NEWAYGO, MICH. — Before automotive supplier Donnelly Corp. opened a new injection molding plant three years ago, top management went on a short work study mission to Japan.
While the group picked up valuable cross-cultural tips from Japanese carmakers on working efficiently through that country's much-praised kaizen lean manufacturing system, the management team had another, entirely different goal in mind:
``We weren't happy with how long it took to change a mold on a press,'' said operations manager Jeff Smith at Donnelly's Newaygo plant. ``The Japanese were doing in less than five minutes what it takes two or three hours to do at many American plants. We wanted to learn from them and adapt it.''
They came back true believers. With production pressures already tugging at plant management even before the building opened in July 1995, the Newaygo plant found a new method to streamline time to change tools.
The process has turned a production-stalling, necessary evil into an activity that revs workers' competitive fires and keeps parts moving.
Today, the facility is relatively unusual among U.S. manufacturers in its mold-change doctrine. When a tool conversion is needed, a two-member team, which managers liken to a racing team's pit crew, keeps the machine's pit stop, or downtime, to a minimum.
The work is feverish for a concentrated period. One person leaps on top of the injection press with a wrench to unhook the overhead clamps. The second crew member unscrews manifold hoses, yanks them off and pulls the steel tool from the press on a rolling conveyor. The process then is reversed for the new tool waiting to slide into the press.
The pit crews carry a stopwatch to time their work. The best time recorded to date has been 82 seconds between press shutdown and restart, with the average mold change time taking two to three minutes. That is in an industry where mold changes can average more than two hours, leaving production workers cooling their heels.
``It's definitely a competition we have going on in the plant,'' said mold-change set-up technician Todd Nagel, who works on one of the plant's 12 teams. ``We all want to be the quickest and the best team.''
The plant's mold-change work has spread to other plants owned by Holland, Mich.-based Donnelly. It's an area easily controllable to hike production, said Robert Morse, Newaygo plant manufacturing manager.
The company developed its own equipment, including metal mold tables with roller bearings to hold the tool as it comes in and out of the press. Setting up the custom-designed process took months of trial and error before the plant opened, Morse said.
``We went at it no holds barred to find a system that worked for us,'' Morse said. ``It meant a lot of hammering, welding, torching and physical work to get the equipment just right. We had issues like getting the mold table door to open and shut quicker and allow easier reach for our technicians.''
Donnelly's work is part of a growing cottage industry. Companies such as D-M-E Co. in Madison Heights, Mich., and Master Unit Die Products Inc. in Greenville, Mich., have devised specialty products that attach to presses or tools for quick mold changes. Other mold makers now prepare their own quick-change plates that clamp to injection presses.
One of those tool builders, Paragon Die & Engineering Co. in Grand Rapids, Mich., builds metal plates that it fastens to the sides of its injection molds. The company, which makes large molds primarily for the automotive industry, adds a clamping mechanism to the plate that allows its molders to easily attach the plate to the press.
``It's something we don't even think about that often,'' said Paragon President Ralph Swain. ``It's become such a standard part of what we do. There aren't many molders, at least in the auto industry, that don't want some type of quick change for its molds. Their presses just can't sit idle that long.''
The industry also continues to standardize. Master Unit Die has been making its MUD quick-change system for more than 35 years. The company's standard mold bases, which can be adjusted for differing heights and thicknesses, slip into a press with a clamping force as high as 500 tons, said Master Unit Die Vice President Michael Martin.
The system allows the mold's core and cavity to be attached easily during a changeout without going to the trouble of lifting out the base from the platen. Some of the company's systems also include a quick hydraulic ejector system to help expunge the mold and an adaptor system to allow quick disconnects from the water manifold system.
Martin said he's seen operators take as long as three to six hours to change out a mold the traditional way, compared with five minutes or less with a quick-change system. Much of that time is absorbed with hoisting the hefty bases, attaching the spaghetti-like cluster of manifold water hoses and warming the new mold to the proper temperature before restarting the press.
``Our bases allow a standard core and cavity to slip into the mold with two clamps,'' Martin said. ``We've seen continuous growth with this, especially with the demand for just-in-time production and quick delivery. It's definitely an evolution.''
The pressure to get parts out the door quickly without stockpiling excessive inventory has helped catalyze the move to quick-change molds, said D-M-E business development manager Larry Navarre. D-M-E, which makes a Round Mate interchangeable molding system for quick changes, has seen a high, double-digit growth rate with those products since the early 1990s, Navarre said.
The biggest obstacle the company faces is mold makers unwilling to give up control of the build process, Navarre said. D-M-E's Round Mate system inserts into a master mold frame with the turn of a wrench, taking away the need for another mold base.
Only the cavity must be machined by the tool builder, Navarre said.
``The biggest hang-up is mold makers' reticence to change,'' Navarre said. ``But when a molder sees the benefits of reduced setup time that can shorten the product life cycle, they start asking for it.''
At the Donnelly plant, time is essential. The 160,000-square-foot injection molding and painting facility makes nylon and acetal door handles and exterior mirror housings and brackets. The plant, which has 450 workers, uses 40 presses with clamping forces of 120-650 tons.
Workers there are cross-trained on equipment, rotating every two hours to a different manufacturing cell. The production process is simplified by having pieces move in color-coded bins from one part of the plant to another.
In 1995, management decided to standardize its mold-change process to avoid press downtime and cut backlogs before shipment, Smith said. The plant's customers include Ford Motor Co., General Motors Corp. and Honda of America Manufacturing Inc.
``It was a matter of dexterity,'' Smith said. ``We wanted to be light on our feet to pick up a part and ship it when needed. We did not want to have a bunch of catalog engineers spending time to inventory parts in the plant to put in a warehouse area.''
The two-member pit crews, each responsible for a different press, include an in-process engineer to set press controls before a mold change. The other mold engineer works on the other side of the press to move the tools in and out of the machines.
The company devised a multiple thermolator system to keep the new mold heated to a temperature as high as 170§F before rolling it into the press, thus saving time spent waiting for tool warmup.
And instead of the morass of hoses attached over the mold's surface, the plant's tools were created with only two clamping points to connect the water system, which cools down the mold.
The teams also built in pneumatic controls and clamping points to attach the mold to a standardized bolster plate on the press. The mold table itself was custom-designed with safety latches to prevent the door from pinching the fingers of employees.
``We've had one crew member weighing about 105 pounds moving molds in and out of the press with ease,'' said Kevin Conley, the plant's manufacturing engineering manager. ``The key to it was standardizing. By doing that on the mold and the auxiliary parts, we saved a ton of time in production.''
Conley estimated that the plant makes as many as 40 mold changes a day on the 12 machines using the customized quick-change system. The plant, which operates seven days a week, is putting a similar change setup on many of its other presses in the next six months, Morse said.
The time spent creating the system in 1995 is paying off today, Morse said. The downside was some arduous days and late nights pounding out mold tables and bolster plates to develop the right equipment.
``We'd rather have invested the time and money in the initial set-up than trying to scramble to do the job faster after the presses are running,'' Morse said. ``That was really the secret to this. If the setup work wasn't done, we couldn't act quickly today.''