A temperature probe works similar to the way a normal probe works. The measurement starts when the sensor contacts the part.
The temperature probing point can be:
A measured point
A vector point
You must measure the temperature probing point along the vector of the temperature probe sensor. Therefore, when you select a temperature sensor as the probe tip and measure a point, PC-DMIS drives the CMM along the vector of the active temperature probe and ignores the theoretical vector of the measured point or vector point. This action ensures that the measurement is correct, and that temperature sensor properly contacts the part.
Temperature Measuring Methods
PC-DMIS supports the following methods for measuring the temperature; however, this support depends on the capabilities of the specific CMM you are using. Some CMMs support only one method. A CMM with a B4 Leitz controller is an example of a configuration that supports both methods.
Temperature is measured after a certain interval of contact with the part (contact time):
In this method, the sensor is kept in contact with the component for a defined time. The temperature is measured continuously to determine the part's temperature. Most of the CMMs that support this mode have a default contact time, which is commonly referred to as a delay time.
To measure the temperature with a contact time other than the default time for the CMM, you must specify the desired contact time by inserting an appropriate "Assign" in your PC-DMIS measurement routine somewhere before the points that will perform the measurement. The name of the variable for the assignment is:
TEMPSENSOR_CONTACT_TIME_SECONDS
An example of an assignment is:
ASSIGN/TEMPSENSOR_CONTACT_TIME_SECONDS=30
The choice of contact time depends on the sensitivity of the temperature sensor. If the time is too short, the temperature of the part may be read incorrectly.
It is not necessary to have an "Assign" statement in the measurement routine. This is required only if you do not want to use the default for the CMM.
Temperature measured by extrapolation method:
In this method, the sensor is kept in contact with the component for only a short time, and the component's temperature is extrapolated from a few measured values. If you use an "Assign" statement that specifies a contact time of 0, then PC-DMIS attempts to use the extrapolation method if the CMM supports it. In this case, the controller controls the time for measuring the temperature.
The assignment for a contact time of 0 is:
ASSIGN/TEMPSENSOR_CONTACT_TIME_SECONDS=0
To enable extrapolation, specify a contact time of 0. To disable extrapolation and use the specified time interval, specify a contact time greater than 0.
Measuring the Temperature on a Large Part
You may want to measure the temperature on a large part at more than one location. In this case, the temperature compensation is based on an average of those temperature readings. To do this, you should measure multiple temperature points. PC-DMIS records the average temperature.
Measuring the Temperature Multiple Times
When you measure the temperature multiple times, PC-DMIS records the temperature each time and uses the average temperature for the TempComp command. When the TempComp command is executed, the sum of the readings is then reset in order to begin a new average for subsequent temperature readings. In addition, the average temperature is recorded. The sum of the readings is also reset when a probe is changed.
If you want to measure the temperature again, you must execute the TempComp command to "reset" the recorded temperature before you measure it again.
More:
Working with Temperature Sensors
Creating a Temperature Probe File