How To Make Press Brake Dies With Laser Hardening Machine

To make press brake dies with a laser hardening machine, machine the die geometry from a suitable steel, establish its core condition, and then harden the selected working surfaces. Laser transformation hardening heats the surface into the austenitic range and uses rapid cooling to form martensite, the hard steel microstructure. The die body provides the heat sink for self-quenching. Fraunhofer ILT describes this mechanism.

For tooling engineers, the important decisions are where to harden, how much hardened material must remain after finishing, and how the laser path treats shoulders, ends and adjacent tracks. These decisions connect die manufacture with heat treatment. A useful process specification describes the finished tool and its hardened layer together.

Key takeaways

• Specify the steel and core condition before developing the laser cycle.
• Match the hardened zone to the die's working surface and final profile.
• Treat power, speed, spot shape and scanning pattern as a combined process.
• Inspect across tracks and through the layer, including overlap regions.
• Set finishing allowances against the remaining hardened depth.

Table of Contents

• Choose the steel and core condition for press brake dies
• Machine the working profile before local hardening
• Control laser transformation hardening and self-quenching
• Balance laser power, scanning speed and spot geometry
• Plan scanning patterns and overlapping tracks
• Measure surface hardening depth and hardness distribution
• Finish the die without losing its functional layer
• Frequently asked questions
• Discuss your die hardening requirements
• References

Choose the steel and core condition for press brake dies

Laser transformation hardening applies to hardenable ferrous materials. Fraunhofer USA identifies hardenable steels and cast irons as the usual material group. The starting point for a die is therefore its specified alloy and heat-treatment condition. A drawing that says only “tool steel” leaves important decisions unresolved.

Separate surface hardness from core condition. Surface hardness concerns the treated working region. The core condition describes the underlying steel that supports that region. Specify both in the tooling requirements, together with the intended bending operation. A hard surface requirement alone gives the heat-treatment supplier no clear basis for deciding which incoming material condition to qualify.

The starting microstructure matters during rapid heating. The AISI 4340 modeling paper explains that carbon must redistribute within the austenite, and that the required diffusion time depends on the initial microstructure. Incomplete homogenization can leave mixed transformed regions. See its metallurgical-transformation discussion. This is a reason to identify the incoming heat treatment, rather than qualifying a route against the alloy name alone.

For a new die, ask the steel supplier for the grade designation and material certificate. Ask the heat-treatment supplier how the incoming condition will be checked. If the die has already been quenched and tempered, identify that treatment on the manufacturing route. For a repaired die, also identify any previous surface treatment and the repair history of the working edge.

Avoid transferring a hardness target from another alloy simply because both materials are used in tooling. A qualification coupon should represent the selected material condition. Where several steel heats or incoming conditions will be used, decide which changes require the heat-treatment route to be reviewed. Keep the decision tied to the material specification rather than a generic machine setting.

The practical purchasing question is: What material and core condition are required at the start of laser processing? Resolve it before ordering the finished blank. This allows machining, incoming inspection and laser trials to use the same starting specification. It also prevents a late disagreement about whether an unsuccessful hardness profile came from the steel supply or the thermal cycle.

Machine the working profile before local hardening

Selective hardening can follow edges and complex shapes. Fraunhofer USA lists edge treatment and forming tools among its laser-hardening applications. For a V-die, translate that selectivity into a drawing of the working shoulders and the required treatment boundaries.

Start with the bending profile, mounting interface and datums. Identify which surfaces need wear resistance and which surfaces establish installation height, alignment or clamping. Mark the treatment zone separately from the dimensional inspection locations. This gives the laser programmer a specific surface to follow and gives inspection staff a clear reference for the resulting track.

Define the working zone as geometry

Show the V-opening, shoulder radius, included angle and die length on the manufacturing drawing. Mark the start and end of each hardened band along the tool. For a segmented die, show whether the treatment must reach the end face and how the ends will be checked. For a reversible tool, identify every working position that needs treatment.

The laser route should be discussed alongside machining allowances. Decide whether the working profile reaches its final size before hardening or receives controlled finishing afterward. If finishing is planned, identify the material to be removed from the treated surface. The same allowance must appear in the heat-treatment discussion and the finishing instruction.

Treat damaged dies as a separate manufacturing route. Measure the existing shoulder profile before deciding how to restore it. Record chips, worn radii and previous local repairs in the area proposed for treatment. If dimensional restoration requires added material, discuss a deposition or repair process first. UBright's laser cladding article describes the related surface-build-up workflow.

Finally, use the tool datums to position the die in the laser fixture. Ask the supplier to explain how it will reproduce the relationship between the programmed band and the finished shoulder. The useful deliverable is a treatment drawing connected to the actual die profile, rather than a broad instruction to harden the upper surface.

Control laser transformation hardening and self-quenching

During transformation hardening, heat moves from the briefly heated surface into colder material below it. The cooling history is part of the process. Fraunhofer ILT notes that thin-walled components can require an external cooling medium and describes surface transformation to a depth of about 1 mm in its technical overview. Its explanation also identifies pyrometers and cameras as temperature-control methods.

For a die, consider the section beneath each treated surface. A qualification piece should represent the local shoulder geometry and surrounding material, particularly where the profile becomes narrow. Ask the supplier how the fixture and treatment sequence will be represented in the trial. A coupon chosen only for convenient cutting may omit the part of the geometry that needs qualification.

Connect temperature control to the tool position

Specify which surface the temperature system observes as the beam travels. Ask how the measurement remains aligned with the heated zone when the head follows a radius or changes direction. The process record should identify the approved sensing arrangement and the temperature-control strategy used for that die family.

For long tooling, define the treatment sequence from the start to the finish of the band. Identify pauses, turns and transitions between bands on the process map. Ask how the cycle handles these locations, and include them in qualification inspection. This makes the route understandable to both the programmer and the metallurgist who reviews the sectioned samples.

The distinction between a machine's available laser power and the qualified thermal cycle matters here. A machine rating describes its capacity. The accepted route describes how a particular surface is heated and cooled. Request records for the latter, including the actual material condition and tool geometry used during qualification.

If a supplier proposes external cooling or a different fixture for a narrow feature, make that arrangement part of the approved route. When the production arrangement changes, review the affected features before treating the next batch. The review should focus on the locations whose geometry or cooling arrangement has changed, rather than repeating an unrelated general checklist.

Balance laser power, scanning speed and spot geometry

Power and scanning speed must be considered together. In Tarchoun, El Ouafi and Chebak's AISI 4340 plate experiments, the researchers selected 500–800 W and 20–40 mm/s after preliminary trials. Those trials showed that higher power combined with slower travel could introduce surface melting. These were laboratory conditions for that material and optical setup. See the experimental paper, Sections 2.1–2.2.

Use these reported values to understand the variables, rather than to prescribe a production die cycle. Ask the supplier to state the combination it intends to qualify: power strategy, travel speed, optical arrangement, path and sensing method. Ask which variable is adjusted by the controller and which variables remain fixed during the route.

For a straight path at constant power, nominal incident energy per unit path length = power / travel speed. Power in watts divided by speed in millimetres per second gives joules per millimetre. This simple bookkeeping relation explains why slowing the path increases incident energy per length. Absorption, spot footprint and heat conduction still determine the actual temperature history, so equal energy per length can describe different treatments.

The spot dimension along travel sets another geometric quantity: nominal exposure time = spot length / travel speed for straight, constant-speed motion. The transverse dimension sets the illuminated width. Rotating an elongated spot therefore changes the exposure and width relationship even at unchanged power and travel speed. Record both spot dimensions and orientation when comparing routes; a single “spot size” value leaves that relationship unclear.

Spot geometry adds another independent decision. In their 42CrMo investigation, Kovalenko and co-authors found that, at constant power density, increasing the spot width perpendicular to travel increased hardened width, while hardened depth first increased and then decreased. The publisher's original abstract reports this non-monotonic depth response.

For a die shoulder, compare the proposed band width with the actual working zone. Ask whether the optical arrangement can cover the desired zone in the chosen orientation. If the route requires several passes, evaluate the resulting overlap instead of assuming that a wider total band has the same depth everywhere.

These choices should appear as one approved route. When comparing quotations, request the intended qualified band geometry and inspection evidence alongside the machine specification. This makes the comparison about the die outcome rather than the largest laser rating offered.

Plan scanning patterns and overlapping tracks

The scanning path changes how heat is distributed. In the same AISI 4340 experimental study, test 7 used 800 W and 20 mm/s. Reported hardened depth/width values were 1011/1154 µm for the linear path, 456/2808 µm for the sinusoidal path, 574/2516 µm for the triangular path and 802/2578 µm for the trochoid path. These results are reported in Section 3.

The practical comparison for a die is therefore between usable width and sufficient depth. Mark the band width required by the working shoulder, then specify how the depth will be assessed within that band. A path that covers the widest area may require a different finishing allowance or inspection pattern from a deeper, narrower path.

Inspect the joins between tracks

Adjacent passes deserve explicit attention. Tarchoun and co-authors' subsequent numerical and experimental paper describes tempered and over-tempered regions in multi-track overlap. It also discusses repeated heating at crossing points in a trochoid path. See its introduction and thermal-distribution discussion.

For production planning, place the proposed pass boundaries on the die drawing. If an overlap lies in a working shoulder, include that location in the hardness map. If the supplier changes band width by adding a pass, ask for the revised treatment map and its qualification evidence. Keep track centers and joins visible in the inspection report.

Read the inspection map as a spatial result. A low-hardness band between acceptable track centers calls for examination of the join and its reheating history. A shallow zone at the outside of a band calls for examination of coverage at that edge. These are different locations with different process questions. Reporting only the best reading at a track center would hide the distinction.

On a long die, include the first and last treated regions in the sample plan. On segmented tooling, compare the locations near the segment ends with a representative middle location. Specify the inspection locations before the trial so the samples answer the actual tooling question.

The route approval should state which path was accepted and where it was used. Avoid describing the treatment only as “robotic laser hardening.” The robot is the motion platform. The accepted path, thermal control and resulting band are the information needed to reproduce the treatment. This distinction is useful when a later tool has a different length or shoulder profile but is proposed for the same production cell.

Measure surface hardening depth and hardness distribution

Surface hardening depth needs a measurement definition. The public scope of ISO 18203:2026 includes determining the thickness of layers produced by laser beam hardening. It distinguishes surface-hardening measurements from other treatment-depth categories. The ISO page identifies the scope of the current edition.

Agree with the testing laboratory which depth term, hardness criterion and test method will appear on the report. Also identify whether the requirement applies before or after final finishing. A purchase specification that gives a depth without its evaluation rule can produce reports that look comparable but answer different questions.

A useful qualification report connects the section location to the die drawing. Include the working shoulder, track center, band edge and any overlap that needs evaluation. Label the surface from which depth is measured. Ask the laboratory to keep the hardness results connected to these locations, including the measurement method and test conditions.

The AISI 4340 numerical/experimental study used microindentations with a 100 µm pitch along vertical and horizontal axes to examine the treated region. Its experimental-validation section explains this mapping method. That arrangement illustrates why a cross-sectional map provides more information than a single surface reading; the inspection method for a production die should be agreed for its own layer and geometry.

Keep metallurgical inspection separate from the tool's dimensional release. A qualified layer addresses the heat treatment. The die still needs its specified opening, angle, radius, height and alignment. If a bending trial is part of acceptance, record the machine setup and sheet specification separately. UBright's press brake deflection compensation guide covers the related machine-deflection issue.

Finish the die without losing its functional layer

Local hardening changes a defined surface region. Fraunhofer IWS describes controlled, localized heating followed by self-cooling to produce a martensitic layer, and identifies robot-assisted treatment in tool and die making among its industrial applications. Its technical page explains this local-treatment approach.

Connect the finishing plan to that treated region. If grinding or polishing follows hardening, specify the permitted removal at the working shoulder. Ask for the final layer evaluation to use the finished surface as its reference. Keep the machining allowance and the final layer requirement on the same route so neither operation is planned in isolation.

For a new die, define which dimensions are released before hardening and which are released afterward. Inspect the profile at the agreed datums after the last operation. If the finishing process needs more removal than planned, hold the tool for review of the remaining layer. The decision should consider the measured profile and layer together.

For uniform removal from a flat reference surface, the depth coordinates on a pre-finishing hardness profile shift by the removed thickness. A shoulder is curved, so the local removal and surface normal also need to be considered. Use the finished shoulder as the reference for the release measurement, particularly where finishing changes the radius. Keep a pre-finishing section as process evidence and a final-surface assessment as the basis for acceptance.

For a used die, measure the worn profile before selecting a restoration allowance. Ask whether the proposed work removes an old treatment, retains part of it or adds a new local treatment. Establish the final radius and mounting dimensions before scheduling another hardening pass. This helps the supplier select a representative trial instead of treating a repaired tool as an unchanged repeat order.

A maintenance instruction should also identify when the working surface requires examination. Record wear or damage against the same shoulder locations used during initial release. When regrinding is proposed, review the remaining treatment against the new finished geometry. A recorded original layer depth is useful only when the subsequent material removal is also understood.

The final manufacturing route is complete when machining, local hardening, finishing and inspection refer to the same tool geometry. That connection makes the die specification usable for repeat manufacture and future restoration. It also gives the buyer a clearer basis for discussing treatment choices than a promise of higher hardness or longer service life alone.

Frequently asked questions

Does laser hardening manufacture the complete die?

Laser hardening is the heat-treatment operation within the manufacturing route. The die's blank, working profile and mounting interfaces still require manufacture. Define the treatment zones on the machined profile, qualify the thermal cycle, and coordinate any later finishing with the required remaining layer.

Can one set of laser parameters be used for every die?

A route should be qualified for its material condition, geometry, optical arrangement and path. When a new die changes one of these features, ask the supplier which parts of the qualification remain applicable and which locations need additional inspection. Keep that decision in the process record.

What should be specified besides surface hardness?

Specify the incoming steel condition, treatment-zone geometry, depth definition, inspection locations and final finishing allowance. Include the die's dimensional requirements separately. This gives the heat-treatment supplier and testing laboratory a shared description of the required layer and the finished working profile.

Discuss your die hardening requirements

Making press brake dies with a laser hardening machine requires a coordinated tooling route: a suitable steel and core condition, a machined working profile, a qualified thermal cycle, and inspection of the finished hardened zone. The useful questions concern the shoulder geometry, usable band width, depth distribution and any later material removal.

To discuss your tooling requirements with UBright Solutions, provide the die profile, steel designation, incoming heat-treatment condition, working-zone drawing and requested layer evaluation. Include whether the project concerns new manufacture or restoration of an existing die. These details support a focused discussion of the process and the evidence needed for acceptance.

References

• Heat Treatment with Laser Radiation — Fraunhofer ILT — Austenitization, self-quenching, thin-wall cooling, temperature sensing and the overview's approximately 1 mm depth.
• Laser Hardening — Fraunhofer USA CMW — Hardenable ferrous materials, selective edge treatment and forming-tool applications.
• Experimental Investigation of Laser Surface Hardening of AISI 4340 Steel Using Different Laser Scanning Patterns — Tarchoun, El Ouafi and Chebak's 2020 plate experiments, parameter ranges and four measured depth/width pairs.
• Effect of Spot Size on Geometrical Characteristics of Laser Deep Quenching Hardened Layer of 42CrMo Steel — Kovalenko and co-authors' 2020 study; original publisher abstract on spot width and non-monotonic hardened-depth response.
• Numerical Investigation of Laser Surface Hardening of AISI 4340 Using 3D FEM Model for Thermal Analysis of Different Laser Scanning Patterns — Tarchoun, El Ouafi and Chebak's 2020 modeling/validation paper; overlap tempering, repeated heating and 100 µm indentation pitch.
• ISO 18203:2026 — Steel: Determination of the thickness of surface-hardened layers — Public scope of the current standard, including laser beam hardening; no procedural acceptance threshold adopted.
• Laser Hardening — Fraunhofer IWS — Local martensitic treatment and robot-assisted tool-and-die applications.