Tech Directions - January 2009 - (Page 24) Making the Die Our CAD equipment consists of software named MillCam Designer, a product of Denford (www.denford. ltd.uk). MillCam is a pretty basic CAD package, but it is easy to learn and, for this activity, is perfect. I spend a short time teaching the Cartesian coordinate system and by the third day students are using CAD to design their products. The CAD program will convert the design into G and M codes required by the CNC software that runs our milling machines. The material that we use for our die blanks is either 6 mm Lexan or Protofoam, a dense machinable foam. Once the dies are milled, students use a router table with a laminatetrimming cutter to put a slight draft angle around the perimeter of the die. The next step requires a vacuum-forming machine to make molds into which they will pour the chocolate. Protofoam dies need no venting, but Lexan needs a few 1/16" holes in order to have the thermoplastic mold material draw down tight to the die and produce a crisp design. Students fill the molds with melted chocolate. into their respective bars. Typically, they try unsalted peanuts, almonds, crushed sugar cookies, and caramel. One team tried beef jerky bits in their chocolate bars. That effort resulted in very limited palatability. Cooling the chocolate is hastened by placing semi-liquid bars in a refrigerator. The following day, the teams wrap their candy bars. Putting It All Together Finally, the day arrives that students have been waiting for. I don my chef’s hat and fire up the double boiler to melt bulk milk chocolate. Teams ration out ingredients to be placed Vacuum-formed molds made from the die blanks What We’ve Learned Many consumer products are developed the same way that we produce our chocolate bars. The more complicated the product, the longer it takes to develop it and the more designers involved. I incorporate mathematics into the activity when we tally the average price for existing candy bars and the weight per gram of chocolate. We also calculate profit and loss margins. Each student works with coordinates and then uses them to design and cut our school logo using the CAD equipment. Students also graph flavor preference survey data and make a graph comparing a candy bar’s weight to its cost. At the 9th-grade level, teamwork is an invaluable skill and sometimes a hard one to master. Students have had many arguments about selecting chocolate bar names, flavors, and designs. I’d like to note that this product design activity provides one of the few times in my classes when my students have become passionate and defensive about their ideas! Missing your December issue? It’s online! Visit www.techdirections.com/ past-issues.html to check it out! 24 techdirections ◆ JANUARY 2009 http://www.denford.ltd.uk http://www.denford.ltd.uk http://www.techdirections.com/past-issues.html http://www.techdirections.com/past-issues.html
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