Designer lauds blow molded barriers

EAST LANSING, MICH. (Nov. 9, 11:20 a.m. ET) — Highway barricade maker Yodock Wall Co. Inc. is switching from rotational molding to blow molding to improve efficiency.

Yodock designs and sells hollow high density polyethylene barriers that are easier and cheaper to transport to job sites than solid concrete competitors. Workers fill the barriers with up to 100 gallons of chlorinated water for ballast once they are in place, then simply drain them when the job is complete. The barriers are typically used at road construction projects and for crowd control and protection.

Each barrier is 5 feet wide, nearly 9 feet long and more than 5½ feet tall. Rotomolding could produce about three barriers per hour, said blow molding consultant Daryle Damschroder, who worked with Yodock to convert the product to blow molding.

The company first came to Damschroder’s D2 Blow Molding Solutions of Elmore, Ohio, in 2007 for advice on how to change processing techniques so it could produce barriers faster, reducing its costs, Damschroder said Oct. 7 during the Society of Plastics Engineers’ 2009 Annual Blow Molding Conference in East Lansing.

His first thought, Damschroder said, was that it could not be done, but by rethinking some of the barrier’s design, Yodock, mold maker FPM Tooling & Automation of Fremont, Ohio, and molder Roth Global Plastics Inc. of Syracuse, N.Y., came up with a barrier that could meet all of the company’s requirements and be molded within five minutes.

The project is similar to other new business coming to FPM — companies looking to convert production to blow molding, said President Martin Cass.

To make the blow molded barrier happen, the engineers also converted some parts to injection molding —- such as sockets and filling pipes —- which are then welded into place on the barrier. A connecting part, roughly the shape of a dog bone, is also injection molded, Damschroder said.

Complicating issues, the completed product must be able to withstand a 30-mile-per-hour impact under federal highway standards. The barrier also must comply with the Americans with Disabilities Act, which requires that nothing sticks out that could trip up people in wheelchairs or using canes.

Yodock also wanted a barrier that could be used alongside existing rotational molded barriers for customers that already owned older units, Cass said.

The finished tool has 13 hydraulic components and Roth uses 130 pounds of resin in a single shot.

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