Designing with prepainted metalBack
Designing with prepainted metal
Designing with prepainted metal is very similar to designing with any other form of sheet metal, but with the additional advantage that the product already has the required surface aesthetics. However, there are a few characteristics of prepainted metal which the designer needs to consider to ensure that the final product design is successful.
- The first and most obvious point to remember is that the paint finish is present before forming. The coatings used on prepainted metal have been formulated to flex with the base metal; different levels of flexibility are available so it is important to select the right prepainted product at the start of the work. The paint coatings will usually retain their adhesion even at a 0T bend radius, but it is important to confirm this before starting the design. The coatings have also been formulated to be very scratch resistant, a range of textures and hardness are available, so it is worth checking with your supplier first to identify the most appropriate product. When assessing the tooling to be used for forming operations, it is important to remember that a scratch in forming is a scratch on the finished product. Any potential issues can usually be overcome with good quality tooling, good design and, if all else fails, the use of a temporary protective film.
- The second important point to remember when designing with prepainted metal is that the finish is applied before any joining takes place. This means that conventional welding is not usually possible without damaging the surface appearance of the product. However, there are numerous joining techniques which can be used in place of welding.
- The third point to consider is that the backside of the prepainted metal sheet may well have a different appearance to the front side. In some designs this can be very useful, for example, providing a simple grey coating for the inside of a filing cabinet. When designing it is important to remember that front and back surfaces are usually different. However, it is possible to specify the same finish on the front and back sides if this is required for the design.
- Finally, it is important to think about the edges of the metal sheets within the final product design. Prepainted metal sheets will always have at least two edges which are uncoated, since they will have been cut from a much larger metal strip. These bare edges can look slightly unattractive and in the worst case, they will be the initiation point for corrosion. However, there are well established techniques for hiding bare edges in the final product.
Learn more about forming and joining prepainted metal sheet, including the common solutions to some of the issues raised above, in the following pages...