Recently, R&M received a progressive stamping job that required a punch with a particular contour to be used to create a decorative thermostat faceplate for a customer.
Made of .015” half-hardened 302 stainless steel, the retainer for the computer display in the thermostat is very cosmetic and can’t have a lot of scratches on it. Unfortunately, because the material being stamped is fairly springy the forms needed to be stamped more than once.
In other words, they would stamp a partial form and then come back and restrike the form. To do so they had to allow clearance in a second forming station for the primary form, which made the form punch rather delicate.
Initially, R&M designed and manufactured the form punches in-house. But they had issues right from the start.
“The punches would hardly last 5,000 hits and then they would crack and brake,” said Darsey Hohl, tooling manager for R&M Manufacturing. “So we changed some different alloys and tried some different heat treats ourselves and made things better, but it still wasn’t a really great fit.”
R&M tried A2, D2 and M4 without much success. They even tried wire cutting the punch using a 3V material with a 58-60 Rockwell and that seemed to be the best.
“Even though we had better success, we were still only getting about 43,000 hits before the punch was ready to fail,” said Hohl.
So the company turned to the application experts at Impax Tooling Solutions® from Wilson Tool, with whom R&M has had a longstanding relationship, for advice.
They recommended making the punch using Impax Tooling Solutions® 3V material and hard milling rather than wire cutting the tooling to produce a better performing punch.
Hard milling the punch eliminates some of the stresses that are often put into the material by wire cutting. This is what caused some of the punch failure that R&M was experiencing with the punches they produced in-house.
“Impax Tooling Solutions® hard milled the contour onto the punch and it’s still running as of today,” said Hohl. “We’re at 251,650 hits so far and it shows no signs of failure.”
The significantly longer tool life virtually eliminates any downtime related to changing out punches when they fail – dramatically increasing productivity.
“The payback on this tooling was in two production runs, really,” added Todd Dyste, president of R&M Manufacturing.
R&M has worked with Impax for more than 10 years now. According to Dyste, the long history between the two companies is due in large part to the excellent service they receive from Impax Tooling Solutions®.
“We first switched to Impax when they did a favor for us years ago. We were in a bind and needed some quick turnaround countersink punches one night,” said Hohl. “I think I ordered them at 3 p.m. and they dropped them off by 6 p.m. We’ve been dealing with them ever since.”
Quality and turnaround time were key factors for R&M when they decided to switch to Impax from a competing stamping tool provider.
“If you take their punch and an Impax punch and put them side-by-side, the finish was better, the back taper was always predictable and the delivery was usually the next day or within two days compared to a week,” said Dyste. “Time is everything in this business.”
August 29, 2016