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Material Handling: Go With Flow

Every metalcasting facility is unique, but a department-by-department examination may highlight ways to improve operations and reduce costs.

A Modern Casting Staff Report

(Click here to see the story as it appears in the October issue of Modern Casting.)

No matter the size of a metalcasting operation, whether it’s a small, family-run shop or a mega facility with volumes in the millions, the question of modernization is not an “if” but a “when.” Machinery fails. Maintenance gives way to replacement. Upgrades need to be made.

Projects can be as simple as swapping out an old welding machine for a new one. They also can involve many more moving parts, such as a new molding line, which requires engineering and logistical planning far more advanced than simply sticking a plug in the wall. Every improvement project requires planning and engineering to ensure it fits into the broader facility-wide material flow and handling.

Misplaced equipment or poorly designed material flow can increase labor, safety risks and costs—inefficiencies that may be avoided by rethinking the facility’s layout. Making changes in addition to a specific installation will increase the cost of that project, but that one-time cost, ideally, would be recovered by eliminating daily cost increases related to unnecessary material handling procedures. If a metalcaster misses an opportunity to improve the flow of material, the bottleneck in handling and flow will be a drain on profits that continues until the proper action is taken.

Foundry Layout

Design considerations for metalcasting equipment are different for every plant, but almost every site needs to consider available square footage, building size and configuration, placement of existing equipment and the relationships between departments.

“A lot of existing installations have been put together over years and generations, where one thing is added here and another there,” said Wil Tinker, president, Tinker Omega Mfg. LLC, Springfield, Ohio. “Each project for existing facilities is one that balances primary objectives with what’s possible within a project’s budget.”

Ideally, the layout between melting, molding, coreroom and cleaning-finishing departments should provide a continuous process flow from the material entering the plant, through each department and eventual shipment. This basic methodology keeps product moving through the metalcasting operations, though each department will require specialized configurations based on the building’s overall shape and size.

Melting

The melting department should be located on an outside wall due to the high volume of metallic materials required for the melting process. Material handling in the melting department is important because it involves both newly acquired metal and returns from within the facility.

Facilities that pour more than one alloy at the same time have additional considerations because melting operations will run side-by-side. Also, the method and location for metal returns to the melting departments need to be considered. Returns such as risers, sprues and pouring basins may occur at different locations throughout the cleaning process. These pick-up points must be incorporated into the material flow because they require transportation back to the melting department. The location of metal removal operations should be as close to the melting department as possible to reduce the distance returns must travel.

Minimizing the distance metal travels from melting/holding units can reduce the required temperature of the metal tapped from the melting/holding furnace. Long distances increase the metal’s temperature, leading to increased energy consumption and cost.

Automatic pouring units, if possible, should be positioned to retrieve the metal directly from the holding/melting furnace. If not, a heated trough can be used to transfer the metal to the pouring unit. Locations of the melting/holding furnaces and automatic pouring are an important feature in the melting department layout.

Molding

When making improvements to or installing new molding equipment, four key features must be considered during initial planning and engineering:

  • Selection of a molding machine system.
  • Method of handling the molds away from the molding machine.
  • Method of core delivery from the core machine to the mold.
  • Location for setting cores in the molds.

 

Different molding systems require different handling methods. Establishing pouring as close as possible to the melting department should be a high priority in material handling, although it requires considerable planning to maximize efficiency.

Matchplate jolt-squeeze machines require either a pallet line or the use of a roller conveyor to move molds from the molding machines. These systems require the melting furnaces to be located at one side of the mold handling line so metal can be delivered and poured on the pallet line. Molding/handling also may be located at the opposite end, away from the molding machines, so metal can be delivered to the molds along each roller conveyor line.

An automatic molding system requires the melting department to be at the side near the molding machine to minimize the distance metal travels. A chemically bonded mold and core system requires the completed molds to be delivered to the melting department. Extra large molds, which are more difficult to transport, require a molding area adjacent to the melting/holding furnaces.

Sand System

Considerations for a casting facility’s sand system include available floor space, core and metal removal, shakeout, sand mulling and sand delivery. New sand storage hoppers should be located along an outside wall with the return hopper located as close to the sand muller as possible, usually inside the building. The sand cooler is located after shakeout, with the metal and core removal system prior to the sand cooler. After mulling, the sand is then transferred back to the molding machines.

Green sand shakeout systems require separation of sand and cores from the castings and the elimination of core sand from the return sand. Chemically bonded molding systems may not require core sand separation, but metal must still be removed from the sand prior to reclamation, which will improve the quality of the sand returning to the muller.

“Recent price increases for silica sand have made reclamation systems (both mechanical and thermal) financially viable for many medium and smaller sized casting operations,” Tinker said. “You want to close the loop as much as possible.”

Many reclamation installations are added to existing sand lines, which will lead to specific engineering considerations. Collaboration between engineers from the equipment manufacture and the metalcaster can help improve the material flow and handling of such add-on projects.

Core Production

Core production should be located near the molding area. Because core production rates rarely mirror mold production rates, storage space between the coremaking and molding departments must be allotted. While often unavoidable, the storage of cores can lead to a few problems:

  • Core scrap may increase due to the extra handling to and from storage.
  • Cores in storage may collect moisture that could produce scrap castings.
  • Storing cores ahead of molding operations can increase the difficulty of tracking casting scrap.

Production of cores at the same rate as molds is the ideal solution because it eliminates handling, reduces core and casting scrap, eliminates the need for storage and improves troubleshooting between coremaking and molding departments.

Casting Cooling

Solidified castings must be cooled before they enter the cleaning process. The cycle time of the cooling process provides an opportunity to transport the casting a distance away from the mold shakeout area while it moves to post processing. This allows flexibility in the location of casting cleaning procedures, and may allow cleaning and finishing operations to be designed in a straight line for continuous casting flow.

The continuous flow of castings into the cleaning area also provides the opportunity for a continuous casting cooling process. Continuous operations require the use of a vibrating pan conveyor or an overhead chain conveyor to deliver the castings to the first cleaning station.

Because the location for starting the cooling cycle for castings is flexible, the design can be based on a number of factors:

  • The removal of metal from the casting creates a considerable amount of material to return to the melting area, so placing the cooling system near the melting department will reduce material handling and distance.
  • Automatic return systems can reduce material handling considerations and minimizes contamination and mixing of metals being charged.
  • The pick-up points and delivery to a designated bin in the metal storage area can be cost effective and improve the plant environment.

Casting Cleaning

At the completion of the cooling cycle, the casting’s metal determines the first operation in the cleaning process, whether that is shakeout, cut-off or knockout operations.

The next operation is shotblasting, with the exception of aluminum castings, which are normally shotblasted at the end of the cleaning process. Continuous shot-blasting reduces manpower necessary for loading and unloading, while batch shotblasting may increase handling due to the ebb and flow of prepared castings.

Grinding may be done with a variety of tools, including stand grinders, belt sanders and chipping tools. From this point, many castings will require heat treatment, reblasting and inspection before being ready for shipping.

Overall Improvements

The metalcasting facility with ideal material flow and handling may not exist, but company executives are becoming more receptive to improved efficiency in an effort to reduce costs and improve performance.

“We’ve seen a definite shift toward efficiencies, both in production and operational equipment,” Tinker said. “We’ve seen [metalcasters] analyzing utility consumption, to where it’s a crucial part of their economic decision-making.”

Early planning provides the time to design an efficient flow program that reduces handling inefficiencies. The results of an effective continuous material flow include:

  • Reduced material and casting
  • handling.
  • Reduced manufacturing time.
  • Reduced inventories.
  • Reduced delivery times.
  • Improved customer relations and satisfaction.
  • Reduced scrap.
  • Improved casting quality.
  • Cleaner work environments.
  • Improved employee relations and satisfaction.

If a metalcasting facility can successfully implement equipment improvements and installations, the metalcaster can expect real, tangible benefits.     

E
ncountering a scenario in which you are forced to suddenly and immediately suspend melting operations for an extended period can be a death sentence for many metalcasting facilities. Small to mid-size businesses are the backbone of the industry, but many do not survive when forced into extended downtime. One disaster-stricken metalcaster, however, found resilience through its own perseverance and a circle of support from peers, friends, suppliers, teams from installation and repair providers, an original equipment manufacturer and even competitors.
Tonkawa Foundry, a third-generation, family-owned operation in Tonkawa, Okla., was entering its 65th year of operation this year when a significant technical failure ravaged the power supply and melting furnaces on January 17. Thanks to the textbook evacuation directed by Operations Manager Carrie Haley, no one was physically harmed during the incident, but the extent of emotional and financial damage, and just how long the event would take Tonkawa offline, was unclear.
Tonkawa’s power supply and two steel-shell furnaces would have to be rebuilt. No part of the reconstruction process could begin until the insurance company approved removal of the equipment from the site. The potential loss of Tonkawa’s employees and customers to competing metalcasters seemed inevitable.
Within two days of the incident, repair, installation and equipment representatives were on site at Tonkawa to survey the damage. Once the insurance company issued approval to begin work, the installation team mobilized within 24 hours to remove the equipment and disassemble the melt deck.
Since the damaged equipment was installed in the 1980s and 1990s, Tonkawa and an equipment services and repair company quickly strategized a plan and identified ways to enhance the safety, efficiency and overall productivity of Tonkawa’s melt deck.
“The most critical issue was for our team to organize a response plan,” said Steve Otto, executive vice president for EMSCO’s New Jersey Installation Division. “We needed to arrive at Tonkawa ready to work as soon as possible and deliver quickly and thoroughly so they could get back to the business of melting and producing castings, and minimize their risk of closing.”
Several years after Tonkawa’s melt deck was originally installed, an elevation change was required to accommodate the use of a larger capacity ladle under the spout of the furnaces. Rather than raising the entire melt deck, only the area supporting the furnaces was elevated. As a result, the power supply and workstation were two steps down from the furnaces, creating a number of inconveniences and challenges that impacted overall work flow in the melt area. Additionally, the proximity of the power supply to the furnaces not only contributed to the limited workspace, but also increased the odds of the power supply facing damage.
The damage to the melt deck required it to be reconstructed. It was determined to be the ideal opportunity to raise the entire deck to the same elevation and arrange the power supply, workstation and furnaces onto one level. The furnace installation company provided the layout concepts, and with the aid of Rajesh Krishnamurthy, applications engineer, Oklahoma State Univ., Tonkawa used the concepts to generate blueprints for the new deck construction. The results yielded a modernized melt system with an even elevation, strategically placed power supply, enhanced worker safety and increased operator productivity.
“Eliminating the steps and relocating the power supply farther from the furnaces was a significant improvement to our melt deck,” Tonkawa Co-Owner Jim Salisbury said.
Within four days of insurance company approval, all damaged equipment had been removed and shipped for repair.
The insurance company required an autopsy on the damaged furnace before any repair work could begin. The forensic analysis was hosted by EMSCO in Anniston, Ala., in the presence of insurance company personnel, as well as an assembly of industry representatives from the companies who had received notices of potential subrogation from the insurance company.
Tonkawa’s furnace was completely disassembled while the insurance company’s forensic inspector directed, photographed, cataloged and analyzed every turn of every bolt on the furnace over a nine-hour workday. The coil was dissected, and lining samples were retained for future reference.
While the furnace sustained extensive damage, it did not have to be replaced entirely.
Structural reconstruction was performed to address run-out damage in the bottom of the furnace, a new coil was fabricated and the hydraulic cylinders were repacked and resealed. Fortunately, the major components were salvageable, and ultimately, the furnace was rebuilt for half the cost of a new furnace.
“The furnace experienced a significant technical failure,” said Jimmy Horton, vice president and general manager of southern operations, EMSCO. “However, not only was the unit rebuilt, it was rebuilt using minimal replacement parts.”
Though work was underway on the furnaces, Tonkawa was challenged with a projected lead time of 14 weeks on the power supply.
When accounting for the three weeks lost to insurance company holds and the time required for installation, Tonkawa was looking at a total production loss of 18-20 weeks. From the perspective of sibling co-owners Sandy Salisbury Linton and Jim Salisbury, Tonkawa could not survive such a long period of lost productivity. After putting their heads together with their furnace supplier, it was determined the reason for the long turnaround on the power supply could be traced to the manufacturer of the steel cabinet that housed the power supply.
The solution? The existing cabinet would be completely refurbished and Tonkawa would do the work rather than the initial manufacturer. This reduced the 14-week lead time to just five weeks.
Tonkawa is the single source for a number of its customers. Although lead-time had been significantly reduced, the Tonkawa team still needed a strategy to keep the single source customers in business as well as a plan to retain their larger customers.
Tonkawa pours many wear-resistant, high-chrome alloys for the agriculture and shot blast industries. Kansas Castings, Belle Plaine, Kan., which is a friendly competitor, is located 50 miles north of Tonkawa. Kansas Castings offered Tonkawa two to three heats every Friday for as long as it needed.
“We made molds, put them on a flatbed trailer, prayed it wasn’t going to rain in Oklahoma, and drove the molds to Kansas Castings. We were molding, shot blasting, cleaning, grinding and shipping every Friday,” Salisbury Linton said.
Others joined the circle of support that was quickly surrounding the Tonkawa Foundry family.
Modern Investment Casting Corporation (MICC) is located 12 miles east of Tonkawa in Ponca City, Okla. Though MICC is an investment shop and Tonkawa is a sand casting facility, MICC’s relationship with Tonkawa dates back years to when Sandy and Jim’s father, Gene Salisbury, was at the helm.
“Gene was always willing to help you out,” said MICC owner, Dave Cashon. “His advice was invaluable for us over the years, so when the opportunity arose to support Sandy and Jim, we volunteered our help.”
 MICC offered to pour anything Tonkawa needed every Friday in its furnace. Tonkawa brought its alloy, furnace hand and molds, while MICC provided its furnace and a furnace hand for three heats. Many of the specialty parts Tonkawa produces were completed with MICC’s support.
When Salisbury Linton approached Cashon and asked him to issue her an invoice to cover the overhead Tonkawa was consuming, Cashon told her if she brought in six-dozen donuts every Friday morning they’d call it even.
“We’re all kind of like family,” Cashon said. “We’re all part of the same industry and though we may be friendly competitors at times, you don’t want to see anybody go through what they’ve gone through and it could have just as easily been our furnace that failed. While we all take the appropriate measures and perform maintenance to prevent these scenarios from occurring, they unfortunately still occur from time to time in our industry.”
Tonkawa had recently added steel work to its menu of services and Central Machine & Tool, Enid, Okla., was able to take Tonkawa’s patterns and fulfill its steel orders so it would not fall behind with those customers, while CFM Corporation, Blackwell, Okla., took three of Tonkawa’s employees on a temporary basis and kept them working during the downtime. Additionally, a couple of Tonkawa’s major suppliers extended their payables terms.
Thanks to Tonkawa’s suppliers, friends and its personnel’s own passion, persistence and dedication, the business is up, running and recovering—placing it among the few shops of its size to overcome the odds and remain in business after facing calamity.
 Nearly eight months after that devastating Saturday evening in January, Salisbury Linton reflected on the people and events that helped Tonkawa rise from the ashes. “We certainly would not have the opportunity to see what the future holds for Tonkawa if it weren’t for all the kind-hearted people who cared about what happened to us. Everyone still checks in on us.” 
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