FLOUTING TRADITIONAL CENTRAL DRYING PAYS OFF
20 October 2006 - DTI Globalwatch

This quick-change manifold system makes it possible to keep up with about 50 mold changes a day, performed with dedicated QMC systems on each IM.

North American Lighting knew improperly dried resin was causing splay defects, and sought a solution. The one they chose didn’t have the smallest price tag, but it’s the return that justifies a good investment.

Some of the most noticeable recent advancements in cars involve the lighting. Headlamps, rear lights, and fog lamps not only perform better but also are great looking, real attention-getters. And since they are so visible, carmakers naturally want them to be, you guessed it, perfect.

Tier One supplier North American Lighting partners with its automaker clients to design those curvy, glowing good looks. It speaks of nothing less than jewel-like quality, and that’s what NAL delivers. But molding optical parts, mostly in acrylic, PC, and ASA, without any visual defects, is not easy. Don Hall, the general foreman of molding at NAL’s Salem, IL plant, says customers won’t accept defective vehicle lenses or housings, and NAL can’t afford rejected parts.

Making Splay Go Away
NAL had been using desiccant dryers for years, and Hall says the company had determined most of its splay defects were the result of improperly dried material. Splay is a bear of a problem in any case, but it’s especially acute with the hygroscopic materials NAL largely uses. The company therefore went about testing dryers, thoroughly. It found excellent results with desiccant-free NovaDriers (Novatec) and began using them. Hall says the dryers consistently reduce dewpoint to .02% in about 2 hours and hold it there. When NAL put them into use on an individual basis, splay problems diminished drastically.

So when the time came to replace an old material handling system for one section of the plant, the NovaDrier got the nod. The molding production section in question has 21 IMs, which collectively average more than 50 mold changes a day and need access to 50 different materials/grades. The materials need to be dry and ready to upload quickly because every IM has a quick mold change system. Did the letters JIT just pop into your mind? It’s a way of life at North American Lighting.

Rising to the occasion, Novatec and its agent, Thermal Tech Equipment (Gladstone, MO), designed and installed a JIT material handling system. For material handling, they employed a dedicated line system and a quick-change manifold that allows any material to reach any machine. Since dried material is conveyed on a JIT basis, the resin is conveyed with dry air from an existing desiccant-type dryer, and the lines are purged with every cycle. At the front end there are 50 NovaDrier units in operation.

Results Count, and Compute
Just about everyone knows that using 50 separate dryers in a system of this type is not common. Even Novatec says that for larger systems it is usually more economical to have a large central desiccant dryer providing air to many hoppers. But North American Lighting had a lot of testing and experience that showed NovaDriers were proven to slash the reject rate, even if using them vs. central drying would cost more initially. Tellingly, the engineering and manufacturing specialists at NAL, part of the Japanese-based Koito Group, a worldwide force in automotive lighting systems, could justify a higher cost to its management.

There are more benefits than reducing splay-caused rejects. Novatec promotes the NovaDrier’s low maintenance, largely due to the absence of desiccant. Change two filters every six months and you’re done. There are no process motors, regeneration motors/heaters, or valves to go down, and cooling coils are not needed on high-temp applications. The dryer uses untreated compressed air from the plant, which eliminates the expense of air treatment equipment. But a patented design that includes the membrane means NovaDriers offer a guaranteed dewpoint of –40ºF or lower. Novatec offers the dryer in a capacity range from .5 to 150 lb/hr (.2 to 68 kg/hr) and says it works with all materials.

Although NAL declines to provide specifics about the cost savings and increased yield, its increasing use of this technology speaks volumes. Including the 50 units in the JIT material handling system, NAL has a total of 70 NovaDriers in its Salem plant. Hall says the company improved product quality with its first NovaDrier, took the advantage into the JIT system, and has significantly improved product quality all along the way.

“That makes us happy,” Hall says, “And more importantly, our customers are happy with our improved performance.”

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