IMM's Plant Tour: Virtual-knowledge micromolding

The term micromolding means different things to different people. Rolla Micro Synthetics (Rolla AG), a micromolder and micromoldmaker in Grenchen, Switzerland, considers parts weighing up to 15g to be large, or mid-range parts. However, Rolla rarely molds anything so big. It calls parts up to 1g small parts. The term micro is reserved for parts weighing 1 mg or less.

For example, Rolla molds more than a million POM copolymer step-motor pinions a week. Each pinion weighs in at .0008g. Molded parts weighing in on such a small scale with micrometer tolerances—that’s what Rolla calls micromolding.

Rolla has created a registered trademark to describe its specialty: M3P, micromolded mechanical products. The superscript 3 is meant to imply cubed, or 3-D products. The key, though, is the word products. Not experimental theories, but real products. For a number of sound competitive and economic reasons, the company recently decided to become exclusive M3P specialists.

Here’s one reason why. Progress in plastics materials over the past decade has allowed plastic parts to be micromolded faster, cheaper, and better than the traditional metal parts they often replace. Modern plastic materials also help designers create brand-new applications involving micromolded components. Such plastic materials are expensive and are hard to come by in Switzerland. But when you can warehouse your production run in your trouser pocket, there is little need for a lot of raw material.

“At Christmas time, we ask our materials suppliers for free samples, rather than for a bottle of wine,” jokes a Rolla source. Unlike shops molding large parts—macromolding shops, they say—Rolla has found that materials account for only 5 to 10 percent of its total micromolding production costs.

Rolf Bucher, Rolla’s director of communications and marketing, tells us Rolla also has found that micromolding involves an entirely different mind-set than macromolding. It is much easier to see this different mind-set at work at Rolla’s plant than it is to see Rolla’s parts. We can try, though. Let’s tour.

Micromolding vs. Macromolding
Though we are anxious to see Rolla’s micromolding technology, Bucher cautions us first that something more than technology is required to produce high precision micromolded parts in large volumes and with consistent quality. Micromolding requires an entirely new approach to using molding technology, he says.

“Micromolding is a totally different field; a different life, feeling, philosophy; a different world. You cannot make big parts and micro parts at the same time and in the same place. We have learned that once you decide to go micro, there is no way back. You lose your customers for simple parts. It’s a critical decision to go micro.”

Bucher goes on to explain that micromolding involves tremendous differences in part design, materials selection, materials and product handling, processing and process control, training, tooling—you name it.

Take processing for instance. “We are always injecting a sprue,” Bucher says. “We are producing parts out of what is normally considered flash. We are unable to hold and control the part using conventional process control. Our parts are too small for cavity pressure transducers to detect, or for hot runner systems for that matter. And it only takes a microsecond to fill a .0008g part. Process control? How? We control the sprue. We make a perfect sprue to make a perfect part.”

Computer process simulation also is too macro, according to Bucher. “We put the gate where there is room, not where the computer tells us to,” he says. “You have to make an abstraction of what you know about molding to do micromolding. Simulations are based on what you know, but there exists no great body of knowledge when it comes to micromolding. We learn by trial and error, but we never turn down a part that is too complex. That is where the value is added. We turn down the ones that are too simple.”

Virtual-knowledge Networking
As you might imagine, micromolding demands an extremely specialized type of expertise, one that leaves little room in small companies for the other types of expertise required to grow a successful molding business. Yet, Rolla is growing and is growing globally. It plans to double its sales and production capacity over the next three to four years.

To do so, Rolla has established what Bucher calls a virtual-knowledge network of strategic alliances. This allows Rolla to learn from and continuously improve those elements of the M3P business it knows best, while allowing its allies to do the same. All share in the results, and all of their customers and suppliers benefit from the companies’ cooperative development efforts.

Rolla and its allies can share in these efforts in real time. The network makes full use of technologies like video conferencing and the Internet to make sure no one is left out of the loop, especially customers. You can see Rolla’s operation in action right now. Just go to its website. Shop-floor video cameras tied into the Web are running all the time.

Each customer has its own protected site for tracking every aspect of the progress of its projects, instantaneously—even through digitized microscopic imaging, if the need arises. With the size of the parts Rolla molds, it often does.

Virtual-reality Micromolding
As we begin our tour, Bucher explains the company’s name. Rolla is a take on the German word for rolling, a process like turning and milling in which Rolla specialized to make small metal watch parts when it first began. Synthetics is a word Bucher says the Swiss and a growing number of other Europeans prefer to use in place of the word plastics. Unfortunately, “plastics” still carries a cheap connotation. ”Synthetics” is classier and more high-tech, Bucher says.

The micro in the company’s name becomes obvious when we enter the first area of the shop. It is here that Rolla molds its smallest parts. Larger parts are molded in an adjoining room. Like everywhere else in the plant, this room is well lit. There are windows everywhere at Rolla. And it is as spotless as a cleanroom. All machine utilities are brought up from the basement where Rolla’s Motan materials handling system also is housed.

A bank of small-tonnage machines with sprue pickers and self-contained, closed loop recycling systems are running unattended. In case of trouble, there is a pager system on the far wall that can automatically contact personnel at home, if needed. There’s much to see, but your eye is drawn to the new Battenfeld Microsystem 50 in the center of the floor.

“We installed the Microsystem only three weeks ago, and we’re just gearing up to full production—at this time we’re doing first samples only,” Bucher remarks. He says they have already seen remarkable savings in materials and cycle times using the all-electric micromolding system, and attributes that to its first-of-its-kind process control capabilities. It allows Rolla to hold and control the part as well as the sprue, a first for the company.

Then we notice the cameras. They are everywhere. In addition to the built-in real-time optics in the Microsystem 50, Rolla has installed cameras and video systems in key areas of its entire plant, and then integrated them with the company’s website. Its customers and the other members of Rolla’s virtual-knowledge network can immediately conference over pertinent project issues, and watch the effectiveness of their solutions as they happen.

How do you handle scrap and products as small as .0008g? Rolla has developed its own solutions. When the mold opens, a robot with vacuum end-of-arm tooling transports parts to machine-mounted, color-coded baby bottles. Parts are separated by cavity for QC and traceability purposes. A sprue picker cuts sprues and deposits them into an under-the-press granulator for automatic transport to an enclosed behind-the-press drum. Recyclate can be directly reused three times before being proportioned into other, larger Rolla parts.

Micromolding Needs Micromolds
Upstairs, in the QC department, Rolla’s Stefen Kindler is performing a noncontact CMM check on attributes of a micro part with an OGP Smart Scope. Nearby is an entire station dedicated to testing the concentricity of a small connector Rolla molds. A dedicated client server gives the customer direct access over the Web to all the SPC data generated.

Bucher explains that Rolla assigns a single engineer, like Kindler, to each part it takes on. This engineer handles everything from design, to machine setup, to QC. Rolla has found that when an engineer is assigned to a specific company rather than to a part, it is more difficult for its M3P technologies to change and to grow. Diversity breeds evolution. This core philosophy is also the foundation of Rolla’s virtual-knowledge network.

Rolla concentrates on its specialties—QC, concurrent engineering, and micromolding—and encourages member companies, like Battenfeld of Austria and Swiss micromoldmaker Mimotec, to do the same. All the network members are dealing with other companies and parts projects, like all of Rolla’s engineers. They all benefit from the knowledge gained by their independent activities. The network’s success depends on independence.

Though Rolla outsources some specialty moldmaking, tooling is another of its in-house specialties. The toolroom also is upstairs, with windows facing the inspiring Alps. We approach a bench where veteran Rolla moldmaker Heinz Junker is working. Junker is one of Rolla’s eight moldmakers. We don’t want to disturb him, though. He’s working on ejector pins smaller than straight pins and cavity layouts smaller than a dime. And he’s doing it with neither a microscope nor an eyepiece. Whispering, Bucher alludes to one similarity shared by micromolding and macromolding—namely, that after all is said and done, no matter how sophisticated molding machines become, success depends on tooling. Bucher laughs out loud. Startling Junker, we ask him about Rolla’s reject rate.

“It’s zero,” he says. “We are producing quality parts right out of the mold. Once we have checked and certified the mold, our parts are forced to be to quality parts. Again, when you have microseconds to fill an .0008g part, you can’t control the part by controlling the process. The mold has to be accurate.”

Bucher summarizes, saying, “Our Microsystem 50 will give us new process control opportunities. We are sure of that. But the part is made from the tool, not the machine. We have successfully molded millions of those .0008g rotors before the Microsystem 50 was developed, thanks to our accurate tools. Our success is not a surprise—it is a result.”