1. Material Handling Systems Design
Applied Basics of Queuing

2. MATERIAL HANDLING Twenty principles of material handling
Selecting material handling methods
Simplifying/eliminating material handling
Simple analysis techniques

3. Material Handling Material handling adds COST, but not VALUE.
as much as 60% of total production cost
20%-30% of direct labor costs
50%-70% of indirect labor costs
What’s the best way to handle materials? DON’T!!
Goal: MINIMIZE COSTS OF MATERIAL HANDLING

4. Muther’s Material Handling Equation
Yes
WHY ?
WHAT
WHERE +
WHEN
HOW +
WHO
MAT’L
MOVE
METHOD No B A Q D
etc. E P C
Type, Qty, Characteristics
Sink, Source Flow; Direction Flow, Volume Type of Move, etc.
Unit Manpower Equipment

5. Muther’s Material Handling Equation
Use to analyze flow within and between:
Receiving
Storage
Production
Warehousing
Shipping

6. The Twenty Principles of Material Handling
1. Orientation Principle: Study the system relationships thoroughly prior to preliminary planning in order to identify existing methods and problems, physical and economic constraints, and to establish future requirements and goals.
2. Planning Principle: Establish a plan to include basic requirements, desirable options, and the consideration of contingencies for all material handling and storage activities.
3. Systems Principle: Integrate those handling and storage activities which are economically viable into a coordinated system of operation including receiving, inspection, storage, production, assembly, packaging, warehousing, shipping and transportation.

7. The Twenty Principles of Material Handling
4. Unit Load Principle: Handle product in as large a unit load as practical.
5. Space Utilization Principle: Make effective utilization of all cubic space.
6. Standardization Principle: Standardize handling methods and equipment wherever possible.
7. Ergonomic Principle: Recognize human capabilities and limitations by designing MH equipment and procedures for effective interaction with the people using the system.
8. Energy Principle: Include energy consumption of the MH systems and material handling procedures when making comparisons or preparing economic justification.

8. The Twenty Principles of Material Handling
9. Ecology Principle: Minimize adverse affects on the environment when selecting MH equipment and procedures.
10. Mechanization Principle: Mechanize the handling process where feasible to increase efficiency and economy in the handling of materials.
11. Flexibility Principle: Use methods and equipment which can perform a variety of tasks under a variety of operating conditions.
12. Simplification Principle: Simplify handling by eliminating, reducing, or combining unnecessary movements and/or equipment.

9. The Twenty Principles of Material Handling
13. Gravity Principle: Utilize gravity to move material wherever possible, while respecting limitations concerning safety, product damage and loss.
14. Safety Principle: Provide safe MH equipment and methods which follow existing safety codes and regulations in addition to accrued experience.
15. Computerization Principle: Consider computerization in MH&S systems, when circumstances warrant, for improved material and information control.
16. System Flow Principle: Integrate data flow with the physical material flow in handling and storage.

10. The Twenty Principles of Material Handling
17. Layout Principle: Prepare an operational sequence and equipment layout for all viable system solutions, then select the alternative system which best integrates efficiency and effectiveness.
18. Cost Principle: Compare the economic justification of alternate solutions in equipment and methods on the basis of economic effectiveness as measured by expense per unit handled.

11. The Twenty Principles of Material Handling
19. Maintenance Principle: Prepare a plan for PM and scheduled repairs on all material handling equipment.
20. Obsolescence Principle: Prepare a long range and economically sound policy for replacement of obsolete equipment and methods with special consideration to after-tax life cycle costs.

12. Unit Load Principle Follows traditional thinking $/unit Quantity
The greater the amount moved per trip, the less the cost per unit moved Maximize Unit Load

13. Unit Load Principle But: Creates more inventory
Requires expensive, heavy-duty material handling equipment
Increases lag time between operations poor process communication, slower reaction to quality problems
Requires more floor space WASTE!

14. Selecting Material Handling Methods
Systematic Approach
1. Define the problem
Preliminary Survey Check sheet (see Appendix at end of section)

15. Selecting Material Handling Methods
2. Analyze the problem
Observe activities
Obtain layouts, flow patters, schedules, etc.
Obtain information on existing material handling equipment
Analyze situation by material handling equation, Twenty Principles of Material Handling, and/or forms such as Basic Data Form (see insert)
Can activities be combined, simplified, eliminated???

16. Selecting Material Handling Methods
3. Identify possible solutions Organize meeting with:
material handlers
machine operators
supervisors
support engineers
4. Evaluate alternatives Meet again to rate alternatives using Factor Analysis

17. Improvement of MH Systems
Cellular Manufacturing
Eliminate Handling
Eliminate Storage
Eliminate Inventory
Eliminate waste due to poor quality
KEYS:
Efficient layout, scheduling, problem prevention

18. Conveyor Systems Reduce handling costs
Better coordination of product thru processes
Design WIP level into material handling system

19. Simple Analysis Techniques
Queuing Analysis
Mathematical analysis of queues (waiting lines which occur whenever the current demand for service exceeds the current capacity to provide that service).

20. Simple Analysis Techniques
Queuing Analysis
Suitable for “quick and dirty” evaluations when a high degree of detail is not necessary.
System
Server (s)
Arrivals
Departure
l Arrival Rate
m Service Rate

21. Simple Systems FIFO (FCFS) Single Server, Single Queue - M/M/1 System
Poisson Arrivals
Exponential Service Times

22. Simple Systems
LIMITED: Mathematical complexity becomes insurmountable if the above is not true
SIMULATION
Objective
Wait $
Service $

23. Material Handling Applications
Highway Trailers: Ship/Receiving
Parts on Conveyor
Pallets/Mc. Waiting for Fork Trucks
Orders Waiting at AS/RS
Many More

24. QUEUING PHENOMENON Example If m > l, why Queues? LOADING DOCK
arrive every 40 min on avg.
l = 1.5/hr.
30 min avg. time to unload
m = 2.0/hr.

25. QUEUEING PHENOMENON EVENT Time (min) Truck Being Serviced
Truck in Queue
Truck Wait Time
Truck 1 Arrive Truck 2 Arrive Truck 1 Leave Truck 3 Arrive Truck 4 Arrive Truck 2 Leave Truck 3 Leave Truck 4 Leave ,
156 min 4 arrivals
= 39 min. avg.

26. FORMULAS for M/M/1 Model=
avg. arrival rate m =
avg. service rate
l m U =
utilization =
1 l-m W =
avg. wait time in system =
l m(m-l) Wq =
avg. wait time in queue =
l2 m(m-l) Lq =
avg. length of queue =
l m-l L =
avg. number of “customers” in system = Pn =
probability that there are n customers in the system n
l m
l m Pn =
1 -
l m P0 =
1 -

27. M/M/1 EXAMPLE LOADING DOCK arrive every 40 min on avg. l = 1.5/hr.
30 min avg. time to unload
m = 2.0/hr.

28. M/M/1 EXAMPLE l2 m(m-l) Lq = = 2.25 trucks in line l m-l L =
= 3 trucks in line & being served also (L = Lq + l/m) Lq =
Lq/l = 2.25/1.5 = 1.5 hrs/truck Lq =
L/l = 3.0/1.5 = 2.0 hrs/truck
l m Lq =
= = .25  25%

29. Cost Function E[TC] = E[WC] + E[SC] E[SC] E[TC] Cost E[WC]
No. of servers

30. WAITING COST TC = CW[E(n)] + S(CS)
Type I. Internal Customers Example: Forklift truck drivers Cost: Lost productivity of drivers
Type II. External customers Example: People waiting for cabs Cost: ??
E[WC] = CW[E(n)]
SERVICE COSTS
Total Cost: S(server cost) = S(CS)
THUS
TC = CW[E(n)] + S(CS)

31. Example #1 Tool Crib Storage Service Time found by sampling!
Inter-arrival time 60 sec/arr.
50 sec/service

32. Example #1 l = 1/60 = 1 arrivals/min. m = 1/50 = 1.2 services/min.
Idle Time of Server = P0 = 1 - l/m = 1-1/1.2  16.7%
Assume:1. Service Attendant Paid $12.00/hour Customers (machine oper) paid $16.00/hour
Cost of Servers
E[SC] = 8 hrs/day  $12.00/hour = $96.00/day
Cost of Machine Operators Waiting for Service plus Service)
L = l/(m-l) = 1/(1.2-1) = 5
E[WC] = $16.00/hr (5 people) (8 hrs/day) = $640.00/day

33. Example #1 1 Conclusions? _________ E[SC] 640 $ 96 E[WC]
Number of Servers
Conclusions? _________

34. MH Cost Justification of Cellular Manufacturing
Compare:
I. Functional Layout --Fork truck Maint. Labor: $10,000/yr Parts: $1,000/yr Driver: $30,000/yr Truck Cost: $4,000/yr ($20,000/5 yrs) $45,000/yr
*1 yr = 2000 hrs

35. MH Cost Justification of Cellular Manufacturing
Compare:
II. Cellular Layout --Fork truck --Cart/Basket Cart Cost: $40/yr ($200/5 yr) 4 Baskets Cost: $24/yr ($120/5 yrs) $64/yr

36. Questions