Error-Proofing in Dispensing
Are there ways to prevent mistakes during dispensing? If an operator must apply six dots of adhesive onto a part, are there ways to make sure he did that? Obviously, automating the dispensing process will help, but in lieu of that, assemblers have some other options to achieve an error-proof process.
There are two ways to minimize mistakes during dispensing: prevent mistakes from happening and detect mistakes when they do occur. One of the best ways to detect mistakes is with machine vision. Often, a fluorescent material can be added to the adhesive to facilitate inspection by vision systems.
Dispensers with a digital timer, memory for storing the parameters used for different products or applications, and lockout features to prevent operators from changing settings can help ensure that every operator in a facility applies the same amount of fluid. Dispensers with a shot counter can be useful for verifying that the correct number of deposits has been applied.
Another important issue is the quality and consistency of the dispensing components-particularly dispense tips, which might have defects that are not visible without examination under a microscope. These defects include:
• "flash" from the molding process inside the tip hub,
• burrs inside steel tips, and
• sharp crimps instead of graceful bends on angled tips.
Any of these defects could obstruct fluid flow and cause variations in the amount of fluid applied. So while vision systems are terrific for verification, it is often small details that determine the quality of what is even visible. Yield rates depend on attention to all of the details.