How to Monitor and Track Height Sense Data
Accurate height sensing is important for consistent dispensing of precise lines and dots because it keeps the valve at the desired distance from the part during high-volume manufacturing. To achieve accurate height sensing, you need process controls that can properly monitor and track height sense data. With Nordson ASYMTEK's Fluidmove® software, there are three methods that an operator can set up to monitor and track this height sensing data to ensure accuracy and improved dispensing results:
- Maximum Height Sense
- Height Sense Limits
- Height Sense Tracking
But, what's the difference between them?
The Maximum Height Sense (MHS) value is defined by the user via the software. When enabled, it compares the actual z-height location found by the system to the limit defined by the user. If the actual z location that is captured by the height sensor is lower than the maximum limit (user defined), then the software prompts the user.
Example:
Applications Corner 2016-06 Newsletter Story - How to Monitor and Track Height Sense Data Applications Corner 2016-06 Newsletter Story - How to Monitor and Track Height Sense Data
Image A shows a normal height sensor position at the top of the board. Image B shows what might happen if the part does not arrive at the point for dispensing correctly and is beyond the maximum limit. The situation shown in B then prompts the user before dispensing begins, avoiding fluid from depositing incorrectly.
Also user-defined, the Height Sense Limits (HSL) method has the added benefit for being able to define a maximum and minimum limit. The user defines the maximum and minimum allowable tolerance the program will accept in order to proceed with the dispensing routine. If the actual height is outside the limits, the operator is prompted.
Example:
Applications Corner 2016-06 Newsletter Story - How to Monitor and Track Height Sense Data Applications Corner 2016-06 Newsletter Story - How to Monitor and Track Height Sense DataApplications Corner 2016-06 Newsletter Story - How to Monitor and Track Height Sense Data
Image C illustrates a normal height sensor position at the top of the board. Image D illustrates what happens when it is beyond the maximum user-defined tolerance while Image E demonstrates when it is beyond the minimum user-defined tolerance. With HSL set properly, both D and E halt any dispensing process.
Height Sense Tracking (HST) compares height sense data within a board. It compares previously recorded data to current data on the same part or board. This height sensing routine continues for the remainder of the height sensing program and essentially tracks the flatness of the board to see if the dispensing occurs within the user-defined tolerance. If the actual height sense is outside the upper and lower tolerance limits then the software prompts the operator.
Example:
Applications Corner 2016-06 Newsletter Story - How to Monitor and Track Height Sense DataApplications Corner 2016-06 Newsletter Story - How to Monitor and Track Height Sense Data
Image F illustrates a normal flat board where the difference between points 1 through 4 should be below the given user-defined tolerance, thus the dispense gap should be relatively the same distance. Image G demonstrates a warped board or part where the dispense gap would most likely not be the same from points 1 to 4. With HST activated, the software checks z data from points 1 to 2, 2 to 3, and 3 to 4. At anytime during the run, if the difference between each consecutive point is greater than the user-defined tolerance, the software prompts the operator.
Note: These methods work with batch and non-batch height sensing mode and laser and mechanical height sensors.