Fraunhofer Institute for Production Technology IPT
Fraunhofer Institute for Production Technology IPT
© Fraunhofer IPT

Upgrading conventional sheet metal working processes

Laser-assisted shear cutting achieves a clear-cut surface ratio of 100%.

© Fraunhofer IPT

Localized laser use reduces tool wear

The cutting force can be reduced by 70% by heating the high-performance materials before critical process steps.

Testing expanded metal using a magnifying glass
© Fraunhofer IPT

Producing expanded metal structures

In water electrolysis, a porous transport layer (PTL) ensures the removal of oxygen gas from the water. We develop and manufacture PTLs on our in-house expanded metal plant. We would be happy to design and optimize your application - contact us!

© Fraunhofer IPT

Efficient combination of system and process technologies reduces costs in the processing of sheet made from high-performance materials

From feasibility test to production readiness

Conventional sheet metal processing methods such as shear cutting or forming often reach their limits with high-performance materials. For example, perfect cut edges are difficult to achieve in transfer and progressive dies for high-strength sheets of steel, titanium or aluminum. New manufacturing technologies are therefore required to meet increasing production and quality demands. Functional integrations, for example high local strength or formed structures in the component, can be realized by local hardening or heating. 

Efficient sheet metal processing in the progressive die

The Fraunhofer IPT developed technologies for local, thermal-assisted sheet metal processing (tailored heat) in the manufacturing process. Integrated into transfer or progressive dies, this allows high-strength sheet metal can be heated locally for a short time before processing. As a result, the materials can be more easily formed or cut in critical areas of the component. Conventional machine and tooling technologies achieve higher cutting qualities and forming degrees with thermal support, and conventional process limits can be extended.

Previous research results on shear cutting show that clear cut percentages of up to 100 percent can be achieved with local heating. At the same time, the cutting forces are reduced by up to 70 percent compared to the conventional cold process. With flange forming, doubled expansion ratios are possible. Local laser heating also offers advantages in bending, embossing and deep drawing: Using a high-strength spring steel, the smallest bending radii and large drawing and stamping depths were achieved. With suitable temperature control for the respective material, locally hardened sheet metal components can also be produced in the progressive die.

Individual solutions for sheet metal processing

The Fraunhofer IPT develops heating processes suitable for series production for your individual sheet metal components and materials. In addition to fundamental know-how in laser system technology, sheet metal processing and materials engineering, modern heating systems and press technology are available for feasibility tests up to pilot series production according to current industrial standards. Metallographic material analysis completes the range of services.

Sheet metal components for fuel cells and electrolysers

One application for sheet metal processing is the production of components, metal-based bipolar plates and expanded metal structures. Expanded metal Structures are mainly used in electrolysis in combination with flat bipolar plates, which can achieve significant cost advantages compared to conventional porous transport layers. The Fraunhofer IPT is working on the efficient and functional production of the structures. The flat joining of the expanded metals is realized by means of medium-frequency resistance pressure welding.

Complementary heating technologies open up a wide range of application fields

The Fraunhofer IPT integrates heating technologies into the manufacturing process, thereby advancing conventional machining processes for high-performance materials. Complementary heating technologies are used for this purpose, such as electrical resistance heating (conduction), induction or local heating by means of laser radiation.

© Fraunhofer IPT

Conduction

Conduction is based on the principle of heating by electrical resistance: the sheet is positioned between two electrodes. When an electric current flows through the electrodes, the resistance of the sheet causes local heating. Conduction can be used to heat surfaces of almost any size in a short time.

© Fraunhofer IPT

Induction

In induction, a magnetic field heats the sheet at a defined penetration depth to varying degrees depending on the frequency. Depending on the application, single- or double-sided inductors can be used. Energy-efficient induction heating is suitable for component areas of different sizes with different sheet thicknesses within short cycle times. 

© Fraunhofer IPT

Laser

The principle of local laser heating is based on irradiating the sheet metal on one or both sides with high light power. The laser energy is absorbed at the surface of the sheet and thus heats the sheet. Almost any complex component geometry can be heated with the highly dynamic beam deflection unit. Laser technology provides high flexibility. Custom control software allows shear cutting geometries to be heated close to the contour.

Integration of modular heating systems

The heating technologies can be integrated into existing production chains as modular expansion systems and are characterized by low investment costs and heating times of just a few seconds. Under the brand name hy-PRESS, the Fraunhofer IPT develops modular systems for three heating technologies: conduction, induction and laser. Different expansion stages can be implemented with the following features, among others:

  • Integrated process monitoring via camera
  • Temperature measurement and control
  • Compensation of sheet metal stroke movements in the progressive die
  • Fixed optics and scanner solutions for laser heating

Process strategies for sheets made from high-performance materials

Depending on the desired goals for processing high-performance sheet materials such as titanium, steel or aluminum, three process strategies are possible for effective production.

Hardening

In lightweight sheet metal construction, functions are increasingly being integrated directly into the component, for example by hardening certain local sections. Compared with press hardening, local hardening offers, for example, the possibility of energy- and resource-efficient production, since the hardened area, the hardening depth and the hardness can be precisely adjusted to the specific component.

Thermal softening

The processing of high-strength and ultra-high-strength sheet metal is challenging due to high process forces, low cutting and forming quality, and active part wear. In addition, the induction of work hardening during shear cutting often leads to limitations in downstream processes (e.g. higher edge crack sensitivity during forming). Here, thermal softening can improve machinability by locally reducing the strength. As a result, the components have a high clear cut percentages as well as reduced edge indentation or improved formability.

Semi-hot and hot machining

In metal or sheet metal working, better formability is usually achieved by hot and semi-hot processing. By limiting the heating zone to a small local area, individual areas can be produced in the tool with all the advantages of semi-hot/hot processing.

Machinery at the Fraunhofer IPT

© Fraunhofer IPT

Hydraulic punch

  • Maximum force 280 kN
  • Heating technologies:
    • Laser: 10 kW, 
    • Induction: 50 kW,
    • Conduction: 40 kW

Special features

  • Basic test bench for sheet metal processing
  • Hydraulic drive with positioning function
  • Force, position and temperature measurement
  • Sheet metal feed axis with linear motor
  • Feasibility studies and small series testing

 

© Fraunhofer IPT

Servo press

  • Maximum force 2000 kN
  • Stroke rate: up to 130 strokes / min
  • Heating technologies:
    • Laser: 6 kW
    • Induction: 50 kW
    • Conduction: 40 kW

Special features

  • Automatic coil line
  • Twin servo drive
  • Database connection (processing of sensor, machine and tool data and AI algorithms) 
  • Investigation of process stability and high volume processes

© Fraunhofer IPT

Expanded metal machine

  • Adjustable stroke rate: 300-900 strokes/min
  • Pneumatic feed
  • Processable sheet thicknesses: 0.1 to 1.5 mm
  • Mesh widths: 0.3 to 8,0 mm
  • Mesh lengths: 0.5 to 16.0 mm

Special features

  • Interlinked production modules
  • Process optimization and investigation of high-volume production
  • Processable materials and their alloys: titanium, stainless steel, nickel

Our services at a glance

  • Feasibility tests for your individual components and sheet materials
  • Determination of optimum heating parameters for defined machining quality
  • Analysis of the influence of local heating processes on the mechanical-technological component properties
  • System development for laser heating, induction and conduction technology
  • Integration of the systems into existing production facilities
  • Cost-effectiveness analysis of the integration of heating technologies in sheet metal working processes
  • Process development and demonstration on a servo press at the Fraunhofer IPT
  • Zero series production with consideration of process stability
  • System development for expanded metal production

Sheet metal components manufactured with thermally assisted machining processes

Heating Technologies

The Fraunhofer IPT has developed various local heating methods for thermally assisted sheet metal processing: In addition to the laser beam as a heat source, also heating by induction or conduction.

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