EDITOR ’ S CHOICE THE PATH TO PRODUCTION
INTERTRONICS
Adhesive considerations at the design stage
Adhesives are often treated as the final piece of the jigsaw puzzle . But by the end of the design stage , it may be difficult to find an adhesive that meets all the criteria , meaning the design must be amended , or even started again . Here Simon Gibbs , Technical Sales Executive at adhesives specialist Intertronics , explains the benefits of considering adhesives early in a project .
Though it may seem initially like a simple task , adhesive bonding is a vital and challenging part of product design . Every application is different and establishing what works best for your application involves detailed discussions and testing . For design engineers without specialist adhesives experience , consulting with an adhesives supplier early on will avoid complications later down the line , saving time and money .
In many cases , manufacturers contact adhesives providers once most of the design work is done — once they have finalised and assessed bondline design , substrate selection , environmental resistance , and more . The difficulty with this approach is , with much of the design finalised , there will be a particular set of requirements the adhesive needs to meet — a very specific gap in the jigsaw for the adhesive to fill . There may not be an adhesive that meets the criteria without major compromise , or a suitable adhesive may not be available in the specified packaging or quantities . If this is the case , the design may need to be changed , delaying the project and increasing the costs .
It is much easier to make changes to the design earlier , while the process is fluid . We therefore recommend contacting an adhesives specialist at a stage where the substrates and bondline geometry could still be changed . Your supplier can lean on previous experience to tell you what a suitable candidate is to test — and explain why .
PROTOTYPE TO PRODUCTION
Adhesive applications are complex and can easily become unstuck . A small change to a design can have a big impact on the performance of the adhesive ;
Simon Gibbs , Product Specialist at Intertronics
Adhesive applications are complex and can easily become unstuck . A small change to a design can have a big impact on the performance of the adhesive .
tweaking one thing can mean an adhesive that previously passed the testing for that application now has the potential to fail . For example , something as simple as how the substrate is pre-treated or cleaned can lead to part failure .
One common reason the bond fails testing at the later stages of a project is that the prototype has been made differently , or using different materials , to the production parts . For example , if the prototype was done using one white plastic and then later changed to another . Though it might be natural to expect the same result , the adhesive may no longer bond .
We recently supported a customer bonding plastic LEDs to plastic housing using a UV curing adhesive . The company then developed another version of the same product , which involved bonding the plastic LEDs to anodised aluminium instead . The new product did not pass the required testing , and the design had to be changed to incorporate a different adhesive .
Another factor to consider when changing the substate is that many modern materials are formulated with specific properties where the benefits to the application , such as chemical resistance or UV blocking , are the same reason that makes the application challenging . For example , properties that make design engineers select polypropylene as substrate ( e . g . low surface energy , solvent resistance , opaque ), are the same properties that may make it more difficult to bond .
As well as changing the substrate from prototype to production , we sometimes see manufacturers change the adhesive . In some cases , design engineers will prototype their product using an adhesive they have available in the lab or which is already used in the factory for another application . They will then select a different adhesive for the production parts using data sheets , subsequently meeting a challenge when production has started and the specified material doesn ’ t pass functional tests . It is important to note that the data sheet may not always give the same insights as practical observations , experience , and tests ; in many cases , the data needs to be interpreted and extrapolated to fit with the individual scenario .
FROM DESIGN TO PRODUCTION
Another possible hurdle is that the specified adhesive does not line up with the production team ’ s schedule . For example , many manufacturers request UV curing adhesives due to their ability to cure on-demand and in seconds , but the adhesive might not meet the functional requirements for the application in question . However , it is a challenge to simply swap one adhesive for another to meet a production-related challenge .
6 PECM Issue 57