From laser sintering to hot gas welding, MANN+HUMMEL GmbH is always at the forefront when it comes to new technologies. The training workshop at the Ludwigsburg site recently acquired a 3D printer for the trainees and students on dual training programmes to enhance their ‘hard skills’.
The printer arrived as a construction set, so our first practical exercise was assembling the individual parts to create the finished article, as well as connecting the electrical components. Our team of four new dual-programme mechanical engineering students were so excited to get started on the project that the planned construction time of “several weeks” was eventually condensed into precisely two days, allowing us to turn our attention to the software and printing straight away.
So, after just a few days, we were ready to insert the filament for the first time and to print our first sample copies. In this case, ‘filament’ refers to the starting material and more specifically its shape, i.e. a long plastic fibre approx. 2 mm in width. However, our first efforts – a cube and a little heart – were rather disappointing. First it was too cold, then too hot, and occasionally the printed item came loose from the heating plate. Something just wasn’t quite right. After a couple of days and some rather unconventional experiments, which I’m sure the manufacturer had not intended, the results finally began to improve as we had gained a better understanding of temperature and other settings along the way. However, the surfaces were still not right.
Nonetheless, a week later we reached the point where the filament needed to be changed and someone (none other than our supervisor) noticed that we had been using the wrong type all along. It emerged that, in our eagerness to get started, we had chosen the wrong material from the many filament rolls available. This material, which was much harder, as intended for use as a chemically degradable support material and was only suitable for processing at higher temperatures. The new material produced almost perfect results right from the start. However, at least this way we had learnt how temperature changes, speed, bulk density etc. affected the printing result. From this point on, things were moving in the right direction and we were able to produce complex models with support material, which meant our eventful journey had all been worthwhile.
In order to put the performance of our 3D printer into context, we were also given the opportunity to have a look at the state-of-the-art laser sintering system in Prototype Construction. And, well, what can I say? We were amazed at what this kind of laser could create from just a small amount of powder. Not even the most advanced 3D printer could keep up.
Then, to finish the project, we were kindly permitted to draft a user guide and instruction manual. Ultimately, safety takes number one priority, so all future trainees and students should be able to learn from our mistakes and avoid tripping over the same stumbling blocks that we encountered.