Horizons Customer Magazine 2026
The Stroke of Productivity: How the Disc Housing Makes Full Use of a High-Capacity Press
Volker Drumm is Forming Group Leader with Feintool. Among other things, he oversees the engineering of forming processes like this one. The disc housing illustrates how much work can be performed in a single stroke of the 6-meter metal forming servo presses in Obertshausen, Germany.
The productivity of metal forming comes from simultaneous operations. That is: the number of steps that can be performed on a part all at once, in a single stroke of the press. With each stroke of a carefully engineered forming process, different parts at different stages move from station to station within the press, so every closure of the press performs the next step for a part everywhere throughout the sequence, and every stroke also results in a part being completed. All of this happens at the rate of just seconds per stroke.
For Feintool, one example of a challenging formed part is the disc housing for an automotive hybrid dual clutch transmission. With operations including deep drawing, roller forming, coining, cutting and punching, the forming sequence involves not only a dozen stations, but a variety of lateral moves within the tool.
Feintool Forming Group Leader Volker Drumm says, “Just to produce this part complete with a single press run was the challenge.” That challenge required significant forming expertise, he says, but also a significant press. In Obertshausen, Germany, Feintool operates forming servo presses up to 2,000 ton with table length up to 6m.
This length of press is rare; few forming providers offer the room for so many stations in a single run on a single press. The disc housing, given the number of stations and the movement of tooling between them, required this large capacity. “The capabilities of this press gave us the opportunity to produce this part for the customer in a single run.”
The disc housing is so detailed, it would be prohibitively expensive to produce in a sequence of separate steps. Only forming provides the way to precisely produce the part and all of its details in a single automated step requiring just seconds.
Here are some of the interim steps in forming the disc housing: (A) cutting the blank, (B) deep drawing, (C) punching the location hole, (D) punching oil holes and (E) cutting the final hole to complete the geometry of the part.
The Disc Housing Sequence
In a car, the disc housing conveys torque from a clutch pack (which in this case includes a fineblanked disc also manufactured by Feintool) through to two different gear sets in the dual transmission. Feintool produces this high-grade microalloy steel housing in quantities of millions per year. Parts come off the press at the rate of one per stroke, on its 6-meter press in Obertshausen.
Photos above capture the part’s progress through this press. Each photo shows a glimpse that lasts only seconds before the press opens and the part proceeds to the next forming step. Drumm describes the sequence that occurs with every stroke, consisting of all the simultaneous operations the company’s engineering team designed into the tooling and its actuation with each press closure.
For the disc housing, here are all the steps that occur at once:
1. Cutting the Blank
Though parts progress linearly along the length of the press, raw material from the coil of sheet metal also moves in a second direction, in and out, to accomplish what Feintool calls a “zigzag” feed. This simple additional movement delivers significant cost savings, because it allows circular blanks to be geometrically nested within the sheet metal for maximum material efficiency. Using a zigzag feed over a linear feed reduces the amount of material purchased by 8 to 10 percent, Drumm says.
2. Deep Drawing
Controlled pressure on the sheet metal blank forms it into the cup-like shape.
3. Punching the Square Center Hole
A central square hole in the part has value that continues only through the part’s time in the press. “We need this hole only for location in performing other operations,” Drumm says. The final part includes a different, larger hole than this.
4. Roller Die Forming, Part 1 (Preforming)
A roller die is a rotating forming tool that also moves in a straight line under constant pressure to form specific details of the part. An initial roller die station forms part of the gear-like serration geometry around the periphery of the part.
5. Roller Die Forming, Part 2
A second roller die station completes the outer diameter profile. “These splines around the flanks are among the most accurate features, because these splines are where the housing is connecting to the disc’s torque,” Drumm says.
6. Radial Cutting, Part 1
The precise height of the part is achieved through a two-step cutting operation that advances along the radial direction of the part—meaning perpendicular to the motion of the press’s stroke. The cutting tool driven by the stroke motion cuts off the top edge of the part, moving from outside the part to inside.
7. Radial Cutting, Part 2
An additional, finer cut realizes the final tolerance of the part. The operation is both fast and repeatable. A sliding tool holds +/– 0.15 mm tolerance at this step.
8. Oil Hole Punching, Part 1
Oil holes around the outer diameter are also produced by sliding tools, moving from the outside in. This punching can only be a two-step process, because each hole has to be supported against the force of the punch on the opposite side of the part. So, all the even-numbered oil holes are punched in this first step.
9. Oil Hole Punching, Part 2
Then, the odd-numbered holes are punched in this next step—again, supported from the opposite side.
10. Coining the Dam
An oil dam is a formed feature within the bowl of the part. This feature is produced through coining: controlled deformation using a die to achieve the dam’s precise shape.
11. Cutting the Center Hole
In a final metalworking step similar to the first step, a circular form is cut from the part. The square location hole lost in this step is replaced by the larger hole that is a critical feature of the final part, cut to H9 tolerance so that no secondary machining is needed.
12. Leaving the Press
The automation continues. At the final station, parts are unloaded automatically and sent to washing, nitriding and packaging.
The zigzag feed of the material coil saves cost by reducing scrap. Obtaining more blanks from a given span of sheet metal reduces overall material use by 8 to 10 percent.
The geometry is done at this stage. After the single press run, no additional work is needed to realize the disc housing’s form, features or shape. All of this part’s detail and precision are realized in a sequence that takes just over 30 seconds for a single part to proceed all the way through these operations, or about 3 seconds for these steps to be performed all at once.
The productivity comes from engineering and planning, along with having the right equipment. For Feintool, the starting point of forming work is extensive process development, relying on simulation to find optimization opportunities, followed by in-house building of the tooling needed. With the process and tooling in place, the result is a single-stroke sequence able to deliver the most productive method conceivable for manufacturing this intricate part.
The size of the press is vital for producing the most complex parts. Large press capacity in Obertshausen provides room for all the different stations and operations the disc housing requires.
Forming is productive because of simultaneous operations. Parts move from station to station with every stroke of the press, so that every stroke performs every operation throughout the run and the outcome of every stroke is a completed part.
Gas Nitriding or Plasma Nitriding?
Nitriding is a process for making the surface of a steel part harder by diffusing nitrogen into the material at elevated temperatures. It is a common postprocessing step for formed parts. For the hybrid dual clutch disc housing, nitriding adds the wear resistance needed for the hundreds of thousands of shifting cycles this part will see over the course of its life.
There are two nitriding approaches. One is gas nitriding, which uses ammonia within a furnace to transmit the nitrogen in a bulk process. The other is plasma nitriding. This uses an electrical discharge to direct nitrogen to the part in a plasma.
“Gas nitriding is cheaper, but not every part is a candidate for gas nitriding,” says Feintool Forming Group Leader Volker Drumm. Plasma nitriding is a more targeted process.
That targeting is important for the disc housing, which relies on plasma nitriding rather than gas. The reason is the part’s critical center hole, which is laser welded to a shaft. A nitrided surface would inhibit this welding, Drumm says. “So we use plasma nitriding, along with a small ring to shelter the hole, and that lets us assure there is no nitriding layer on the center hole surface,” he says.
Next steps after the press include washing and nitriding, but no further metalworking is required. A single large-capacity press supports annual production in quantities of millions.
