Everything You Need to Know About Joining Prepainted Steel

02 April 18

You probably know that working with pre-painted steel can save cost, time and hassles.

But what you might not know is pre-painted steel can also be joined seamlessly without harming the beautiful surface that it exhibits.

Almost all finished metal products are assemblies of different metal components, and steel products are no different.

Many manufacturers prefer joining steel components first and then painting them later, as opposed to directly working with pre-painted steel, because they believe the latter approach does not provide a high-quality finish and bond.

This isn’t true however.

Prepainted steel can blend seamlessly into a steel assembly by employing any of the following methods:

  • Adhesives
  • Mechanical assembly (with or without fasteners)
  • Welding

Adhesives are used in applications where the smoothness of the surface really matters. This method of joining provides clean contours and is also well known for conferring excellent protection to the assembly against a variety of natural elements.

You can shop from a wide range of available adhesives and the selection will depend on several factors:

  • Epoxies provide great strength and meet a variety of joining needs.
  • Urethanes are most commonly used when working with permeable or impermeable materials. They resist humidity and temperature changes well when cured.
  • Acrylics provide a quick bond (handling strength can be achieved in minutes) and deliver good sheer strength.
  • Cyanoacrylates are ideal for bonding non-porous surfaces at room temperature.
  • Anaerobics work well with manual or automatic applications. They deliver good shear and tensile strength for flat surfaces.
  • Silicones are ideal for applications where the steel product is likely to be exposed to UV and ozone attacks.
  • Hot melts work well with rigid and flexible bonds.

Whichever adhesive system you may choose, make sure that its formulation is paint friendly. Ask your pre-painted steel coil supplier for a tailored guidance.

Next, we have mechanical assembly techniques.

Mechanical assembly of pre-painted steel components can be done with or without fasteners.

If you want to use fasteners, you can basically choose from bolts, nuts and screws or you can choose rivets.

Bolts, nuts and screws are the simplest form of mechanical fasteners. They come cheap, provide wide design flexibility and allow ease of disassembly. Rivets are known for their durability and strength. They can be self-piercing or may require punched or pre-drilled holes for installation.

You can also assemble pre-painted steel components without fasteners through clinching, lock seam assembly and pierce and tab methods.

Finally, we have welding, and although welding is an effective method of joining pre-painted steel, it does not provide a finish as smooth as the other two joining methods. This is because paint cannot conduct electric current, and therefore to weld pre-painted steel components together, some of the paint needs to be scratched before the welding can be done. The most common type of welding used for joining pre-painted steel is capacitor discharge welding. Some manufacturers also use resistance and laser welding.

So, if you want to save time, cost and hassles, AND want a perfect seamless finish for your steel product, start working with pre-painted steel.

Looking for a pre-painted steel supplier?

Sinowell Metal can help you. We supply and ship pre-painted steel coils and metal sheets at competitive rates all across the world. We have our own manufacturing and quality testing facility to ensure that you only get the highest quality product, customized to meet your needs. Contact us for more details.

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