By comparison, injection molding’s accuracy is 0.005 in. On the highest performance Stratasys machines, though, part accuracy or tolerance reaches as high as 0.003 in. In Stratasys machines, for example, the material flowing from the nozzle typically measures 0.008 to 0.038 in. The more expensive extrusion systems use servo drives and lead screws, which deliver the needed accuracy for more precisely built parts as shown in the Stratasys example here. Lower cost extrusion systems often use stepmotors that drive belts to move the plotter system, but the tradeoff is accuracy and speed. Ensuring that the material and the nozzle move together is challenging, as both are constantly changing. The Stratasys Fortus 900 mc, for example, uses ball screw drives. The more expensive etrusion systems use servo drives and lead screws, which deliver the needed accuracy for more precisely built parts. The lower cost extrusion systems often use stepmotors that drive belts to move the plotter system, but the tradeoff is accuracy and speed. As the head speed changes, the drive wheels need to adjust the material flow rate to deliver a precise ribbon width that changes as needed to produce the part. In addition, the X-Y movement of the nozzle must coordinate with the Z movement of the build plate for consistent material deposition. Ensuring that the material and the nozzle move together is challenging, as both are constantly changing the extrusion head accelerates and decelerates as it travels across the build platen. In Stratasys systems, for example, drive wheels push a thermoplastic filament into the heating chamber of the extrusion unit, which heats it to a flowing consistency.Īs long as the flow rate of the material is coupled with the motion of the extrusion head, your parts will have consistent and accurate dimensions. (By contrast, laser sintering systems rely on the crystalline nature of powdered material to change to a curable liquid state when hit with high heat.) The material flows through the nozzle under pressure to ensure a constant rate of flow. The extrusion process consists of simultaneously advancing and melting a ribbon of material through a computer controlled nozzle deposition unit. For total throughput time, you may also want to consider the programming time for a CNC, support removal for a 3D printed part, as well as curing and applying an infiltrant if necessary. Build speed in extrusion systems is a function of the material feed rate, the plotting speed, the rate at which the material can be melted, and the weight of material. Such an argument does not necessarily consider part complexity, material, and other factors. One critique often leveled at 3D printing technology is that parts tend to take longer to build, compared to a CNC subtractive operation. Another strength is that these systems can handle any geometric complexity you can create. One of the strengths of this technology is that it can use a range of materials to develop good and strong mechanical properties in parts. As of today, there are more FDM® machines than any other type in the world, including the consumer targeted units. The others are jetting lamination melting as in electron beam melting or direct metal deposition photo curing and sintering. Extrusion is one of the six primary processes in 3Dprinting/additive manufacturing. These 3D printer systems use extrusion to deliver material that is used to build a three-dimensional part. RepRap coined the term fused filament fabrication to avoid trademark conflicts. Crump has expired, enabling companies like RepRap to use that knowlege to develop their versions of extrusion systems. At least one of the patents issued to Mr. The term FDM is trademarked by Stratasys. The technology behind Fused Deposition Modeling was invented by Scott Crump, CEO of Stratasys. Why invest in a $15,000, $35,000 or higher cost fused deposition modeling/fused filament fabrication (FDM®/FFF) 3D printing technology when there are other extrusion printers out there that are under $2000 (such as RepRap)? Well, it depends on what you want to do with your system, and, as the caveat goes-“you get what you pay for.” With the arrival of low-priced consumer targeted 3D printers, some users of this technology ask why it needs to cost so much and when will the higher-priced versions go on sale? A look at the inner workings of these printers answers these questions.
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