IMM's Plant Tour:Self-reliant molding specialists

Location, location, location. It’s just as important in custom molding as it is in real estate. So why did Ironwood Plastics choose a remote spot in Michigan’s Upper Peninsula? According to Mark Stephens, whose family founded the company, there was a desire to simplify, something that couldn’t be done in the city. Detroit, that is. Although the plant is located in the same state, it is 600 miles from Detroit. “Washington, DC is actually closer to Detroit by five miles,” quips Stephens, who is the division manager for the Ironwood, MI plant.

This relatively distant location has shaped the way Ironwood operates as well as the services it offers to customers. “Molders located in the city can win most of the easy jobs,” Stephens says. “We realized that we had to supply the market with extraordinary capabilities, or it wouldn’t make sense for customers to make the trip.”

As a result, the company specializes in reel-to-reel insert molding, both horizontal and vertical; turnkey stamping services; and close-tolerance molding services for electronics, automotive, industrial, and military customers. “Our customers are looking to us to take a project and run with it,” Stephens says. “On insert molding projects, for example, we take responsibility for metal stamping and plating as well.”

Ironwood has also learned to be self-sufficient. More than 80 percent of all molds are designed and built in-house, allowing the company to maintain control of the project. A staff of 23 toolmakers (12 in Ironwood; 11 at a second location in Two Rivers, WI) produce production tools along with prototype steel tooling.

At first, Ironwood struggled to convince customers that parts wouldn’t get snowbound or that production wouldn’t be halted because of bad weather. To survive, the company became expert at shipping, squelching the snowbound fears. And although snowfall can reach 305 inches in the winter, Ironwood has missed only six shifts in 20 years of operation (13,687 shifts) due to weather. “Our people are our biggest asset,” Stephens says. “Their work ethic and stability have been essential in setting Ironwood apart from the competition. Our county has high unemployment—more than 10 percent—so people take their jobs seriously, making turnover very low.”

Molding Floor Specifics

We begin the tour on the molding floor, which is divided into two bays by a self-contained materials room located between the rows of molding machines. On one side are smaller machines up to 100 tons, some of which are vertical presses with rotary platens for insert molding. The other side contains larger machines from 150 to 250 tons. All molds are loaded by means of an overhead crane.

Each group of six machines is controlled by a section leader, who is responsible for troubleshooting and production. One operator can cover all six machines because most presses run automatically, thanks to a $4 million investment in 1997. “We installed Yushin robotics on every press,” Stephens explains. “After purchasing a new material handling system, we pulled the granulators, dryer, and the new equipment into a materials room.”

All of the presses are connected to the closed loop materials system. Cleanliness has improved and sound levels are contained with this layout. Stephens had originally planned to put the auxiliary equipment in the basement of the plant, but his father vetoed the idea. “My grandfather worked in an iron mine, and my father refused to put any of his employees in an underground facility.”

Because operations are largely automated and turnover is low, Ironwood can boost training to entry-level personnel. All operators are trained in visual and dimensional inspection and SPC, and earn the title of product inspector. Several are certified by ASQ as mechanical inspectors.

Over the next 18 months, due to customer projections for increased business, Ironwood plans to install nine new Engel molding machines. According to Stephens, being a turnkey supplier means that the plant becomes an extension of the customer’s production line. The planned investment is aimed at keeping Ironwood one step ahead of projected increases in demand.

Nerve Center

Between the two molding bays is the self-contained structure that houses both the materials room and quality department. Taking a look inside the materials room is a bit like peering into the body’s central nervous system. Material flows into and out of pneumatic tubes with precision, while granulators automatically send regrind to specific barrels. A central dryer presides over the entire room.

Only one operator is needed to run the materials room, dubbed the “Motan” room because all of the equipment (except blenders from Maguire) comes from that company. Twenty hopper-silos send material to the presses, including regrind if applicable. Each hopper can send material to one of six machines. “Our main goal with this room was to improve the consistency of material,” Stephens says, “and this system ensures that.”

Chillers and other cooling system components sit on the floor above the materials room. Ironwood’s quality department also resides in this island, separated from the materials room by a wall. Achieving and maintaining QS 9000 means that quality personnel are often interacting with the rest of the plant. “Giving this department a central location made more sense,” Stephens adds.

Special Attractions

One workcell in the plant attracts the most attention, perhaps because it contains two huge reels and a bevy of image sensors. Ironwood molds connectors for PCMCIA cards here, and the entire cell was constructed in-house, from the reel automation to the stamping and coining equipment.

The process begins with a large reel of plated metal stampings. A continuous strip is fed into a stamping station, which snips off the carriers. Leads are then coined in the next stage and continue on to a vertical Arburg press, where nylon 4/6 is overmolded onto the edge of the stamping using a four-cavity mold. The hot runner tool requires a 10-second cycle time, and the strip then cools as it is reeled up at the end of the workcell.

Ironwood produces 225,000 connectors each week for its customer, which uses the reels in another continuous process. “If there are any connectors in the reel that don’t meet specifications,” says Stephens, “our customer’s assembly line stops. So to avoid that, we have installed a vision system on this cell that checks for both bent leads and proper spacing.”

The imaging sensors (from DVT) are placed at several points in the process. If the system picks up any deviations, it alerts an operator via alarms. The technician can then either stop the process or cut out the offending connector and splice in a new set of leads without shutting down. With high production quotas, operators have become very adept at welding in strips on the fly, according to Stephens.

Another project that required creativity involved molding valves for blowmolded gas tanks. The valves needed to be injection molded, but the customer wanted to weld the same resin when attaching the valves. So Ironwood must use a 10 percent mica-filled HDPE blowmolding resin for the job. “We developed our own processing parameters through several DOE trials,” Stephens says.

Tooling and Techniques

Its remote location forced Ironwood to become its own moldmaker, but in retrospect, that necessity has allowed the molding operations to run more efficiently.

“For the types of jobs we do, precision is a must. Having our own toolmakers on board and the ability to design tools with moldability in mind is one of the reasons we can take on close-tolerance work, insert molding, and reel-to-reel jobs,” he adds. The list of tooling that can be produced runs the gamut from multicavity, hot runner, and shuttle molds to face-mounted, prototype, and insert tooling.

Almost all tools are made of hardened or prehardened steel. Ironwood typically produces prototype tooling in three to four weeks, but shies away from aluminum. Most of the jobs are too intricate, toolmakers say, and aluminum won’t hold up.

Unusual requests such as automatic unscrewing cores don’t seem to be a problem for Ironwood, which has invested in experienced toolmakers. One recent project, a radiator cap with molded-in screw threads, came off without a hitch.

An emphasis on secondary operations also sets Ironwood apart from its competitors. In addition to pad printing, hot stamping, and ultrasonic welding, it offers metal insertion, adhesive and solvent bonding, customized machining, and automated assembly.