Fast prototyping helps appliance maker
Rochester Hills, Michigan - Appliances with stainless steel outer panels, particularly refrigerators with French doors, have become a hot item in home décor, and manufacturers are scrambling to get new models into stores. For help in getting new products to market fast, GE, one of the world’s largest appliance makers, turned to 3-Dimensional Services Group.
Rochester Hills, Michigan - Appliances with stainless steel outer panels, particularly refrigerators with French doors, have become a hot item in home décor, and manufacturers are scrambling to get new models into stores. For help in getting new products to market fast, GE, one of the world’s largest appliance makers, turned to 3-Dimensional Services Group (www.3dimensional.com), a firm that specializes in design, engineering and analysis, in-house tool construction, and complete build of first-off prototype parts and low-to-medium volume production runs.
3-Dimensional’s job was to create the outer door panels for five new models of stainless steel French door refrigerators (two French doors and a freezer door per model). Approximately 250 three-door sets were required for each of the five models. In addition to the stainless, these five new French door bottom-freezer armoire style models required that some doors be formed from smooth pre-painted cold-rolled steel and others be formed from textured pre-painted cold-rolled steel. This meant that 3-Dimensional Services would be dealing with different material thicknesses, ranging from 0.024 in. to 0.032 in., depending on the material employed. To top it all off, the entire project had to be completed in eight weeks.
The first challenge was to create the tooling for the four hydraulic presses, ranging from 400 to 1600 tons, that 3-Dimensional Services intended to use to make the new parts. The rapid creation of accurate tooling is a problem the company faces and solves on a regular basis. The parts had to have a Class-A finish, free of scratches or blemishes or any kind, because GE wanted models available for consumer in-home testing, as well as in Home Depot as sales display models, even before full production began, in order to gain a step on the competition in this rapidly changing market.
In approximately four weeks, 3-Dimensional created tooling with steel inserts to ensure optimum part definition. This was not a small order because multiple die sets for each of the five models were required. The tooling was meticulously polished to help ensure a cosmetically superior finish, and the parts were protected with plastic sheeting during forming.
Subsequent to forming came trimming operations, first with trim dies and then with 3-Dimensional’s 3- and 5-axis lasers. In addition to laser trimming, careful handling of the parts as they were transferred between operations helped ensure that the excellent finishes were maintained.
The quality function was a three-stage process. There was a visual inspection of all the parts. This was critical because it was the same inspection that customers would perform in the stores. For dimensional accuracy, coordinate measuring machine (CMM) inspection was employed with the CMMs taking data points every 100 mm.
Finally, there was fixture inspection. Like everything about this project, the check fixtures had to be created quickly and accurately, so 3-Dimensional Services used stereolithography (SLA) to create them, with the SLA's laser beam rapidly curing light-sensitive polymers into the desired shapes. The check fixtures mirrored the plastic end caps that GE would fit to the tops of the doors. They had to fit precisely for the doors to open and close easily -- a must for consumers.
3-Dimensional had to ensure that the parts would arrive at GE in perfect condition so 3-Dimensional created its packaging. Using a CNC-heated wire machine, 20 lb. polystyrene foam end pieces were cut to the precise shapes the 3-Dimensional team determined would best protect the large thin door sets and their excellent finishes, a design so successful that GE adopted it for their use.
Responding to GE’s stringent quality and time constraints, 3-Dimensional created 250 door sets for each of the five new GE models in a brief period of time. As Mike Baranowski, Program Quality Assurance Manager, observes, “The challenge didn’t consist merely in making the doors. The challenge consisted in making the doors, the check fixtures, designing and manufacturing the packaging, and doing it all in eight weeks in order to help GE re-energize its product line. That was the big story.”