Big ball draws on vacuum formingBig ball draws on vacuum forming

Atlanta-Even on his best day, Mark McGuire couldn't possibly hit these balls out of the park. Created to promote last year's Major League All-Star Game, each one of these plastic baseballs measures 66 inches across and weighs about 250 lbs. And though plastic promotional items tend to be cheesier than the nachos served up in the stands, big balls do showcase the capabilities of deep-draw vacuum forming.

Molded by Piedmont Plastics (Charlotte, NC), the balls start out as two parts, which are later joined with screws and heat-staked threaded inserts. According to Scott Johnson, a Piedmont technical manager, each of the ball's 33-inch-deep hemispheres pushes the limits of the vacuum-forming materials and machinery. "These are some of the biggest parts we make," he says.

For the ball material, Piedmont uses Kydex 510, an acrylic/PVC sheet from Kleerdex Co. (Aiken, SC). "We knew Kydex had a reputation for taking deep draw," reports Scott Johnson. The material also had the right combination of physical properties to hold up to an outdoor environment and potential fan abuse-including a weatherable acrylic cap, an impact strength of 15 ft-lb/inch at 73F, and a tensile strength of 6,100 psi. The material also had to be paintable since the balls, customized for each major league team and for the All-Star game, sport custom decoration.

For more information about PVC/Acrylic sheet from Kleerdex: Enter 533