real world success

DW Product Development Used Moldflow Plastics Advisers to Create the Next-Generation Black & Decker Workmate

By Laura Carrabine, Editor

DW Product Development, Inc. (formerly Design Workshop) is an award-winning product development firm located in Ottawa, Ontario, Canada. The 21-year old company offers a variety of services from design development and consulting services, to full-blown, art-to-part production-ready geometry, as well as rapid prototyping and rapid tooling. The firm focuses on the consumer goods, telecommunications, medical, and appliance markets. Its 15-person staff comprises industrial designers, mechanical designers, and model makers. DW’s roots are from broad and diverse industries, serving the needs of small, medium, and Fortune 500 companies. Prior to September 11, 2001, approximately 40 percent of DW’s work came from the telecommunications industry. Since then, the firm has refocused its sights on other markets.

In addition, DW forms strategic alliances with outside partner companies when a project requires expertise beyond DW’s multi-disciplined staff. According to Aldo Balatti, senior product designer and plastic applications specialist, DW will work with its outside finite-element analysis (FEA) group when the need arises. "We trade our industrial design (ID) services for engineering or FEA services. If a client, for instance, needs a structural analysis, we will include a structural FEA analysis in the proposal that has been performed by a partnering firm that excels in FEA. And, vice versa, that firm may need our ID services for a project. This business strategy has worked very well for us."

DW designers use Moldflow Plastics Advisers® (MPA®) software for plastic injection molding analysis, and SolidWorks® and Pro/ENGINEER® products for 3D CAD modeling. The firm has been performing mold-filling analysis since 1998. MPA software allows users to test every part and mold concept for manufacturing feasibility before the tool is cut, when the cost of change is minimal. Seamless integration with CAD solid models enables users to perform simulations and view results directly on the solid model.

Balatti adds, "We use MPA to reduce trial and error, improve part design and quality, and slash time-to-market. It’s a powerful tool to optimize parts and improve plastic processing conditions. We have been able to save time and money by reducing or eliminating tool rework. We use MPA on the majority of parts that we are designing to obtain fast feedback on wall thicknesses, weld-line placements, material selection, and gate locations. We want to make sure that the new part is designed right and ready for production prior to being sent to the mold maker, because there is typically no time to make changes with the mold. There’s no margin for error because there are firms in Asia and other countries in Europe that are making molds considerably faster than their North American counterparts. Because of that, there is no time for tweaking or adjusting molds. Using MPA and our expertise, we have eliminated the mold trial and error phase from the molding process. The conventional trial and error method has to be eliminated from the equation. MPA allows us to have a virtual molding machine on our desktops."

Increasingly, more and more products are comprised of plastic materials to reduce weight and cost, as well as for miniaturization. It is a trend to make products lighter, less expensive, and more efficient in production. In addition, by using molded-in color plastics, there are fewer finishing operations. Balatti says, "We are seeing more metal replacement in traditional products. Using plastic materials is more cost effective in a lot of applications, and they perform better in many cases in terms of insulation and impact resistance. The automotive industry is a good example of the increasing use of plastic parts in cars."

Seventy to 80 percent of the components that DW’s designers create are injection-molded parts. Once the designs are developed in the 3D CAD systems, the parts can be optimized using FEA software. MPA is used to optimize part design, gate location and mold filling. In doing so, DW can reduce the amount of material to decrease costs, speed up the cycle time, and assure that the parts will be injection moldable.

When replacing a metal material with a plastic material, the first thing that Balatti and his team do before designing the part is determine that the selected exotic plastic material, which typically has a low melt flow rate, will fill the mold. "We have to make sure that it can fill properly at the thinnest cross sections," says Balatti. "So, we create a shape that closely resembles what we want and then go ahead and simulate the part filling in MPA. If it short shots, then we know that the part wall is maybe too thin, and we optimize the part. In addition, we can simulate different materials, different wall thicknesses, and we can use MPA with the FEA software."

Black & Decker Workmate 375 Project

The Black & Decker Workmate product has been on the market for about 30 years. It’s traditionally known as a big, stationary piece of industrial equipment that typically is kept and used in a garage, basement, or other workspace. In November 2001, DW researched the Workmate marketshare and realized that the Asian competition was taking away profits with smaller, cheaper Workmate clones. DW created a redesigned Workmate — one that is portable, on wheels, rugged yet handsome, and tailored for many types of users, not just a tool-savvy workman. DW, along with Camalor Mfg. (Brockville, Ontario), the current Workmate manufacturer, approached Black & Decker with the next-generation Workmate design in January 2002. The project for developing and manufacturing it was approved and funded by Black & Decker in March 2002, and the units began shipping in September 2002, just in time for holiday sales.

"During the design of the new Workmate 375, we developed the possibility of manufacturing the jaws out of plastic instead of the traditional wood laminate. We used FEA to investigate loads on the front and rear jaws. Each molded jaw weighs approximately 1.9 pounds, is 23 inches by 7.25 inches in size, with a nominal wall thickness of about 0.200 inch. We needed to optimize the ribbing inside for structural integrity, mostly because Black & Decker requires that its products pass stringent safety, impact, and load testing. The company guarantees that the jaws can withstand a static load of 350 pounds. We tested the jaw parts we designed by quickly creating CNC machined polypropylene prototypes and tested them for strength and durability at DW and at Camalor," Balatti says.

"In the end, because of plastic creep, we felt it was necessary to put a small metal stiffener inside each jaw to resist creep that could occur, such as someone leaving a heavy object on the Workmate for a long period of time. The stiffener is a preventative feature.

"Camalor, which manufactures and assembles the new Workmate, is molding the jaws on a two-cavity family mold so that the front and rear jaws are in the same mold. That’s a big shot of plastic in a 750-ton machine. We wanted to make sure that we would not short shot and that we could pack those parts, which are thick with a lot of ribbing. The mold, built by Ottawa Mould Craft (Ottawa, Canada) was constructed of cores of Moldmax beryllium copper to extract the heat from the core. This was to make sure all the ribs cool very quickly so we would have limited warpage on the surface. That proved to be an excellent decision. For the gating solution, we came up with a very different approach. Our first solution was to gate at the end of the long part so the part would fill length-wise. However, that meant pushing a lot of plastic through a long flow length," Balatti adds. Using MPA, this seemed to be a good solution. But the molder would have to position the mold and the sprue offset in the mold - a tricky proposition.

Then, Balatti and his team investigated the handle area as a better gate location. He says, "That was a beautiful place to drop a hot tip and cut the flow length in half. We devised 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 the inside work area and another sub-gate facing the handle area toward the outside. This configuration eliminates any knit lines and cosmetic issues," he notes.

Then the DW design team, working closely with PolyOne, the polypropylene resin supplier of the new Workmate plastic parts, requested more advanced simulation performed by Moldflow Plastics Insight® (MPI®) software. MPI software is used by companies that need detailed predictions about all phases of part and mold design, manufacturing, and resulting part quality. Integrated suites of software tools cover a wide range of thermoplastic and reactive molding processes. The software was used to perform mold filling and warpage analysis. Balatti and his colleagues wanted a second opinion on the gate locations and soon confirmed, after seeing MPI results, that the handle gating location was the best option. The MPI results were nearly identical to DW’s MPA calculations.

In addition, Balatti sensed that the part would warp upwards because of the interior rib pattern being thinner. "Using MPI, we wanted to know the extent of the warpage. A warp analysis was performed and, based on the results, we advised Camalor that it needed to add a fixture to assure that the jaw parts, that act as a working surface, stay flat after molding," adds Balatti. Today, in production, after the one-minute molding cycle, the parts are then put into custom cooling jigs so they stay straight. After a few minutes in the jigs, the parts are moved to the assembly area.

According to Camalor engineer Marc Fortin, "We partnered with DW to design this new product. They handled the majority of the plastic parts and we worked together on all of the mechanical steel, structural aspects of the product. We used their expertise to design the vice jaws to meet the program specifications directed by Black & Decker. After DW performed Moldflow simulations, we reviewed the results with DW to make sure that the manufacturing conditions that we were looking for would suit what was required in terms of the plastic parts. We had to meet certain cycle times to keep costs down.

"In terms of the vice jaw, when we first considered it as a plastic part versus a wooden part, we initially thought that it would run as an 80 to 90 second cycle time. That was unacceptable from a capacity point of view. We couldn’t produce enough vice jaws in the time frame required with the tooling that we had budgeted for. So we had to look at different ways to reduce the cycle time. That’s where Moldflow helped to reduce the cycle time to meet the capacity and delivery requirements. That particular mold is the longest lead time item. Because of the short time to develop the product, tool it, and start producing, we had to work concurrently on the part design and tooling design so that we could have that tool done in time to produce the product. There was no room for error. We started the tool design almost at the same time we started the product design. The project worked out very well," notes Fortin.

"The Black & Decker project is testimony to the premise of using MPA - a tool that can test every part and mold concept for manufacturing feasibility before the tool is cut, when the cost of change is minimal," says Peter Rucinski, Moldflow’s director of product marketing and MPA product line manager. He adds, "Savvy companies like DW can identify and eliminate problems at a very early stage of design, achieve significant tangible and intangible benefits regarding time and cost savings, and capture market opportunities such as the present holiday sales market."

Because DW designed the parts as injection molded parts, the team added other molded-in features into the design, such as color, measuring rulers, tool storage holes, pocket recesses for nails, screws, beads and other building or craft materials so they don’t roll on the work surface. In addition, the next generation Workmate features handles for easy portability.

DW designers used Moldflow products to analyze all the new plastic parts, to assure accurate gate locations and to determine filling and cooling processes. Black & Decker is very serious about aesthetics. "The software was very helpful in terms of cosmetics, performance, and safety," Balatti explains.

In stores now, the new generation portable Workmate 375 can be used in living rooms, kitchens, dens, as well as workrooms and garages. From construction jobs to craftwork, the unit accommodates any task by any type of user. The durable wheels make it easily mobile, and it folds flat for quick and easy storage.

"The Black & Decker 375 Workmate is a great example of out-of-house suppliers working together with B&D project managers to deliver a world class product. DW and Camalor’s expertise in product design, CAD and simulation software applied to metal components and high performance plastics resulted in a long-time B&D product line moving forward to a new level in a very short time frame," adds Colin Dyke, Black & Decker’s Global Vice President of Engineering.

For information about DW Product Development, visit www.dwcanada.com. For information about Camalor Mfg., visit www.camalor.com.