4. Material Handling

• Basic purpose is to provide automatic transfer of workparts between automated machines, and interface with individual work stations.

4.1 Introduction

• Basic layouts for material handling include,

lines: stations arranged along a fixed part transfer path.

batch: stations are grouped by function and batches of raw materials/WIP are brought in batches

job shop: individual parts are carried through one or more stages by one worker

job site: equipment is brought to the work

• These transfer systems can also be categorized by their timing approach,

synchronous: the entire line moves parts with a fixed period cycle. This is well suited to mass production of similar products.

asynchronous: parts are moved as completed or needed. Often buffers are required, but this is more tolerant of problems than synchronous systems.

continuous: the product flows by without stopping

• Basic Requirements,

Random, independent movement of palletized workparts between workstations in the FMS

pallets can flow from any station to any other
parts are mounted in pallet fixtures
pallets can move independently to avoid interference

Temporary storage or banking of workparts

queues allow parts to wait for machines, thus increasing efficiency

Convenient access for loading and unloading workparts

easy to do manual load/unload.
automatic loading/unloading of parts at workstations
can load/unload from either side of system

Compatible with computer control

Provision for future expansion

modular extensions to system are desirable

Adherence to all applicable industrial codes

safety, noise, etc.

Access to machine tools

allow unobstructed floor level access to each workstation

Operation in shop environment

must be reliable when exposed to metal chips, cutting fluids, oil, dirt, etc.

• Common type of Material handling systems

power roller conveyors

 

power and free overhead conveyors

 

shuttle conveyors

floor “towline” systems

 

robots (in a limited sense)

indexing (geneva mechanism)

walking beam

 

4.2 Vibratory Feeders

• When small parts are hard to orient we can dump them in a vibratory feeder.

• The vibrations cause parts to ‘hop’ forward.

• Various cutouts, tracks, etc are added to sort parts.

4.3 Problems

Problem 4.1 What are pallets used for?

Answer 4.1 to act as holders for work that is being transported

Problem 4.2 List possible methods for guiding an AGV.

Answer 4.2 guide wire, vision, painted lines, chain

 

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