Molded Fiber Glass

Why make the switch?

MFG, Union City, Pennsylvania, began using closed molding for heavy truck components, rail transportation components and water treatment products back in 2005, says Dennis Vorse, general manager for MFG Union City, Construction Products and Water Treatment Products. The business is currently around 75 percent open molding and 25 percent closed molding. They made the switch because they wanted a cleaner work environment, consistency in product and part thickness, two smooth sides and better physical properties.

The benefits

Vorse says MFG gets more tool turns per day with light RTM than with open mold. Emissions are also lower, resulting in a healthier work environment, which he says can help gain and retain talent. He also says closed molding can increase part strength by 50 percent, depending on the part (glass configurations can have a positive or negative impact).

For clients, the benefit comes from having two smooth sides, which Vorse says results in better thickness control and a more attractive looking product.

The challenges

Vorse says closed molding isn’t as quick to production as open molding, where tooling is much faster and prototypes can be developed in less time. He says closed molding can also be a tough sell to customers because of the additional up-front cost associated with tooling.

“I usually get a customer face to face and show them the texture of the back side of a part made with a closed mold versus a part made with an open mold and try to explain the benefits they would get. If they don’t care if the back is coarse, it’s going to be a real tough sell to get them to double their tooling.” Two smooth sides matter more to some industries than others. Rail transport, heavy truck, automotive and marine are becoming more and more interested in that benefit, Vorse says. For products such as a bathtubs or shower stalls, where the rough side is hidden between the studwork of the home, having two smooth sides isn’t as important.