Micromolding makes very small parts, but nanomolding is a different world, and one that is—and may be for some time—a very small market niche for applications, many of them medical, where micro is just too big.
As if “micro” parts aren’t small enough, there are applications for even smaller parts, primarily for use in medical devices, but as electronics products continue to shrink, more components become candidates for nanomolding as well. Talk to anyone who works with micro and nano parts and you’ll quickly learn that there’s a huge difference between the two—no pun intended. In the August 2010 issue, MPW published an article about micro- and nanomolding in which Mark Kinder, president of Plastic Design Corp. (PDC), a Scottsdale, AZ micromolder, provided a good working definition: You can see micro parts, but nano parts you can’t see, except with a high-powered microscope.
Medical Murray’s Sesame nanomolding machine molds any standard injection molding material, including thermoplastics, thermosets, and silicones, and has an easily convertible feeding mechanism to allow molders to go back and forth between thermoplastics and thermosets.
“About 15 years ago, after the two principals founded the company, they realized an opportunity existed in molding medical devices smaller than the micromolding technology of that time could offer, yet there were no options out there,” explains Brent Roland, VP of marketing and sales for Medical Murray, which is exhibiting at the MD&M West show in Anaheim, CA this month in Booth 942.
If you build it . . .
The company’s owners then designed, developed, and patented a nanomolding machine they called “Sesame” because it was capable of molding parts smaller than a sesame seed—something micromolders at that time could not do. As the technology moved forward, notes Roland, micromolders have become capable of molding smaller and smaller parts.
“Nano parts are very small parts that require magnification to see what you’ve got,” says Roland. “My personal description of nanomolding is when the micromolder says, ‘I’ve given my best shot and can’t do it—it’s too small,’ that’s where we come into the picture and can do several multiples smaller than the micromolder can.”
For Medical Murray, demand and applications for nanomolding come mostly from the medical device industry. “Our heavy focus area is disposables—Class II and III disposables for such devices as complex catheter systems with many nano components,” explains Roland.
Another area for nanomolding of devices that are ideal for Medical Murray’s Sesame nanomolding machine is those made from bioabsorbable polymers. “Many of these bioabsorbable devices are drug laden and both the polymer and the drug are extremely heat sensitive,” notes Roland. “Machines that use a screw that keeps the material in a high-temperature state while waiting for the next shot are not good for bioabsorbable materials. Our machines don’t keep much material in a melted state, so we’ve had a lot of success in bioabsorbable polymer applications.”
Most of the customers who come to Medical Murray with these applications don’t call it nano, but they do know that micromolders can’t solve their problem. “When you get into it, for nanomolding applications, the micromolders are trying to use a very large hammer to hit a very small nail,” Roland adds. “Using the same analogy, our Sesame uses a very, very small hammer to hit a very small nail.”
Medical Murray started out thinking that perhaps the company could develop a very good market for its Sesame molding machines, but quickly found that customers wanted to buy parts, not molding machines. “Our interest is in developing new medical devices, not building molding machines,” says Roland. Medical Murray now has several Sesame molding machines in its manufacturing and development facilities.
When asked if he considers nano a niche market, Roland opines that it is only a niche because medical component designers and manufacturers don’t yet understand that parts of extremely small size can be injection molded using nanomolding technology and equipment. “People have to be aware that these sizes of components can be commercially molded,” he said. “In the bell curve of molders, by part size, we’re way over on the small side of the scale.”
To that extent, “It’s a marketing issue,” Roland says. “If you stop customers at a trade show and ask them about micromolding, they’re familiar with that. Those of us who make something smaller than that haven’t done an effective job in letting people know they can design and mold these parts.”
Typical Medical Murray nanomolding clients have often started with a micromolder who ultimately was not able to help them due to the extremely small size of the device. “The client then searches for another solution provider who can mold very, very small, geometrically complex parts, such as those we mold at Medical Murray,” Roland says.
There’s no other machine like the Sesame, according to Roland. “It’s not magic, but it does use some technology that’s quite different from a normal injection molding machine,” he says.
Roland explains that the capabilities of Sesame nanomolding machines use numbers much smaller than those used to describe micromolding machines. “We talk about parts per pellet of polymer,” he states. “Typical shot sizes are 0.08-0.35g, with at least a 100:1 turndown,” he says. “Part volumes are typically in the range of 0.01-100 mm3.”
Nanomolding is a different world. Roland says that out of every 10 applications that come to Medical Murray’s door, eight are ones where the company can help, and the other two are people wanting to mold devices at the molecular-size level. “That we can’t do,” he admits. “Below a micromolder’s capabilities, we can help. And while micromolders have greatly increased their capability to create smaller and smaller parts, there is an increasing number of applications where a 5-ton press is way too big.” —Clare Goldsberry