Air bubbles can have a devastating impact on production. Medium viscosity adhesives, silicone, UV, epoxies, latex and oil are just some of the fluids that are particularly affected. Trapped gasses can ruin the fluid or the part it is dispensed onto costing tens-of-thousands-of-pounds in lost production time. In the electronics industry, where epoxy resin encapsulation or coating is often an essential process, air bubbles lead to catastrophic parts failure. In the final part of our two-part blog series Loris Medart, SR-Tek founder and a fluid dispensing engineer of more than 20 years’ experience, discusses four of the eight most common causes of gas entrapment and the simple steps that can be taken to avoid or greatly minimise the chances of air bubbles in industrial fluids.
- From R&D to full production – is this fluid right for me?
Often in applications requiring adhesives such as cyanoacrylate, the wrong adhesive is selected for the application. Whilst perfectly capable of doing the job it was selected for at the research and development stage, multiplying that many times over to get to full capacity (e.g 1 part/day produced vs 100 parts/day produced) can often lead to a number of problems including the production of air bubbles. In some cases, this may mean going back to the drawing board and identifying a new adhesive or other industrial fluid. If this isn’t possible, then having complete control of the environment the fluid is in during production using some of the steps mentioned in part one of this blog can lead to a custom solution that enables the fluid to meet application and production requirements.
2. Are the chemicals compatible?
Often overlooked, but something to consider when other lines of enquiry have been pursued is whether fluids are reacting with any wetted parts to create gas bubbles? Sterile production systems with limited components are best practice for any process involving fluids. A chemical reaction can cause chemicals and air to leach in and out of fluids.
3. Is the system set up correctly?
There are a number of practical steps that can be undertaken to minimise the likelihood of the formation of air bubbles at the system set up stage. Minimising the distance between the fluid container and the dispensing/spraying head is one, along with considering pressure and flow rate and how everything is connected to the compressed air. One simple area that is often overlooked however is the fluid tubing itself. If too long, with an oversized diameter, there is a risk for loops, high points and low points, that can cause air bubbles to be formed and dragged through the system by the fluid.
4. How can you transfer fluid?
The movement of fluid from one container to another can absolutely cause air bubble entrapment. Dependant on the fluid viscosity trapped gas may raise to the surface over time, but this is not guaranteed. Attention should always be given to the manufacturers advice on the best process and systems for storage and handling. However, as a rule of thumb, dispensing directly into the pressure vessel is often the best approach. In some cases the production chamber can also be placed into a vacuum or centrifuge to remove bubbles ahead of production.
Would you like to know more about how SR-TEK can help you to prevent fluid entrapment in your manufacturing processes? Get in touch with Loris Medart, founder of SR-TEK via our website or connect with Loris on Linked In.