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