I’ve worked with coprocessing to a point so far that I’ve been able to figure out where it stands in the area of manufacturing, assembly, and design. I’ve adapted my definition of coprocessing as a result:
Coprocessing: Modifying and adjusting a 3D printed job as it is being manufactured to produce integrated content.
This definition covers a bit more than my original definition, and focuses less on the ease of manufacturing and more on what you can do with it. Coprocessing has the potential to change the way we view additive manufacturing. Instead of just laying down material to build up a part, additive manufacturing can take a new form: adding components and material simultaneously to build up an entire assembly.
Because I’ve still been working out the design rules behind coprocessing, finalizing a part meant to be coprocessed can take a couple of prints. My iterative process usually involved the following design and prototyping steps, give or take a few depending on part complexity:
- Initial Printing Test: Can it be easily 3D printed and does it look like it will work in general? Are there issues with build adhesion, warping, or tolerances? Usually this print will be a basic CAD model up to the layer that the part would be coprocessed at, and then removed and inspected.
- Tolerance Test: Does everything fit the way it is supposed to, and was enough clearance given for everything to slide into the part during the print smoothly? This print will again go up to the point of coprocessing, after which the components will be test fit into the part while still on the print bed.
- Post-Coprocessing Test: After the parts are coprocessed, does the print continue alright? Was enough space given to allow the printer to print over the added components, and does the filament stick to the surface? Usually this iteration will be designed to be easily broken open so that components can be retrieved.
- Functionality Test: Does everything do what you want it to after the print? If there are mechanisms and electronics involved, are they behaving correctly?
- Excess Material Removal: Can any features be minimized or removed to cut down on the mass and/or the time estimate of the print job? If so, be sure they do not conflict with previous design checks.
- Final Print: The part is ready to be finalized! Make sure you have gone over and possibly practiced the coprocessing steps to make the job quick.
Like most manufacturing methods, these steps can be combined with good design practices and experience. For example, if you’ve designed for 3D printing before, the first step can often be eliminated. With developments in 3D printing, we can push the technology forward so that printers can be designed to make coprocessing and its design stream easier and faster. If you’re interested in learning more about coprocessing, please check out the coprocessing guidelines document I’ve created to aid both myself and anyone interested in the coprocessing method.
Prototyping coprocessed parts can come at a large cost; although integrated content can be made straight from a CAD file, it takes a long time, and a lot of material. Should the print job fail, the part will need to be entirely remade. The final print of last week’s post used about 100 g of PLA, and I prototyped about 10 iterations of it, so that’s about 900 g of waste. Coprocessing can produce a lot of material waste, so please think about ways to recycle it!
Another issue arises in the slicing software of a given printer: having a pause feature in the slicer is incredibly valuable when coprocessing because it allows you to precisely define when you will be coprocessing. Higher end printers lack this feature for the most part, meaning that you will need to sit by the printer and wait for the right time to pause the job.
Because 3D printing as a manufacturing process takes a long time and a coprocessed part is not very versatile, currently its main use lies in prototypes close to the end product. It’s very difficult debugging a circuit when it is already encased in plastic, which may be one of the biggest drawbacks of coprocessing. Unless the part is designed so that it can be disassembled and reassembled after the print (another design challenge I am working my way through), you will usually need to break the entire piece apart to access internal components. Although there are some drawbacks, the integrated nature of coprocessing allows for some really innovative ideas and products in the manufacturing and assembly space. I can’t wait to see where it goes.
And for my last thought, I may not be posting for a while as the school semester is over and summer has begun. I will likely have access to a 3D printer over the summer, but I’m not quite sure yet! I will definitely be continuing my exploration of coprocessing as much as I can, if not over the summer then in the fall. If there is anything in particular you would like to see, please comment or send me an email at 3dprinteraction(at)gmail.com.