11-08-2012, 11:20 AM
An Introduction to Material Handling Equipment Selection
An Introduction to Material.pdf (Size: 204.32 KB / Downloads: 188)
Introduction
This document provides an overview of different material handling equipment. It is intended to
familiarize readers with the various material handling technologies and provide some general guidelines
for selecting a particular technology for a particular application. Thus, its role is primarily informational
or educational and not as a mechanism for detailed design of a specific system for a particular application.
General Considerations
When deciding what material handling equipment to use, it is important to take into account the general
characteristics of the equipment types available in the market. Then, the decision maker should determine
which equipment matches better to the required application. In this sense, Dunning [84] provided the
following general guide for some big equipment categories that can be helpful in this decision process.
Static Storage Systems
Static storage systems include storage racks, block stacking systems, mezzanines and shelf and drawer
storage. The common feature of static storage systems is that loads remain stationary or “static” in their
storage locations until removed from the system. Static storage systems are more likely to be associated
with low turnover inventories where manual storage and retrieval is a cost effective mode of operation. In
this section, only selection guidelines for storage racks, mezzanines, shelf and drawer storage are
discussed since block stacking does not require mechanical structures. Block stacking generally deals
with lane storage of pallets or other unit loads stacked directly on top of each other in high volume, low
turnover applications. Generally, block stacking provides a low cost, high density storage alternative
when loads are stackable and not susceptible to crushing. In some cases, pallet stacking frames can be
used for block stacking of unstable or fragile loads. Pallet stacking frames are discussed in more detail in
a later section.
Industrial Steel Storage Racks
Several characteristics influence the type of unit load storage rack appropriate in a given application.
These include unit load specifications, selectivity requirements, throughput requirements, the material
handling equipment used, and the building configuration. Unit load specifications refer to the load
dimensions, the weight, and the type, condition and volume of pallets stored. Selectivity requirements
refer to the number of stock picking locations that must be immediately available. This factor directly
influences the depth of storage lanes as well as the picking speed. Throughput requirements refer to the
number of storage positions maintained, the time frame of load movement through the system, inventory
control policies and load dispatching rules. Material handling equipment directly influences the type of
rack selected since factors such as turning radius, aisle width, lifting capacities, and reach capabilities
determine the ability of handling equipment to interface with a given rack system. Building configuration
refers to ceiling height, floor condition, structural features and other facility characteristics that influence
the selection of a rack system. Pallet rack design alternatives include standard selective pallet rack,
double deep rack, bridge across rack, drive in and drive through racks, gravity flow racks, push back
racks, and cantilever racks. Standard selective pallet rack is the most common alternative which allows
100% selectivity for high picking efficiency.
Shelving and Drawer Storage
The major factors driving the design of a shelving and drawer storage system include the types of
products stored, the type of storage equipment used, the material handling system involved, the
characteristics of the facility and the applicable government regulations and building codes. The design
6
process involves analysis of the dimensions and weight of stored items and the determination of how each
item is to be stocked, e.g., individual items, packages, cartons, pallets, rolls, drums, etc. Inventory levels,
the form of material issues, transactions throughput, and the number of stock keeping units must then be
determined. This is followed by creation of a drawing of the front elevation of the storage units and
notation of the specific items to be stored in each.