December/January 2019

| 38 | December/January 2020 www.smartmachinesandfactories.com | TECHNOLOGIES | cause a print to fail, which translates into downtime, but, luckily, it can be prevented. Technologies such as Needle Valves, for example, seal against the inside surface of each nozzle to block off the flow of filament when required, eliminating the issue of stringing and greatly reducing feed problems. This technology also improves overall print speed in dual material prints, with material changes taking just 0.4 seconds. How are nozzles integrated or changed? Depending on the manufacturer of your 3D printer, there are different options in terms of how the nozzle is replaced. Modern 3D printers use a swappable print head system meaning that the nozzle is an integral part of the print head so, to change nozzle type and diameter, the entire head needs changing. The main benefit here is that all components within the head are calibrated and standardised. The electronics will also automatically update the printer and software ensuring the best settings are always used for that specific head, reducing setup time to a minimum. Several other manufacturers use interchangeable heads or cartridges. These also automatically feed the hot end and nozzle diameters back to the printer and software, ensuring the best settings and print quality. These systems are plug and play and can be very easy to use but do come at a price premium. The other option on many 3D printers is to manually swap the nozzles from the heater block. Your printer’s manual will show if this is possible, but, typically, great care must be taken including heating and gripping the delicate and very hot parts to avoid breakages. Once you’ve screwed in the new diameter nozzle, you then need to update the settings within the printer software. This process involves highlighting the new nozzle diameter and adjusting a host of settings while running tests to reduce stringing and blobbing with the new configuration. What nozzle should I select for each filament type? We’ve seen how the nozzle diameter dictates the surface finish or detail and speed, but there’s more to consider. Most materials will print through a standard brass or copper nozzle, but there are specialist options also available for different materials. Brass is the most common material as it is very thermally conductive. This means it transfers heat efficiently from the heater block to the nozzle to ensure a smooth flow of molten filament. The downside is that brass is a very soft metal, so a few too many knocks into the build platform or use of abrasive materials and the nozzle will start to wear affecting the quality of your prints. Copper is another popular choice. These nozzles are often Nickel plated and can sustain higher temperatures than the brass equivalent. They also have the benefit that the Nickle plating