Laser deposited powder process repairs tooling

Direct metal deposition is a generative laser process, in which powder material can be laser-deposited precisely on 3D forms that has now been optimised for practical use.

Direct Metal Deposition (DMD) is a generative laser process that Trumpf has optimized for practical use.

It employs a powder nozzle to deposit metal onto existing tools and components layer by layer in 3D.

"The TrumaForm DMD 505 can be used for numerous applications in tooling technology, especially when the goal is to deposit material precisely onto high-quality structures without damaging the base material due to excessive heat input," says Robert Ganter, Project Manager at Trumpf Laser- und Systemtechnik.

The range of applications includes mold inserts from injection mold tools, press tools all the way to parts in offshore technology.

Because sensors regulate the process, the layers are generated practically free of pores and cracks, thus forming an extremely tight bond with the base material.

Downstream processing (i.e cutting work) is easily possible.

One noteworthy feature is that different powders can be mixed or alternately deposited in order to create customized layered constructions.

In addition, by limiting heat input to a defined area, part distortion by the laser is minimized.

The effort and cost required for refinishing, e.g heat treatment, is therefore reduced in the overall production chain.

Multi-talented tool repair and modification - the potential to save time and money by modifying existing tools is enormous.

Design changes to an end product, production errors in tool manufacturing or simple tool fatigue might be the motives behind this.

Material deposition can render an old tool useable again.

In some cases, this is more than 80 percent faster than creating a new tool.

The selectable powder nozzle of the TrumaForm DMD 505 allows the user to manufacture material compounds.

For instance, a complex surface structure made of expensive tool steel can be added to a base of less expensive material.

The result is a wear-resistant serial tool that does not sacrifice the cost benefits of the base material.

The material combination can also have a positive impact on the heat balance in a tool.

For example, materials with higher heat conductivity levels can be used for the core in a tool whose surface consists of wear-resistant material.

Clearly superior to conventional deposition methods - the starting materials for this process are pure metal powders - with no additional binding agents - that are measured out according to specified technological parameters.

During the process, the powdered particles are sprayed coaxial to the CO2 laser beam onto the molten pool created on the component surface and are completely melted.

The laser beam is guided by a 5-axis kinematics system along the NC-programmed path.

Based on the high energy density and excellent focusing ability of the laser beam, the heat entering the component is very low compared with conventional welding methods like TIG repair welding, for instance.

Distortion is reduced to a minimum and heat treatment after repair welding is unnecessary.

The permissible load capacity of the repaired tool equals that of the original tool.

And, if need be, the TrumaForm DMD 505 is capable of localized heat treatment.

Process sensors continuously monitor the layered construction during the DMD process.

Geometries are measured and relayed to provide real-time control of the DMD machine.

"This ensures that additional metal layers are applied with the highest possible quality and can be reproduced every time," says Ganter.

The selected metal can be deposited on the workpiece without any intermediate steps.

Perfectly dense metal layers are produced by a complete melting of the powder.

A highly resistant metallurgic bond that can be subjected to mechanical stress is thus forged between the layers and the base material.

With up to four different powder conveyors, varied layers can be deposited, creating mixed structures or customized alloys on the spot.

In the case of repair work, DMD technology enables new material to be deposited in a similar structure as the original base material.

The surfaces can be polished or etched immediately after electrical discharge machining or refinishing.

The option of creating customized bi-metal alloys like steel/copper, tool steel/cast iron, tool steel/stellite improves material properties and opens up new fields of application.

Documented quality based on 3D machines - the TrumaForm DMD 505 is based on the proven Trumpf Lasercell for the cutting and welding of 3D components.

Trumpf developed this machine for powder processing in order to make Direct Metal Deposition a practical option.

In addition to protection from reflected radiation and metal powder, patented sensor technology as well as rapid control and simple programming, the machine's capacity for Internet networking is especially noteworthy.

Data can be exchanged between the programmer and the machine operator.

In practice, this means that process know-how and programming expertise do not have to be on site in order to operate the machine.

The machine's axes positioning range of 1000mm x 2000mm x 750 mm and the work space accessible from three sides allow the processing of components and tools that are much larger than the machine's actual positioning range.

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