Preparing surfaces for thermal spray coating is a crucial part of the spray coating process and one that should never be skipped.
A mechanical bond is needed between the surface of an object being sprayed and the spray in order to create adhesion – providing a high-quality finish and surface that will last. To ensure this mechanical bond is successful, any surface due to be given a thermal spray coating must be carefully prepared.
Preparing Surfaces For Thermal Spray Coatings
Preparing the surface of a component, part – or any object that is to be sprayed isn’t as complicated as you might think! The first two steps are similar to what a DIY’er would do at home when preparing a surface to be painted. They are:
Cleaning the surface: thermal spray coatings need to be applied to a clean surface that is free from any contaminants. Contaminants can be left over from the manufacturing process or items that are being re-sprayed could be dirty. Oils, grease, and dirt particles can all negatively affect a spray coating and interfere with the bonding process.
Roughening the surface: like paint, thermal spray coatings bond and stick better to rough surfaces. Successful thermal spraying requires the coating to form a bond with the object being sprayed. That process is more successful when the surface is abrasive and gives the spray something to initially cling to.
Surfaces being sprayed will sometimes have to be masked with special tapes if there are any areas that shouldn’t be roughened, or where coating shouldn’t be applied. This is done by hand and can be quite labour-intensive.
Cleaning & Grit Blasting
The industry standard for preparing surfaces for thermal spray coatings is to use grit blasting, sometimes referred to as abrasive blasting. Grit blasting is useful because it cleans and roughens a surface at the same time. After a surface has been grit blasted it will have a noticeably rough surface, not dissimilar to the texture of sandpaper. This is ideal for the surface to then receive a thermal spray coating.
Grit blasting may be familiar to those who have prepared surfaces for spray painting and the principle is the same (particles are blasted against the surface being prepared using compressed air), but the process is different when preparing surfaces for thermal spray coatings. Thermal coatings need ‘pits and crevices’ to cling to, so the composition of the grit blast is different when used in this application. The types and sizes of particles used in grit blasting can vary depending on what type of surface is being prepared for spraying, and what type of coating spray will be used afterwards.
Laser Preparation
Increasingly, lasers are also being used for surface preparation before thermal sprays are applied. Lasers have several benefits and are often used where high precision is required. Lasers can perform double duty the same as grit blasting by both cleaning and roughening a surface ready for spraying. Because lasers can be incredibly precise where they are targeted, this technique is ideal for smaller components, or parts that require precision in small detail. Lasers also eliminate the need for masking.
Alphatek Thermal Spray Coating Services
Alphatek is here for all your thermal spray coating requirements, including surface preparation. Our range of spray coating services are used across a wide variety of industries, and we are trusted by some recognisable and high-profile companies.
If you have any questions about preparing surfaces for thermal spray coating, or want to know more about our thermal spray services, please contact us.
You are also welcome to come and visit our facility to gain a better understanding of how we work and see the process of spraying preparation/spraying for yourself!
Located less than 20 miles north of Manchester and supported by great arterial motorways, railways and airports, we are easy to get to and find. Just give us a call or send an email if you would like to visit!
Call 01706 821021 or email postbox@alphatek.co.uk
We look forward to hearing from you.
