Dalton Foundry Uses Technology to Benefit Customer

The gray iron casting facility utilized new technology for stress analysis and mold-making to solve a customer’s quality and lead-time issues.

Shannon Wetzel, Managing Editor

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

All 10 castings in the initial trial run showed the crack. It was at the corner of a rib, sometimes in several points. Filling and solidification modeling had indicated no issues. Dalton Foundry, Warsaw, Ind., had a case to solve for its customer, and time was running short.

The part was a 442-lb. gray iron gear case cover housing used in industrial air compressors located in free-standing boxes at worksites to generate industrial air and power. It was a prototype casting to go into production in late 2016, and further development of the air compressor assembly hinged on its successful and timely manufacture.

Dalton Foundry, which is a division of Neenah Enterprises Inc., had built production intent metal prototype tooling for the part after casting process modeling showed no filling or solidification problems with the design. Unfortunately, the crack appeared from the first prototype poured.

“We went through several gating design changes and process changes to see if there was a way to eliminate the crack,” said Rob Burita, tooling engineer at Dalton Foundry. “Every time we ran one of the changes, we still had the crack. We started realizing it was something inherently built into the design of the part.”

Due to the nature of the crack and its location at the corner of the rib, Burita suspected it could be caused by stress during solidification. Dalton Foundry attempted to alter the design of the casting on its own by manually filing the core to alter its shape, but the crack persisted. The metalcaster now had the unpalatable task of telling the customer their design was the culprit.

“We knew there would be a pretty significant design change,” Burita said.

Recently, Burita had been exposed to the MAGMAstress extension module for use in casting process modeling, and he knew it would help identify what was causing the stress and how to resolve it. Although it ran MAGMA solidification software, Dalton Foundry did not own that particular stress module.

“After we exhausted all the process, gating and design changes and had a pretty good suspicion it was stress-related, we finally went to the customer and said, based on our experience with the stress simulation, we think we need to run the part in the stress program,” Burita said.

The customer agreed and Dalton obtained the software to use through the design iterations of the part. According to Burita, the first simulation run in the stress program using the original design predicted stress in the locations the crack had been appearing perfectly, confirming the origin of the crack was built into the customer’s design and not the result of poor casting practice.

“The big thing was the significance of the change that had to be made,” Burita said. “We wanted to make sure we were confident the design was going to work because we had metal tooling. Before we cut it, we wanted to make sure we were right.”

The engineers discovered the stress in the casting was occurring in the original design because the base was so large and voluminous it took much longer to solidify than the rest of the casting. The bottom was pulling down on the ribs that connected to the top rim, while the top was resisting because it was already frozen solid. This caused a pull where the rib attached to the sidewall, leading to the stress cracking.

“There is nothing you could do in the process to prevent, change or alter that,” Burita said. “The simulation helped prove that to the customer. Seeing the actual picture really sold it.”

Based on the simulation results, Dalton engineers, along with the customer’s engineers, began making modifications to the design, eventually working through 10 design changes before settling on one that indicated zero stress issues in the simulation.

The final, successful gear case housing design featured thinner ribs that were more curved in shape with a little more draft angle, which provided a more solidification-friendly transition from the diameter of the casting’s top, around the windows of the rim, and down to the massive base on the bottom.

Making Up Lost Time

Because the prototypes were going into production, Dalton had originally built metal tooling. The plan was to cut the metal tooling again, but because of the time it took to redesign the part, the customers were in urgent need of the cast parts as soon as possible. The gear case housing was one of five prototype parts Dalton Foundry was producing for the customer’s final assembly. Four of the parts were ready. The customer wanted to move on to the next stage of development for its assembly to stay on schedule for production in late 2016.

Metal tooling modifications in the corebox would have taken several weeks. Like the use of stress simulation, Dalton Foundry turned to new technology to solve the problem. The metalcaster opted to make the mold and cores without tooling using 3-D sand printing.

“Our customer was up against the wall needing parts. We were aware of 3-D printing and that a printed core could be turned around in less than a week,” Burita said. “But this was our first use.”

In the customer’s situation, Dalton Foundry saw how it could take advantage of the ability to print directly from the model without upfront tooling cost, particularly with a prototype that had a history of crack defects. If more changes were necessary, they could be done quickly and a new core could be printed within days.

“Speed is a factor,” said Harold DeVaux, national account manager, Neenah Enterprises Inc. “You can turn these 3-D-printed cores around in a short amount of time. Accuracy is very close to production-likeness. Using the customer’s model, you get a casting that is going to be very close to the production model, plus it allows you to do whatever types of changes are necessary inexpensively.”

It turned out the design changes made with the aid of the stress simulation proved on target. The first pour of the gray iron part using the 3-D-printed core package was successful. Eventually, the entire prototype order of 20 pieces was made without defect using the 3-D-printed cores, and the lead-time was reduced to a few days rather than several weeks if produced with metal tooling.     

“The success of the part required two leaps of technological faith: stress analysis and using printed cores,” Burita said. “Both worked out great.”
After the first success using the printed cores, Dalton Foundry decided to try its next prototype for a different customer using the same method. Now, just about every prototype the metalcasting facility makes is via 3-D sand printing.

“We had been looking at 3D printing for awhile and this issue provided us the perfect opportunity to try it out in our own process,” said Chuck Fennell, program manager, Dalton Foundry. “It was the catalyst for us to do all our prototypes now with the new technology.”   

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.”