One of the greatest benefits of additive manufacturing is that it allows us to approach certain from fresh, new angles, even when working within predetermined constraints. For example, we’ve seen that 3D printed houses don’t have to look anything like conventional square units, because the conventional restraints of straight walls and corners simply don’t exist. This lets engineers step back, ask questions, and propose innovative solutions rather than just doing things the way they’ve always been done.
As an illustration of this approach, Theo Hillers, a plastic injection-moulding specialist based in Germany, realized that their existing robotic handling system was causing excessive waste. Rather than accepting the structure’s flaw, they turned to 3D printing technology to re-invigorate the system.
The automated machine in question was tasked with handling plastic mesh filters for the pharmaceutical industry without damaging. The previous method of transferring the filters from injection moulding machines to the next production stage required the robotic arm to grip the parts by their sprue (the plastic waste left in the whole through which the mould was filled) and snap it off, dropping the filters onto a conveyor belt. While this method gets the job done, it damages many filters in the process, resulting in what the company called “an unacceptable level of waste.”
ASS Maschinenbau, a German company that develops solutions for the automation and robotics sector, was called on to fix the issue. Rather than just fall back on existing methods and doing things the way they’ve always been done (which would mean making new grippers out of modular aluminium components), ASS decided to go a different route: why not just make them more lightweight and gentler so that they don’t damage as many filters?
In this case, neither Theo Hilllers nor ASS were free to completely redesign the system. For cost reasons, the existing 3-axis sprue-picking equipment had to be used meaning that the new robotic hands would have to fit around it In order to place the filters gently onto the conveyor. Other design restraints meant that the gripper could not weigh more than 500 grams, and need to have at least eight to 12 suction cups in a limited space. Theo and Hillers also wanted a simplified yet more reliable version than what they previously had to work with.
Since there was very little previous experience in working with lightweight polyamide over aluminum, ASS partnered up with yet another German firm, the industry-wide leader EOS. They 3D printed the grippers overnight on an EOSINT P 390 system using black polyamide powder as the material.
In terms of design modifications, the new robotic grippers have either 8 or 12 cavities. To save weight, internal air ducts were integrated into the CAD design so avoid the need for extra hoses, and the connections for the vacuum suction pads were incorporated directly into the device, eliminating the brass adapters. Not only did these changes reduce the weight, they made the robotic hand tidier and easier to maintain overall. The heavier design (with 12 suction cups) weighs less than 400 grams.
With a simplified design and more lightweight construction, Theo Hillers' waste-reducing grippers are just one way 3D printing technology is helping engineers rethink conventional methods at every level of the manufacturing process, leading to new approaches and unprecedented solutions.