Citizen Watch introduced its first wristwatch in 1931. Since then, it has grown into the global brand it is today: an innovative firm with a solid reputation earned through products like the ‘Eco Drive’, which works by converting light into electrical energy, and radio-controlled clocks that update to the correct time within 1 second every 100,000 years using standard radio waves from an atomic clock.
As part of its development strategy, Citizen has an in-house prototyping division. Before purchasing the ProJet® 3500 HD 3D printer (now sold as the ProJet 3510 HD), engineering used NC lathes to create mock-ups of finished watches and assembly jigs. Because machining in this manner frequently generates additional costs and adds timeline delays, however, engineering decided to explore options in 3D printing to reduce prototyping costs and shorten development time.
The ProJet 3500 range of printers offers a variety of high volume, high performance 3D printers using MultiJet Modeling technology, which creates plastic parts for functional testing and verification, end use parts as well as wax patterns for investment casting. The printers work with the VisiJet materials, which are UV-curable plastics in a range of colors and tensile strengths, with wax material as supports.
Going from a designer’s sketch to a prototype involves repeated design reviews and adjustments, and machining a new prototype for each suggested change takes time and money. Since timeline restraints limit the number of verification models that can be made, the engineers could not explore all the ideas using machining. So the company decided to investigate 3D printing as a means of giving its designers time to thoroughly review designs during early stages to produce better final designs. Among the ten 3D printers evaluated, 3D Systems’ ProJet HD satisfied all of Citizen’s needs, including detail precision and surface quality. After evaluating the ProJet, engineering expected it would serve a variety of other needs beyond external design as well, including the jigs that hold the parts.
“If it offered nothing else, the ProJet HD has an extraordinarily high level of precision, which is extremely important when piecing together small watch assemblies,” said Mr. Naito of Citizen’s Technical Development Division. “The ProJet has other significant advantages as well. There is minimal distortion, warping or variation in batches, and the surface quality is superb, with fine details and sharp edges. The material is of a higher quality, stronger and less brittle than competitors’ and has easy post-processing, with the ability to melt wax away. It’s also exceptionally easy to use; even a beginner can master it in two to three days.”
Citizen’s main reason for acquiring its 3D printer was to evaluate mock-ups of wristwatches for new model proposals. “Since the VisiJet® material can be dyed or painted, we are able to quickly and easily evaluate mock-ups with the look of a finished product,” said Mr. Naito. “We saved three times the installation cost of the ProJet HD within six months, and we can spot problems with physical models that we couldn’t see with CAD alone. We can now fine-tune and make improvements before producing the final mock-up, which has led to improvements in quality alongside beneficial reductions in time and cost.”
Engineering is also using the ProJet HD to magnify and print tiny structural parts at three times their actual size to examine their movement and produce new assembly jigs. Before getting its 3D printer, they produced one variety of assembly jig. Since acquiring the printer, however, they have created new jig candidates, enabling them to make the best-suited shape for the required fit in the shortest amount of time. The ProJet HD has transformed a 20- to 30-day process into overnight production, and has been seamlessly incorporated into Citizen’s workflow as a powerful development tool.
With support from D-MEC, the reseller involved with the project, complete support, from benchmark to technical tips, the 3D printer was in immediate operation and is used by many designers. It has made operations less confusing, and has inspired the watchmakers to continue looking for ways to use it beyond its research and development departments. “We want to move beyond traditional divisions and include departments with pressing needs of their own that are directly involved with production,” Naito said.