When consumer tastes change, appliance manufacturers have to respond. That was the case when stainless steel refrigerators came into vogue. Aided by their frequent appearance on home decorating TV shows, appliances with stainless steel outer panels, particularly refrigerators with French doors, became the hottest item in home décor and manufacturers scrambled to get new models into stores. For help in getting new product to market fast GE turned to a firm that specializes in design, engineering /analysis, in-house tool construction, and complete build of first off prototype parts and low to medium volume production runs. Their methods/manufac-turing technologies mean prototype parts – not just models -- are typically provided up to 70% faster than conventional prototype shops.

“When we were contacted, they said they needed to make a new line of refrigerators with stainless steel outer doors to meet market demand,” recalls Steve Kelly, senior sales engineer. “GE had to move fast in order to get these new models into the stores by spring in order to take advantage of this major sales opportunity. Our part in the process had to be done fast and it had to be done right.”

3-Dimensional Services developed 250 three-door sets of stainless steel refrigerator panels within eight weeks to assist GE in the launch of its new models.

The company 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 to be formed from textured pre-painted cold rolled steel. This meant that they 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 ton needed to make the new parts.

Class A Finish Required

“These parts had to have a Class A finish, free of scratches or blemishes or any kind,” says Mike Baranowski, Program Quality Assurance Manager. That’s because GE wanted models available for consumer in-home testing, as well as sales display models, even before full production began, in order to gain a step on the competition in this rapidly changing market.

“They wanted the highest quality prototype parts we could produce,” continues Baranowski. Toward that end tooling was created with steel inserts to ensure optimum part definition. This was no small order as multiple die sets for each of the five models were required. This was accomplished in approximately four weeks. 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- and 5-axis lasers. The company’s lasers coupled with in-house cutting expertise enable optimum tolerances on everything from thin sheet metal to thick armor plate. The formal stage of the quality function was a three-stage process. There was a visual inspection of all the parts. This was critical, as it was the same inspection that customers would perform in the stores. For dimensional accuracy, coordinate measuring machine (CMM) inspection was employed 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 stereolithography (SLA) was used 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 in order for the doors to open and close easily – a must for consumers.

But rapidly producing dimensionally accurate and cosmetically attractive parts was not the last challenge: the company had to ensure that the parts would arrive at GE in the same condition. Not convinced that conventional packaging would do the trick, it created its own. Using a CNC heated wire machine, 20 lb. polystyrene foam end pieces were cut to the precise shapes that would best protect the large thin door sets and their excellent finishes. The design was successful and GE adopted it for their use once the parts were in production.

Responding to stringent quality and time constraints, 250 door sets were quickly created for each of the five new models. As Mike Baranowski observes, “The challenge didn’t consist merely in making the doors, the challenge consisted in making the doors, the check fixtures, and 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.”

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