AM strategy Procter & Gamble cleverly combines additive and subtractive technologies
Additive manufacturing is a key technology for US consumer products group Procter & Gamble. The global player in particular emphasises the favourable aspects of combining different technologies for producing and modifying machine and tool components.
Components are usually designed for ablative manufacturing. This means they are often more material intensive and more voluminous than their actual function requires. That is why the combination of additive and subtractive technologies is at the heart of Procter & Gamble’s additive manufacturing strategy. “With the additive approach, parts can be designed in such a way that the necessary properties are created specifically at the desired points. Combining additive and subtractive processes also offers potential for optimisation,” Klaus Eimann, head of the group for additive manufacturing methods, explains.
Therefore, P&G is increasingly using hybrid concepts to maintain machines and tools. “With mould inserts in injection moulding, it is often the case that material breaks away or wears down. These spots can be repaired effectively and quickly using additive technologies, such as laser deposition welding. There is no need to purchase or stock a spare part or even a spare tool. Instead, the repaired component is reused in a refined form, so to speak — with at least the same properties as a new part. This procedure reduces downtimes to a minimum,” says the expert.
Since as early as 2006, Procter & Gamble has been using the powder-bed-based process laser metal fusion (LMF) as well as laser metal deposition (LMD) in tool production and maintenance. Eimann and his team were now able to reduce the cycle time of the production by seven seconds through the combination of the two processes.
The company wanted to optimise the production of its Oral-B toothbrush. In this case there is an approximately eight-centimeter-long steel pin which is integrated into the injection moulding tool. It shapes the plastic profile that the brush has later. One problem was that the steel pin only cooled off relatively slowly. Once the plastic touched the steel, there was not sufficient heat dissipation. The consequence of this was that the injected plastic deformed, which resulted in a large number of rejects. With the support of the experts from Trumpf, Eimann and his team came upon an unusual but efficient solution.
The tool experts initially concentrated on the benefits that LMF offers: Complex internal structures. They built up the steel pin and introduced highly efficient spiral cooling into the small part of just twelve millimeters in diameter. Tests showed that the channels flushed with cooling water increased the heat conductivity of the steel pin by ten times. This still was not enough. The breakthrough came when laser metal deposition was brought into the equation. The experts placed the copper pin into the additively manufactured steel mould pin. In order to ensure a stable and seamless connection, they then covered both with tool steel using laser metal deposition. The result was a firmly bonded connection from one mould. The AM specialists wants continue to concentrate on getting the best out of the two additive technologies — laser metal fusion and laser metal deposition.
In a keynote address at the international event for 3D printing, Rapid.Tech 3D. in Erfurt, Germany, on 18 May 2022, Eimann will focus in particular on the sustainability aspects of additive manufacturing technologies for producing and modifying machine and tool components.