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1Figure 3.6 Five levels of automation and control in manufacturing.
Level
5Enterprise
level
Plant level
Cell or systemlevel
Machine level
Device level
Description / Examples
Corporate information
Production system
Manufacturing system-groups of machines
Individual machines
Sensors, actuators, otherhardware elements
4
3
2
1
Flow of data
2Figure 4.13 Enterprise-wide PC-based DCS.
Business and engineering systems
Engineeringworkstation Finance Production
planning Purchasing Qualitycontrol
Enterprisecommunications
networkLocal operator
stationCentral
control roomLocal operator
station
Process station
Rawmaterials
process
Signals to andFrom process
Product
Process station Process station Process station
Communicationsnetwork
3
Figure 9.1 Material handling in the production system.
Productionsystem
Enterpriselevel
Factorylevel
Automationand controltechnologies
MaterialHandling
technologies
Quality controlsystems
Manufacturingsystems
Manufacturingsupport systems
Facilities
Manufacturingsupport systems
3.4 Material Handling Technology
4
3.4.1. Overview of Material Handling Equipment
■ Types of Handling Equipment Transport Equipment Storage System Unitizing Equipment Identification and tracking system
■ Considerations in Material Handling system Design
3.4.2. Material transport systems : Their characteristics
■ Automated guided vehicle (AGV), Conveyor system
3.4.3. Analysis of transport systems : Flow rates and delivery cycle time
■ Charting technique in Material Handling ■ Analysis of vehicle – Based system ■ Conveyor analysis
5
Forks
Deck
Drive wheelBumper
Vehicle electricalpickup
Motorizedvehicle
Monorail(I-beam)
Electrified rail
Rolls
Frame
Crane railHoist
Figure 9.2 Examples of the five basic types of material handling equipment: (a) fork lift truck, industrial truck, (b) unit load automated guided vehicle, (c) monorail, (d) roller conveyor, and (e) jib crane with hoist.
(a) (b) (c)
(d) (e)
Basic Types of Material Transport Equipment
6
Figure 9.3 Examples of unit load containers for material handling:(a) wooden pallet, (b) pallet box, and (c) tote box.
Unit Load Container, Storage System, ID/Tracking
(a) (b) (c)
Figure 11.6 A horizontal storage carousel.
Carousel structure
Drive motor system
Carousel track
Conveyor
Load/unload station
Bins for inventory
Figure 12.6 Stationary moving beam bar code scanner located along a moving conveyor.
Conveyor
Bar code Carton
Moving beam
Scanner
Storage carousel ID/Tracking System
container
7Figure 9.4 General types of Material transport equipment as a function of material quantity and distance moved.
Quantitiesof material
moved
Conveyors ConveyorsAGV trains
Powered trucksUnit load AGV
Manual handlingHand trucks
High
Low
Short Long Movedistance
Determining Factors for Handling System Design
Material Characteristics Flow rate, Routing, and SchedulingPlant layout Flow rate of the materials to be movedRouting factors Scheduling of the movesThe quantity or amount of material to be moved
: timing of each individual delivery.Responsive to the need of timely pickup/ deliveryPick up and drop-off locations Move distance Routing variations
8
Cart
PinSlot in floor
Towline(cable or chain)
Tow force
Figure 10.8 In-floor towline conveyor.
Rolls
Skate wheels
Figure 10.6 (a) Roller conveyor and (b) skate wheel conveyor.
(a) (b)
Forwardloop
Idler roll
Support sliderReturn loop
Drive roll
Figure 10.7 Belt (flat) conveyor(support frame not shown).
Vc
Various Types of Conveyors
9
Track(I-beam) Pull
force
Trolley
Chain
Load suspendedFrom trolley
Figure 10.9 Overhead trolley conveyor.
Conveyor cart
Conveyor rails
Drivewheel
Figure 10.10 Cart-on-track conveyor. (Diagram courtesy of SI Handling Systems.)
Spinning tube
continued
10Figure 10.11 (a) Single direction conveyor and (b) continuous loop
Delivery loop
Return loop
Conveyor pathUNLDLOAD
Ld
Vc
(a)
(b)
LOAD UNLD
Vc
Vc
Recirculating conveyor (c)
conveyor
11
Conveyor Analysis : Single Direction conveyors
Conveyor pathUNLDLOAD
Ld
Vc
(a)
Td : Delivery time : Carrier Flow rate :
Ld : length of conveyor between load and unload stations ,
Vc : conveyor velocity
Rf : material flow rate (parts/min) RL : loading rate (parts/min) SC : carrier spacing
<Example>
TL : time required to load the carrier VC
Unload time constraint : Material flow rate, VC
SC
12
Continuous Loop Conveyors
Ld : length of the delivery loop Le : length of the return loop nC : number of carriers
Delivery time : Total travel time :
Total number of carriers : Total parts in system :
TC =L
V
L : total length of the conveyor SC : carriers at distance apart
Delivery loop
(b)
LOAD UNLD
Vc
Vc
VC C
VCMaterial flow rate :
13
Recirculating Conveyors To smooth out the effects of changes in the rate of loading and unloading
□ no loaded carriers available at the unloading station
□ no empty carriers available at loading stationTo meet this requirement ;
VC
VCFor example :
conveyer speed :
time required : VC VCflow rate capacity :
14
15
Automated Guided Vehicles
■ Types of AGVS
16
Vehicle Guidance and Routing Technology
Embedded guide wires Paint stripes Self – guided vehicles
The function operating the AGVs : Vehicle guidance and routing traffic control and safety System management
■ Guidance system
Frequency generators : < 40V , < 400m A frequency 1~15 KHz
■ Routing : Selecting among alternative pathways Guided vehicle layout multiple loops branches, side tracks spurs
Selecting path frequency select method path switch select method
17
Vehicle Management and Safety
Traffic Control and Safety The traffic control : collision avoidance blocking system
On – board vehicle sensing Zone blocking On – board sensing (forward sensing) : detect the presence of vehicles (optical/ultrasonic Sensors)
Zone control : Divide the AGV zone into separate zones and the operating rule is the at no vehicle is permitted to enter a zone if that zone is already occupied by another vehicle.
1 2
5
9
3
4
7
6
8
10
18
From – To Chart Showing Flow Rates
19
20
AT = 60 A Tf E
Determining Number of Vehicles in an AGV
WL = Work load (min/hr), Tf : traffic factor ne = number of vehicles, E : work efficiency A : availability
Delivery cycle time, Availability
TL : time to load at load station (min) TU : time to unload at unload station
VC : carrier velocity Ld : distance between load and unload station
Le : distance the vehicle travels empty
□ Rate of delivery / vehicle □ Number of vehicle (Delivery cycle time)
Possible time losses include
Availability (A) Traffic congestion (Tf)
Efficiency of manual (E) drivers for manually operated trucks
21Figure 10.15 AGVS loop layout for Example 10.1. Key: Unld = unload, Man = manual operation, dimensions in meters (m).
LoadMan
Direction ofvehicle movement
UnldMan
AGV
AGV guide path
20
55 40
20
Tc = 0.75 + + 0.50 + = 5.05 min 110
50
80
50
WL = 40(5.05) = 202 min/hr
AT = 60ATfE60(0.95)(0.90)(1.0) = 51.3 min/ hr per vehicle
nc = = = 3.94 vehicle 202
51.3WL
AT
22Figure 10.16 AGVS layout for production system of Example 10.2. Key: Proc = processing operation, Aut = automated, Unld = unload, Man = manual operation, dimensions in meters (m).
ProcAut
AGV ProcAut
AGVguide path
ProcAut
UnldMan
LoadMan
Direction ofvehicle movement
4
35
15
50 30
50
2
30
10
30
15
3
1010
Ld = = = 103.8m 9(50) 5(120) 6(205) 9(80) 2(85) 3(170) 8(85)
9 5 6 9 2 3 8
+ + + + + ++ + + + + +
4360
42
Determining L for a More complex AGVa Layout d
23
Automatic Data Capture (ADC)■ Automatic Identification Methods
Encoded Data
Machine Reader
Decoder
1. Optical2. Magnetic 3. Electromagnetic4. Smart card 5. Touch techniques 6. Biometric
Figure 12.6 Stationary moving beam bar code scanner located along a moving conveyor.
Conveyor
Bar code Carton
Moving beam
Scanner
24
Bar Code ( Encoded Data)
Figure 12.5 A typical grouping of characters to form a bar code in Code 39. (Reprinted from [4] by permission of Automatic Identification Manufacturers, Inc.)
9 Bits
Typical datacharacter
StopData
Start
Quietzone(10X)
3
* T 1 2 3 0 2 4 *
Quietzone(10X)
1 0 1 1 0 0 0 0 0
Figure 12.8 A 2-D stacked bar code. Shown is an example of a PDF417 symbol.
Figure 12.9 A 2-D matrix bar code. Shown is an example of the Data Matrix symbol.
One – Dimensional Two – Dimensional
garments
in a variety of configurations
multiple rows of conventional lines bar codes
Matrix symbologies
25
Storage System Storage system performance(1) storage capacity, (2) density, (3) accessibility,(4) through-put. In addition, standard measures used for
mechanized and automated systems include (5) utilization (6) reliability.
Storage Location Strategy
Inve
nto
ry le
vel
50 day cycle Time
Order quantity= 100 cartons
Depletion rate= 2 cartons/day
Average inventory level
Safety stock level
120
100
80
60
40
20
0
Figure 11.1 Inventory level as a function of time for each SKU in Example 11.1.
26
□ Automated Storage / Retrieval Systems □ Carosel Storage System
Automated Storage Systems
Figure 11.5 A unit load automated storage/retrieval system.
S/R machine
Storage structure(rack framework)
Storage module(pallet loads)
H
L
Pick-and-deposit station
Figure 11.6 A horizontal storage carousel.
Carousel structure
Drive motor system
Carousel track
Conveyor
Load/unload station
Bins for inventory
27
Carousel Storage System Storage capacity
Figure 11.9 Top and side views of horizontal storage carousel with 18 carriers(nc = 18) and 4 bins/carrier (nb = 4).
Total number of bins = ncnb
Side view
Top viewLoad Unld
Carriernc = 81
Binsnb = 4
W
L
C = 2( L –W ) + πW scnc = C
TC = + Tpd4
C
VC
Rt = RC = 60
T C
ncnb = 75 x 6 = 450 bins
C = 2( 12 – 1) + 1π = 25.14 m TC = + 20/60 = 0.647 min25.14
4(20)
Rt = 60/0.647 = 92.7 retrieval transactions / hr
28
□ Rate of delivery / vehicle □ Number of vehicle
Delivery cycle time
Possible time losses include
Availability (A) Traffic congestion (Tf)
Efficiency of manual (E) drivers for manually operated trucks