Redesign rejuvenates popular hardware product

When the market dominance of one of Black & Decker’s best selling products, The Workmate, began to be challenged by cheaper, Asian-built clone products, the company decided a redesign was needed.

Industrial design firm DW Development, Inc. (Ottawa), and contract manufacturer Camalor Mfg. (Brockville, ON) played integral roles in the Workmate 375 redesign project. The project, begun in January of 2002, was finished late last year and resulted in a more compact, lighter model with enhanced aesthetics and many new plastic components.

DW Development studied the feasibility of substituting plastic in place of the long-time traditional material, laminate wood, in the construction of the Workmate’s jaws. Black & Decker specifications require the jaws to withstand a static load of 350 lb. Finite Element Analysis was used to investigate the loads on the front and rear jaw, and a CNC-machined polypropylene prototype was quickly created and tested at DW’s facilities. After testing, the design team decided to add a small metal insert inside each jaw edge to counteract plastic creep during prolonged periods of loading.

The final production part was designed with optimal internal ribbing for structural integrity. Each molded jaw is 23 in. by 7.25 in. in size, weighs approximately 1.9 lb. and has a nominal wall thickness of about 0.20 in. Camalor injection molds the polypropylene jaws on a 750-ton machine in a two-cavity family mold built by Ottawa Mould Craft, located in Ottawa. The mold was constructed using cores made of Brush Wellman’s Moldmax beryllium copper. The metal alloy cools the part more quickly than conventional steel, minimizing risk of warpage in the ribbing.

DW relied on Moldflow Corp.’s Moldflow Plastic Advisor (MPA) and Moldflow Plastic Insight (MPI) to analyze mold filling, warpage and the best locations for gating. On the basis of the information obtained from the software, the team decided to move the gate from the end of the part to the handle area.

“This was a beautiful place to drop a hot tip and cut the flow length in half,” says Aldo Balatti, senior product designer at DW. “We developed a spider with one drop per part. The hot tip sits on a very small runner that has three spider sub-gates. There are two sub-gates facing inside the work area and another sub-gate facing the handle area toward the outside. This configuration eliminates any knit lines and cosmetic issues.”

Balatti reports that the final design incorporates many new injection molded parts and effects. These include tool storage holes, measuring rulers, pocket recesses for nails and screws and enhanced color.