INTRODUCTION TO MATERIAL HANDLING
OVERVIEW OF MATERIAL HANDLING EQUIPMENT
A
great variety of material handling equipment is available commercially material
handling equipment includes: (1) transport equipment. (2) storage
systems.(3)unitizing equipment, and (4) identification and tracking systems.
Material Transport Equipment: Material transport includes
equipment that is used to move materials inside a factory, warehouse, or other
facility. This equipment can be divided into the following five categories,
illustrated in fig
1.
Industrial
tractks. Industial tracks divide into two types: non powered
and powered. Non powered trucks are platforms or containers with wheels that
are pushed or pulled by human workers to move materials. Powered industrial
tracks are steered by human workers to move materials. Powered industrial
trucks are steered by human workers. They provide mechanized movement of
materials.
2.
Automated
guided vehicles (AGVs). AGV s are battery: powered,
automatically steered vehicles that follow defined pathways in the floor. The
pathways are unobtrusive. AGV s are used to move unit loads between load and
unload stations in the facility. Routing variations are possible, meaning that
different loads move between different stations. They are usually interfaced
with other systems to achieve the full benefits of integrated automation.
3.
Monorails
and other rail guided vehicles. These are self propelled
vehicles that ride on a fixed rail system that is either on the floor or
suspended from the ceiling. The vehicles operate independently and are usually
driven by electric motors that pick up power from an electrified rail. Like
AGVs, routing variations are possible in rail-guided vehicle systems.
4.
Conveyors.
Conveyors constitute a large family of material transport equipment that are
designed to move materials over fixed paths, generally in large quantities or
volumes. Examples include roller, belt, and tow-line conveyors. Conveyors can
be either powered or nonpowered. Powered conveyors are distinguished from other
types of powered material transport equipment in that the mechanical drive
system is built into the fixed path. Nonpowered conveyors are activated either
by human workers or by gravity.
5.
Cranes
and hoists.
These are
handling devices for lifting, lowering, and transporting materials, often as
very heavy loads. Hoists accomplish vertical lifting: both manually operated
and powered types are available. Cranes provide horizontal travel and generally
include one or more hoists. In addition to the equipment types listed here.
Which are discussed in great detail in chapter ….there are many kinds of
transport equipment that move materials outside the factory or warehouse,
including highway tractor-trailer tracks, railway trains, cargo aircraft,
ships, and barges.
CONSIDERATIONS IN MATERIAL HANDLING SYSTEM
DESIGN
Material handling equipment
is usually assembled into a system. The system must be specified and configured
to satisfy the requirements of a particular application. Design of the system depends on the materials to be
handled, quantities and distances to be moved, type of production facility
served by the handling system, and other factors, including available Budget.
In this section, we consider these factors that influence the design of the material
handling system.
Material characteristics.
For handling purposes, materials can be classified by the
physical characteristics presented in table suggested by aa classification
scheme of Muther and Haganas . Design of the material handing system must take
these factors into account. For example, if the material is a liquid and is to
be moved in this state over long distances in great volumes. Then a pipeline is
probably the appropriate transport means. But this handling method would be
quite inappropriate for moving a liquid contained in barrels or other
containers. Materials in a factory usually consist of solid items: raw
materials, parts, and finished or semi finished products.
Table 9.1 characteristics of
Material in Material Handling
Category Measures
or Descriptors
Physical state solid
, liquid, or gas
Size volume,
length, width, height
Weight Weight
per piece, weight per unit volume
Shape long
and flat, round, square, etc.
Condition Hot,
cold, wet, dirty, sticky
Risk of damage Fragile,
brittle, sturdy
Safety risk Explosive,
flammable, toxic, corrosive, etc.
PLANT LAYOUT
Plant layout is an important
factor in the design of a material handling system. In the case of a new
facility, the design of the handling system should be considered part of the
layout design. In this way, there is greater opportunity to create a layout
that optimizes material flow in the building and utilizes the most appropriate
type of handling system. In the case of an existing facility, there is less
flexibility in the design of the handling system. The present arrangement of
departments and equipment in the building usually limits the attainment of
optimum flow patterns.
The plant layout design should provide the following data
for use in the design of the handling system: total area of the facility and
areas within specific departments in the plant arrangement of equipment in the
layout, locations where materials must be picked up (load stations) and
delivered (unload stations), possible routes between these locations, and
distances traveled. Opportunities to combine deliveries and potential locations
in the layout where congestion might occur must be considered. Each of these
factors affects flow patterns and selection of material handling equipment.
In section 1.1 , we described the conventional types of
plant layout used in manufacturing: fixed – position layout, process layout,
process layout, and product layout. Different material handling systems are
generally required for the three layout types. In a fixed position layout, the
product is large and heavy and therefore remains in a single location during
most of its fabrication. Heavy components and subassemblies must be moved to
the product. Handling systems used for these moves in fixed position layouts
are large and often mobile. Cranes, hoists, and trucks are common in this
situation.
In process layouts, a variety of different products are
manufactured in small or medium batch sizes. The handling system must be
flexible to deal with variations. Considerable work-in-process is usually one
of the characteristics of batch production, and the material handling system
must be capable of accommodating this inventory. Hand trucks and forklift
trucks (for moving pallet loads of parts)are commonly used in process type
layouts. Factory applications of automated guided vehicle systems are growing
because they represents a versatile means of handling the different load
configurations in medium and low volume production. Work – in – progress is often stored on the factory floor near the
next scheduled machines. More systematic ways of managing in process inventory
include automated storage systems.
Finally, a product layout involves production of a
standard or nearly identical types of product in relatively high quantities.
Final assembly plants for cars, trucks, and appliances are usually designed as
product layouts . The transport system that moves the product is typically
characterized as fixed route, mechanized, and capable of large flow rates.
Types of Material Handling
Equipment Associated with three layout types.
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Layout Type
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Characteristics
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Typical Material Handling Equipment
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Fixed Position
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Larger product size, low production rate
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Fixed Position
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Fixed Position
|
Larger product size, low production rate
|
Fixed Position
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Types of Material Handling
Equipment Associated with three layout types.
Layout Type Characteristics Typical Material Handling Equipment
Fixed Position Larger product size, low production
rate
Process variations in product and processing,
Low and medium production rates
Product Limited product variety,
high production rate
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