Chapter 2 material handling

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CHAPTER 2

MATERIAL HANDLING

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Introduction

Definition – the movement, storage, protection and control of material (MHIA).

The purpose is to handle safely, efficiently, at low cost, on time, accurately, and without damage to the material.

Advantages – safer operating condition, lower cost, better utilization and better performance of material handling systems.

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IntroductionExamples

Movement – industrial trucks and robots. Storage – rack, drawer, bins. Protection – wooden pallet, pallet box, tote

box. Control – bar codes, magnetic stripes, radio

frequency tags.

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Position of MH

Autom ation and c ontro l tec hnologies in the produc tion s ys tem

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Equipments of MH

Categories of the equipment includes:

1. Transport.

2. Storage System.

3. Unitizing.

4. Identification & Tracking System.

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Equipments of MH… cont.Transport

Used to move material inside a factory.i. Industrial trucks – non-powered and powered.ii. Automated guided vehicles – battery-powered and

automatically steered.iii. Rail guided vehicle – self-propelled and

independently operating.iv. Conveyors – move material over fixed paths in

large quantities.v. Cranes and hoists – horizontal travel and vertical

lifting for heavy loads. Manually or powered operating.

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Equipments of MH…cont.Transport

F our w heel dolly

T w o-w heel truc k

Hand-operated low -lif t pallet truc k

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a). Walkie truck,

b). Fork lift truck,

c). Towing tractor

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Equipments of MHTransport

T hree types of autom ated guided vehic le: (a) dr iveles s autom ated guided train , (b) AG V pallet truc k,(c ) Unit load c arr ier

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Roller c onveyor

Belt ( falt) c onveyor

S kate w heel c onveyor

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Equipments of MH... Cont.Transport

In-f loor tow line c onveyorO verhead tro lley c onveyor

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Equipments of MH... Cont.Transport… cont.

Cart-on- trac k c onveyor

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Equipments of MH…cont.TransportJ ib c rane w ith hois t

a) Sketch of hoist b) Mechanical advantage

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Equipments of MH…cont.Transport… cont.

a) Bridge crane b) grantry crane

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Equipments of MH…cont.Storage System

To store materials for a period of time. To permit access when required. Storage performance is measured according

to the capacity, density, accessibility and throughput.

There are bulk storage, rack systems, bins, drawer storage and automated storage systems.

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High dens ity bulk s torage provides low ac c es s ib ility and bulk s torage w ith loadsarranged to form row s and b loc ks for im proved ac c es s ib ility

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P allet rac k s ys tem for s torage of unit loads on pallet

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D raw er s torage

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Automated storage/retrieval system

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A horizontal s torage c arous el

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Equipments of MHStorage System Performance

Include:

- storage capacity

- density

- accessibility

- throughput

- utilization

- reliability (availibility)

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Equipments of MHStorage System Performance… cont

Storage capacity, measured by:

- total volumetric space available

- total num. of compartments available Storage density

- volumetric space available for actual storage relative to v.s in the storage facility

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Equipments of MHStorage System Performance… cont .

System throughput

- the hourly rate at which the storage sys.

- receives and put loads into storage

- retrieves and delivers loads to the

o.p station

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Storage transaction;

- pick up load at input location

- travel to storage location

- place load into storage location

- travel back to input location

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Retrieval transaction includes;

- travel to storage location

- pick item from storage

- travel to output location

- unload at output location

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Utilization:- the proportion of time that the system is actually being used for performing storage and retrieval operations compared with time it is available.

Availability (reliability);- the proportion of time that the system is capable of operating (not broken down) compared with the normal scheduled shift hours.

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Equipments of MHStorage Method and equipment

Storage equipments:

- bulk storage

- rack system

- shelves and bins

- drawer storage

- automated storage systems

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Equipments of MHStorage Method and equipment… cont.

Bulk storage

- storage of stock in an open floor area

- advantages: highest density possible,

lowest possible cost per sq ft

- disadvantage: low accessibility

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Rack systems

- stacking unit loads vertically without the need for the loads themselves to provide support.

- advantages: low cost, good storage density and accessibility.

- the common rack: pallet rack

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Pallet Track System

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Other storage rack system:

- cantilever racks

- portable racks

- drive-through racks

- flow-through racks


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Shelving & Bin

- is a horizontal platform, supported by a wall/frame on which materials are stored

Drawer Storage

- modular drawer storage cabinets are available with a variety of drawer depths for different items and are widely used for storage tools and maintenance items


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Drawer Storage

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Automated Storage System

- reduce/eliminate of human intervention to operate the system. Load enter or retrieve under computer control.

- two general types: Automated Storage/Retrieve System and carousel storage system.


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Equipments of MH Automated Storage System

AS/RS defined as a storage system that performs storage and retrieval operation with speed and accuracy under a defined degree of automation

Consists of one/more aisles that are each serviced by a storage/retrieval machine

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Equipments of MH Automated Storage System… cont.

Objectives for AS/RS:

- to increase storage capacity

- to increase storage density

- to recover factory floor space

- to improve security and reduce pilferage

- to reduce labor cost and increase labor

productivity in storage operation.

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Equipments of MH Automated Storage System… cont.

- to improve safety in the storage function

- to improve control over inventories

- to improve stock rotation

- to improve customer service

- to increase throughput

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Equipments of MH Sizing the Automated Storage System

Total storage capacity of one aisle depends on how many storage compartments are arrange horizontally and vertically in the aisle.

capacity per aisle = 2nynz

where ny = num of load compartments along the length of the aisle

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Equipments of MH Sizing the Automated Storage System… cont.

AS/RS which ny = 9 and nz=6

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Let x = the depth dimension, y = width dimension and z = the height of the unit load.

W = 3(x+a)

L = ny (y+b)

H = nz (z+c)

where a, b and c are allowances designed into each compartments to provide clearance.

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Eg:

Each aisle of a four aisle AS/RS is to contain 60 storage compartments in the length direction and 12 compartments vertically.

x=42 in, y=48 in, z=36 in, a=6 in, b=8 in and c=10 in. Determine capacity, W, L and H.

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Soln:capacity per aisle = 2 (60)(12) = 1440 unit loads. With 4 aisle, the total capacity = 1440 x 4 = 5760 unit loads.W = 3(42+6) = 144 in = 12 ft/aisle

overall W = 4(12) = 48 ftL = 60(48+8)=280 ftH = 12(36+10) = 552 ft

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Equipments of MH Carousel Storage System

Consists of a series of bins or baskets suspended from an overhead chain conveyor that resolves around a long oval rail system

Horizontal or vertical, sizes range: 10m and 30 m

Application: storage and retrieval operation and transport and accumulation, work in process and unique operation.

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Equipments of MH Carousel Storage System… cont.

Storage and retrieval operations - effectively when individual items selected from groups of items in storage (pick & load).

Transport and accumulation- used to transport/sort materials as they are stored.

Unique applications- involve specialize eg electrical testing etc.

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Storage capacity:

- the size of carousel cab be determined:

C = 2(L – W) + πW

Where C=circumference of oval conveyor track, L and W are length and width of the track oval.

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Top and side view of horizontal storage carousel with 18 carriers (nc) and 4 bins/carrier (nb)

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Let Sc = carrier spacing and nc = num. of carrier;

Sc nc = C

and Tc = C/4vc + Tpd , Rt = Rc = 60/ Tc

Where Tc =S/R cycle time, vc = carousel velocity, Tpd =average time required to pickup

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Eg:The oval rail of a carousel storage system, L=12m, W=1m, 75 carriers equally spaced around the oval, suspended from each carrier are 6 bins. Each bin =0.026m3 volumetric capacity, speed=20m/min. average P&D time for a retrieval=20 sec. Determine volumetric capacity and hourly retrieval rate.

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Sol:

total num. of bins, ncnb = 75x6=450binstot. volumetric capacity = 450(0.026)=11.7m3

The circumference of the carousel rail, C = 2(12-1) + 1π = 25.14m.

Tc= 25.14/4(20) + 20/60 = 0.647min

Rt = 60/0.647 = 92.7 retrieval transaction/hr

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Equipments of MHUnitizing

Containers used to hold individual items for protection.

Equipment used to load and package the containers. Examples: wooden pallet, pallet box and tote box.

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Equipments of MHIdentification & Tracking System

To collect the data in material handling automatically.

There are three basic components: encoder data, machine reader and decoder.

Examples of technologies: bar codes, magnetic stripes, radio frequency tags and machine vision.

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Equipments of MHIdentification & Tracking System

S tationary m oving beam bar c ode s c anner loc ated along a m oving c onveyor

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Material Handling System Design

There are some considerations before design the system as follows:

1. Material characteristics.

2. Flow rate, routing, and scheduling.

3. Plan layout.

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Principle of MH

The purpose is to be applicable in the analysis, design and operation of MH system.

1. Planning2. Standardization3. Work4. Ergonomic5. Unit load6. Space utilization7 System8. Automation9. Environment10. Life cycle cost

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Automatic Data Capture/Automatic Identification and Data Capture

ADC/AIDC –technologies that provide direct entry of data into a computer.

Drawback:

- Error occurs

- Time factor

- Labor cost

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Automatic of identification methods

Components:

- encoded data

- machine reader/scanner

- decoder

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ADC technologies categories:

- optical

- magnetic- magnetic stripe

- electromagnetic - RFI

- smart card

- Touch techniques

- Biometric

Automatic of identification methods…cont.

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Automatic of identification methods…cont.ADC technologies

Radio Frequency Identification (RFI)

- widely used to augment bar code identification - comm. between remote bar code and central terminal.

- using identification tag which is containing electronically coded data

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ADC technologies…cont.RFI

- advantages:

no physical contact, more data contained,

data can be altered

- disadvantages:

expensive, appropriate for certain

environmental situation, high unit values

in mfg.

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Magnetic stripes

- is a thin plastic film containing small magnetic particles whose pole orientation can be used to encode bits of data into the film.

- advantages: large data storage capacity and the ability to alter the data contained in.

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Optical Character Recognition(OCR)

- is a machine readable by an optical device.

- optical character recognition is a 2D symbology.

- advantages: low first read rate and high substitution error rate when hand-held scanning, lack of an omnidirectional scanner for automatic checkpoint and widespread and growing adoption of bar code technology.


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Machine Vision- used for automated inspection task.- Machine vision system is required to

read 2D matrix symbol.- Can be used for stacked bar code.

Chapter 2 material handling

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