November 2021 Volume 3

EQUIPMENT & TECHNOLOGY

“When I got here, we had no machining facilities to speak of,” Jennings said. “We noticed over time that some of our ring customers were having us ship their orders directly to machine shops to be finished, so I proposed that we start a machine shop to add value to our product and gain some revenue by so doing. In the late 1990s we bought our first CNC machine to perform some of the rough, or ‘nuisance’, machining on our ring products.” This worked out well, and a few years later SRP bought a second machine; and then a third machine; and then a vertical turning lathe, and so on. As the machine shop came into its own, it started doing finish-machining as well as rough machining. The company trained its existing employees as machinists to do the work. Eventually, it got to the point where the company bought a building adjacent to its Bensalemproperty to house the machining operation. SRP now has five buildings on its property. “As we kept buying more machine tools, it became quite a learning curve for our people to learn the machining trade. But as we honed our machining skills, we also acquired various machining fixtures, coordinate measuring machines and other items until we became a full-service machine shop,” Jennings recalls. During the growth of their machining operation, SRP started taking on revenue from independent machining customers in addition to its captive ring-rolling operations, which still command most of the machine shop’s total capacity. Additionally, the machine shop also produces and maintains all the tooling, punches and rolls used in their ring-rolling process. At present, SRP is “pretty maxed out” with its machining operation. Alex Jennings would love to put on a second shift but can’t find enough qualified people to staff it. This is not COVID-related, in that it was tough to find qualified people even pre-pandemic. However, COVID has affected the availability and lengthened the lead times for H-13 tool steel.

Despite some early resistance to the addition of a machine shop to the ring-rolling operation, Jennings concludes, “The value-added from machining has definitely saved us money, increased our product margins and the company’s profitability.”

A machinist sets up for the next job. Photo courtesy of Specialty Ring Products.

About Sinking and Re-Sinking Dies Tools and dies used by forges are the cardiac center of their operations. The forging process is such that the tool steel, into which a die impression has been sunk, eventually wears out with production. Die life measured by parts produced can vary significantly from one operation to another and from one part geometry to another, but eventually a die cavity will wear out, crack, lose its dimensional tolerance, or the die block itself will lose its integrity. Additionally, the forging of ‘softer’ metals such as aluminum, affects dies differently than the forging of hard steels. Given that the production of forgings is destructive to their tooling, forges found ways to make the most out of their tool steel

investments. Instead of buying new tool steel, which is expensive, and outsourcing machining services to sink new die cavities, they invested instead in machinery that would help them re-use the dies they needed for additional production into the already-worn die blocks. This process is known as re-sinking and, by the late 19th Century, a dedicated die room, equipped with machining and grinding equipment, became an integral part of many commercial forges. In 1952, another method of re-sinking dies was introduced when the first flood welding was done by Matt Kiilunen, founder of Weld Mold Company, on a Chrysler die. To perform flood welding the worn die cavity on an existing die block must be removed, or

excavated, completely. The remaining cavity is then flooded by means of specially formulated electrodes and an electric arc struck within the excavated cavity, filling it in with metal in preparation for re-sinking. After post-welding heat treatment for stress relief and material softening, the newly metal-flooded die block is ready for machining. As handheld and pneumatic machining tools of old evolved into multi-purpose CNC machining centers, forges at last had powerful tools at their disposal to meet their tooling needs in-house. “New die steel was always a budget line item for a forge of any size,” said David Lee, Technical Director at Weld Mold Company of Brighton, Michigan. As these new dies wore out, they could be re-sunk 3-5

FIA MAGAZINE | NOVEMBER 2021 18