What is in this article?:
- Reducing milling costs
- Lighter cuts, higher MRR
- The math is clear
- Convincing skeptics
- Corkscrew milling, and other highlights
- “Job-match every aspect …”
A close view of high-feed milling in process. Ingersoll’s high-feed Powerfeed Plus tool feeds faster and cuts lighter, to accelerate metal removal and protect Wemco’s light-frame CNC machines.
Diversifying into contract machining can be a lifesaver for a branded capital equipment manufacturer, as long as it stays both profitable and competitive. At the operational end, this may require advanced machining practices and equipment – and confidence in those practices — and an appetite to try new things. Wemco Inc. in Airway Heights, Wash., is a handy example.
Wemco learned these lessons in contract machining early and well, about five years ago, and today it continues to gain the benefits of the switch. In 2008, 90% of the business involved made-to-order heavy equipment, very cyclical and vulnerable to economic turndowns. Today the business is 40-60 % contract milling, which is steadier work, more profitable and more amenable to scheduling. It keeps 28 shop workers busy, 10/5, in a 36,000-sq. ft. machining and fabrication shop.
“At the manufacturing end, our key to success has been to embrace leading-edge machining practices, mostly high-feed milling, and to keep pushing it,” according to Juston Rouse, manufacturing vice president. “We’ve reduced our plant-wide milling costs by half as a result, and can deliver a contract job within three weeks on average. We can win a lot of jobs with that capability — and still hold good margins.”
In this effort most of the tooling Wemco has selected is from the Ingersoll Hi-Feed series, which feeds faster but takes lighter cuts that lead to higher material removal rates (MRR) with less wear and tear on the machines. The typical parameters for mild steel are 240 IPM at 0.050 in. DOC, versus 80 IPM at 0.070-0.120 in.
“The math is clear,” Rouse said. “Tripling the feed while reducing DOC by maybe half means we’re doubling the MRR, at least.”
Wemco’s bottom line looks good today, but it didn’t happen overnight, nor without serious doubts. The company started contract machining about seven years ago, after converting the shop to modern CNC operation but with conventional tooling. That move created a lot of free machine time to sell, but because of local competition Wemco got the work and couldn’t make any profit on it.
About a year and a half later, Rouse sought ideas from a range of tooling suppliers to lower the shop’s machining costs. Ingersoll’s Chris Murray immediately recommended high-feed practices and promised at least a 50% improvement in machining rates.
“I won’t repeat my exact reply at the time,” said Rouse, “but, long story short, we tested the idea and the result was a 3-to-1 gain in MRR.” He immediately bought $87,000 worth of Ingersoll high-feed tooling and scrapped what they had. “We didn’t have time to inch into the new practices,” he added.