Efficient scale up – Adhesive processes
One of the questions our tech team asks engineers seeking an adhesive recommendation is “How many assemblies will you be manufacturing?” Although from a business perspective this is nice information to have; it is critical information to make an ideal product and process recommendation.
Often, the right viscosity, rheology, and set time of a process can be as important as ultimate bond strength. We recognize that design engineers may not always have the expected annual throughput or often are unable to share that information for proprietary reasons. So following are a few examples that may help in planning for scale up and avoid additional adhesive selection and testing.
One viscosity may work well for manual application but dispensing via an automated dispensing system may suggest a different viscosity.
A start up company underestimated the success of one of their products. Great news right? They needed to switch from manual assembly to a high speed automated process. The adhesive they had chosen was a slightly viscous cyanoacrylate which was easy to apply and spread manually. To switch to the high speed dispensing they wanted a lower viscosity which would flow across the bond area. A lower viscosity cyanoacrylate was supplied and passed the manufacturers testing.
A common issue in scale up of epoxy and acrylic adhesives is stringing, (also called tailing.) When dispensing an epoxy that has stringing tendencies, the epoxy applied to the part, has a string or tail of adhesive attached to the dispense tip. This string of epoxy breaks off, but it can land as an unsightly mess on your components. This phenomenon is not always noted during manual testing or manual dispensing – but in high speed production where there is less time between each application, it can become an issue.
A manufacturer of a proprietary device was only able to share the two substrates they needed to bond – and that he wanted a strong bond. A cyanoacrylate adhesive was recommended that would provide very high strength bond. As it happened, in this case scale up was a larger size assembly as opposed to more assemblies. As the size grew, the bond area grew, which resulted in the cyanoacrylate curing before the manufacturer could finish applying the adhesive. A two part no mix structural acrylic adhesive was much more desirable.
Adhesives are preferred over mechanical joining means in both manual and automated processes. Keeping the ultimate manufacturing process speed in mind during the testing phase can result in a seamless scale up process.
To review your application with a Permabond adhesive specialist, contact our technical team.