How does the joint design influence the bond strength? Ways forward.

Thanks for those who read my first blog on “What is the best process to assemble materials in medical device design?” here. Here the follow up on proper joint-design for medical devices.

When joining flexible parts with rigid parts, peel stresses are present at the joint, as the dissimilar materials react differently to the loads applied. How do you know how much stress will make your device fail? And how do you know if failure will happen at the bond line?

Target is to achieve a joint stress far above the requirements set by the related device standard. Ideally, in case of joint beaks, you want the substrate to fail long before the adhesive bond is broken. 

As a stress is applied to a flexible-rigid joint, the deformation of the flexible part will create peak loads concentrated at the joint edges. Under load one of the three elements will fail: rigid substrate, flexible substrate or the joining material (i.e. adhesive). If you choose the proper adhesive, the substrate would be failing first.

With our products LOCTITE AA 3951 and LOCTITE AA 3953 a higher bond strength is achieved and the substrate fails before the bond line. Watch the video below:

As you can see, a proper bond joint-design will allow for increased strength before failure. Through the combination of optimum adhesive and bond joint-design, rigid and flexible parts can be efficiently and effectively assembled with the maximum load resistance capabilities.

Want to discuss your challenges further?  We collaborate with medical device manufacturers regularly supporting their design efforts and evaluate potential solutions that best fit them.

This blog is part of a series of blogs on medical device assembly innovation.

Want to read more? Check out our medical blogs on “Flexibility in Medical Device Design” here  and “Choosing the right material for your device”  here .

Author: 

Esthefan Zumbado, Manager Medical Devices IA Latin America North