Converting Solutions Blog

FAQ: why did my adhesive fail? Let’s take a step back…

Posted on Thu, Aug 30, 2018

Being converters since the 1960’s we’ve seen all sorts of adhesive fastener technology. And over that time period we’ve seen at least ten times as many unique applications.

In an ideal world, the experts at Gleicher were part of the team choosing the solution components and cutting techniques so that the finished fastener handled the job and performed well in operating conditions. Unfortunately, that’s not always the case.

Every day we get a call from a Product Engineer after the initial solution has failed on one or more dimensions. So we thought we would share how we take a step back and go over the decision tree. Here are some of our first questions:

1. Exactly what adhesives did you test so far?
There are all sorts of acrylics adhesives engineered for all sorts of application. You already realize this and thought you had chosen the right acrylic, but it’s failing. So it’s back to the drawing board to start over exploring the options.

What’s the chemistry of the adhesive you’ve tried? Do you have a data page on your chosen adhesive and are you sure the adhesives is a good match? When our phone rings it’s because It is decidedly not a good match, hence the problem. Often we find that the data page was never secured or was not read. There is a wealth of information about the use-case and limitations of use contained within these data sheets so you should always get one with every sample you test.

2. Did you plan and execute the correct surface preparation before affixing the adhesive?
Clean surface with isopropyl alcohol. 50:50 with water.

3. If you’re using PSA, did you measure the pressure applied?
For many PSA’s the rule of thumb is approximately 15 lbs pressure when you apply tape. To get full contact across the entire surface area you can use a straight edge of some sort, or a roller.

4. Is the tape thick enough to make good contact?
Tapes can be thick or could be thinner – the contact point will dictate. If you don’t really know the optimum thickness, that’s a good time to get your Converter involved. A careful review of the two things being joined will help narrow the options to the few that work best. It will be from that short list you can determine the one that meets the remaining functional requirements.

5. Did you allow enough set time?
Acrylic's takes time to build strength. If you put a load on an acrylic adhesive right away you could experience bond failure. You might have to use belt and suspenders approach. This “3rd hand” approach gives acrylic time to wet out.

6. What total weight do you need the bond to hold?
We sometimes find the failure is a mismatch where the weight to be held is too much for the tape. Pull tests at different weights will help you find out the limits of the solution you are testing.

7. Are there exposures to sunlight, heat or cold that could affect the bond line?
Getting things to work tight in lab conditions can be just half the testing. Real world exposures can affect the bond line in unexpected ways. Be sure to test the prototypes in real-world conditions and not only in the lab.

Try these seven tips to troubleshoot your adhesive failure. Or if you want to save the time and money of trial and error Ask Gleicher. Chances are we’ve seen it before…