Rowe's Nobake Expansion Lifts Productivity, Lowers Costs.
At first glance, the casting of industrial counterweights (used to balance drawbridges, electric rail and construction and handling equipment, such as forklifts and backhoes) may appear less complex when compared to the many other intricate components foundries produce. However, due to the sheer size of these parts and their unique cosmetic requirements, production concerns "weigh" much more heavily on an operation that casts them.
Counterweights are highly visible on the final product, and surface defects or inconsistencies mean bottlenecks in the grinding department and delayed delivery. In addition, if production costs skyrocket due to increased manhours, scrap remelt costs or equipment delays, a foundry loses any profit it usually would see. Expectations for counterweight castings are no lower, and production practices are no less important.
Rowe Foundry, Inc., Martinsville, Illinois, which manufactures counterweight castings from 50-4000 lb, has been able to achieve the efficiency, on-time delivery and quality levels that are all-important to attaining success in this market segment. Rather than maintaining the status quo, Rowe has shown an interest in its future as a viable counterweight casting facility by improving production through a $4.3-million modernization.
The counterweight market is a tough one, and Rowe considers itself among the top three foundries in the U.S. to pursue this small segment. With strong competition both at home and from foreign operations, Rowe found itself confronted with the prospect of losing business to foundries with more modern operations. To combat this, the foundry has concentrated on offering quality components and on-time delivery with a new, modern nobake molding operation, part of a long-term expansion and modernization project that started 10 years ago.
This three-phase update incorporates the newest in foundry technology: a state-of-the-art cupola (phase one), a sand reclamation system (phase two) and an automated nobake molding system that replaced an aging green sand molding operation.
The foundry sits in the same spot it did at the turn of the century, as the expansion was rebuilt on the old site piece-by-piece. Yet, in looking at the modern gray iron molding operation and office building, passers-by don't see the foundry as a rag-tag conglomeration of four buildings. Instead, it's clear that the setup was well-thought-out and planned with the future in mind.
Founded by Edgar Rowe in 1898 (he first poured metal at age 10), Rowe Foundry celebrated its centennial year 2 years ago. In 1908, the foundry built its first melting furnace, and, at the time, its main business was casting river clamps for oil and gas pipelines in green sand. During World War II, the foundry made bumper castings and flywheels for jeeps, but river clamps continued to be the mainstay.
In the 1950s, a steel strike led to a decline in business, while, at the same time, clamps began to be cast in concrete, essentially eliminating 90% of the foundry's jobs. To pick up the slack, Rowe began casting counterweights for agricultural and industrial markets, and that product continues today. Customers include Caterpillar, Crown, Case/New-Holland and Toyota, and the foundry prides itself on maintaining the tight specifications these end-users require.
In 1986, the business changed hands within the family, as the previous owners, Raymond and Ellen Zschau retired. Ellen Norton and John Williams expressed interest in continuing their grandfather's foundry tradition. Glenn Kuehnel was hired as production manager and began initial planning of a cupola modernization project.
At that time, Larry Norton (Edgar Rowe's great-grandson and the foundry's current superintendent) had been working at General Motors' Central Foundry Div., Danville, Illinois. Coming back in 1988 to the foundry where he had worked as a young man was going to be a challenge for the automotive foundryman, as much of the equipment was older and the operation was too labor-intensive. "The only way we could stay competitive was to take the labor out of the operation--that's the name of the game," Norton said. It was at this time that Kuehnel and Norton laid out plans to change Rowe into the modern automated operation it is today.
Weighty Production Issues
The latest phase of the three-part expansion was the most ambitious project, as the foundry undertook a complete shift in its molding method. Until the mid80s, the molding operation was strictly green sand and required more production time and effort than was considered practical. "Back then, we were making 1500 lb castings, but we were 'making' them in the grinding room," Norton said.
The initial investment for a new green sand system that could handle the jobs Rowe typically produces would have been "extremely high," Norton said. So, to improve dependability and smooth workflow concerns with the old system, the foundry began looking at adding an automated nobake molding line. "We're trying to make an inexpensive casting the cheapest possible way."
In addition, nobake molding seemed ideally suited to the type of casting that is Rowe's bread and butter: counterweights. Dimensional tolerances in this type of casting are an issue (typical tolerances are 2 mm), because the weights must fit into a compact package. While castings will tolerate a broad range of iron chemistry, carbon and silicon are monitored to avoid shrinks and swells that potentially cause bottlenecks at finishing.
Nobake molding has strength for larger jobs and automation helps the foundry maintain consistency. "Switching to nobake allowed us to cast larger weights and hold dimensional tolerances," Norton said, adding that the scrap rate at the foundry is just 2%. "We don't have the shrink that we used to have, and we've been able to cut our gating and risering in half. It's also really helped move production through our finishing and grinding department quicker."
Starting Out Light
Before Rowe decided to install a fully automatic system, the foundry purchased a used line to become acquainted with nobake molding. Between 1993-95, the foundry began phasing in the nobake system in its west wing and phasing out use of green sand, in preparation for a new automatic system.
Rowe decided to use a furan nobake binder for its economic and environmental performance. The foundry also switched from lake to silica sand (with a 45 AFS GFN), which is better suited to the nobake binder and provides a smoother surface finish. The change to nobake went smoothly--the low sand-to-metal ratio in counterweight casting worked well in the new system. Not only does nobake sand hold tolerances better with larger casting weights, but the sand also is reclaimed by the heat of casting. As a result, Rowe was ready to completely commit to the nobake expansion.
Installation of the new nobake line began in 1999. The original foundry had a low roof line, and because the large counterweight castings generate heat and smoke during the pour, a goal was to raise the roof height.
Design Complements Flow
Every part of Rowe's operation was pieced together with the thought of minimizing casting distance traveled, reducing manual handling and improving throughput.
Sand begins in an automatic mixer that combines silica sand with 0.9-1.1% resin and 19-21% catalyst at a rate of 2500 lb/min. The PLC-controlled mixer is programmed for each pattern/flask, the number of molds for each job, mix time required, binder additions and desired cure time. The system is capable of producing three blends of sand specifically tailored to the job being run. In addition, a pattern-tracking system monitors the location and status of each of the 100 active patterns the foundry maintains.
After the pattern box is filled, the mold is vibrated on a compaction table (both time and frequency are programmed for each pattern box). The mold then travels to an automated strike off and to a rollover machine. The rollover will not strip the pattern until the mold has completed its preprogrammed cure cycle time. The rollover will handle 60 x 80 x 24 in./24 in. molds, and the system will produce 15 complete molds/hr (12 is average).
The molds move by conveyor to a water-based coating station, and they are fired in a drying oven [5 min/mold at 181F (83C)] before moving to the coreset station. In addition to the switch in molding, Rowe has changed from oil sand to nobake coremaking. Core sand is automatically mixed and blown by a three-stage indexing machine (with blowing, gassing and stripping stations). The operator is able to program the proper blend of sand, how much sand is required for each corebox and the purge time of the system. On similar boxes, the machinery has an 18-sec cycle time. Cores then are coated with an alcohol-based refractory. The core department at Rowe produces 1500-2000 cores/day, and an average mold takes 16-17 cores. Employees manually set these cores before the molds move to an automatic mold closer that accurately positions and closes the two mold halves and places them on a pouring plate (bottom board).
At the heart of the foundry is its computer-based monitoring system. Monitoring starts at molding, pouring and shakeout and continues through to reclamation. A diagnostic tells operators when there's a problem on the line, what the problem is and which piece of equipment is affected, essentially keeping "tabs" on molds in each stage of production. This system also has been useful in maintenance of the line, as it keeps a running history of machinery failures and production figures. Computer-based monitoring is important to tracking operations to help keep costs contained and deliveries on time, Norton said.
Modern Cupola Melting
The molds then move on to a staging area for manual pouring--usually molds are poured [at 2400-2500F (1316-1371C)] every other day. The staging area has room for 100 molds produced on the automatic line, and Rowe is looking toward doubling this capacity, Norton said.
Class 50 gray iron is shuttled to the pouring area from the foundry's 10-year old cupola. In 1989, during phase one of the expansion, Rowe set about replacing its original cupola (installed in the late 1960s) with a new wet cap scrubber and coldblast cupola system. The foundry decided to continue cupola melting because it is relatively inexpensive. In addition, because the foundry's castings are not subject to tight metallurgical requirements, cupola melting makes sense, Norton said. The new system is capable of melting 20-22 tons/hr. The foundry operates two 10-hr shifts each day.
After cooling, the poured molds are moved by conveyor and transfer car to the pouring plate return line. As the mold passes the shakeout area, the pusher shoves the mold onto a pan conveyor. Here, the hot casting and gating are removed from the sand by a 6000-lb payload capacity robotic manipulator. The sand then is transferred onto the mechanical reclaimer while castings are stacked, sent to shot blast and on to the grinding department.
This entire system requires a total of only six employees, including four molders/pourers, a supervisor and one shakeout worker. With the old green sand system making half as many molds per day, 12 workers were required to make molds and four others worked shakeout, Norton said.
Reclamation Weighs In
A big part of ensuring smooth workflow and efficiency in its nobake molding is the foundry's 5-year-old sand reclamation system. In 1995, as phase two of the expansion and modernization, Rowe installed a reclaimer, cooler/ classifier and storage silos capable of processing 20 tons/hr. Much of the nobake sand in Rowe's system is thermally reclaimed by the heat of casting [at shakeout, sand reaches 1400F (760C)], so the reclamation system, located in the facility's south wing, only is required to mechanically process and restore the sand for reuse in the foundry. Approximately 95-98% of the foundry's sand is reclaimed, so little new sand must be added to maintain the system. Before this system was in place, Rowe was paying $17/ton to landfill its spent sand, so the system has paid for itself within 2 years, Norton said.
The 80,000-sq-ft facility takes up more than a city block in the heart of a small, southeastern Illinois town, and keeping neighbors happy was a chief concern in the foundry's modernization. "For the most part, people have been happy with us because of the continuous improvements we have made," Norton said. "We're now controlling our dust much better than we did. Our neighbors see what we've done over the years to improve the system."
To date, the reclamation system has run 13,000-14,000 hr with little required maintenance, Norton said.
Devil in the Details
Rowe's biggest production expense is its finishing department, Norton said. Surface finish is important in counterweights because they are highly visible on the machinery they help balance. As a result, castings often must be finished with a smooth automotive-quality surface, which requires more post-casting attention.
After rough grinding, the castings move across an industrial roadway into a new building converted in the summer of 1999 for finishing operations (including a dippainting operation) and short-term storage before shipping. There, any surface defects are smoothed with a finishing putty and sanded/polished before the castings are manually dipped in the paint. Eventually all finishing operations will be relocated to this building to consolidate efforts and allow room in the production facility for greater expansion, Norton said.
Weighing the Future
The modernization has met management's expectations for productivity improvements. In 1989, Rowe Foundry was producing 530 tons of castings/month with 51 employees. Today, the foundry makes 1700 tons/month with 108 employees, a 33% increase in productivity.
While some of the jobs Rowe casts are too big for the current system, the footprint of a nobake line that could handle every job would have been too large for the space, Norton explained. "So we decided to install a line that would handle 80% of the work" he said. "No matter how large we could have built this system, a customer will always come along who has a job that's larger."
The used nobake molding equipment is still in use today (50% of the foundry's jobs run through this line), but Rowe plans to eventually phase the equipment, using the space for a new nobake molding line that can handle larger-scale jobs.
Rowe Foundry, Martinsville, Illinois
Metal Poured: Class 50 gray iron.
Molding: Automated PLC furan nobake system.
Melting: Coldblast cupola.
Size: 80,000 sq ft.
1999 Production: 19,000 tons.
Market: Industrial counterweights.
Staff Officials: Ellen Norton, president; John Williams, vice president Glenn Kuehnel, production manager; Larry Norton plant superintendent/engineer, Kelly Norton, purchasing manager; Tony Williams, quality manager.
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|Comment:||Rowe's Nobake Expansion Lifts Productivity, Lowers Costs.(Rowe Foundry, Inc.)|
|Article Type:||Company Profile|
|Date:||Dec 1, 2000|
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