Stampers: Consider Adding CNC Punching Machines

Traditional metal stampers would do well to incorporate CNC punching into their production regimens, thus providing the ability to gain new short- and medium-run work without the expense of hard tooling.

Providing reasons for making the jump is Jeff Tyl, North American sales manager-fabrication for Murata Machinery USA. He’s met with and surveyed more than 200 metal stampers to help determine how CNC punching can be leveraged in a traditional metal stamping environment.

The majority of metal stampers surveyed do not employ punching-machine technology,” according to Tyl, with lack of process familiarity and capabilities a possible reason why.

“Stampers should understand that stamping presses and punching machines operate in the same manner—down and up motion,” Tyl offers. “The major difference: Instead of employing a single tool for a single hit as is the case with the components in a stamping die, punching-machines provide multiple tools for multiple hits for multiple parts. And, just like presses, punching-machine drives have evolved to employ hydraulic, mechanical and servo technology. In addition, these machines process similar materials with similar thicknesses. We need to remove the mindset that presses and punching machines are completely different pieces of equipment.

CNC punching machines provide a valuable complement to stamping operations, and an economical alternative for shorter part runs. Their part-nesting capability and use of sheet blanks also offer significant material savings.

Take Back the Short and Medium Runs

In his detailed discussions with stampers, Tyl found that many see long-run tooling as a sweet spot, and stamping presses truly do excel in such applications.

“But stampers can miss the boat with short-run and middle-volume jobs, often opting to outsource this work,” he says. “One stamper told me that he outsources $300,000 in short-run work each year.”

The tooling capability of punching machines comes into play in these applications, and where the investment in CNC punching can produce a rapid ROI.

“For example,” Tyl says, “our standard 20-ton turret punch press houses 44 tools. Depending on the size of a tool, users can punch round holes in diameters from 0.5 to 4.45 in. without changing a tool in the turret. And, should a new tool be needed to produce a particular feature to accommodate a part-design change, tool changeout is a simple process. On the other hand, revising a hard tool brings a high cost. Many times, a tool component or feature in a progressive die is ‘one and done,’ meaning that it produces a feature for one particular part. A part revision means altering the die or building a new die, with significant costs in time and money.”

In the turret punch press, a complete toolset may run $1000 to $1200, according to Tyl. Revisions to hard tooling, or creating a new die may run from $10,000 to more than $100,000. On top of that, CNC punching tools may provide millions of hits and accept as many as 20 sharpenings throughout their useful lives, he says.

Tool cost and variety, along with ease of changeout, make profitability via CNC punching very possible on 2000 part/mo. jobs, for example, that stampers tend to outsource.

“Hard-tooling costs amortized across that amount of parts leads to the outsourcing decision,” Tyl says. “That part customer may have been buying long-run parts from a stamper for 50 years, but the stamper never sees the shorter-run business available from that customer. With CNC punching machines, these jobs make the money. With so many stampers taking themselves out of the competition and not even entertaining such work, lower part counts bring higher margins.”