TWI Frequently asked questions
If it is not too severe there are a number of things you can do. Trial and error is the fastest policy in this case, but you must check your surface preparation first.
Check:
- That your substrate preparation is adequate. If you do not degrease and grit blast your substrate immediately before spraying then this is the most likely cause of delamination.
- Your spraying parameters. If you are too close to / far from, the substrate you may be causing the problem. Likewise if you are using equipment that has not been calibrated for a long time.
- Try and work to standards as these will help you with best practice and quality
Try some of the following:
- Changing the grit type and / or the grit blast size. This will help provide an anchor for the coating. This becomes critical as the hardness of the substrate increases.
- Try to put the coating down in layers that are not too thick (check what is recommended with the supplier of both the equipment and consumables)
- Look at the substrate and check its temperature. Significant oxidation of the substrate should not occur because of spraying. Cooling may be required.
- Try preheating the substrate prior to spraying e.g. with a few passes of a spray gun.
- If all has failed, try a bond coat. Your equipment or consumable supplier should be able to recommend a suitable bond coat. For example good bond coat materials include nickel chrome and tungsten carbide coating materials.
If you require more help, please contact surfacing@twi.co.uk with your specific problem.
