Straightening and aligning workpieces is a controlled deformation operation in which geometric deviations are corrected by means of axial force introduction. The operation is applied to shafts, profiles, plates, tubes and other structural parts in which dimensional accuracy, straightness or concentric alignment is disturbed. A hydraulic workshop press is suitable when the technical conditions fall within the working area of the press and the operation can be carried out reproducibly and in a balanced manner.
This page describes when straightening and aligning falls within this application range – and when it does not.
When is a hydraulic workshop press suitable?
A hydraulic workshop press is suitable for straightening and aligning operations when:
- the deformation can be applied axially without torsion or impact loading
- the force can be built up controlled, gradually and in small steps
- the workpiece can be supported stably, with full surface contact and free from vibration
- the direction of force introduction can be defined exactly
- the material is ductile enough to deform plastically in a controlled manner
- the measurement reference can be determined reproducibly before, during and after the operation
When these conditions are not met, the operation falls outside the intended technical range of a workshop press.
Technical considerations
Pressing force & force build-up
The required force for straightening and aligning operations is determined by:
- material type and yield strength
- cross-sectional geometry of the workpiece
- magnitude and location of the deviation
- required correction accuracy
- length of the workpiece and critical buckling length
Important requirements for force build-up:
- force must be increased step by step, with intermediate measurements
- local overstressing must be avoided
- the force progression must be followed to interpret the transition from elastic to plastic deformation correctly
- force reduction between steps must be applied to assess springback
In straightening, elastic deformation is applied first. Only when the yield strength is exceeded does plastic deformation occur. The difference between the two determines how much the workpiece springs back and therefore determines the accuracy of the final position.
Interference, alignment & support
For accurate straightening:
- support must be placed close to the correction location to avoid unwanted global bending
- the workpiece must be clamped stably and with full surface contact
- no lateral loading may occur during the operation
- the force introduction must take place exactly perpendicular to the desired alignment axis
- the measurement method must be constant, reproducible and free from parasitic movements
When the workpiece is not supported uniformly, a complex bending moment arises with unwanted secondary deformations. As a result, the workpiece can twist locally even when the axial direction is chosen correctly.
Structural requirements for the press
A suitable hydraulic workshop press has:
- a welded steel frame that minimises lateral deflection
- linear stroke guidance that maintains the force axis exactly
- a flat, stable working table that introduces no torsion or local deformation
- pressing tools with a defined contact surface that prevent shearing and point loading
- sufficient mass to dampen microvibrations
Even slight lateral deviations in the press column generate parasitic loads that deform the workpiece unevenly, preventing correct straightening values from being achieved.
What is often underestimated in practice
- elastic springback that affects the final measurement value
- local overstressing due to incorrectly chosen pressure point
- deformation of thin-walled profiles due to insufficient support
- influence of existing residual stresses that distort the force curve
- cumulative error formation when multiple corrections are performed without intermediate measurements
- sensitivity to torsion when the workpiece is not supported symmetrically
These factors determine whether the final geometry falls within the required tolerances.
Typical operations within this application
- straightening shafts with slight bending
- aligning profiles, tubes and structural members
- correcting assembly frames or weld-distorted parts
- restoring dimensional errors in maintenance and rework situations
- precision straightening of structural parts in series production
This list describes the nature of the operation; not which press configuration is needed.
Relation to press classes (HD programme)
Placement within the HD programme is determined by:
- material type
- section height
- straightening length
- required force band
Light-duty press class (20–60 tonnes)
Suitable for:
- small profiles, thin-walled workpieces and short shafts
- low correction forces
- situations in which support can be reproduced easily
Medium-duty press class (80–160 tonnes)
Suitable for:
- typical workpiece sizes and structural parts
- straightening operations in which the transition from elastic to plastic deformation must be controlled precisely
- workshop use with reproducible straightening settings
Heavy-duty press class (180–500 tonnes)
Suitable for:
- large profiles, massive shafts and stiff structural parts
- situations requiring high straightening forces
- workpieces with high section modulus that deform little under normal loading
The correct press class is determined by geometry, force trajectory and straightening profile – not by pressing force alone.
When is a workshop press not suitable?
A hydraulic workshop press is not suitable when:
- torsion, rotation or impact loading is part of the straightening method
- the workpiece cannot be supported stably, with full surface contact or safely
- the deformation is highly variable or the material is too brittle
- the geometry is so complex that linear force introduction is not possible
- the risk exists that local overstressing cannot be prevented
Further navigation within the site
Based on this application, reference can be made to:
- the relevant press classes within the HD programme
- the available standard models
For operations outside these boundary conditions, reference is made to the engineering and custom-built hydraulic press trajectory, in which non-standard geometries and complex straightening conditions are assessed technically.
Request technical evaluation
When straightening or aligning falls within the described technical boundary conditions, a technical evaluation can be requested to position the application within the correct press class.