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Powder spraying (coating) :

A painting process in which electrostatic and compressed air transfer mechanisms are used to apply finely ground dry plastic to a part. The applied powder is heated to its melting point and flows out, forming a smooth film. It cures by means of a chemical reaction.
(Computer-Based Design and Manufacturing An Information-Based Approach, Emad Abouel Nasr,. Ali K. Kamrani ,p 383)



Process Monitoring

Computer process monitoring system involves a computer which is directly connected ith the manufacturing process for the purpose of collecting the data on the process and the equipment.
The hardware components of the computer process monitoring system used to input the data from the process are sensors and transducers, analog-to-digital converters, limit switches and photo detectors, pulse generators etc.
A data acquisition system is a computer system used to collect the data from a process or piece of equipment. These perform an analysis of data or transmit the data to another computer for processing and analysis. A microprocessor is used as the controller/processor in a DAS. Other controllers use minicomputers or single board computers. The function of the controller/processor is to synchronize the data sampling and storage and tabulate data for presentation and statistical and other analysis.
( CAD/CAM/CIM, P. Radhakrishnan S. Subramanian V. Raju,p652)


Proportional–Integral–Derivative Controller (PID controller)

Many mechanical systems are controlled by proportional-integral-derivative (PID) controllers. There are many permutations of such controllers which use only certain portions of the PID controllers or use variations of this kind of controller. In this section we consider this very common type of controller.
Proportional Control
Proportional control results in action that is linear with the error (recall the error definition in ) The proportional term, Kp • e, has the greatest effect when the process value is far from the desired setpoint. However, very large values of Kp will tend to force the system into oscillatory response. The proportional gain effect of the controller goes to zero as the process approaches set point. Purely proportional control should therefore only be used when
• The time constant of the process is small and hence a large controller gain can be used;
• The process load changes are relatively small so that the steady-state offset is limited;
• The steady-state offset is within an acceptable range.
Integral Control
Integral control makes a process adjustment based on the cumulative error, not its current value. The integral term Ki is the reciprocal of the reset time, Tr, of the system. The reset time is the duration of each error-summing cycle. Integral control can cancel any steady-state offsets that would occur when using purely proportional control. This is sometimes called reset control.
Derivative Control
Derivative control makes a process adjustment based on the current rate of change of the process control error. Derivative control is typically used in cases where there is a large time lag between the controlled device and the sensor used for the feedback. This term has the overall effect of preventing the actuator signal from going too far in one direction or another, and can be used to limit excessive overshoot.
(Mechanical Engineering Handbook, Ed. Frank Kreith, Boca Raton: CRC Press LLC, 1999, sec.6, p29-30)


Destructive Testing

This is a procedure that results in destruction of the item in order to measure the property of interest. A common example is the tensile test on a metal specimen to determine the metal’s strength and ductility properties. Destructive testing is often employed as an inspection procedure, because it is often applied to raw materials, partially processed materials and component parts. It can also be applied to the final product. However, destructive test for final products is very expensive and would be done on a very limited sampling basis. Tests at the prototype stage yield valuable information for product improvement.
( CAD/CAM/CIM, P. Radhakrishnan S. Subramanian V. Raju,p509)