There are many reasons to choose a liquid adhesive or a tape for your bonding application. In addition to the joint, surface and manufacturing process, considerations such as automation, reworkability or supply chain simplification may also impact the decision. In addition, within the chemistry families, there are endless possibilities to provide varying flexibility, speed, strength, or conformance to industry specifications.
At 3M, we use an acronym called ASPEC to walk you through important considerations that will lead you to determining the best product for your needs. ASPEC stands for Assembly, Substrate, Process, End Use and Cost, five factors that go into choosing an adhesive. Armed with knowledge of the joint design, surface science, and adhesive chemistry, ASPEC can bring you closer to determining which adhesive is the best option for your assembly.
Review the six assembly types
Many bonding applications are represented by one of the following six common types of assemblies. They are: Panel to Frame/Stiffener to Panel, Large Surface Lamination, Mounting and Trim Attachment, Small Joint Assembly, Gasket Attachment, and Sealing, Potting and Encapsulating. These six assemblies are common applications where adhesives and tapes are proven to work well. They can be found in a variety of product designs across many markets and industries. Identifying the closest assembly type for your application will helps narrow the choice of available tape and adhesive families that are suitable, based on the geometry of the joints and typical manufacturing methods.
One of the advantages of bonding tapes and adhesives is the ability to bond a wide range of substrates. Different substrates have different characteristics that impact an adhesive’s or tape’s ability to bond. Surface energy, texture, roughness and cleanliness are all substrate conditions that can influence the choice of adhesive or tape. Knowing what materials will be bonded is one of the key steps to making a selection. Recognising that adhesive and tapes can bond dissimilar materials can help you unlock more design potential for your assembly.
Understanding how a part will be assembled can help narrow selection of bonding tape or adhesive formats. Making a careful selection here can help provide throughput, yield or productivity improvements over other assembly methods by helping reduce process steps, rework and labor costs. Adhesives and tapes can be applied manually or be part of automated dispensing solutions and often these are lower capital investments than welding or other assembly equipment. Generally, tapes can provide a fast bond and immediate handling strength. Liquid adhesives can offer more assembly flexibility for positioning and complex joint designs. Available floor space, regulatory, and safety are other factor that will influence the selection.
The end-use of the product being assembled will also determine what type of bonding materials are best for a given product design. Knowing how the end-product will be used by a consumer and what environmental conditions it will be exposed to are important factors. UV, temperature extremes, humidity, immersion and chemical exposure are common end-use considerations to be aware of, there are many tape and adhesive solutions that can endure these conditions. Some common design advantages of adhesives and tapes are the ability to uniformly distribute stresses, bonding and sealing simultaneously, energy absorption or alternately energy transfer through the joint, isolation of metals to prevent galvanic corrosion and the ability to join dissimilar materials.
When considering the total material and manufacturing costs for a given assembly, adhesives and tapes often offer advantages in total cost. For material costs, adhesives and tapes can enable lighter weight, thinner or less expensive material substrates to be part of the assembly because of the ability to bond dissimilar materials and the avoidance of hole drilling and mechanical fastening. For manufacturing costs, cost savings over welding or fastening are often found from reducing the number of process steps such as the need to grind welds, refinish blemished surfaces or from eliminating the need to seal each penetration from fasteners. Labor costs to apply tapes and adhesives are often lower and require minimal training. Finally, the capital equipment cost may be lower than other assembly methods such as welding.
Certainly, the cost of liquid adhesive or tape is also important. Per linear foot, liquid adhesives are generally less expensive than tapes, but there may be tradeoffs in fixturing, drying or curing time to be aware of. The chemistry and performance level of the adhesive or tape will also influence cost of this material. Generally, the more extreme conditions a tape or adhesive can survive, the higher the price. Through the selection process, be sure to know the end-use conditions that are required and select based on what is needed for the application.
The Science of Adhesion Educational Series is designed to be a comprehensive introduction to Adhesion Science and the use of tapes and adhesives in design applications. Visit the Science of Adhesion to view all articles or choose from the selected topics below.