In-process sensors are a significant technology helping
manufacturers to meet the challenges inherent in manufacturing a
new generation of precision components. In process sensors play
different roles in manufacturing processes. First and foremost, they
allow manufacturers to improve the control over critical process
variables. This can result in the tightening of control limits of a
process as well as improvements in process productivity. For example,
the application of temperature sensors and appropriate control to
traditional machine tools has been demonstrated to reduce thermal
errors, the largest source of positioning errors in traditional and precision
machine tools, and the work space errors they generate119.
Secondly, they serve as useful productivity tools in monitoring the
process. For example, as already stated, they improve productivity
by detecting process failure as is the case with acoustic sensors detecting
catastrophic tool failure in cutting processes. They also reduce
dead time in the process cycle by detecting the degree of engagement
between the tool and the work, allowing for a greater percentage
of machining time in each part cycle.
Incorporation of an in-process sensor as a mission critical
component of a manufacturing unit operation requires a high level of
engineering confidence in the ability of the sensor to reliably detect
the desired process characteristic. Without this confidence, manufacturers
justifiably do not leverage in-process sensor technology to
achieve the higher levels of process productivity they offer.