bonNDTinspect® Bondability Test

bonNDTinspect

Overview

The fully automated and non-destructive bonNDTinspect® wettability test checks and verifies the paintability or bondability of assembly parts out of a variety of materials and over large areas.

Advantages

The wettability and thus bondability of the surfaces of assembly parts can now by inspected automatically, reliably and in-line. 100% of the entire surface is tested this way. This provides a key advantage over methods such as contact angle measurement or application of test inks which are primarily used in the laboratory. Because unlike bonNDTinspect®, these methods are merely used on a random sample basis. They also contaminate the test part during the testing process. Surface pre-treatments used to prepare parts for bonding, such as plasma activation of CFRP surfaces, are tested and characterised reliably by bonNDTinspect®.

The data obtained in this way allows for complete and automatic documentation of the inspection results. Permanent optimisation of the production process is possible this way. High costs incurred through the further processing of parts whose surfaces weren't properly prepared at the time of bonding or painting can be avoided with bonNDTinspect®. In addition to checking the pre-treatment steps, bonNDTinspect® also reliably detects contamination with silicon oils, grease and release agents. This sort of contamination interferes severely with the ability of parts to be bonded, and thus with the bond strength and/or durability of bonded joints, and leads to improper bonds (weak bonds; kissing bonds). Process interruptions due to drying times or time-consuming laboratory testing are eliminated. Because bonNDTinspect® tests the assembly parts directly in the production line with an optimised cycle time. The bondability of the surfaces isn't affected by the inspection process. Further processing of parts which are identified as suitable can take place immediately.

Parts on which the surfaces haven't been sufficiently activated or with surface contamination which would weaken bonds are separated out, e.g. for further processing. Automated testing of the parts with bonNDTinspect® to determine if they are ready for coating or bonding is objective, reliable and at the same time very fast. The inspection system can easily be integrated into existing production processes. We would be happy to prepare a preliminary analysis for you with no obligation.

Principle

bonNDTinspect® is a robot-assisted system for testing the wettability and bondability of assembly part surfaces. The inspection method is contactless and non-destructive. (NDT = Non-Destructive Testing.) After cleaning and if applicable activation of the surface, an ultrasonic nozzle wets the surface of the part to be bonded or coated with an extremely fine mist of ultrapure water. In the same process step, a camera takes an image of the droplet pattern before the water evaporates again from the surface to be bonded, quickly and without leaving any residue. The captured droplet pattern is analysed with image processing software.

This step is also automatic, and adapting it to individual parameters is flexible, easy and fast. bonNDTinspect® uses the same physical principle as the contact angle test to determine whether surfaces are ready for bonding. But instead of measuring the side contact angle of a single drop, it analyses the size and distribution of thousands of defined micro-droplets per cm² from the top view, dramatically increasing the statistical significance.

The system observes the effects of the surface energies of the test part – a property which is crucial to the bondability – on the surface tension of the ultrapure water. On parts which are readily wettable and ready for bonding (e.g. cleaned, activated CFR surfaces), very flat contact angles (<90°) are observed, indicated by droplets which spread out a lot.

bonNDTinspect® is a reference-based inspection system. This means that the bondability of the parts being tested is determined quickly, reliably and non-destructively by comparing the droplet characteristics with those of a defined good part. This ensures that the prerequisites for good adhesion of the bond or paint are given. Changes in the droplet characteristics indicate a problem with the pre-treatment process. These changes are a timely indication that the part isn't ready for bonding/painting, are detected reliably by bonNDTinspect® and are indicated by a NOK signal.

Applications

bonNDTinspect® is designed for automated 100% testing of the paintability and bondability of larger parts. Bonding is the preferred modern joining method, especially in lightweight construction. Typical applications for bonNDTinspect® involve testing the bondability of surfaces in vehicle body manufacturing and in the aerospace industry. The wettability test principle, based on a patent held by the Fraunhofer Institute IFAM, was developed as a quality assurance method for bonding of composite materials. CFRP components are often used in safety-relevant applications, making reliable and strong bonds particularly important. bonNDTinspect® tests the bondability of CFRP surfaces. This is tied directly to correct activation of the composite material (e.g. using plasma rays). bonNDTinspect® can also be used to test the suitability for coating or bonding of GFRP parts, and of course also for plastic or metal parts.

 


bonNDTinspect® Bondability Test