1. Material Handling Module7
Definitions
Material Handling Equipment & Classifications
Analysis and Design of Material Handling
Conveyor Systems
AGV systems
AS/RS

2. Material Handling in Production Systems

3. Introduction
Purpose of Material handling (MH) is the movement, storage, tracking (or control) of all materials during manufacturing; and; also during distribution, consumption, and disposal.
Materials include raw materials, finished parts, tools, and supplies
Cost of MH could be a significant portion (10 to 70%) of total production cost
MH equipment is the conduit for materials flow and physical integration within a factory (95% of time).
Automated MH is a key element in any flexible manufacturing system (primary and secondary systems)
Because of movements, MH equipment are associated with many accidental injuries on the job.

4. Requirements Safety (humans and products including fragile items)
Efficient (low cost)
Effective (Timely, Accurately)

5. Equipment: Classification by Types
Hand Trucks: dollies, wheeled trucks for manual transport of all material.
Powered Trucks: forklifts (powered by propane, battery or gasoline), tractor-trailer trains, and other vehicles.
Cranes and Hoists: specialized overhead equipment for lifting and manipulating heavy objects usually powered.
Conveyors: move large quantities of materials over a fixed path. Can be continuously moving or use gravity.
Automated Guided Vehicle Systems (AGVS): powered vehicles that automatically follow a fixed path.
Automated Storage/Retrieval Systems (ASRS): mechanized systems that automatically store and retrieve items.
Others indexing table, pipelines

6. Non-Powered Trucks

7. Powered Trucks

8. Cranes and Hoist

9. Conveyor Systems: Types of Conveyors
Roller: a series of short tubes roll under the action of gravity or powered ( belts or chains). Very common.( Skate – wheel conveyors)
Belt: a continuous belt loop driven by pulleys for moving pallets, parts or bulk materials (troughed).
Overhead trolley: an endless moving cable or chain carries trolleys on overhead rails. Hooks or baskets suspended from the trolleys to carried loads.
In-floor tow line: a moving cable or chain buried in the floor moves wheeled trailer carts along a fixed path.
Cart-on-track: individual carts ride on tracks driven by rotating tube. (high positioning)

10. Types of Conveyors-1

11. Types of Conveyors-2

12. Conveyor Accessories Angle Pushers Diverters Turntable Switches
Flow Control – traffic cop
Gates
Sorting

13. Automated Guided Vehicle Systems (AGVS):Vehicle Types
Driverless train: a guided vehicle tows several trailers carrying heavy loads (up to 50,000 lbs) over long distances.
Tow
train
Pallet truck: a manually loaded guided vehicle for dispatching medium-duty (<6000 lbs) pallets along a guide path on demand.
Pallet
truck
Unit-load carrier: a lighter duty ( lbs) version of the pallet truck with its own automatic load/unload mechanisms.
Unit load
carrier
Maximum speed for all is 3 mi/hr = 264 ft/min

14. Automated Guided Vehicles -AGVs

15. Automated Guided Vehicle Systems (AGVS): Factory Applications
Warehousing, shipping and receiving: moving large quantities over large distances in large factories and warehouses typically require drivereless trains.
Storage and distribution: unit load carriers and pallet trucks typically move materials randomly and in varied quantities to and from automated storage systems.
Assembly-Lines: extra light duty (<500 lb) unit-load carriers move part kits between workstations assembling several variations of the product on the assembly line
(4-10min cycle time)
FMS: unit-load carriers and pallet trucks move parts and tools between workstations, staging areas and storage areas under the control of the FMS supervisory controller.

16. Vehicle Guidance Technologies
Fixed Pathway
Impeded Guide Wires (magnetic (coil) sensors)
Paint Strip (UV sensors)

17. Vehicle Guidance Technologies
Flexible Pathway
Self-Guided Vehicle (SGV)
Has on board navigation computer
Term “Dead Reckoning”

18. Vehicle Management and Safety
Objectives
Minimize waiting time at loading/unloading stations
Equipment utilization and service time management issues
Minimize traffic congestions
Operate safely

19. AGVS: Vehicle Management and Safety
Traffic Control (on-board sensing)
Zone Control (control units on pathway)
Vehicle Dispatching
On-board control panel
Remote call stations
Central computer
Safety (speed, safety bumper, obstacle detection, etc)
Additional technologies that can improve above issues are ?????

20. Material Handling System Design Consideration

21. Material Handling System Design
Objectives
Safety (humans and products ‘fragile’)
Efficient (low cost)
Effective (Timely, Accurately)
Factors that influence design
Material Characteristics
Flow rate, Routing, and Scheduling
Plant Layout

22. Material Characteristics

23. Flow rate, Routing, and Scheduling
Flow rate (dedicated and shared?)
Routing (distances? conditions?)
Scheduling (MH system response?)

24. Plant Layout Information required for system design are:
Path of materials flow and potential obstacles
Load and unload locations
Materials flow pattern and potential congestion points
Distances traveled
Arrangement of equipment within each department
Storage requirements and location for WIP
Total area of the facility
Plant layout strongly influences the type and the configuration of equipment in a MH system (new ?)
- Fixed-position, Process (or Cellular) Type, Product-Flow

25. Plant Layout

26. The 10 Principles of MH (Table 9.3)
Planning Principle
Standardization Principle
Work Principle
Ergonomics Principle – human capabilities and limitations
Unit Load Principle
Space utilization principle
System principle
Automation principle
Environmental principle
Life Cycle Cost principle

27. Analysis of Materials Handling Systems
From-to chart
Flow diagram

28. Conveyor Systems: Common Characteristics
Are generally mechanized and sometimes automated
Follow fixed path (single direction, continuous loop, recirculating)
Mounted on the floor or overhead
Move materials mostly in one-direction
Move discrete parts or bulk (continuous load)
Used for transport and dynamic storage (Later?)
Non-powered individual carriers or pallets ride on the powered or gravity-driven conveyor

29. Conveyor Analysis: Single Direction Conveyors
Assumptions:
1. Belt moves in one direction
2. One load station at the input end
3. One unload station at the output end
Load
Station
Unload
Station Ld vc TL TU sc
where:
Td = delivery time (min/carrier)
Ld = conveying distance between load and unload stations (m,ft)
vc = conveyor speed (m/min, ft/min)
Rf = material flow rate (parts/min)
RL= loading rate (parts/min)
np= number of parts per carrier
sc = carriers spacing on conveyor (m/carrier, ft/carrier)
TL= loading time (min/carrier)
TU= unloading time (min/carrier)
TU < TL

30. Conveyor Analysis: Example 1
It takes 20 sec to load 18 parts into each tote pan and 4 sec to load the tote pan onto the single direction belt conveyor.
Ld =200 ft
vc= 50 ft/min TL TU sc
Find:
(a) delivery time, Td (min)
(b) minimum tote pan spacing, sc (ft)
(b) maximum possible parts flow rate, Rf (parts/min);
(c) maximum unload time TU
Belt conveyor
= 4.0 min (for a specific tote)
sc = vc TL = (50 ft/min) (20 s + 4 s) (1 min/60 s)
= 20 ft
TU < TL < 24 s/pan
0.40 min/pan
= 45 parts/min

31. Conveyor Analysis: Continuous Closed-Loop Conveyors
Return leg Le
Empty carrier
Consider a continuous closed-loop conveyor, such as an overhead trolley system with one load and one unload station. Assume that all carriers are emptied at the unload station.
Load station
Unload station vc np
Full carrier
Delivery leg Ld
nc = number of carriers in the system
Ld = length of the delivery leg (ft or m)
Le = length of the return leg (ft or m)
sc = carriers spacing (ft or m/carrier)
Np = total number of parts in the system
np = number of parts in each carrier
Rf = part feed rate (parts/min)
vc = conveyor speed (ft/min or m/min)

32. Conveyor Analysis: Recirculating Conveyors
Continuous loop conveyors can be used for storage, if loaded carries are allowed to flow back on the return leg raising the following possibilities:
Empty carriers are not available when needed for loading
Full carriers are not immediately available for unloading
(airport conveyor)

33. Conveyor Analysis: Recirculating Conveyors
Kwo’s recirculating conveyor design requirements with ONE load station and ONE unload station. Three rules
Speed rule: Operating speed within a certain limit determined by #carriers/min (vc/ sc ). The lower limit should be greater than or equal the required loading or unloading rate whichever is the greater.
The upper limit should be less or equal to the capabilities of the material
handlers. c p L U s v n
, R
> Max R
parts/min c s v
<Min 1 TL TU ,
min/carrier

34. Conveyor Analysis: Recirculating Conveyors
Capacity constraint: The flow rate capacity of the conveyor must be at least equal to the flow rate requirement to accommodate reserve stock and allow for the time elapsed between loading and unloading due to delivery distance.
Uniformity Principle: empty and full carriers should be uniformly distributed along the line to avoid excessive waiting for carriers. c p f s v n
> R

35. Conveyor Analysis: Example 2
A recirculation conveyor has a total length of 300m. Its speed is 60m/min, and the spacing of part carriers along its length is 12m. Each carrier can hold 2 parts. The time required to load 2 parts into each carrier is 0.20min and the unload time is the same. The required loading and unloading rates are both defined by the specified flow rate, which is 4parts/min. Evaluate the conveyor system design with respect to Kwo’s three principle.
Find: Specified flow rate , Rf = 4 parts/min
Conveyor speed, vc = 60m/min
Spacing of carriers, Sc =12m
Number of parts per carrier, np = 2 parts
Loading TL = Unloading TU = 0.2 min/carrier
Solution: 1) Speed Rule c p L U s v n
, R
> Max R c s v
<Min 1 TL TU ,

36. Example 2 (continue) s v n > R 2) Capacity Constraint
Actual flow rate capacity = 10 parts/min (> 4 parts/min) c p f s v n
> R
3) Uniformity Principle
-Loading rate = unloading rate
-Other
Flow rate capacity (10 parts/min) is substantially greater than
required loading / unloading rate (4parts /min)

37. AGVS: Common Characteristics
An AGVS is a automated material handling system consisting of independently operated, self-propelled vehicles that are automatically guided along defined paths.

38. AGVS: Common Characteristics
On-board batteries usually power AGVS vehicles for 10 to 16 hrs of operation.
On-board control system uses sensors to detect the position of wires buried in the floor or strips of reflective paint and guide the vehicle along the desired path within a certain margin of error (pp ).
Vehicles automatically (sensors) detect obstacles and avoid collisions with other objects

39. AGVS: Factors to Consider in System Design
Guide path type (?) and vehicle type
Path routing and layout
Flow direction along each path segment
Number and location of docking points for loading and unloading
Number and locations of vehicle parking sites
Required number of vehicles
Dispatching rules and frequency of pickups and deliveries

40. AGVS Analysis: Delivery Cycle Time
Analysis begins with estimating the total time Tc in a delivery cycle of a vehicle on the average, ignoring effects of traffic congestion:
Tc = delivery cycle time for one vehicle (min/del)
TL = loading time (min)
Ld = average distance traveled while loaded per delivery (ft or m)
vc = AGV speed which is assumed to be constant (ft/min, m/min)
TU = unloading time (min)
Le = average distance traveled while empty per delivery (ft or m)
Other Assumptions?

41. AGVS: Factors affect Delivery Cycle Time
Availability (A)
Traffic congestion (Tf )
Efficiency of manual elements (E)

42. AGVS: Rate of deliveries

43. AGVS: Number of Vehicles

44. AGV: Example It is desired to design a particular AGVS system that is
capable of making 40 deliveries/hr. The performance
characteristics of the system are:
Vehicle velocity = 150 ft/min
Average distance traveled per delivery = 450 ft
Average distance traveled empty = 450 ft
Pick up time = 45 sec
Drop-off time = 45 sec
Traffic factor = 0.90
Determine the required number of vehicles.

45. Storage Systems

46. Storage System- Types of Materials

47. Storage System- Location Strategies
SKU?
Most Common:
Randomized Storage
Designed based on the average inventory level
Dedicated Storage
Designed based on max inventory level
Class-based dedicated storage
Designed based on activity level
Which uses less Space?
Which is Faster?

48. Storage Capacity : Example 4
Total 50 SKU
Note : a different SKU arrives each day
Determine the number of storage locations required in the system based on the randomized storage and dedicated storage strategies

49. Storage System- Performance
Storage cycle (pick, travel, place, travel)
Retrieval cycle?
Traditional Systems
Storage Capacity
Density
Accessibility
Throughput
Mechanized and Automated Systems:
Utilization
Availability (Uptime Reliability)

50. Storage Capacity/ Density/Accessibility
Storage Capacity is defined by the number of total unit loads stored in the system
Physical capacity should be greater than the MAX number of unit loads anticipated to be stored (Why?)
Storage Density is defined as the volumetric space available for actual storage relative to the total volumetric space in the storage facility (floor area?)
Accessibility refers to the the capability to access any desired unit load in the system
Trade-offs are made between storage density and accessibility

51. System Throughput
Defined as the hourly rate at which the storage system
Receives and puts loads into storage (storage transaction) and/or
Retrieves and delivers loads to the output station (retrieval transaction)
Single command cycle or Dual command cycle
System is designed to handle the MAX hourly rate required.

52. Utilization and Reliability
Utilization is defined as the proportion of time that the system is actually being used for performing storage and retrieval operations compared with the time it is available (80-90%)
Utilization varies throughout the day
Availability is a measure or reliability. It is defined as the proportion of time that the system is capable of operating (not broken down) compared with the normally scheduled shift hours.
General approaches to improve reliability (preventive maintenance, redundancy)

53. Some Formulas Scheduled time/shift = hrs in a shift (8 hrs)
Available time/shift = (Scheduled time/shift) – (Downtime/shift)
Utilization = (Actual time used )/ (Available time)
Availability = (Uptime) / (Scheduled time)

54. Automated Storage and Retrieval Systems (AS/RSs)
An AS/RS is an automated system of storage, control and actuating devices which handles, stores and retrieves materials with precision, accuracy and speed.
An AS/RS automatically:
Stores an item at predetermined storage site
Removes a specified item from a storage site
Transports the item to a processing or transfer point

55. Automating Storage Operations

56. AS/RS Common Characteristics
Custom designed
Computer Controlled (or manual)
Storage locations serviced by S/R (storage/Retrieval) machines
One or more P&D stations (Pick up and Deposit). Manually operated or interfaced to handling system
Two basic types of AS/RS:
Standard (unit load) or Conventional
Carousel storage systems

57. Unit Load AS/RS

58. AS/RS : Standard Systems
Several types
Unit load
Miniload
Man-on-board
Others

59. Carousel AS/RS

60. Unit Load vs Carousel Storage

61. Top view Unit-Load Layout Front view Storage/Retrieval S/R machine
Pickup/Deposit
(P/D) stations
Aisles
Interfaceconveyor
Storageracks
Row
Bay
Front view
Adapted from: Groover, M.P, “Automation Production Systems,” Prentice-Hall, 1987, p. 409.

62. Unit Load AS/RS (most common)
A Unit load AS/RS is a massive structure for handling individual bulky items or groups of items on pallets or in containers
Unit load systems have the following physical features:
Storage Structure. A series of storage racks arranged horizontally in rows and vertically in bays separated by aisles for access
A Storage/Retrieval (S/R) machine servicing each aisle
One or more Pickup/Deposit (P/D) stations
Storage modules (unit load containers-pallets)
Special features
Aile Transfer Cars (when S/R car services more than ONE aisle)
Full-Empty Detectors
Sizing Station
Load Identification Stations (tracking)

63. AS/RS Design: System Requirements Specification
Storage capacity:
load sizes
size and number of storage compartments
number of rows and number of bays in each row
Space requirements:
bay width, bay depth, rack length and rack height (30-90')
aisle spacing, number of racks and system overall size
System performance:
required number of (store/retrieve) cycles per hour,
capacity of each S/R machine in (cycles/hr)
number of S/R machines required
cycle time for retrieve, store or for both

64. AS/RS : Sizing and Space Requirements
The dimensions Ls , Hs and Ws of an aisle unit are given in terms of the dimensions x, y and z of the basic unit load and clearance: Ws
For a standard pallet:
x = 42 inch and a = 8 inch
y = 48 inch and b = 10 inch
z = 36 inch and c = 6 inch
K = 1-3
Aisle unit
Ls = nh (x + a)
Hs = nv(y + b)
Ws = k (z + c) Hs nv nh
nv is the number of rows and nh is the number of bays. Each aisle unit contains 2nv nh compartments. Ls
z+c
The size of the overall system is determined by the number of aisle units Na needed to hold the inventory levels
y+b
x+a
Basic storage compartment containing a unit load

65. Sizing AS/RS system : Example
A four –aisle AS/RS is to contain 60 storage compartments in the length
direction and 12 compartments vertically. All storage compartments will be the same
size to accommodate standard size pallets. Determine Storage capacity and dimensions
of the storage rack structure.
Aisle unit Hs Ls Ws
y+b
z+c nv nh
x+a
Storage capacity per aisle = 2 nv nh = 2(12)(60)
= unit loads
Total Storage Capacity = 4(1440) = 5760 unit loads
Ls = nh (x + a) = 60 (48 + 8) = 3360 in = 280 ft
Hs = nv(y + b) = 12 (36+10) = 552 in = 46 ft
Ws = k (z + c) = 3 (42 + 6) = 144 in = 12 ft
x+a

66. AS/RS : Throughput
Transaction cycle time Tsc depends on average travel times of the S/R machine and pickup or deposit times:
Assumptions
Single-command cycle initiating a store or retrieve transaction (dual-)
Randomized storage of pallets
Storage compartments of equal size
P/D station located at base and end of aisle
Uniform horizontal and vertical speed of S/R machine
Simultaneous horizontal and vertical movement of S/R

67. Storage System Performance Criteria
There are several standard measures
Storage Capacity
Density
Accessibility
Throughput
Utilization
Reliability (Uptime Reliability)

68. AS/RS Design: # S/R Machines and Throughput
The number of single-command transactions nsc each S/R machine completes each hour is
Where:
nsc = number of P/D cycles a machine can make per hour
Tsc = single-command transaction cycle time per machine (min)
A = fraction of time an S/R machine is available
The minimum number of S/R machines required is:
Where:
Nm,min = minimum number of S/R machines required
nsc = number of P/D cycles a machine can make per hr
ndt = total number of P/D cycles required per hour
The actual required number of S/R machines Nm should at least equals the number of aisles, Na.
Nm = max (Nm,min, Na)

69. AS/RS Design: Example 6
Determine the number of S/R machines required to achieve up to 240 pickup or deposit transactions per hour. The horizontal travel speed of the S/R machines is 320 ft/min and the vertical speed is 80 ft/min. Each P/D operation takes about 0.50 min. The horizontal travel is 280 ft and the vertical travel is 46 ft
Solution:
Need to determine cycle time Tsc:
th = Ls/Vh = 280 ft/320 ft/min = min
tv = Hs/Vv = 46 ft/80 ft/min = min
T = max (th, tv) = max (0.875,0.575) = min
Q = min (th/T, tv/T) = min (0.875/0.875, 0.575/0.875) = min (1.0,0.657) = 0.657
Tsc = T [(Q2/3) + 1] + 2 tpd = [(0.657)2/3 + 1] + 2(0.50) = 2.00 min
Minimum number of S/R machines Nm,min
nsc = 60A/Tsc = 60 (min/hr) (1)/2.00 min = 30 cycles/hr per machine
Nm,min = ndt / nsc = 240/30 = 8 machines.
The number of ailes Na?
Combination of Single & Dual cycles?

70. AS/RS: Storage Carousel
Groover, M., 1987, Automation, Production Systems, and Computer Integrated Manufacturing

71. Carousel Applications & Advantages
Low cost versatile, and reliable
Storage and Retrieval applications (kitting, service room)
Transport and Accumulation (assembly system?)
Suited for Automated WIP applications (others?)

72. AS/RS: Advantages (Table 15.2)
Efficient use of valuable space (up instead of out)
Improved inventory management (find and account for any and all inventory items)
Increased responsiveness to materials handling service requests
Minimized waste, theft and spoilage
Ease of interfacing with other automated systems such as FMS, CNC and AGVS
Ease of tracking products for quality and regulatory purposes.

73. Traditional WIP Storage
Batch and Job shop
While the cell is processing one order
Several orders awaiting at the cell
Finished orders awaiting to be transported
WIP placed in Close proximity to cell
Disadvantages
Lost parts and /or orders
Identification
Priority of processing
Longer lead time
Cost, etc

74. Automated WIP Storage Justification Kitting of parts for assembly
Integral part in an assembly system
Support JIT (critical components)
Buffer storage (un-equal operation time)
Improved control and tracking of materials
Support factory wide automation (including Automated Data Collection)