MAPS – Metal Additive using Polymer Sheets

The design freedom and ability to mass-customise parts has made metal additive manufacturing an attractive option for many industries, but the feedstock has held back it’s adoption in several ways. Loose powders used in most systems pose significant safety hazards, and the risk of contamination means that machines are often locked in to print just one material. Several of the companies interviewed for this project sited challenges with safety and contamination as a reason for production delays, and many voiced their frustration about the inability to produce parts made of multiple materials.

Solution

This research proposes a new method of powder delivery which solves many of the limitations of conventional metal printing. The technology uses flexible metallic powder sheets in place of loose powder which are stored in rolls and fed into the path of the laser. When the laser is incident on the sheet, the polymer binder is vaporised and the consolidation (welding) of the metal powder is achieved simultaneously. This one step continuous process provides many advantages over traditional loose powder approaches to additive manufacturing

Results

The sheets contain up to 99% powder by weight, yet still maintain a significant degree of flexibility, a critical factor concerning integration with the roller delivery system. Due to the powder being encased within the polymer binder, there is very little chance of the powder coming loose, either during transportation or during the printing process.

Early trials of the material carried out in TCD where very successful, leading them to successfully apply for a commercialisation fund from Enterprise Ireland. While development and scaling up of the production process for the powder sheets was carried out in TCD, IMR began construction of a custom prototype printing platform. The printing prototype uses a custom roller system to deliver material into the processing area. Argon provides a shielded environment to avoid oxidation of the material while a 400W fibre laser provides the necessary powder to melt the metal and vaporise the polymer, which is safely removed from the processing area using a filtered extraction system. The roller system and vertical axis for both the laser galvo and build plate carrier has movement resolution down to 20 micrometres are controlled by a custom build GUI that also interfaces with the laser control system.

Impact

The new printer will provide the team in TCD with the perfect test bed to develop custom process parameters for a wide range of material to cater to a variety of industries and customers. Successful tests have already been carried out with 316L steel, commercially pure copper, and titanium 6Al4V.

The flexibility of the new material is expected to have significant cost savings over traditional loose powder systems. Machine down time will be reduced during material changeovers, as it takes minutes rather than days to deep clean and change material. Investment in safety procedures and equipment are reduced as there is minimal loose powder and associated risks. Multiple materials can also be processed on the fly on the same substrates, opening the door for multi-material printing.