The automated transfer
line process is an example of hard, or fixed-position, automation
where the production machines are designed to produce a standardized
product, such as engine blocks, valves, gears, or spindles.
The entire plant is often
designed exclusively to produce the particular product, using special-purpose
rather than general-purpose equipment.
Product size and processing
parameters such as speed, feed, and depth of cut can be changed.
However, these machines are specialized. They can not be modified
to any significant extent to accommodate products that have different
shapes and dimensions.
To allow changes in the
design of the product, the hard automation systems need to be as
flexible as possible while retaining the ability to mass-produce.
This led to the following developments:
- The machines are
constructed from basic building blocks or modular units that
accomplish a function rather than produce a specific part.
- The production machine
modules are combined, by transfer mechanisms, to produce the desired
system for making the product.
Transfer mechanisms move
the workpiece from one station to another, or from one module to
another, to enable various operations to be performed on the part.
It is important not to
confuse this process with an assembly line.
Several methods are used
to transfer the workpieces:
- Rails along which
the parts, usually placed on pallets, are pushed or pulled by
- Rotary indexing tables.
- Overhead conveyors.
Sensors and other devices
are usually used to transfer the parts from one station to another.
Tools on transfer machines
can be changed easily. These machines are equipped with various
automatic gaging and inspection systems. These systems ensure that
the dimensions of a part produced in one station are within the
acceptable tolerances before the part is transferred to the next
Manufacturing Engineering and Technology.