IMM's Plant Tour: Tour de force in micromolding

Going the extra mile-or in this case, the extra micron-is all in a day's work at Micro Precision Plastics (MPP). Built from the ground up for micromolding and small parts production, this Canadian custom molder pays attention to even the tiniest of details in a major way. What else elevates MPP to the "tour de force," or exceptional achievement, level? During IMM's recent tour, many of the answers could be found both on the shop floor and under the microscope-amazingly complex and demanding micro parts produced to zero defect levels for OEM customers that include heavyweights such as Xerox.

Make no mistake, micromolding can strain the limits of even the most exacting molder. Gary Lane, president, explains that MPP differs from others in the field because it is geared entirely to this niche. "When my wife, Chris, and I started the business in 1994," he says, "we saw an opportunity for molding small-sized, high-precision parts on small machines. Other molders were running small or micro parts on large machines, and were unable to control dimension and sizes. Often they would have to put so many cavities in to balance the shot size that they'd end up fighting with dimensions. Instead, we invested in mainly 25- and 35-ton machines that are sized for small part molding."

Apparently, the Lanes' hunch was correct. MPP has doubled sales every year for five years. Initially, the plant supplied parts to other molders. These early customers needed someone to mold parts for assemblies-parts that were too small for their machines. Although MPP still does a fair amount of this type of work, most of the business is now geared to OEM end users in business machine, electrical connector, and automotive markets.

Creative Design
Roughly one year ago, the Lanes moved operations to the current building. From the time MPP designed its new plant to the time construction began, business had grown so rapidly that it had already outgrown the space, even though it had yet to move in. The Lanes hit on the idea of creating a second floor mezzanine when they looked at the 24-ft ceilings still under construction. "Most of the space was empty, so putting another floor there nearly doubled our manufacturing space," he explains. The plant now has two floors, each with 12-ft ceilings.

Small advantages proved important here, too. The machines are not as large or heavy as typical 300- to 1000-ton presses. As a result, the mezzanine didn't need much reinforcement-just enough to aid in dampening vibrations. This second floor is actually a free-standing structure floating on its own support beams within the building, and there are 26 presses on it. With larger machines, this creative use of space would have been impossible.

The entire plant is fully air-conditioned to control the environment year-round. For health and safety reasons, the system also includes an air-to-air heat exchanger so that there is no fume buildup in the air (MPP runs a good deal of acetal for gears). "We've designed the plant for uniform part quality, and eliminating variations in environment is important to that," Lane says. In addition, the plant includes a central chiller instead of a cooling tower to control water temperatures. Air, water, and power utility lines are mounted on the ceiling of the first level, so they are routed up either to the mezzanine or down to the first floor machines.

The second floor consists of two rows of Battenfeld Plus machines ranging from 25 to 35 tons. Each press is equipped with part-removal robotics and runs 24 hr/day during the week. All 25 of these Plus machines have been acquired over the last five years. Lane says he carefully researched the small-machine market and chose the Plus after reviewing the data and consulting with other molders who had used the machine and its competitors. Their biggest upside, Lane adds, is a user-friendly control system that simplifies setups and offers consistent accuracy.

In addition, on the first level, there are six Milacron Roboshots devoted to running connectors, four Nissei HM7 machines, and six Bantam 9-tonners. On weekends, there are eight to 10 machines running.

Five years ago, when MPP opened its doors, there was a problem getting auxiliary equipment that met the needs of the small-parts molder. That scenario is changing, though. Today, the plant includes special mold temperature controllers (Conair MicroTemp, the smallest on the market) and a dryer system (Dri-Air) that is made to handle 10 lb/hr of material.

"The majority of dryers are in a central location," he says, "but we are slowly moving them to individual machines because we are now scheduling machines to run only one material. For example, some machines will run only nylon, so those will be equipped with individual dryers. For some of the smaller machines, though, it's impossible to mount a dryer on them because of their size. In these cases, we'll continue to use a central dryer arrangement."

For the 26 machines on the mezzanine, it takes only one setup person, two operators, and one inspection specialist to keep production running. The nature of the business and the demands of just-in-time requirements dictate many short runs. MPP often does 20 or more mold changes per day.

When it comes to waste, there is a paradox involved in micromolding. The runners tend to be larger than the parts themselves. To cope, MPP has installed a closed loop regrind system on many of the Battenfeld presses. "We can store weeks worth of material in a Rubbermaid trash can," Lane quips. The runners are sent through a granulator (Rapid); a proportional feeder picks up the regrind and mixes it into an autofeeder. MPP regrinds and uses its production scrap in percentages agreed to by clients. Regrind can be as much as 30 percent but is most commonly around 20 percent.

Tooling Tactics
Tooling for small and micromolded parts is an area in which customers often need to be educated. "We've pushed customers to go to fewer cavities. Instead of running an eight-cavity mold with half of the cavities blocked off, we go with two four-cavity molds on smaller machines to control dimensions better. I always feel it's better to have two molds than one for a part that is running all the time, because if the mold goes down, you at least have the other one going. On one project, we ship 35,000 parts per day from two four-cavity molds. Having two molds also gives us time for maintenance."

Also, with small machines there is no need to go to more expensive and difficult multicavity molds to gain production economies. MPP can

be competitive with single-cavity molds, even on parts in which production is as much as 100,000 or more per year. In fact, one single-cavity mold makes a million parts per year. Though the company has worked with hot runner molds in certain situations, with one or two cavities it is just as easy to design the mold with very small runners and spare the expense of hot runners.

Interacting with its toolmaker is no problem for MPP, because its supplier, C&L Molds, is located in the same building. In an unusual arrangement, C&L Molds, owned by Dave Coles and Steve Lee, owns the building and land jointly with MPP, yet each operates as a separate company. C&L consists of seven toolmakers and builds molds exclusively for MPP, which buys only about 10 percent of its molds elsewhere, and usually then only to meet workload or specialized technology needs.

With more than 800 part numbers, either as full molds or inserts, MPP builds 80 to 100 new molds per year. Work frequently comes in sets of between 10 and 20 molds when a major customer releases a program for a new product. MPP uses standard mold components and inserts frequently to lower costs and to cut startup time on a new project. In case of a customer emergency, a pulley or gear mold can be turned around in a couple of days. Usually, though, lead times are four to six weeks. "For a good customer, we are happy to make whatever effort it takes," says Lane.

Although they have used standard mold bases, MPP and C&L have designed their own line of bases for micromolding. For gear molds, the toolroom has a supply of blank inserts already cut that need only to have gear teeth and drops put in. "In this way, we can improve our response time to the customer," adds Lane. When a client had a crisis with an acetal gear, for example, C&L was able to cut a cavity and core for a prebuilt P-20 tool and Lane had parts to the customer the next day. This is highly unusual, but indicative of the lengths to which MPP will go.

In addition, some small parts have required brushes in the mold to sweep out parts that are sticking. This requires specific expertise, but when the parts are too light to be handled by air, this technology is needed to ensure consistently good part removal. "Because they are so small and light, static will make them stick to the mold. We use compressed air from the materials handling system [filtered and dried] to remove most parts, but at times, we have to combine this with brush removal. The brush is a toothbrush fitted into an air cylinder to impart a light action," he says.

Quality Details
With a zero-ppm defect rate for customer Xerox, it's clear that MPP pays close attention to quality. SPC and

P-charts are used extensively in concert with ISO 9002 procedures. On most parts, checking weight is almost impossible because parts don't have the mass required to give good resolution on a scale. As a result, inspection equipment includes two video measurement systems, a Microview 250x magnifier, and a newly added computerized gear checker.

Each molding machine has its own sorting table, located away from the press, where operators pack and sort parts. The table also doubles as the station for part information. Every job has a Part Information Book (PIB) that contains work orders, shipping labels, quality plans, SPC inspection charts, drawings, and change sheets. The PIB is central to communications.

For a new job, after mold trials are performed, the engineer produces a mold setup sheet that must be approved by the engineering department. Any changes to an approved setup must also be approved. SPC checks are done every hour, and at startup, every half hour. At shipping time, the QA inspector produces a ship log audit, and is the only person who is allowed to close a box of parts and certify them for shipment. No one can break that rule.

According to Lane, quality is paramount at MPP. "And cleanliness is just as important," he adds. Rather than employing air blowers, MPP vacuums the floors every shift, using a central vacuum system installed on each floor. It helps reduce the dust level in the plant, which directly assists quality. The environment would meet Class 100,000 cleanroom standards if it were audited. "We could easily switch to cleanroom molding if that becomes necessary," he says.

As the company was getting started, an automated material feeding system and robotic pickers were considered too costly. That opinion quickly changed as Lane realized how their benefits override the cost. He explains, "If there was one thing I would change in the company's history, it is that we would have automated more and faster."

Lane buys only new equipment; most of the current equipment is less than three years old. He also prefers that everything on an injection molding machine come from that machine's manufacturer, including robotics and auxiliaries. "You buy it as a complete system, and if there are any problems, you only have to make one phone call."

A Micro Future
Lane sees many growth possibilities both with current customers and new ones. Awareness is increasing among designers about the possibilities for small and micro parts in plastic. In addition, many products already on the market are being miniaturized, and emerging electronic marvels are aimed at being small, personal, portable, palm-sized, and wristwatch-sized. The parts inside of these products, which include everything from mobile phones to laptops, must be small and precise. And as the world miniaturizes, MPP is cheering it on.

Lane has no plans to move to larger machines. "There is plenty of room to grow in the small parts market, and there are some very significant market advantages for a manufacturer like MPP," he explains. "When you can ship a three-month supply of a part to a customer in a package that is less than one cubic foot, the customer can be almost anywhere in the world, or at least anywhere UPS, FedEx, or DHL will go."