Expert Article: DED Repair of Injection Molds (H13 Tool Steel)

Sustainability and Cost Savings in Toolmaking

Injection molds made from hot-work tool steels like H13 (1.2344) are immensely expensive to manufacture and are subject to heavy abrasive wear at the parting lines and cores. Traditionally, massive wear meant the end of the mold’s life or a very labor-intensive manual repair welding (TIG welding) process, which introduced enormous residual stresses and distortion into the component.

Directed Energy Deposition (DED)—often also referred to as Laser Metal Deposition (LMD)—is currently revolutionizing tool and mold making. By precisely melting H13 metal powder or wire using a laser beam via a robotic arm, worn areas can be rebuilt accurately and with a full metallurgical bond.

Advantages of DED Repair over Manual Welding

• Localized Heat Input: The laser melts the material with pinpoint accuracy and low overall energy input. The heat-affected zone (HAZ) remains extremely narrow, reducing macroscopic distortion of the expensive tool to an absolute minimum.
• Multi-Material Capabilities: It is easily possible to deposit an extremely hard layer of Stellite or Tungsten Carbide onto the H13 base body, elevating the wear resistance of critical flanks even beyond the level of the original mold.
• Automation: The DED process can be programmed via CAD/CAM paths. A 3D scanner captures the worn state of the mold, software calculates the missing volume, and the DED head deposits exactly the required amount of material.

Post-Processing is Mandatory

As with all welding processes, DED creates surface roughness that prevents a "net-shape" (final dimension) finish. The deposited areas must subsequently be finish-milled back to their precise original geometry on a 5-axis CNC milling machine. Therefore, DED is frequently used in hybrid machines, where the DED laser head and milling spindle operate interchangeably within the same setup.

Through DED, repair costs can often be reduced by up to 80%, while lead times (compared to procuring a massive new tool) shrink from several months to just a few days.