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Hybrid additive manufacturing extends useful life of molds

28 October 2020
Article by Isaac Ferreira, researcher in the field of Additive Manufacturing and Process Development. With contributions from Diogo Fula, João Sousa and Domingos Moreira.

The productive capacity of the national mold industry is affected by a common problem: the limited life cycle of injection molds. The life cycle of a mold, at an industrial level, is determined by a wide range of factors - such as the construction material, manufacturing process, temperatures, pressures, among others - that often force its repair or destruction. Increasing the service life of the molds and strengthening the ability to repair them is, therefore, an investment that brings great gains to any company.

Maintenance is increasingly a critical process, essential to avoid interruptions in production, whether due to premature wear, adjustments, or even for changes resulting from market needs.

The matrixes used in these processes, when rectified, are typically repaired by welding with tungsten inert gas (TIG). However, the repaired components tend to only last, on average, 20.8% of the useful life of the original matrix, and further interventions are necessary1.

In order to improve this context, INEGI, as part of a mobilizing project, TOOLING4G, has been working on a new solution. It is a hybrid repair process, which involves machining the damaged areas of the molding cavities, their subsequent reconstruction through additive manufacturing using the deposition of DED material (Directed Energy Deposition) and, subsequently, the surface finish, by conventional manufacturing technologies (subtractive manufacturing).

Hybrid manufacturing offers greater process control

Compared to conventional repair processes with manual welding, repair via DED has different advantages: less localized heating, resulting in less deformation and distortion, and a higher cooling rate, less dilution, excellent metallurgical connection between the deposited layers, high precision and the ability to fully automate the process.

In general, through DED it is possible to have better control of the process, from the macro level (amount of material to be deposited) to the micro (microstructural). This technology allows one to create coatings and rebuild in critical areas, with materials that provide better mechanical properties, in order to extend the life of the mold, that is, the number of original cycles, reduce costs, and make the manufacturing process more "green".

The repair method proposed on the basis of the DED may thus become extremely attractive to industries with a high dependence on molds, reducing the need to manufacture new molds, the frequency of repairs, and, consequently, the downtime of production.

In specific areas of the molds, even in the product development phase, and with prior knowledge, it is still possible to apply the technology in areas of greater wear, in order to obtain a better compromise between the cost of the mold and the number of injection cycles. Additionally, this technology allows companies to make inserts with internal channels with complex geometries for cooling the molding area more effectively.

This technology is being developed with the support of research and development projects, and TOOLING4G allows a specific advance for the application of this new technology in molds, starting from a solid research base and with a partnership in a consortium that brings together entities from all the value chain.

DED laboratory cell installed at INEGI is the first in the country

DED technology is a typology of 3D printing or metallic additive manufacturing, which has proven to be of high added value for the industry. It consists of the deposition of a metallic powder or wire, whose fusion between layers is ensured by the energy provided by a laser beam.

This technology is being developed by INEGI, which operationalized the first DED laboratory station in the country, making it possible to manufacture metallic additives for large complex parts (2000 x 1000 x 500 mm), where by adding a subtractive post-processing (usually combined with this additive process) provides high quality, dimensional and geometric precision.

The described solution is being developed within the mobilizer project TOOLING4G - Advanced Tools for Smart Manufacturing, which is financed under the Compete 2020, Portugal 2020 and European Regional Development Fund programs.

1.   Bennett, Jennifer & Garcia, Daniel & Kendrick, Marie & Hartman, Travis & Hyatt, Gregory & Ehmann, Kornel & You, Fengqi & Cao, Jian. (2018). Repairing Automotive Dies With Directed Energy Deposition: Industrial Application and Life Cycle Analysis. Journal of Manufacturing Science and Engineering. 141. 10.1115/1.4042078.

Article originally published in the October edition of the magazine O Molde.

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