Page 85 - Sensors and Control Systems in Manufacturing

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Cha p te r
T w o

can be linked together via satellite communication links irrespective
of the location of each center. Manufacturing centers can be located
several hundred feet apart or several thousand miles apart. Adequate
sensors and control systems together with effective communication
links will provide practical real-time data analysis for further
determination.
The output of the cell is the product of the module of the flexible
manufacturing system. It consists of a finished or semi-finished part
as well as data in a computer-readable format that will instruct the
next cell how to achieve its output requirement. The data are con-
veyed through the distributed communication networks. If, for
example, a part is required to be surfaced to a specific datum in a
particular cell, sensors will be adjusted to read the required accept-
able datum during the surfacing process. Once the operation is suc-
cessfully completed, the part must once again be transferred to
another cell for further machining or inspection processes. The next
cell is not necessarily physically adjacent; it may be the previous cell,
as programmed for the required conversion process.
The primary reason for the emphasis on integrating sensors and
control systems into every manufacturing operation is the worldwide
exponentially increasing demand for error-free production opera-
tions. Sensors and control technology can achieve impressive results
only if effectively integrated with corporate manufacturing strategy.
The following benefits can be achieved:
• Productivity. Greater output and a lower unit cost.
• Quality. The product is more uniform and consistent.
• Production reliability. The intelligent self-correcting sensory
and feedback system increases the overall reliability of pro-
duction.
• Lead time. Parts can be randomly produced in batches of one
or in reasonably high numbers, and the lead time can be
reduced by 50 to 75 percent.
• Expenses. Overall capital expenses are 5 to 10 percent lower.
The cost of integrating sensors and feedback control systems
into the manufacturing source is less than that of stand-alone
sensors and feedback systems.
• Greater utilization. Integration is the only available technol-
ogy with which a machine tool can be utilized up to 85 per-
cent of the time—and the time spent cutting can also be over
90 percent.

In contrast, a part (from stock to finished item) spends only
5 percent of its time on the machine tool, and actual productive work
takes only 30 percent of this 5 percent. The time for useful work on