Huntsman wins accolades for new 3-D machine

For the Araldite Digitalis development team at Huntsman Advanced Materials, Basel, Switzerland, winning the EuroMold 2008 Gold Award in December for its polymeric additive fabrication system was a welcome milestone in what has been described as nothing short of an adventure.

“It has been a challenging adventure,” observed Philippe Michaud, global technology director for Huntsman, “and it is not finished.”

The adventure began just about 3 years ago when the Huntsman team decided the estimated $1.2 billion rapid manufacturing market called for a new radiation curing technology that would fill the need for more accurate and repeatable parts than can be obtained from existing technologies, such as stereolithography.

Though Huntsman is one of the pioneers of SL resin materials, the team knew coming up with a more accurate radiation curing technology would take more than just a new chemical, said Michaud. “We had to take the step to change the process.”

That meant a new machine—fundamentally different from other technologies, neither based on lasers nor on light-reflecting microelectromechanical systems used in 3-D printers. Enter Araldite Digitalis with a new technology that Huntsman has dubbed “Micro Light Build.”

There are three main components of the machine: the operating console, the vat enclosure with recoater and the exposure system—the MicroLightSwitch. Described as “the heart of the machine,” the MLS unit is operated via a computer-controlled micromechanical shutter system that selectively exposes the surface area of radiation-curable resin in a single step.

Unlike other radiation curing techniques on the market, such as laser-based MEMS technology that exposes one point at a time, the Araldite Digitalis machine is said to be capable of exposing 40,000 points at a time.

By comparison, SL techniques that use a laser can only expose one point at a time, drawing line by line with a varying angle that depends on where the laser irradiates.

The machine’s ability—thanks to the MLS units—to cure a larger surface area of resin that is selectively exposed at one time is among the key benefits of the technology, according to Huntsman. The MLS units can selectively irradiate micron-size points onto a resin surface via the micromechanical shutter built into silicon MEMS chips.

Ultraviolet light is distributed through fiber optics onto the exposure bar where MLS units distribute UV light pixels onto the resin surface. The computer-controlled shutter mechanisms steer the exposure of the UV light to avoid scattering. The illuminating angle of the UV light is set at 90º, which is said to guarantee uniform and pinpoint accuracy. Microlenses refocus the UV light after leaving the MLS unit.

Huntsman demonstrated the machine’s capabilities by reproducing a rose. For a full vat of roses, Michaud said, production time would take just a few hours with a head speed of about 10mm per second.

The Araldite Digitalis has a build envelope of 650mm × 370mm × 600mm, an exposure system consisting of two UV lights and 16 MLS units, and a head speed of 3mm to 50mm per second. The machine is capable of producing resolutions of 10µm, 50µm or 125µm on the X-axis, 10µm on the Y-axis and 50µm, 100µm or 150µm on the Z-axis.

In trials, added Michaud, the Araldite Digitalis produced “some pretty complex shapes with hearing aids.” Producing everything but the electronics, he continued, the machine could produce up to 400 hearing aids at a time, with each device about 2cm × 1cm in size with details in the 50µm to 100µm range.

Without this process, noted Michaud, the hearing aid would have to be built in several parts and steps.

“That’s why people want to use this technology,” continued Michaud, “because it can produce very small, complex 3-D structures.”

Though not shipping yet, Michaud said Huntsman is already taking orders for the machine, which in May made its official debut at the RAPID 2009 Conference and Expo in the Chicago area.

Araldite Digitalis, a new rapid manufacturing machine capable of producing large numbers of parts simultaneously. The MicroLightSwitch, the heart of Araldite Digitalis, shown in inset. Photo courtesy Huntsman Advanced Materials.

At press time, the company was still working out pricing for the machine, Michaud noted, along with that of the resin material designed specifically for use with the Araldite Digitalis.

“We can’t divulge too much about the material,” he added. “The current technology used for lasers—due to wavelength differences—cannot be used for this machine. So we had to develop new resin technology for the Araldite Digitalis.”

Since Huntsman introduced the machine at the EuroMold 2008 exposition in Frankfurt, Germany, last December, Michaud said interest has been strong from companies looking to purchase the machine.

“We have very positive feedback from the market,” added Michaud. Winning the EuroMold 2008 Gold Award, he added, was important because it was recognition of the team’s effort to bring the machine to market in just over 3 years.

Gold, silver and bronze awards, according to the EuroMold Web site, are given to exhibitors at the worldwide trade fair for moldmaking, tooling, design and application development. Winning entries, the site noted, must display “great novelty and truly distinctive innovation, representing new market strategies, enhancing international competitiveness and customer value, supporting cooperation among companies, introducing energy-saving and environmentally sound technology, improving manufacturing processes and having the potential to generate new jobs.”

“I am delighted for everyone in the team to have won this prestigious award,” observed Michaud. “It truly has been an adventure. You have the feeling you pioneered something ... something concrete.” µ