The measuring and evaluation part of the system is dedicated to measuring the tightness of spark plugs. The whole system was manufactured as a single-purpose device of the spark plug manufacturer, and it serves both for routine and developmental measurement. The tightness of five spark plugs is measured simultaneously. Measurements are based on compressed air applied under exact conditions specified by the standard (e.g., precise high temperature).
The system measures five pressures representing the air penetration through the spark plug. The pressure drop and the five temperatures at the base of each spark plug are measured. In addition, a series of digital signals representing the state of the automatic machine (e.g., tilting the measuring cups) are sensed. The program performs temperature regulation to achieve the required parameters, too.

The program allows three levels of cooperation with the operator. Unprotected is intended for operators who enter the type of candles and standard data. Instructed operators can set parameters such as temperature, duration, allowed variance, etc. The most experienced operator has access to virtually all measurement parameters to modify them when changing customer requirements or standards.

The measurement is carried out in two phases. In the first phase, the program tests the machine’s readiness and its tightness. During the second phase, pressure and temperature are measured in a cycle. Measurement is performed for a specified duration. A graph of pressure versus temperature is displayed on the monitor screen during the measurement. After the measurement, the system creates a data file in which the measurement data is stored. It also saves the primary test results in the database.

Throughout the test, it is verified that the results did not deviate from the set limits (which can occur, for example, if the spark plug sealing ring is damaged). If something like this happens, the program ends the measurement and reports the problem to the user.

The program is prepared in the TestPoint development environment. Here’s an example of using a resulting log in the Lean process at the customer promise:


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