x 12 x 8 400 300 100 500
E 10 x 6 x 6 360 320 20 100
ISE 312 Material Handling & Facility Design
3. A series of (6) machines are arranged in a circular arc so that a robot arm can reach & perform loading & unloading actions on a manufactured part. The part must be machined sequentially through operations One to Six. Parts come to the robot on a fully automated conveyor system & leave on a fully automated conveyor system. (9)
Determine the cycle time & production rate for this Machine & Robot configuration.
Robot Action Times Machine Action Times
> Unload a station = 0.10 minutes > #1 Bore 3.0 minutes
> Move to a station = 0.20 minutes > #2 Drill 2.8 minutes
> Load a station = 0.20 minutes > #3 Mill 4.0 minutes
> #4 Attach 1.5 minutes
> #5 Weld 2.2 minutes
> #6 Grind 1.2 minutes
ISE 312 Material Handling & Facility Design
4. What would the cycle time & production rate be for the configuration in problem #3 if the Mill Operation #3 was 5.50 minutes instead of 4.0 minutes? (5)
5. The flexibility of using an AGV is important for responding to a changing workload & product mix, which is a common benefit to the flexible manufacturing system that you are currently designing. Your AGV system design has been chosen for delivering small parts from storage to six shops in a plant. Determine the number of vehicles needed, given the information available below. Assume that each vehicle can carry parts to & from only one shop at a time. Your AGV design under consideration can travel at a rate of 140 feet/min.
(The traffic congestion factor for this type plant is known to be 0.90). (10)
Shop Number Distance from Storage Number of trips/hour Loading/Unloading
1 280 ft 20 2 (minutes) 2 300 20 3
3 330 16 2
4 385 8 4
5 430 12 3
6 480 10 2
ISE 312 Material Handling & Facility Design
6. A bank (buffer space) is provided at the end of a conveyor system to absorb fluctuations in production. Items arrive at an operation on the conveyor following a Poisson distribution with a lambda of (3.2) units per minute. The operator processes these items with a mean of 0.25 minutes per unit following an Exponential service rate. What is the required capacity of the bank so that the probability of not being able to accommodate an item in the bank is less than 25.0 percent? (Be careful with rounding off). (10)
7. The operation in problem #6 experiences a calibration once a day for at most 1 minute. What is the probability of not accommodating an incoming item if the bank capacity is set to the value you calculated in problem #6? (Assume no items can be processed during calibration). (10)
ISE 312 Material Handling & Facility Design
8. A company has found that loading & unloading of an operation is profitable by a robot. The robot has one gripper to complete all actions required to maintain loading & unloading of the machine. See below for the operation time of the sequential activities associated with using the robot to load and unload work pieces. What is the cycle time for this configuration? At 90% efficiency, what is the production rate for an eight-hour day? (7)
Machine Operation 45.2 (second / part)
Robot Unload 3.5
Move to Conveyor 3.0
Release Unit 2.2
Move to Input Conveyor 3.1
Pick Up Unit 5.0
Move to Machine 2.5
Load Machine 4.5
9. How would your answer for problem #8 change for a 2-gripper robot? Provide cycle times & production rates to support your answer. (05)
10. Describe the differences among product, process, and group technology layouts. Describe the circumstances in which each type of layout is appropriate. (7)
ISE 312 Material Handling & Facility Design
11. You are required to determine the number of handling units needed to perform a material-handling task where receiving docks for a plant are supplied by both rail cars and trucks. Analysis should indicate the required number of docks and the required number forklift trucks needed to perform the material-handling function. The following data describes the characteristics of the plant: (10)
There are 4 docks labeled: R, S, T, U (R & S employ 12 hrs/day; U & T employs 8 hrs/day)
Dock Hours employ allowances of 17.5%
Forklift trucks can only service one dock area (No Sharing)!
Forklift trucks have an estimated capacity of 12 loads/hour for all raw materials.
Dock R is serviced by Rail Cars (100,000 lb bulk loads) that bring in raw material A. A Grab Hook unloads 800 lbs. per attempt to an open storage bin (No forklift needed for storage area). 4 min/unload.
Average Loads/Day = 8.0
Peak Loads/Day = 9.0
Design specifications Loads/Day = 9.0
Docks S is serviced by Rail Cars.
(For Dock S Raw Materials > Forklift will carry to storage area).
Raw material B (100,000 lb bulk load). Shovel unloads 400 lbs/load to F-Lift for storage.
(5 min/unload)
Raw material C (100,000 lb bulk load), Shovel unloads 600 lbs/load to F-Lift for storage.
(4 min/unload)
Raw material D (20 pallets), 1 pallet/load for Forklift to storage. (4 min/unload)
Raw material E (20 containers), 1 container/load for Forklift to storage. (12 min/unload)
Raw Materials:
Average Loads/Day: B = 4.0 C = 3.0 D = 1.0 E = 2.0
Peak Loads/Day: B = 4.5 C = 4.0 D = 3.0 E = 5.0
Design specifications Loads/Day: B = 5.0 C = 3.5 D = 2.5 E = 3.0
Dock T is serviced by Trucks (3,000 gal load) that brings in raw material F. Unload to underground tank at 1,000 gal/hour. (No forklift needed).
Average Loads/Day = 10.0
Peak Loads/Day = 12.0
Design specifications Loads/Day = 12.00
Docks U is serviced by Trucks.
(For Dock U Raw Materials > Forklift will carry to storage area).
Raw material G (30,000 lb bulk load). 1,500 lbs/container for Forklift to storage.
(10 min/unload)
Raw material H (10 pallets), 1 pallet/ load for Forklift to storage. (5 min/unload)
Raw material I (21,000 lb loads), 1,500 lb/container for Forklift to storage area.
(8 min/unload)
Raw Materials:
Average Loads/Day: G = 7.0 H = 8.0 I = 12.0
Peak Loads/Day: G = 8.0 H = 9.0 I = 14.0
Design specifications Loads/Day: G =7.5 H = 8.5 I = 13.0
12. Your company has just received a five year contract to produce and ship a new top-secret robotic repair device and electronic surveillance units for the military. This clandestine project will command a special elite army unit which will also administer all shipping regulations for the shipping department. You are required to determine the minimum number of loading docks needed for shipment of all military equipment under military supervision. Trucks will be loaded from a warehouse at a dock. Shipping rates are summarized below. (8)
Data:
Average Truck Load = 3,000 lbs.
Average Service Rate = 1,200 lbs/work-hr
Command will allow 1 operator / dock
For security reasons expect 100 minutes
for trucks to enter & leave.
Cost of operating one dock = $30 /hour
(includes operator & forklift)
Cost of truck = $60 / hour
(includes truck operator & truck expenses)
Empty Truck Arrivals = 0.24 truck / hour (Poisson arrival)
Ans:
- 2 -