3D printing applications for tool steel

The tool industry plays a key role in the entire process industry sector. Tools have a significant impact on the quality of final products, which is why the requirements for this industry are constantly increasing. On the one hand, it must work with some of the most demanding materials, and on the other hand, it must offer the highest possible service life of its products. For this reason, it is natural to constantly search for new solutions to produce better tools. The tool industry is an excellent field for additive technologies, because it fits perfectly into the mainstream of printing, i.e. the production of small-series elements with complex geometry.

Additive technologies have been present in the tool industry for many years, initially they were used to produce bronze and maraging steel tools. However, with increasing demands and wider adoption of 3D printing technology by the industry, new materials with even greater hardness are emerging.

Direct Metal Laser Melting (DMLM/SLM)

The direct metal laser melting (DMLM/SLM) process minimizes the porosity that is typical of the sintering process. Thanks to this, it is possible to achieve a density close to 100%. Producers can also reuse valuable metal powders that are not melted in the process. The GE Additive 3D printers optimize the process by using many high-power lasers that can work simultaneously on one working field or on several working fields at the same time. Such a multiplication of lasers significantly accelerates the process of melting the material layer, while the use of high-power lasers allows to increase the thickness of the layer, additionally shortening the entire manufacturing process.

Surface quality and minimal porosity are two key advantages of the DMLM/SLM process. Due to the ability to move the bed in increments of only 20 microns, objects have a smooth surface, minimizing the time and cost of required finishing.

Tool steel H13 in the DMLM process

Hot work tool steels are a class of medium carbon, high strength alloys. With a combination of high strength, hardness and good wear resistance, they are the ideal material for applications such as die casting, extrusion, die forging and other processes that require hot or cold working.

A recently developed novel parameter for H13 steel has been implemented in the M2 Series 5 machine. The H13 steel powder has a chemical composition in accordance with ASTM A681. The key feature of the new parameter is a surface roughness of less than 10 µm for most surfaces without blasting or shot peening. Thanks to the use of two lasers, high process efficiency is also ensured.

Table (state after printing without heat treatment):

One of the main applications of H13 tool steel for DMLM 3D printing technology is the creation of injection molds with conformal cooling. The cooling time accounts for as much as 70% of the cycle time in injection molding. 3D printing allows for the production of conformal tooling, which reduces the cooling time by up to 30%, thus significantly reducing the total cycle time. Even temperature distribution throughout the mold and faster cooling of the mold minimize defective parts and ensure higher part quality due to less warping and lower internal stresses.

DMLM 3D printing enables the design of conformal cooling channels and temperature-inaccessible functions as well as unique structures such as spiral cooling channels on tool bodies and small diameter channels.

The cooling channels form a mesh structure that allows the surface of the glass insert to cool evenly, just 2 to 3 mm below the mold contour.

GE Additive M2 SERIES 5

The M2 Series 5 is designed to meet the most critical requirements of the highly regulated aerospace industry. Thanks to the use of 3D optics, it is possible to obtain a variable size of the laser spot. This allows for accurate execution of details and increased productivity.

• Build volume: 245 x 245 x 350 mm (XYZ)
• Lasers: 2×400 W oraz 2x 1 kW
• Materials:
  • Steel (316L, Maraging M300, H13)
  • Aluminium (AlSi7Mg, AlSi10Mg, A205)
  • Titan (Ti6Al4V, Ti6242)
  • Nickiel (625, 718)
  • Cobalt CoCrMo

Electron Beam Melting (EBM)

One of the most promising techniques in the field of metal additive manufacturing is electron beam melting (EBM). Currently, this technology is mainly used to produce high-performance titanium-based alloy components for the aerospace and medical industries. Among the industrial applications foreseen for EBM in the near future, the production of high-carbon steels for the tool industry, such as Cr-Mo-V, is of great interest.

The EBM process uses a high-power electron beam that generates the energy needed to melt the material quickly. The hot process produces parts without residual stresses and the vacuum ensures a clean and controlled environment. EBM is a hot process, meaning that the electron beam heats each successive layer until the entire powder bed reaches the optimum process temperature specific to the material used. As a result, this process produces components without residual stresses and generates microstructures free of martensitic structures.

The high solidification rates during EBM processing lead to very fine and homogeneous microstructures. Additionally, the electron beam melting process takes place in a vacuum chamber to ensure a clean and controlled construction environment. Vacuum manufacturing is an important aspect of the EBM process as it maintains the chemical specification of the building material.

Vibenite®

VBN Components, using GE Additive Arcam EBM since 2014, redefines materials with high strength, heat and wear resistance for use in the harshest environments. Since founding VBN in 2008 with Peter Vikner and Martin, the team specializes mainly in steel, high-strength, heat-resistant materials and how they are used in the additive manufacturing of metals.

VBN’s patented materials such as Vibenite® 290 – now with a hardness of 72 HRC – is the toughest steel available on the market, ideal for cutting other metals and heavy wear applications, and Vibenite® 480 – an award-winning hybrid carbide (carbide/hard metal ), are of great interest. Higher levels of carbon in tool steel increase the material’s tendency to fracture during production under high temperature gradients. This makes high carbon steels unsuitable for low ambient additive manufacturing processes such as laser powder melting (PBF). EBM technology is able to process alloys with high fracture susceptibility due to the high build temperature and achieve design complexity that cannot be achieved with conventional manufacturing processes.

Leading companies in the oil and gas, mining and industrial sectors turn to VBN for tools and components such as rock drills, tooth inserts and other cutting equipment for the toughest working conditions.

Additive manufacturing allows greater design freedom to create geometries that are not possible with conventional machining technologies. It also allows VBN customers to choose the best material for their application, rather than a material that only fits conventional manufacturing methods.

GE Additive Arcam EBM Spectra L

The Spectra L allows mass production of parts, offering a unique EBM feature that allows parts to be tightly packed throughout the volume of the chamber without compromising quality. Electron beam melting technology provides design freedom, any supports are primarily for heat dissipation and can be easily removed after construction.

• Build volume: 350 x 430 mm (Ø/H)
• Electron beam power: 4,5 kW

Source: press materials www.drukarki3dge.pl