Material Handling Systems - Department of Mechanical Engineering

Report
MENG 464
COMPUTER INTEGRATED
MANUFACTURING
Material Handling System
1
Material Handling System
Material Handling is the movement, storage,
control and protection of materials, goods and
products throughout the process of
manufacturing, distribution, consumption and
disposal.
2
Material Handling System
The Material Handling System (MHS) is a
fundamental part of a Flexible Manufacturing
system since it interconnects the different
processes supplying and taking out raw material,
work-pieces, sub-products, parts and final
products.
3
Material Handling System
Components:
 Robots
 Conveyors
 Automated Guided Vehicles(AGVs)
 Automated Storage/Retrieve System
4
Robots in Manufacturing

Industrial robot is a
Programmable
 Multi-functional
 Designed to move materials, parts, tools or special
devices
 Through programmed motions
 To perform many different tasks

5
Robots in Manufacturing


First industrial robot was developed in the 1950s
Further advancements enable to utilize robots in




Variety of types
Style
Size
Their functionalities may include but not restricted to

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


Welding
Drilling
Painting
Military applications
Assembly
Explosive material removal
Pick-and-place
Material handling
6
Robots in Manufacturing




A typical robot consists of many different part
connected to each other
Most robots resembles a human arm
Its motions are controlled by a computer program
Depends on the type of robot, movement
capabilities of them are measured by the term
degrees of freedom
7
Robots in Manufacturing
Robots with different degrees of freedoms
2-3 dof
Robots used in surgery
8
Robots in Manufacturing

How do robots work: there are 3 power sources
Hydraulic
drive
Joints are actuated by hydraulic drivers
The major disadvantages are:
 Floor is used by the installation of hydraulic system
 Leaks may seen often and cause messy floor
Advantages
 Due to the speed and power, they are used in large industrial robots
 Also desired to use in the environments where electric-driven robots might
cause fire etc.
Electric
Drive
Comparison to Hydraulic systems, less power and slower speed
Most common robot types in the industry
There are two distinct group: Stepper motors and Direct current (DC)
servo-motor driven
Pneumatic
Drive
Usually installed to small robots
Tends to have less degrees of freedom
Operations are simple and less cycle times
Less expensive, Since most of the robot parts are commercially available,
small institution can build their own robots
9
Robots in Manufacturing

How do we know the location of robot arms?


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Sensors are used to monitor the motion of robots
Motion of robots is sustained by the power based on the given
input (computer algorithm)
Once the order is given, it is important to know the location of
robot’s arm/parts
Its movements should be controlled during the entire motion
Robot should also be capable of sensing their environments
Sensors provides feedback to the controller and give flexibility
to robots
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Robots in Manufacturing
Type of sensors being used in robotics
1. Position
Sensors
Monitors the location of joints
Coordinate information is feedback to controller
This communication gives the system the capability of location the end-effectors,
which is the part usually performs the tasks.
2. Range
sensors
Measures the distance between a point in the robot and interest point that surrounds
the robots
The task is usually performed by television cameras or sonar transmitter and
receivers
If the sonar or camera misses a point, undesired coincidences may occur
3. Velocity
sensors
Estimates the speed using a moving manipulator
Due the the effects caused by, mechanical force, gravity, weight of load etc, desired
speed and required force to reach the speed should be computed continuously
4. Proximity
sensors
Sense and indication of presence of another object within specified distances
Prevents accidents and locate the existence of work-piece
11
Robots in Manufacturing

Robot movements:
Robots are feasible when they are fast but also the
stability is high
 The trade-off between speed and stability is sustained
by a powerful control system
 Robotics and Control are two joint disciplines

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Robots in Manufacturing
Robotic movements and joints

1.
2.
3.

1.
2.
3.
4.
Robots required to perform
Rotational movements
Radial movements
Vertical movements
Type of joints
Rotational joints
Twisting joints
Revolving joints
Linear joints
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Robots in Manufacturing
Analysis of robot motions:
Forward and Backward Kinematics concepts


Forward Kinematics: Transformation of coordinate of the
end-effectors point from the joint space to the world space


Position of end-effectors is computed based on the joints
locations
Backward Kinematics: Transformation of coordinates from
world space to joint space


In this concept the position of end-effectors is known in
world coordinate system
Required motion is computed based on this information
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Robot Configurations
(x1, y1) L2
(x2, y2)
L3
L1
(x, y)
(x, y)
(x, y)
LL Robot: Base is static,
arms are linear joints
RRR Robot: Base is
static, arms are rotational
joints
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TL Robot: Base is
rotational and the arm is
linear joint
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Robots in Manufacturing
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Essentials of robot programming
Requires

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The path robot should follow
The points it should reach
Details about how to interpret the sensor data
How and when the end-effectors should be activated
How to move parts between given locations
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Robots in Manufacturing


Essentials of robot programming
Programming techniques

Teach-by showing:


Textual language programming


Robot can repeat the motion already been done by the
programmer
A computer programming is written using logical
statements
Some of the languages are:

Wave, VAL, AML, RAIL, MCL, TL-10, IRL, PLAW,
SINGLA and ACL
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Robots of IE CIM LAB
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Robots of IE CIM LAB
A four-axis, table-top mounted SCARA
robot, the SCORA-ER 14 is designed for
work in industrial training facilities. This
rugged and reliable robot performs lightpayload
assembly,
handling
and
packaging applications with impressive
speed and accuracy.
SCORA ER14
• Handling and packaging operations with
palletizing and storage devices
• Assembly operations with automatic screw
driving and gluing devices
• Quality control operations with machine
vision and high-precision measurement
devices
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Robots of IE CIM LAB
The SCORBOT-ER 9 is a five-axis
vertically articulated robot designed
for work in
industrial training facilities.
With a multi-tasking controller that
provides real-time control and
synchronization of up to 12 axes, 16
inputs and 16
outputs, the
SCORBOT-ER 9 supports both
stand-alone applications as well as
sophisticated automated work cells.
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SCORBOT ER9
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Steps in Robot Programming
Programming of an Industrial Task
1. Teach Pendant Operation

move the robot arm in



AUTO MODE
Joints
Cartesian
Tool coordinates
Control robot grippers and
the speed of motion
 Record positions to the
robot controller’s memory
 Move robot arm to
recorded positions

1
AXIS 1 X
CLR
GROUP
SELECT
RUN
CONTROL
ON/OFF
OPEN
CLOSE
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AXIS 4
7
2
AXIS 2 Y
5
AXIS 5
8
3
AXIS 3 Z
6
AXIS 6
9
0
SELECT
AXIS
AXIS 7
AXIS 8
AXIS 9
SINGLE
STEP
SPLINE
INSERT
MOVE C
DELETE
MOVE
SPEED (%)
ENTER
MOVE L
SPEED L(%)
EXECUTE
ABORT
RECORD
POSITION
21
Steps in Robot Programming
Programming of an Industrial Task
2. Writing robot programs


Use ACL (Automatic Control Language) to edit robot
programs.
Commonly used robot program statements.
MOVE:
MOVED:
OPEN:
CLOSE:
SPEED:
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Steps in Robot Programming
Programming of an Industrial Task
3. Executing Robot Programs

Use ATS DIRECT Mode;
 Statements to execute;
RUN prgname : To execute the program prgname
ABORT: To abort the current running robot program.
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Conveyors In CIM
Conveyors type:
 Belt Conveyors
 Roller Conveyors
 Crane Conveyors
 Screw Conveyors
 …
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Conveyors In CIM
The package conveyor business has been in
existence for almost one hundred years.
Material handling engineering, in an oversimplified, basically, consists of determining
"how a product should be moved from one
place to another, within the shortest allowable
period of time, for the least cost and with the
least amount of manual effort".
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Conveyors In CIM
Classification of conveyors:
 Active; Energy is supplied to the component
for the movement of the materials, upward
movements.
 Passive; No energy is supplied to the
component and gravity force is utilized for the
movement of the materials, mostly downward
movements.
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Conveyors In CIM
Classification of conveyors
 Continuous movement; Applicable for the
movement of continuous material such as
liquids, sand, soil and cereals.
 District movement; Applicable for the
movement of district material such as boxes,
parts, cans and…
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Material Handling
Systems
Automatic Guided Vehicle Systems
AGVS
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Understanding AGVS
History of AGVS
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History of AGVS
1953 First AGV

The first AGV system
was built and
introduced in 1953( A
modified towing
tractor that was used
to pull a trailer and
follow an overhead
wire in a grocery
warehouse)
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History of AGVS
1973 Volvo Assembly Plant

In 1973, Volvo in Kalmar,
Sweden set out to develop
non-synchronous
assembly equipment as an
alternative to the
conventional conveyor
assembly line. The result
was 280 computercontrolled assembly
AGVs.
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History of AGVS
1970s First Unit Load

Introduction of a unit load vehicle
They have the ability to serve several
functions;
a work platform,
a transportation device, and
a link in the control and information
system
They transport material in warehouses, factories, mills, hospitals, and other
industrial and commercial settings.
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History of AGVS
Smart Floors and Dumb Vehicles

In the 1970’s the principal
guidance technology was to
induce an electronic
frequency through a wire
that was buried in the floor.
‘floor controller’
•These first generation navigation schemes were expensive to install.
•All floor cuts needed to follow the exact path of the AGV.
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History of AGVS
Dead Reckoning Capability


As the vehicles became more
intelligent, the path became
less sophisticated
Dead reckoning is a term that
describes the ability of a
vehicle to traverse steel
expansion joints on the
factory floor or to cross a steel
grate
The biggest advantage was that dead reckoning eliminated the need to make
the cut radius turns at intersections. (Installation was greatly simplified).
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History of AGVS
1980s Non-Wire Guidance

The introduction of laser and inertia
guidance.
Allow for increased system flexibility and
accuracy
 No need for floor alterations or production
interruption

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AGV NAVIGATION

The principles which make it possible for an
AGV to navigate its way between any two
locations are really quite simple. All navigation
methods use a path. The vehicle is instructed to
Follow a Fixed Path or Take an Open Path.
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Fixed Path Navigation
Following a Path



The paths are well
marked on the floor
The paths are
continuous
The paths are fixed, but
can be changed
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Fixed Path Navigation:
Creating a Path
The principle techniques for creating paths are to:




Apply a narrow magnetic tape on the surface of the floor
Apply a narrow photo sensitive chemical strip on the
surface of the floor
Apply a narrow photo reflective tape on the surface of the
floor
Bury a wire just below the surface of the floor
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Fixed Path Navigation:
Buried Wire Path

Bury a current-carrying
wire just below the
surface of the floor
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Fixed Path Navigation:
Steering Correction Coils

The vehicle steers itself to
FOLLOW the magnetic field
surrounding the buried wire.
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Fixed Path Navigation:
Path Selection

In this illustration, a vehicle at “A”
has two choices on how to get to
“B”. A computer either on board
the vehicle or at some central
location selects a path based on
established criteria.

Criteria:
 The shortest distance
 The path with the least traffic
at the present time

All of the “PATH FOLLOWING”
methods permit routing options
that include guide path switching
and merging.
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Open Path Navigation:
Taking a Path

Unlike “path following
navigation,” where the guide
paths are fixed, and more or
less permanent, vehicles
operating in the “Take a
Path” category are actually
offered more variation if not
an infinite number of ways to
navigate the open space
between two points.
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Open Path Navigation:
Navigation Methods

The three most common open space
navigation methods are:
Laser Guidance
 Inertial Guidance
 Cartesian Guidance

The choice of navigation method for a
particular application is often a simple matter
of preference.
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Navigation Methods - Laser
Guidance


Reference points are
strategically located
targets
A beacon on top of
the vehicle emits a
rotating laser beam
which is reflected
back to the vehicle
when it strikes (sees)
a target.
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Navigation Methods - Inertial
Guidance


An on board gyroscope establishes and maintains a vehicle’s heading.
Distance traveled is calculated by an on board encoder which counts wheel rotations.
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Navigation Methods –
Cartesian Guidance


Location precision is
accomplished by way of a
fixed grid pattern that
covers the entire floor
area.
The possible travel paths
in a given, unrestricted
operating area for a grid
based system are infinite
and most like that
provided by laser
guidance
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AGVS Dispatching

Dispatching AGVS is much the same as dispatching taxi
cabs.

The dispatch function makes sure that all customers get
timely services from the vehicle best able to service a
request.

Remote and local dispatch are most commonly described as
offboard and onboard dispatchers respectively.
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AGVS Communications

Communications include message commands such as:





where to go,
when to start,
when to slow down,
when to stop.
Four types of basic communication media:




Radio Communication
Infrared Communication
Guide Wire Data Communication
Inductive Loops Communication
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AGVS Communications
Radio Communication

Maximum flexibility in
system control

Vehicles can be programmed
“on the fly”

system speed of response to
changing load movement
demands is improved
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AGVS Communications
Infrared Communication




Optical infrared communication is
highly reliable but has the
disadvantage of not being
continuous; it is point to point.
Vehicles may be stopped during this
data exchange which usually occurs
at load stations where the fixed and
mobile units are aligned and in close
proximity.
Or, the vehicle communicates at fixed points along its guide path as the vehicle
travels through a given zone.
Infrared communication is best suited for small systems with few vehicles and load
stations.
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Remote Dispatching
The Dispatcher

The remote dispatch function generally resides in a



computer (PC),
Programmable Controller (PLC),
or other microprocessor, known as the Dispatcher.
The Dispatcher accepts input from the various system Components
(generally transport requests) and directs the AGVS to fulfill the command
in the most efficient manner.
Remote dispatch can occur with vehicles at single or various dispatch
points.
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AGVS Monitoring

Types of monitoring :



System monitoring
Vehicle monitoring
The functions and
reporting capabilities of
each are important to
the safe operation of the
AGVs.
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Material Handling
Systems
Automatic Storage Retrieve Systems
AS/RS
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Principles of Materials Handling
Introduction:
Certain fundamental principles for analyzing and designing solutions to
materials handling problems have been developed over a period of time
based on experience of many materials handling experts. These can be used
as general guide by any fresh materials handling practitioner, for analyzing
a materials handling problem and arriving at a solution to same. Many of
the materials handling problems may be initially treated by these principles
before undertaking detailed technical analysis. In certain materials handling
problems, these principles may become the only resort to an acceptable
solution where the exact analysis is too costly or difficult.
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PLANNING PRINCIPLE

All handling activities should be planned. This is the most basic principle
which is in line withthe Materials Handling Equation (see block below).Suggestions
for carrying out planning principles are:

• Consider the plant layout before equipment / system design.
• Plan correct location for materials supply and disposal. Plan for scrap removal.
• Assure adequate storage space at the workplace.
• Avoid placing materials directly on the floor. Place product on a pallet, skid etc. at
the beginning
of the process.
• Use same container throughout the materials movement, as far as practicable.
• Observe principles of motions economy.
• Plan productive operations and inspections during material movement, if possible.
• Use judicious amount of manual handling.








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SYSTEMS PRINCIPLE

Integrate as many handling activities as possible encompassing full scope of
operations like receiving, storage, production, inspection, packaging,
warehousing, shipping/transportation.
Suggestions:
 • Consider the entire scope of the handling activities, beyond the scope of
immediate concern.
 • Integrate operations into handling systems like processing, inspection, packaging
etc.
 • Avoid/ minimize intermediate storage.
 • While designing a materials handling system, the practices/requirements of the
suppliers, clients
 and transporters are to be considered.
 • Allow necessary flexibility considering future requirements/emergencies.
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MATERIAL FLOW PRINCIPLE
Plan operations sequence and equipment arrangement to optimize
material flow.
Suggestions:
 • Eliminate obstacles from material flow.
 • Plan material movement in a direct path (avoid backtracking, zig-zag
movements etc.)
 • Use product layout whenever possible.
 • Keep related work areas close together.
 • Combine operations to reduce material movement.
 • Minimize movement between floors.
 • Move bulky / weighty materials the least distance.
 • Process heavy / bulky materials close to receiving.
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SIMPLIFICATION PRINCIPLE
Reduce, combine or eliminate unnecessary movement and/or equipment. It
increases efficiency of materials handling.
Suggestions:








• Apply principles of motions economy. Avoid unnecessary handling. Eliminate rehandling as
much as possible.
• Plan direct moves. Reduce or eliminate long, awkward or complicated moves.
• Deliver materials at correct location first time.
• Use material out of original container.
• Avoid use of variety of equipment types, sizes and makes.
• Plan adequate material handling equipment capacity.
• Do not mechanize unnecessarily.
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GRAVITY PRINCIPLE
Utilize gravity to move material whenever practicable.
Suggestions:




• Use roller conveyors, slides, chutes between equipment/processes.
• Use ramps between varying work or floor levels.
• Use sloping floor when materials movement by hand truck is mainly in
one direction.
• Use spiral chutes to feed machines at different floors.
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SPACE UTILIZATION
PRINCIPLE
Make optimum use of building volume.
Suggestions:








• Space equipment/processes close together.
• Eliminate or reduce temporary storage of materials.
• Stack materials to use building height.
• Use racks to permit higher stacking.
• Use stacking containers to permit stacking.
• Exercise economic order quantities to reduce inventory.
• Clean storage areas and dispose scrap regularly.
• Use narrow aisle handling equipment to reduce aisle width.
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MECHANIZATION/AUTOMA
TION PRINCIPLE
When appropriate, use mechanized or automatic materials handling
equipment.
Suggestions:
 • Consider mechanized system in the following cases:
 (a) Large quantities or volumes of materials, (b) Repetitive movement, (c)
Long moves,
 (d) Hazardous move/materials, (e) Two man lifting, moving tasks, (f)
Excess manual handling,
 (g) Replacing large number of persons involved in handling, (h) Heavy
materials, (i) Scrap
 removal, (j) Feeding/unloading of high speed automated production
machines.
 • Do not over mechanize.
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EQUIPMENT SELECTION
PRINCIPLE
Before selecting materials handling equipment, consider all aspects of
materials handling,e.g., materials to be handled, moves to be made,
methods to be utilized.
 PRINCIPLES OF MATERIALS HANDLING 13
 Suggestions:
 • Select versatile equipment.
 • Select standardized equipment.
 • Consider unitization of load for handling.
 • Select capacity judiciously. Provide additional capacity based on future
plan.
 • Compare alternatives based on cost of handling.
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STANDARDIZATION
PRINCIPLE
Materials handling methods and equipment should be standardized to the
extent possible.
Suggestions:



• Use standardized containers.
• Purchase standard types and sizes of equipment.
• Use standard sizes of pallets to fit products, bay sizes, equipment and
transport trucks.
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FLEXIBILITY PRINCIPLE
Use methods and equipment, which can perform different tasks and
applications.
Suggestions:





• Buy flexible equipment like Fork Lift Truck, Conveyor etc.
• Use variable speed drives.
• Make use of attachment & accessories.
• Use four ways pallets, skids and containers.
• Utilize mobile in favour of fixed equipment (e.g. trucks in favour of fixed
conveyors)
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MOTION PRINCIPLE
Stoppage of mobile equipment should be minimum.
Suggestions:










• Reduce loading/unloading time.
• Load/unload while materials handling equipment is in motion, if possible.
• Use mechanized loading/unloading equipment.
14 INTRODUCTION TO MATERIALS HANDLING
• Use self-loading/unloading equipment like lift truck.
• Plan materials movement on both ways movement of materials handling equipment.
• Use equipment where carrying device is attached to motive unit like platform-type
trucks, trailers
etc.
• Use pallets, skids etc. to hasten loading/unloading.
• Use devices like tipplers, bottom discharge containers etc.
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IDLE TIME PRINCIPLE
Reduce idle or unproductive time of both materials handling equipment
and manpower.






This principle is similar to motion principle, so far as materials handling
equipment are concerned,
hence same suggestions are applicable. Additional suggestions for
‘‘manpower’’ are:
• Deliver materials at proper rate so that operators are not idle for materials.
• Use indirect labour for materials handling.
• Install handling equipment to reduce labour.
• Combine jobs i.e. one man handles two or more machines or jobs.
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