Or a dry dissertation.

This one is peripherally related to a song challenge idea.

Last year, Milwaukee Electric Tool Corporation wished to address what it saw as a gap in the market by being the first company to produce a cordless reciprocating saw. The company wanted to introduce the new product at an annual hardware show, which meant that the product lead-time was only four months. This case study details how this ambitious project was carried out using a combination of effective planning and a range of time-compression technologies.

Case Study:Rapid Development of a Reciprocating Saw Tom Markert PSI Alliance

Milwaukee Electric Tool Corporation was founded in 1924 and manufactures premium performance, high durability, portable electric tools. It has a very broad product line with over 400 different tools. Its banner product is the Sawzall ™ reciprocating saw. In April of 1996, Milwaukee saw the opportunity to strategically enhance its product line by being the first company to market with a cordless Sawzall ™. Battery technology had advanced far enough to make this a feasible tool that would perform up to the company's high standards. The company made the decision to develop and introduce the new product in a mere four months-less than half the time for a usual program of this type. The target introduction date was the annual Hardware Show in Chicago, traditionally one of the major venues for introducing new products in the power tool industry.

The program was headed by Dave Selby, Chief Engineer of Cordless Products. Dave's internal team consisted of Mechanical Engineers, Designers, Electrical and Electronics Engineers, Tool Designers, Manufacturing Engineers, and Marketing and Purchasing personnel. Starting with a working motor design, the group had to develop a charger, battery, geartrain, and packaging (the housing of the actual tool). The build of this design consisted of 11 different plastic components, namely a motor housing; left and right handles; left, right, and top battery housings; left and right battery latches; lock slide; connector block; and a charger insert. Selby discussed the program with Tom Market, Project Consultant for the PSI Alliance.

Dave Selby discussed the goals of the program with PSI and reviewed the requirements of the plastic components. Project consultants at PSI try to understand the particular needs of the end user. Some of the more important issues are lead-times, functionality of the parts, volumes, accuracy, and how the prototypes will be used. From this information they can generate options for producing the parts that will meet the end user's needs.

The first step for Milwaukee was to produce color renderings of the tool. Engineering worked with the Industrial Designers and Marketing to produce a design. This started out as sketch work for the entire Sawzall™ and then became drawings for the individual parts. The individual part sketches came fairly early, especially on the handles because the design was of particular concern.

From these designs, work began on the 3D modeling of each component using ProEngineer. The handle of the tool merited special attention. The Sawzall ™ handle design has a distinct, brand-identifying look. The switch in the cordless version is slightly larger then the A/C switch in the corded designs, so the handles had to be made bigger to accommodate the switch. However, at the same time, the handle styling needed to be as close to the original Sawzall handle as possible. From the early ProE files, Milwaukee cut wren wood models of the entire tool on a Fadal VMC30 CNC machine. Wren models were used because the capability to do so was available in-house. Also, the internal details of the parts were not a concern-the desire was solely to get the outside shape for ergonomics. These models were held and examined to ensure that they had the proper feel and look. Marketing worked closely with Engineering to validate the design. As each CNC model was made, changes were incorporated into the CAD file and another set of handles would be cut. Three iterations were completed in one week to arrive at an optimum shape.

It was now time to move onto the next stage. The design engineers needed to begin verifying the fit and details of the parts. The ProE files were sent via modem to the vendors (later the files were sent using file transfer protocol [ftp] because this method was found to provide better and easier transfer) and stereolithography (SL) parts were produced. ATI was one of the companies providing Milwaukee with SL models for fit and cosmetics review. The company is part of the PSI Alliance and specializes in RP parts. "These models were very similar to printing out a rough draft of a text document. We wanted to have parts in our hands to look at," says Dave Selby. "We reviewed the fits between parts, looked at clearance issues, ergonomics of the parts, etc. Looking at actual parts made it easier to see problems such as sharp corners or poor fit up between parts."

Three to four SL models were made of each part. As with the wren models, any changes were incorporated into the CAD file and a new model was produced with the revised designs. According to Dave Selby, "The SL parts were excellent for this purpose. They provided clean, crisp, accurate models in a very short period of time. Some of the parts were turned around in as little as 24 hours." Milwaukee was able to hold design reviews with the SL parts and have early manufacturing studies done. The battery supplier and the Milwaukee Manufacturing cell used these models to develop assembly processes. Previously, manufacturing would not have been able to work with actual components until much later in the project. After assembling several complete tools with SL parts, several design improvements were identified that aided manufacturing and provided a better overall product design. They also were able to use the SL models to look at wiring, routing and internal component placement and were able to arrange some of the internal features of the part to help make the wire rerouting easier. The carrying case for the product was even designed using the SL models.

The next phase required a limited amount of functional testing. ATI met this need with Selective Laser Sintering (SLS) parts in glass-filled nylon. These parts were robust enough to allow several tools to be assembled and run as working models. One part-the charger insert-required higher heat resistance than the SLS or SLA material was able to provide. This single part was made on a finite deposition-modeling machine using the ABS material. The SLS parts served various purposes. The feel and balance of the tool was checked during operation. The battery runtime was verified by using an SLS-built tool to cut 2" x 4" lumber. Tool temperature characteristics were also evaluated and several opportunities were identified for improvement. This in itself validated the extra round of SLS parts. Overall, the SLS parts allowed design optimization to occur without impacting production tooling. After the SLS evaluation, Milwaukee released part designs for injection mold tooling. With only eight weeks to the hardware show, time was running short.

"There were two possible scenarios for the injection-mold tooling," said a PSI Project Consultant. "The first option was to build what we call Tru Tools. These are foundry-cast tools made from a SL pattern. The tools have cooling lines cast in, full ejection is added, and the tool is run in a standard injection-mold press. The tooling investment is much lower than cut tools. The parts are molded in the production-specified resin and are equivalent functionally to production parts. The drawbacks are that the tool life is limited (2000 parts), the part cost is somewhat higher than cut tool parts and the aesthetics do not meet production quality. This option is excellent for projects that require a limited number of parts for testing and design verification in specified resin.

The second option was to make CNC machined tools out of QC7 aluminum. These tools produce parts that meet or exceed the quality standards of most customers. Tru Tools are typically 30- 50% of the cost of a cut production tool. Cut QC7 aluminum tools are typically 70-75% of a production tool. In this case, Tru Tools represented a 4-5 week process, cut tools were 4-8 weeks, and production tools typically ran in the 12-20 week period. Cut aluminum tools have tolerances in the .005-in. range. TruTools-as cast-have tolerances in the .012-.020-in. range-this can be improved for critical areas by machining.

Milwaukee decided to use the CNC cut tools. With this option, the company was able to bridge into production using the aluminum tools to supply production parts until the actual steel tools were ready. Omega Plastics-another PSI Alliance member, which specializes in prototype, bridge to production tooling and molding-was able to meet the high quality requirements and supply the first 10,000+ units. "The accuracy, look, and function of the parts was outstanding" say Selby. "We were able to get an additional three months of sales on the front end by using these tools."

To kick these tools off a meeting was held with Omega, PSI, Milwaukee's engineering team, and the production molders to review the designs and work through any concerns before building the tools. Critical dimensions were flagged and a Quality Control plan was outlined. The ProE files were not fully dimensioned at this point. Milwaukee provided Omega with critical dimension drawings for the QC plan. Omega has over 35 lead toolmakers in house and was able to begin work on all 11 tools at once. "Our focus, capacity, and internal systems are all geared for rapid turnaround of tools," says Jeff Kaczperski, National Director of Customer Support at Omega. "Couple this with our experienced people and you can handle large programs like this in a very short time." CAD files were ftp'd directly to Omega from Milwaukee and came through with no discrepancies; both companies are ProEngineer users. Once the files arrived, the toolmaker and CAD engineer worked together to develop the cavity and core splits.

Omega keeps the QC7 aluminum in stock so once the tool is developed they can go right into the millwork. When running the SLS tools, Milwaukee discovered several features that needed adjustment. One example was the function of the battery latches. Omega was able to react quickly to make the change-the fix took 3 days as an engineering change to the tool-and still met the delivery schedule. The production toolmaker was also able to make the changes in his tooling. According to Selby, "not only did they finish the tools in 8 weeks, they were also able to react very quickly to these type of design changes. The longest tooling revision took only one week." Milwaukee and production molders attended many of the mold samplings to speed the approval process and learn as much about the injection-molding parameters as possible. This transfer of knowledge aided in the startup of production tooling later on.

Omega's tooling allowed Milwaukee to introduce the cordless Sawzall ™ at the Hardware Show and build tools for its customers immediately, while the production injection-mold tooling was being finished. The bridge tooling allowed the company to enter the market three months before the actual production tools came on line.

"It was truly a team effort", says Selby. "The resources and hard work of our internal people was nicely complemented by the PSI Alliance companies. We were able to apply the proper technologies at the right stages of the project to ensure we met our goals." The Cordless Sawzall ™ won the 1997 Wisconsin Governor's New Product Award and the Plant Engineering Product of the Year Gold Award for 1996. Sales have exceeded expectations and continue to grow.