I can see clearly now

With perfect clarity as the elusive goal, optical lens molding is among the most challenging molding jobs around. After some struggles, one molder turned to fines dedusting equipment to create a more reliable process.

As IMM caught up with Jack Schubert, he’d just finished shutting down his press and trading his process tech hat for that of CEO. “I’m just sitting here unwinding,” Schubert says after another day at MagEyes, where he serves as machine operator, tool changer, QC inspector, marketing manager, and when he gets the chance, president and CEO.

“CEO stands for ‘catches every odd job,’” Schubert jokes. “If I have to pull the barrel and screw and clean them, I get the hot gloves and fork truck.”

Things weren’t always this hectic, but an unexpected price hike from a supplier put Schubert and MagEyes in the molding business much sooner than anticipated. “At some point we intended to take over the molding ourselves,” Schubert says, “but [our supplier] precipitated it by quadrupling its prices.”

Schubert was recruited to MagEyes for his 22 years of molding experience, and he would need it all to mold the centerpiece component of MagEyes’ product—optical lenses. A small company built around the invention of hands-free magnifiers worn like a visor, MagEyes creates these magnifiers to assist vision-intensive work like sewing, fly tying, or model building.

With a brand-new, 90-ton, all-electric JSW press, a dryer, and 1500 lb of optical-grade acrylic on hand, Schubert was ready to go. One last shipment of lenses from his old supplier bought him some time, but he knew he’d need a reliable process soon.

Rose-colored Glasses
At first, it looked like Schubert wouldn’t need that extra time, since the new in-house molding operation clicked right along. “We went through about the first 600 or 700 lb of material almost flawlessly,” Schubert says. “Then all of a sudden we just could not make a good lens.”

An instrument that demands perfect optical clarity, the magnifying lens must be devoid of any defects, and MagEyes’ first run became rife with them. Schubert describes everything from curlicues of unmelted plastics to what looked like little rocks embedded in the lenses. Yields were down to 50 percent and not getting any better.

“If I loaded the machine and I was wearing a red shirt,” Schubert explains, “there’d be red lint in the lenses. If I wore a blue shirt, there’d be blue lint.”

Schubert had taken what he thought would be adequate precautions, filtering the material dryer air, tying off the bag of material, and doing everything to ensure dust didn’t infiltrate the acrylic, but it simply wasn’t enough.

Breakdown, Breakthrough
“I came into the office,” Schubert says, “and I was totally frustrated. I thought, ‘What do I have to do? Where do I have to go?’”The answer came in a magazine ad as Schubert flipped through a plastics periodical. There, he saw information on the Pelletron P1 Mini-Deduster. Too late to call Pelletron, Schubert visited the company’s website where online testimonials and case studies recalled travails similar to his own. The next day, he ordered Pelletron’s smallest unit, the P1, which had a throughput of 150 lb/hr with fines separation of particles as small as 10 µm.

Using a flux field generator to produce a low-power electromagnetic field, the P1 disrupts the electrostatic bond between the resin and any unwanted particulates. Inside a Venturi chamber, an updraft of air removes even heavy particles like streamers and carries all unwanted materials out to a dust collector while cleaned material moves on for processing.

Yield rates immediately shot up from 50 percent to as high as 92 percent, and Schubert watched the cost of lenses fall from the outsourced price of $2.36 to $.75 to create them in-house. Schubert is still MagEyes’ Jack-of-all-trades, but now he spends far less time wearing his QC inspector hat.

“We have good days and bad days,” Schubert says, “but they’re not due to the equipment—they’re due to me. Lens molding requires attention to detail; once you get a good process, you’ve got to stick to that routine. We’re still learning, and we don’t pretend to be a professional optical molder, but we’ve been forced into it.”