Straightening Processes for Aluminium Profiles

CNC stretch straightening with individual twist correction

Twist, bow and inconsistent geometry make aluminium profiles harder to process. GW develops stretch-straightening machines and automated cells that measure each part, apply an individual correction and verify the result.

Concept of a 400 kN CNC stretch-straightening machine by GW

Accurate profiles for the next production stage

During quenching, asymmetric cross-sections of high-strength aluminium profiles can cool unevenly. This can cause twist and deviations from a straight line in the horizontal or vertical plane. These deviations make sill, frame and battery-box profiles harder to assemble and can lead to rework at welded joints.

As deviations vary from part to part, our straightening process starts with an individual measurement of every profile.

How stretch straightening works

The profile is clamped at both ends and stretched axially beyond its yield point. At the same time, CNC-controlled rotating clamping heads correct the measured twist. Axial tension and torsion work together under controlled conditions. Middle clamping can provide additional support for long, flexible profiles.

Measure: Capture twist and bow of the incoming part using laser sensors in the machine or an external tactile measuring station.
Clamp: Use profile-specific jaws and adjust the clamping positions to suit the part.
Stretch and de-twist: Adapt axial tension and twist correction to the measured deviation.
Verify: Re-measure the straightened profile. Part-specific documentation and OK/NOK sorting can be integrated into the process.

Rotating clamping heads during stretch straightening of an aluminium profile

Automation from raw-part buffer to finished part

We design the straightening station as a stand-alone machine or as part of a complete production cell. An automated concept can combine raw-part conveyors, coupled transfer, automatic fixture positioning and measurement before and after straightening. Changeover to another profile type uses program selection and quick-change jaws.

Gantry handling, robots, downstream machining and unloading into finished-part racks can also be integrated. Cycle time, part mix and available floor space determine the system concept.

Machine design to suit your profile

Stretch force: from 5 to 800 kN, depending on the machine configuration.
Part length: configurations for approximately 0.8 to 6.2 m.
Applications: including sills, battery-box profiles, frame sections and structural profiles.

The required tensile force depends particularly on the load-bearing cross-section and the actual material properties. We assess alloy, temper, geometry and tolerances during the feasibility study. The 400 kN machine shown is an example configuration.

Your next step

Send us drawings or 3D data together with the alloy, temper, tolerances and production volumes. We assess feasibility and develop a measurement, clamping and cell concept, including a cycle-time estimate. Straightening trials with your profiles are available at our plant in Stadtlohn on request.

Discuss your straightening application with GW ›