Recently, Polymaker released some shots from the Shanghai Construction Group's 3D printer production process. The 3D printed plastic footbridge took 30 days to complete because it was 15 meters long and weighed 5,800 kilograms.
The 3D printer is manufactured by Shenyang Machinery Group, and the extruder system is manufactured by CoinRobotic, with a total investment of about $ 2.8 million. Polymaker Industrial will provide ASA (acrylonitrile styrene acrylate) plastic for printing, which is a material with good chemical resistance, thermal stability and toughness. To determine the best plastic, Polymaker3D printed a 5-meter version of the bridge and several different compounds before choosing the overall strength and printable print of AS100GF.
Plastic contains 12.5% by weight glass fiber, which increases strength and also reduces the warping effect that plagues large 3D printing. Large-scale 3D printing is related to thermal insulation and uniform heating, which is becoming more and more difficult for printing / printing. In this case, the construction room is 24 meters long, 4 meters wide, and 1.5 meters high (planned to be expanded to 3 meters high). The 144 cubic meter building room is insulated by a large corrugated tent that moves with the gantry. Realized. Heat the tent to 38 ° C and place a blanket on top of the print to slow down the cooling process and relax the polymer chain without warping; the blanket can also protect the print from dust. The build room is very large, and technicians work inside the 3D printer, while monitoring printing is easy.
The construction room is 24 meters long, 4 meters wide and 1.5 meters high. The staff works inside the 3D printer.
As the print size increases, the printing time for each layer takes one hour, which brings another problem. When the extruder starts to print the next layer, the previous layer has cooled significantly. The adhesiveness of the material is reduced. Blankets and glass fibers help slow this cooling, but they did a lot of work here on the print head. They reheated the print layer with four 600 ° C hot air guns. The working place is always hot to get the maximum layer adhesion.
Nozzle diameter 5mm, extruding 8kg of plastic per hour, accuracy 0.1mm, tamping while printing
Here is a new approach to the interlayer problem that is not seen on other 3D printers: compaction. The nozzles are round, which means that their extrusion is round, they have a tapered top, which is not ideal for layer bonding. For a desktop 3D printer with a nozzle size of 0.4mm, the taper is small enough to hardly notice, but the nozzle size used by the SGC3D printer is 5mm, so the tamping of the plastic after extrusion has increased the layer level and adhesion. difference. Despite its huge size and the fact that it can squeeze up to 8 kg of plastic per hour, the printer is accurate to 0.1 mm.
The footbridge over the lake is a great way to showcase the largest 3D printed plastic objects, as it is both a daily practical application and an interaction that involves people touching or even relying on 3D printed objects. Many people have never been exposed to 3D printed objects, and they still consider it a part of fantasy and future technology, so such projects do a lot of good things in terms of the public facing the possibility of reality and 3D printing.