How practical testing can give manufacturers confidence when investing in an adhesives process

Kevin Cook explains why manufacturers must go beyond the datasheet and carry out environmental tests to ensure that chosen bonding methodologies will meet assembly and production requirements

Upfront evaluation of the performance of materials and equipment for a manufacturing process to establish how they will perform in the real world can greatly reduce the risk of problems later down the line. 

One of the steppingstones to productivity is a simple, efficient and error-free process when first setting up the production. 

Considered evaluations and pre-production methods mean businesses can start full manufacturing with more confidence and less risk. 

Though the adhesive or equipment manufacturer will have done extensive testing to determine the basic datasheet parameters, it is vital to evaluate products in a real-world application, ideally on production parts, so manufacturers can be sure that they function adequately on their unique assemblies.

Part of the practical evaluation process in selecting an adhesive and the accompanying application and curing technology will be understanding overall process costs; often, these costs outweigh material costs on a per-part basis. 

Choosing a process where costs are optimised will impact on the overall economic calculation for the assembly, the associated return on investment (ROI) estimate, and ultimately the investment decision.

While product data sheets are a useful way of shortlisting adhesives and other materials to test, we do not recommend selection based on the data sheet alone. 

Published product parameters are usually determined from laboratory testing or under ideal circumstances. It is important to verify that the expected performance is achievable on the intended parts with their particular surfaces and geometries, as well as in the proposed use environment. 

The data sheet will not answer every question the user has; for example, the list of which substrates it can bond may not be exhaustive. 

An experienced adhesives supplier will have a wealth of knowledge from real world applications to help you understand the data sheet in practical terms. Nevertheless, this is still no substitute for testing. The evaluation process translates the data sheet onto your real-life application.

Always a compromise, never perfect

It is important to remember that, when evaluating a material, there is no such thing as the perfect adhesive — there will always be some level of compromise. Often, this revolves around ultimate functionality versus practical processability. Over-specifying parameters like operating temperature range or solvent resistance will limit adhesive choice, and potentially add to costs. 

Keeping this in mind will ensure that the test results are interpreted pragmatically, and that an unachievable standard is not being pursued. The evaluation should take a holistic approach, with an understanding of which selection factors are set in stone, and which can have their tolerances widened in order to arrive at a dependable product which can be used efficiently and at an appropriate cost.  

Practical testing can establish that the assembled part can withstand whatever environmental conditions it will be operating in. Environmental testing involves subjecting the finished product to the conditions it will likely face in its lifetime to see how it performs, when exposed to the relevant humidity and temperature extremes and changes. 

Testing will confirm that the chosen bonding methodology will meet the requirements of the assembly and production in terms of accuracy and repeatability, meeting quality and productivity needs. 

Examples include the measurement of a number of deposited shot sizes from proposed equipment, using statistical analysis to confirm the required precision; the assessment of a UV curing function to ensure that it complies with the overall takt time; or the determination of the minimum and maximum adhesive quantities in a bond which still produce the required strength. 

Tried, tested, trusted

The best salesperson is one that sells you what you need, not what you think you want. When working with an adhesives supplier, it is important that you have trust and confidence in the relationship. It is quite common that a material selected early in the process does not suit an application in real life, and an adhesives partner can work through this with you to help you select an alternative.

To support customers through their testing and evaluation process, Intertronics operates a Technology Centre in Kidlington, Oxfordshire, where customers can either send their parts for our team to bond together as a prototype for the customer to test, or where customers are welcome to attend in person or via video to experience process development live. We also provide our customers full laboratory reports with supporting images and videos to give them insight into their process choices.

We find that many of our customers benefit from developing their adhesives process in a knowledgeable environment, and that the technology and materials we have available on site can open their eyes to alternative ways of doing things, inspiring them to forget their preconceptions and be inspired by new options. We firmly believe in collaborating with customers throughout process development to give them confidence that their process is the best possible option, with minimal compromise.

Evaluation and testing is a crucial step in pre-production, to help establish a productive process, reduce risk and provide confidence.

Kevin Cook is Technical Manager at adhesives specialist Intertronics.