Ensuring Quality Control In Metal Spraying
From anti-corrosion coatings on railway tracks to non-stick coatings on industrial machinery to ensuring that medical implants are biocompatible, specialist coatings applied using metal spraying techniques help to keep us all safe and our society functioning day-to-day.
But how do we know that a coating has been correctly applied and that a component has the correct properties after treatment? Today we're looking at key considerations for ensuring quality control in metal spraying.
What Is Metal Spraying And Why Is It Done?
In its simplest form, metal spraying is the process of covering metallic surfaces with a special covering or 'finish'.
The coating may be to simply enhance the visual appeal of a surface and make it more aesthetically pleasing, but more often it's used to apply specific properties to a surface that make it fit for purpose. For example, a metal part might need to be magnetic, non-stick, water-repellant or corrosion-resistant.
There are many different types of coatings available, and a range of different methods and metal spraying techniques are used to apply coatings to surfaces.
Why Is Quality Control In Metal Spraying Important?
Quality control is vital to many industries, and the metal spraying industry is no exception.
In our day-to-day lives, we rely on quality control to ensure our safety and comfort. Every time we use an appliance or a piece of furniture, or get into a vehicle, we're relying on the quality control measures the item has been through in order to be deemed fit for purpose.
The same is true with thermal coatings. If surfaces and components weren't tested after being coated with specialist finishes, then we'd have no way of knowing that the metal spraying process had worked and that the surface was suitable for use.
An example of this might be if the surface of a bridge was sprayed with an anti-corrosion coating but not tested afterwards. People would assume the bridge was suitable for use, and that it would stay sturdy and rust-free for years to come. But if the metal spraying process was unsuccessful, the bridge could quickly corrode and become unsafe without anyone realising.
So how do we test whether or not a protective coating has worked?
Quality Assurance Measures For Metal Spraying
One quality control measure in metal spraying takes place before the coating is even applied. This is because how well a coating adheres to a surface is largely dependent on the readiness of the surface before application. Therefore all metal components must be thoroughly cleaned and all old coatings removed to allow the new coating to be properly applied.
Another quality control measure relates to the environment that the metal spraying is taking place in. Factors such as the temperature of a workshop and the moisture in the air can all affect how successful the metal spraying process is. Therefore rigorous checks must be done to ensure that the environment is safe and suitable.
After metal spraying is complete, it's possible to assess the quality of the coating using a variety of Destructive and Non-Destructive Techniques (NDTs).
NDTs are often easier to carry out, since they don't require a sample of a surface to be destroyed during testing, but they can be less reliable at uncovering isolated defects in the coating.
NDTs include techniques such as radiography and ultrasound to test the properties of a coated surface without damaging it.
As its name suggests, destructive testing of coated metal surfaces involves damaging them to test their resilience to the factors they have been treated against, however, for obvious reasons, this isn't always practical or financially viable.
As an alternative, if consistency in spraying conditions can be guaranteed, then it's possible to spray both the original surface alongside a test or control item with identical properties. This allows the control to then be rigorously tested – and destroyed if necessary – without damaging the original part. This can be useful when metal spraying is being used to repair isolated or small numbers of metallic components, making destructive testing unsuitable.
Alphatek – Metal Spraying Specialists
We hope this has helped to explain the key considerations for ensuring quality control in metal spraying.
With over 120 years of cumulative coating experience, Alphatek is a leading independent metal spraying specialist. We provide a complete range of thermal coating services to a diverse array of industries and pride ourselves on delivering the highest quality, best value and most effective thermal spraying solutions to our clients.
To learn more about the services we offer, don't hesitate to get in touch. You can also email us at postbox@alphatek.co.uk or call 01706 821021 to speak to a friendly member of the Alphatek team.
Alternatively, if you'd prefer to visit us in person, you can find us 20 miles north of Manchester city centre. Please be sure to check our current opening times before planning your visit to Alphatek.
