Attaching Metal Grilles and Screens to Plastic Frames

For many years, metal grilles and screens have been attached to plastic housings and frames by the use of additional fasteners. These fasteners may be screws, clips, rivets, hot-melt glue or adhesive. Each of these processes cost money, require inventory and are subject to fluctuating degrees of consistency in quality.

In recent years, many manufacturers have designed or redesigned their products to incorporate heat staking or swaging process. This can typically be done with minimal expense to new or existing injection molding tools. In many cases, the final product, when staked or swaged, becomes much stronger and robust than its predecessor that required hardware for attachment.

Besides the reduction in product cost by eliminating hardware, there are many advantages, as cited by our customers, for why switching to staking/swaging is such a benefit to many products. Listed below are just a few.

• Rattles from loose fasteners become non-existent.
• Screens or Grilles do not become loose over time.
• Products become tamper proof.
• Production rates increase with smaller workforce.

As shown in Examples #1 & #2, a heavy duty, construction grade screen is heat staked onto a plastic Vent Housing. The Housing has 16 heat stake posts equally spaced around the perimeter. A machine operator locates the housing into a part holding nest, and then places a precut screen over the surface with posts. Upon initiating the machine cycle, the parts become an assembly within 10 seconds.

As shown in Examples #3 & #4, a black painted grille is swaged into the rib of a plastic engine frame. The process of “swaging” is basically embedding the metal grille directly into the plastic. This process is much more difficult than straight forward heat staking as shown previously. In this application, the heat stake iron (tooling) must remain only a few degrees below the plastics actual melting point. Any point over will produce a stringy mess. With quality tooling and equipment, the iron temperature can be closely maintained to repeat this assembly with ease. Thermal Press International employs machine controls with precise tooling to make assemblies such as this routine.

Many other screen materials such as nylon, felt and fabric can be easily staked as well. To discuss your application and whether heat staking/swaging is a viable option for you, please Contact Us at Thermal Press at (925) 454-9800.