Adhesives and tapes come in a variety of forms—the selection process can be overwhelming and quite honestly, confusing. Sometimes, you may not even realize you could be using adhesive-based products to bond your work instead of rivets, screws or fasteners. Here, 3M gives us seven things to consider before selecting the proper adhesive-based product—including some unexpected applications where tapes and adhesives could be superior alternatives to mechanical fasteners:
Don't Be Tacky
Whether its human or adhesive behavior, tackiness comes in varying degrees. Tapes are solids but remain tacky—gradually building full bond strength. Liquid adhesives, however, generally need to dry or cure. Some, like hot melts, cool quickly, becoming dry and tack-free relatively fast. Others, such as epoxies need a chemical reaction to form a solid bond, so they may take longer to lose their tackiness. Depending on the product, it could be minutes or hours before the adhesive finishes its reaction.
Fortunately, there is a wide variety of technologies in tapes and liquid adhesives that enable you to select the method that fits your production needs. Before you get started, remember this: adhesives aren't designed to bond skin, so stop the thumb tests. Instead, refer to the manufacturer's spec for dry or cure times.
If your surface energy is low, you might have a hard time bonding.
Low surface energy (LSE) does not refer to a surface's laid-back personality—surface energy impacts the ability of a surface to accept wetting via an adhesive or tape. If the adhesive or tape cannot flow over the surface, then the bonding strength will be reduced. LSE materials like thermoplastic polyolefin, polypropylene and polyethylenes repulse adhesives, creating tension that inhibits their ability to "wet out" the surface to create a bond. In the past, adhesion promoters or energizers, such as plasma were used to modify the surface or increase the surface's energy. Technology, however, has advanced, and adhesives alone are capable of high performance bonding to LSE substrates. 3M™ Scotch-Weld™ Structural Plastic Adhesive DP8010 Blue and 3M™ Scotch-Weld™ Structural Plastic Adhesive DP8005 are examples of products uniquely formulated to bond to LSE plastics.
Walt Disney Concert Hall
Tape is the Secret Design Feature in Some of the World's Most Beautiful Buildings
In particular, 3M™ VHB™ tape. This tape permanently bonds with amazing resistance to wind and thermal loads. 3M™ VHB™ tape can be found holding up the Walt Disney Concert Hall's stainless steel exterior curtain and creating a seamless appearance in Duisberg, Germany's Five Boats Office complex. It's the perfect tape for combining stunning beauty with surprising strength.
How to Lift an Elephant With Adhesives
The average African Bush Elephant weighs in at about 13,000 pounds. According to the recent video from 3M below, two metal coupling plates joined using only a thin layer of Scotch-Weld™ Epoxy Adhesive DP420 could lift a cargo container filled with concrete, weighing 14550 pounds.
Although no actual elephant was lifted in the making of the video, it could have been. It took very little adhesive to hold more than 7 tons of weight, and the bond held strong, even under constant stress from a concentrated load. Holding the weight of an African elephant may never be part of your design requirements, but you can be confident in epoxy adhesive's ability to maintain structural strength bonds.
You're Not Counting Calories With CARB Compliance
CARB is the acronym for California Air Resource Board. California was one of the first states with a regulatory agency managing air sanitation, but other states have adopted their standards for healthy air quality. CARB standards apply to everything from paints, coatings and deodorant to cleaning products and adhesives. 3M was a pioneer in reducing volatile organic compounds from its adhesive formulations and offers a full line of high bonding, low VOC-emitting products. When selecting an aerosol adhesive, check the product description for CARB compliance or Low VOC labeling.
Slow Your Roll or Lose Your Screws
When working with fiber reinforced composite materials, it's important to keep the reinforcing layers that give the material its strength intact when drilling holes for fastening. Under pressure to improve throughput, drilling feed speeds can be pushed to exceed recommended forces. This can lead to fiber damage and de-lamination of composite materials, which can actually reduce load bearing capacity. Additionally, drilling creates leak points and unsightly surface disruptions. One way of avoiding this risk is to bond composite materials using adhesives or bonding tapes. Adhesives and bonding tapes require no drilling and are formulated to work with a variety of composite compositions. In addition, they leave a smooth, aesthetically pleasing surface by replacing bolt heads, screws and rivets throughout your design.
Throw Bowling Balls at Your Glass Objects
A new video from 3M demonstrates how a 15 pound ball dropped from a four foot height will not destroy the joint of a thin protective barrier, nor the hand-blown glass balls placed beneath it.
Here's the catch—the joint needs to be bonded with tapes or adhesive. Mechanical fasteners (rivets and screws) fail, allowing the glass to shatter because they cannot distribute stress the same way tapes and adhesives do. An intense hit from the dropped sphere easily breaks through the panels where the mechanical fasteners concentrate their bonding strength. Meanwhile, tapes and adhesives, with their unique viscoelasticity properties, spread stress across the full length of the bond, minimizing the chance of failure. When designing for routine or extreme stress, consider tapes and adhesives as an alternative to mechanical fasteners—they will ensure an even distribution of stress in your designs.