Challenges
Procter & Gamble wanted to optimise the production of its Oral-B toothbrush. Specifically, in this case there is an approximately eight-centimetre-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.
Solutions
With the support of the TruPrint experts from TRUMPF, Klaus Eimann and his team for additive manufacturing methods at Procter & Gamble came upon an unusual but efficient solution. Not just one, but two additive manufacturing technologies reduce the cycle time by seven seconds through a clever combination. The number of rejects has also reduced to a few per each thousand.
Implementation
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 millimetres 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.
Forecast
The additive manufacturing specialist team around Klaus Eimann will continue to concentrate on getting the best out of the two additive technologies – laser metal fusion and laser metal deposition. With their edge when it comes to expertise, Procter & Gamble already plays a leading role in their industry when it comes to this field.
