1. Material Handling System 7-9
7.3 Material Handling Equipment
In this section we list the various equipment that actually transfers materials between different stages of
processing. In manufacturing companies, various material handling devices (MHDs) are used and
together they constitute a material handling system (MHS). If we regard materials as the blood of a
manufacturing company, then MHSs are the vessels that transport blood to the necessary parts of the
body. The major function of an MHS is to transport parts and materials; this type of activity does not
add any value to products and can be regarded as a sort of “necessary waste.” However, in some cases,
MHSs perform value-added activities. The MHS is an important subsystem of the entire manufacturing
system; it interacts with the other subsystems. Thus, when we try to design or run an MHS, we should
look at it from a system perspective. If we isolate an MHS from other subsystems, we might get an opti-
mal solution for the MHS itself, but one that is suboptimal for the entire system.
In the following sections, we will first introduce seven basic types of MHDs. We then discuss how to
choose the “right” equipment and how to operate equipment in the “right” way.
7.3.1 Types of Equipment
Several different types of MHDs are available for manufacturing companies to choose. These companies
need to consider a number of factors including size, volume of loads, shape, weight, cost, and speed. As
mentioned in the introduction, we need to consider the entire system when we try to make our choices. Of
course, in order to make good decisions, we need to have an overview of different MHDs. There are seven
basic types of MHDs [1]: conveyors; palletizers; trucks; robots; automated guided vehicles; hoists, cranes,
and jibs; and warehouse material-handling devices. We will introduce these types one by one briefly.
7.3.1.1 Conveyors
Conveyors are fixed path MHDs. They are only used when the volume of material to be transported is
large and relatively uniform in size and shape. Depending upon the application, many types of convey-
ors are possible, including: accumulation conveyor, belt conveyor, bucket conveyor, can conveyor, chain
conveyor, chute conveyor, gravity conveyor, power and free conveyor, pneumatic or vacuum conveyor,
roller conveyor, screw conveyor, slat conveyor, tow line conveyor, trolley conveyor, and wheel conveyor.
Pictures of a few conveyors are shown in Figure 7.8. The above list is not complete. Readers can refer to
www.mhia.org for additional information on conveyors (and other types of MHDs).
FIGURE 7.8 Various conveyor types and their applications in material movement and sorting (a–d). (Courtesy of
FKI Logistex, Dematic Corporation. With permission.)

2. 7-10 Introduction to Logistics Engineering
FIGURE 7.8 (continued)

3. Material Handling System 7-11
7.3.1.2 Palletizers
Palletizers are used to palletize items coming out of a production or assembly line so that unit loads
can be formed directly on a pallet. Palletizers are typically automated, high-speed MHDs with a user-
friendly interface so that operators can easily control them. Another type of equipment that is related
to a pallet is a pallet lifting device. This MHD is used to lift and/or tilt pallets and raise or lower heavy
cases to desired heights so that operators can pick directly from the pallets. A palletizer is shown in
Figure 7.9.
7.3.1.3 Trucks
Trucks are particularly useful when the material moved varies frequently in size, shape, and weight;
when the volume of the parts/material moved is low; and when the number of trips required for each
part is relatively few. There are many different types of trucks on the market with different weight, cost,
functionality, and other features. A sample is shown in Figure 7.10.
7.3.1.4 Robots
Robots are programmable devices that mimic the behavior of human beings. With the development of
artificial intelligence technology, robots can do a number of tasks not suitable for human operators.
However, robots are relatively expensive. But they can perform complex or repetitive tasks automati-
cally. They can work in environments that are unsafe or uncomfortable to the human operator, work
under extreme circumstance including very high or low temperature, and handle hazardous material.
7.3.1.5 Automated Guided Vehicles
Automated guided vehicles (AGVs) have been very popular since they were introduced about 30 years
ago and will continue to be an important MHD in the future. AGVs can be regarded as a type of spe-
cially designed robot. Their paths can be controlled in a number of different ways. They can be fully
automated or semiautomated. They can also be embedded into other MHDs. A sample of AGVs and
their applications is illustrated in Figure 7.11.
FIGURE 7.9 Palletizer. (Courtesy of FKI Logistex, Dematic Corporation. With permission.)

4. 7-12 Introduction to Logistics Engineering
FIGURE 7.10 Order-picking trucks. (Courtesy of Crown Corporation. With permission.)
7.3.1.6 Hoists, Cranes, and Jibs
These MHDs use the overhead space. The movement of material in the overhead space will not affect the
production process and workers in a factory. Typically, these MHDs are expensive and time consuming to
install. They are preferred when the parts to be moved are bulky and require more space for transportation
(Fig. 7.12).
7.3.1.7 Warehouse Material-Handling Devices
Warehouse material-handling devices are also referred to as storage and retrieval systems. If they are
highly automated, they are referred to as automated storage and retrieval systems (AS/RSs). The primary
functions of warehouse material-handling devices are to store and retrieve materials as well as transport
them between the pick/deposit (P/D) stations and the storage locations of the materials. Some AS/RSs
are shown in Figure 7.13.
FIGURE 7.11 Application of AGVs (a and b).

5. Material Handling System 7-13
FIGURE 7.11 (continued)
Xijkl number of units of part type i to be transported from machine j to k using MHD l
FIGURE 7.12 Gantry crane and hoist (a and b). (Courtesy of North American Industries and Wallace Products
Corporation. With permission.)

6. 7-14 Introduction to Logistics Engineering
FIGURE 7.12 (continued)
FIGURE 7.13 Automated storage and retrieval systems (AS/RSs). (Courtesy of Jervis B. Webb Company.
With permission.)