Horizons Customer Magazine 2026
An Impossible Part? Copper and Aluminum Battery Poles Made in One Piece
Aron MĂĽller
Feintool Head of Technical Sales
Head of Technical Sales Aron Müller worked with Feintool’s tool engineering team to develop the battery pole coining solution.
These EV battery components seem to demand joining, even though the weld compromises performance. Through extreme coining, Feintool makes the battery poles in one piece—no welding required.
Some of the most fundamental components for drawing on battery power within an EV are the car’s battery poles. These are the mated parts—identical except for their material—that both contact the power cell. A battery pole made of copper (the anode) and a battery pole made of aluminum (the cathode) are built into the compartment that holds the cell. Together, they close the circuit and connect the cell to the rest of the vehicle. And crucially, the way they are manufactured today tends to impede their electrical performance. A rivet-like pin is joined to a plate through welding.
Feintool has successfully created single-piece copper and aluminum battery poles through a four-stage forming operation using a fineblanking press. Two different sides of the same set of rivetless, non-welded parts are seen here.
"It’s Not Been Done" (Until Now)
The answer might have been no. Raised features produced through coining typically are not this high. To make this specific battery pole in one piece meant forming a pin 6.4 mm high from the surface of what becomes a flat plate 1.5 mm thick.
"When I first approached people about this, they said it’s not going to work. It’s not been done," Müller says. He had doubts himself. The height of the pin seemed likely to surpass the forming limits of the material. But then, he says, "We started discussions internally, asking ourselves: What exactly is not going to work? Why do we think it’s not going to work?"
This line of questioning led to the engineering simulation and experimentation that ultimately allowed Feintool’s tool engineering team to deliver the successful solution: single-piece, massively formed aluminum and copper battery poles.
The initial blank for the formed battery poles is not rectangular, but instead has a pillow-like shape. The blank is seen at right in contrast to the form of the pole’s plate. The blanks are produced via fineblanking before they are used in the coining (forming) operation. The pillow shape yields a final profile near to the intended rectangle after the forming sequence, so minimal trimming is required.
The Process
The blank for these parts is two to three times the final thickness of the flat plate. Forming occurs in four stages through a transfer sequence, all within a fineblanking press ranging from 4,500 to 8,800 kN (because copper requires about double the force of aluminum, MĂĽller notes). The material is formed into both the central pin and the thinner plate.
Though the final plate is rectangular, the initial, much thicker blank has something more like a "pillow" profile (see illustration). This is the starting shape the team’s analysis found to produce a formed profile nearest to the intended rectangle. Getting close to the final shape through forming alone reduced the amount of material that must be lost to final trimming. "Aluminum and copper are expensive. We aimed for minimum material consumption," Müller says.
Transforming the blank into such a radically different form involves not just the massive force but also control and delicacy in applying it. The precision requirements of the central pin include a runout tolerance of 0.05 mm. "To go from the slug into forming a pin and thinning the bottom at the same time in combination with the tolerances we have to hold is quite tough," Müller says. "It’s also challenging on the tooling and machine elements."
Traditional battery poles consist of a pin affixed to a thin plate through welding. The joining step introduces process variability, while the weld itself impedes electrical conductivity. Above: battery pole placement on the cell compartment.
He notes the transfer die allows force to be spread among different operations along the length of the press. And for precision, this force is mirrored, with multiple coining sequences for multiple identical parts happening in unison. He says, "The smallest version of this process we would run would have one transfer die going to the front and one going to the back, so the force imbalance from this heavy coining is always mirrored through the center of the press."
The one-piece battery poles are currently prototypes, being evaluated by the customer for adoption into production. In addition to the dimensional requirements, Müller says another of the customer’s requirements relates to increased material hardness. This hardness might have made the parts impossible to produce through forming without overloading the machine. Due to the forming work done in the transfer die, the hardness is increased. Drawing on this effect permitted the team to begin with aluminum in a softer state. That freedom to start with softer metal than intended is one of the factors that makes this success possible. The Feintool team found success factors such as this only by questioning, and not immediately accepting, what initially seemed to be an impossible application.
The Part
Aluminum and copper battery poles.
Function
These parts conduct current from the battery cell in an EV battery.
Challenge
Joining via welding adds electrical resistance and adds a potential error source in production.
Solution
One-piece production via forming. Extreme coining on an 8,800-kN fineblanking press raises the central pin while also producing the thin rectangular plate.
Customer Benefits
- Performance improvement: better conductivity, reduced heat development and improved mechanical stability.
- Part count reduction: Fewer steps and sources of variability, reduced potential for errors.
- Workflow improvement: More scalable process for production volume increase.
- Reliability: Single-piece construction eliminates a failure point, contributes to service life.
