Mar 29, 2016 | By Alec
Though 3D printing is a computer-controlled production process, it still requires a lot of manual steps that need a human user – from designing and choosing a CAD model, all the way to removing the finished print and determining its usefulness. Before 3D printing can become a viable large scale production tool, those steps will need to become more automated and that, in a nutshell, is what the latest MIT patent approved by the US patent office is all about. They have invented a 3D printer with an automated part inspection and removal system – which could greatly reduce the need for human intervention during production.
The recent MIT patent, called Automated three-dimensional printer part removal, just one of the 6,746 that has been issued by the US patent office this week; a list that you should definitely take a look at if you want your faith in scientific progress reaffirmed. Developed by Alfonso Alexander Perez, Christopher Michael Haid, Forrest W. Pieper and Mateo Pena Doll, the automated 3D printer patent was first filed way back in January 2014 (Appl. No. 14/157,027).
Like all patents, the research is described in detail, but at its heart this MIT invention is just the next step towards fully automated 3D printing. Drastically cutting down the number of steps involved to 3D print an object, it features an automated part removal system – to optimize 3D printing times – and a sensor feature that can register printing errors. Using machine vision, any deviation from the CAD file is registered and causes a 3D print to be labeled a failure.
As its developers explain in the patent, 3D printing is still quite a laborious process. “[Existing 3D printers] typically require six or more user steps […]. First, a user designs a 3D model on CAD software. The user manually then uploads a 3D model of the part to be made to a slicing program. After the user manually calibrates 150-250 settings, the slicing program generates machine code for the 3D printer […]. The fourth step of a process is to upload the machine code to a printing host in the form of a program on a computer or an SD card. From there, the machine code is streamed to a microprocessor on the printer 10, controlling actuation. After the printer is done printing, the part is removed manually. After inspecting the quality of the part, the user decides if the part needs to be reprinted,” they summarize.
But in their fully automated 3D printing system, they are looking to remove the operator as much as possible – with part removal being the easiest step to skip. To be sure, systems like that already exist, most notably featuring a conveyor belt or heating/cooling systems. But these solutions, they argue, are either too expensive or are in danger of causing warpage or shrinkage. “In general the disadvantages of these systems are detrimental to the printing process and/or the removal process. Conveyor belt systems have not been successful generally because the platform is flexible, leading to warped parts. A conveyor belt with rigid tracks might provide a rather expensive solution. It is also known to attach a removal paddle or block to an extruder head. Such arrangements typically cause excessive stress on the drive train and may cause misalignment in the print nozzle leading to leveling issues,” they say. Heating/cooling systems, finally, can lead to shrinkage and ‘popping’ of the parts.
To avoid those dangers, they have developed several versions of a part removal system that relies on a ‘blade’ that sweeps across the print bed to release the part from the surface. Obviously, this blade won’t cut into the print. “The blade may be cantilevered from a support on one side of the printing surface. Alternatively, the blade may be supported on both sides of the printing surface. For a cantilevered blade, it is preferred that the support form a compliant joint. It is also preferred that the blade have a hardened steel portion that engages the part,” they write. This can thus take different forms, including one featuring a vibrating blade to facilitate part removal. After determining whether or not the part is a failure, the blade, powered by a solenoid-controlled pneumatic piston, can dispose of the failed print, or place the successful print where it belongs.
Depending on the power of the swing, this blade system could definitely make part removal easier and safer. But for the skeptics, their patent also includes another technique that drastically reimagines a print bed. Instead of being a solid flat surface, this concept features a hole-covered array. “Pins are arranged in an array matching the array of holes and means are provided for pushing the pins through the holes to lift the part from the surface. In one embodiment, the means for pushing the pins through the holes comprises lowering the printing surface onto the pins. Alternatively, means may be provided for pushing the pins through the hole by raising the pins,” they explain. Other part removal options include blowing compressed air through a single hole, or electromagnet-based vibration to separate the part from the surface. While only time and experiments will tell which one of these techniques is most viable and safe, every one of them will go a long way towards making 3D printing a fully automated process.
Posted in 3D Printing Technology
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