Modern Casting

Opening scene: The stage is a foreboding crop field a farmer must till, and fast. But his ground is never the same––rocks lie hidden or it may be covered in cornstalk debris from the last harvest. Enter the star: a new tillage machine from Summers Manufacturing (Devils Lake, North Dakota) loaded with market-first features direct from farmers’ wish lists, including the strength and stamina to hit a hard object and keep going without a glitch.

To pull off this complex engineering drama, set in early 2018, a new part needed to be cast perfectly for a leading role. Literally.

Summers partnered with AFS Corporate Member Dotson Iron Castings (Mankato, Minnesota) to design and produce an iron casting component for Summers’ new VRT Renegade, and the foundry not only achieved the manufacturer’s much-needed labor savings and compressed time requirements––but, in the end, produced an almost unheard of ROI for Summers upon their first machine order. And the large annual savings that followed? Pure, abundant gravy.

“Most customers would be very happy with a one-year return on investment, but with this project the savings were so huge it paid off in less than two months,” said Jim Headington, Dotson’s technical sales manager. “The savings per casting times the annual usage came out to a total annual savings of $96,000.

“This wasn’t Summer’s first rodeo,” he added. “They have a talented engineering group and they saw right away the advantages of moving this to a casting.

A Better Way

The solid trip arm casting for Summers’ new VRT Renegade replaced a C-shank part carried over from previous models of the machine. The C-shank––a U-shaped piece of spring steel––was integral to the company’s new disc trip system that makes the Renegade uniquely adjustable, said Summers Design Engineer Paul Wilhelmi. There was just one problem.

“One of the issues we saw on the original VRT was the bending and the breaking of those C-shanks because of the aggressive tillage we were trying to do at high speeds,” he said. “We were looking for a solution to the bending and breaking of the C shank.”

Actually, breakage wasn’t the shank’s only issue––in the Renegade prototype, this part comprised five individual fabricated pieces, each requiring 30 minutes to weld and a total of one-and-a-half man hours per fabrication. With 32 to 48 total trip-arm components required for every finished 25- or 40-foot unit respectively, that labor time was a manufacturing deal-breaker.

That’s when Wilhelmi and one of his engineering colleagues started looking for alternatives while studying their CAD screen one afternoon, and they realized converting the C-shank to a casting was the answer. Their company had enjoyed a beneficial relationship with Dotson for some 13 years, which made them a logical phone call, but trusting Dotson to handle the design and execution hinged on more than rapport.

“Depending on the capacity of our engineering group, we will sometimes design a cast part internally,” Wilhelmi said. “But we didn’t have the capacity at that point in time––we were busy making refinements to the rest of that product line along with all the other products we build here. We chose Dotson, No. 1, because they had the engineering resources to do the majority of the design work on the casting. And No. 2 was Dotson’s short lead times.”

Wilhelmi’s goal was to get the entire project––from design to tooling to finished machined pieces––done in six months and he hit the mark in five, partly due to rapid turnaround on the casting. As it happens, new-product lead times are something of a specialty for Dotson.

“A lot of folks turn to us when they need newly designed castings up and running in a short amount of time,” said Headington.  “Our engineering team has developed a very robust new job start-up process, and as a result we’re often able to build new tooling and provide samples in four weeks or less.  In this case, there was a lot of back and forth during the design stage, so it was key that our engineering teams worked really well together.”