Flame Straightening – Thermal Straightening of Welded Structures and Large Components

Correct welding distortion and dimensional deviations on large components up to 50 t – material-friendly thermal flame straightening without material removal, as a contract service in Lorch.

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Straightening without material removal

Thermal straightening restores dimensional accuracy – without removing substance or re-welding.

Even heavy parts up to 50 t

Straightening directly on the 2×25 t crane system – no size limitation from furnaces or fixtures.

Material-friendly temperature control

Controlled heating preserves the properties of quenched-and-tempered and higher-strength steels to S1100.

Everything from a single source

Welding to DIN EN 1090-2 EXC3, flame straightening and machining at one site in Lorch.

DIN EN ISO 9001:2015

Quality management with documented manufacturing processes.

Flame Straightening – Process and Working Principle

In flame straightening, the material is heated rapidly in a locally confined area with a torch. The surrounding cold structure restrains the thermal expansion – the heated zone is upset. On cooling, the upset area contracts and pulls the component into the desired shape. This corrects welding distortion and residual stresses without removing material or re-welding.

Heating figures – spot, line or wedge – let the operator control the direction and amount of shrinkage. Experience and controlled temperature management are essential: heating stays below critical temperatures so that the material properties are retained – even for quenched-and-tempered and higher-strength steels.

Flame straightening complements vibration stress relief. While vibration stress relief (VSR) reduces residual stresses, flame straightening corrects the visible distortion. Combined, the component stays dimensionally stable – the ideal preparation for subsequent precision machining.

We also perform flame straightening as a contract service on customer-supplied components from external manufacturing. Welded structures fabricated in Lorch are straightened directly after welding, before they move on to machining or final assembly – without external logistics and without an interface break.

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Suitable Components for Flame Straightening

Flame straightening is suitable for welded structures and steel components with thermal distortion:

Distorted welded frames and base structures
Large plates and panels with bulges or waviness
Beams, profiles and welded box structures
Machine beds and frames before precision machining
Components in steel, Hardox, stainless steel and fine-grain structural steel up to S1100

Flame straightening is available as a standalone service or combined with our in-house welding and machining capabilities.

Heavy Welded Structures →

Typical Applications

Flame straightening is used across industries in heavy-component manufacturing:

Distortion correction after welding of large steel structures
Straightening of crane, lifting-gear and plant components
Flatness correction on plates and welded panels
Dimensional accuracy of frames and structures before machining
Re-straightening of components after transport or machining

Straightened components proceed directly to precision machining in the same facility – without external logistics or an interface break. Heavy parts up to 50 t are handled on our in-house 2×25 t crane system.

CNC Heavy Machining →

Flame Straightening at Bock – Your Advantages

Bock Maschinenbau offers flame straightening as an integrated step in the manufacturing and quality process:

Distortion corrected without material removal: Thermal straightening restores dimensional accuracy without removing substance or re-welding.
Suitable for heavy parts up to 50 t: Straightening directly on the 2×25 t crane system – no size limitation from furnaces or fixtures.
Material-friendly temperature control: Controlled heating below critical temperatures preserves the properties of quenched-and-tempered and higher-strength steels.
Everything from a single source: Welding to DIN EN 1090-2 EXC3, flame straightening and machining at one site in Lorch.
DIN EN ISO 9001:2015: Quality management system with documented manufacturing processes.
Straightening for the region: Steel fabricators and metalworking companies from the Stuttgart area and the DACH region have us flame-straighten warped welded structures to precise dimensions here in Lorch.