In this episode of Tale of the Tape, Matt Tempelis walks you through what to consider while selecting pressure sensitive adhesives.
Transcript:
Hello, and welcome to another episode of Tale of the Tape. I'm Matt Tempelis, President of Engineered Materials, and of course, your Minister of Tape. Today, I'd like to talk a little bit about design considerations when selecting a pressure sensitive adhesive. There are many factors that you want to think about, but you want to think primarily about joint design, the surface that you're bonding, the environment that that bond is going to see over its entire life, and then, of course, the application process. When you think about joint design, there's a couple of forces you want to try to avoid when you're designing your joint and you're understanding your application. One of them is peel force. Well, pressure sensitive adhesives bond quite well. And you can get some pretty good peel forces. You're putting all the stress on just one small edge of that tape, and that's going to minimize the overall strength of that tape and that bond.
Secondly, if you talk about cleavage forces, right, that's also creating a force that's stressing the tape at just one edge. Cleavage force is when you see joints that are creating stressors, like so. That's going to be something that you want to try to avoid as well. Any stress, obviously, is something you want to consider. But if you design your joint in a way that you're getting tensile force, you're seeing tensile force, you're maximizing that overall strength of the adhesive. Right here we have 3MTM VHBTM RP+040GF that we're using to bond these L brackets. If we have this bond where we're only seeing tensile strength, we know we're maximizing the overall surface area of the bond.
Same goes for shear strength. If you have forces that are pulling these things in shear fashion, just like so again, you're maximizing the overall bond. It's much more ideal to create bonds and joints that see those stresses. Let's talk about surfaces. If you're talking about surface energies, you've got to know them. Is your material like aluminum that's high surface energy material or is it polyethylene? That's a very low, difficult to stick to surface area. Here we've selected 3MTM Adhesive Transfer Tape 9472LE. Why? Because we need to bond to this polyethylene, and that's awfully hard to do. If you're bonding other plastics, if you're bonding painted materials, you've got to know what that surface energy is and you've got to pick tapes that that will bond to those materials.
Another consideration is surface texture. Do you have high textured substrate? Well, then you need more pressure sensitive adhesive to wet into those microscopic pores or even visible pores of your textured surface. If you don't, you're resting right on the very peaks of those of that texture. You're going to minimize the overall surface area of the bond, thereby minimizing the strength. If you have contours, you need to think about those because they create stressors on rigid materials. For example, if you have a radius.
And then lastly, surface contamination is very important. If your surface got oils, dust, mold, you need to get those off before you create the bond. Environment is very important to think about. Obviously, if you've got a part that you're making for office furniture and it's going to be indoors, you know, you don't have to worry too much about the tape you're selecting for that environment. But what if you're outdoors on an oil rig in the Gulf of Mexico? You're going to see humidity, you're going to see heat. You might even see some solvents or oils or gas. These are all things that you need to consider. And the tape needs to be able to withstand those types of situations.
Lastly, application process. Obviously, you want to make sure you're getting good pressure on your bond. You want to make sure you have a clean substrate when you're making the bond, you want to make sure that you have some time so you get 50% of that strength up front with an acrylic with pressure. But over time it wets out the substrate and it gains additional strength in 72 hours to a week later, you're going to have a lot stronger bond. So if you're seeing forces and stressors right on that bond shortly after manufacture, you need to select a tape that's going to be able to handle that situation.
You know, we've talked a little bit about considerations, design considerations for selecting a pressure sensitive adhesive. Hopefully we've given you some food for thought. Certainly, we're here to help you through those processes. Remember, at Engineered Materials, we deliver results that spur your company forward, and we're here to help. Thanks. And join us next time on Tale of the Tape.
