3D Printer Short NOTES_Sp2024.pdf

COLLEGE OF ENGINEERING Department of Mechanical Engineering ME 308L: Advanced Manufacturing Processes Lab (Short Notes) 3DPrinterNotes:ME308LAdvancedManufacturingProcesses (By:AthiqAhamedKhazi) P a g e 1 | 10 Rapid prototyping Technology (3D Printing) Is a group of techniques used to quickly fabrica...

COLLEGE OF ENGINEERING Department of Mechanical Engineering ME 308L: Advanced Manufacturing Processes Lab (Short Notes) 3DPrinterNotes:ME308LAdvancedManufacturingProcesses (By:AthiqAhamedKhazi) P a g e 1 | 10 Rapid prototyping Technology (3D Printing) Is a group of techniques used to quickly fabricate a scale model of a physical part or assembly using three-dimensional computer aided design (CAD) data. Construction of the part or assembly is usually done using 3D printing or "additive manufacturing" technology. Additive Manufacturing:   Additive manufacturing refers to the process of extracting data from a digital file, such as a 3D CAD file created using 3D packages. This data is then transferred to a PC that then uses another type of software to slice up the file in layers. Slicing up the file into layers is a language that the printer understands as this is the same process the printer uses to print the complete part…by means of adding layers on top of each other, hence the term “Additive Manufacturing”. What we now term as “3D Printing” should in fact be termed “Additive Manufacturing” as the latter more accurately describes the production technique used to create the final product. INTRODUCTION TO 3D PRINTING: 3D Printing is an additive manufacturing process that creates a physical object from a digital design. There are different 3D printing technologies and materials you can print with, but all are based on the same principle: a digital model is turned into a solid three-dimensional physical object by adding material layer by layer. OR The action or process of making a physical object from a three-dimensional digital model, typically by laying down many thin layers of a material in succession. "if you use 3D printing for prototypes you will simply be able to go to market faster" HOW IT WORKSEvery 3D print starts as a digital 3D design file – like a blueprint – for a physical object. Trying to print without a design file is like trying to print a document on a sheet of paper without a text file. This design file is sliced into thin layers which is then sent to the 3D Printer. From here on the printing process varies by technology, starting from desktop printers that melt a plastic material and lay it down onto a print platform to large industrial machines that use a laser to selectively melt metal powder at high temperatures. The printing can take hours to complete depending on the size, and the printed objects are often post-processed to reach the desired finish. Available materials also vary by printer type, ranging from plastics to rubber, sandstone, metals and alloys - with more and more materials appearing on the market every year. 3DPrinterNotes:ME308LAdvancedManufacturingProcesses (By:AthiqAhamedKhazi) P a g e 2 | 10 Fused Deposition Modelling (FDM): FDM printing:  FDM is essentially a type of “additive manufacturing”, meaning that the 3D model is not created in one whole process such as moulding, but rather by means of adding continuous layers of the melted material (typically a type of plastic) to build up the final solid 3D model from the bottom up. The model then cools down to one solid piece. FDM printers are made up of components that move in all three axes, the x-axis, y-axis and zaxis to create the 3D object (logical, right?). The printer must read a 3D generated model (usually in.STL format) created using a 3D package. And then start to print it out. However, because FDM 3D printers are designed to created things by means of layering, it means that the 3D generated model (which is essentially solid) must then be sliced up into layers using a Slicer Software. 3DPrinterNotes:ME308LAdvancedManufacturingProcesses (By:AthiqAhamedKhazi) P a g e 3 | 10 StereoLithoGraphy (SLA):   SLA printing: SLA works very differently to FDM in as much as it does not build up layers of heated plastic materials to create the finish product after cooling. However it is still an “additive manufacturing” process where UV light is used to harden / cure liquefied resin to create the finish product. The process of reading and slicing up the model using slicer software is the same though!   A vat is filled with a photo-curable resin and an ultraviolet laser beam shines onto the layer of resin. The laser beam traces a pattern on the surface of the liquid resin which ultimately solidifies the pattern. The process continues, and each layer that hardens, solidifies to the next layer in order to create the final product. Essentially, this process works in reverse order to FDM, in as much as it builds the 3D model from the top down… although some printers do allow for printing from the “bottom up” which has a huge advantage, the printed model can be much bigger than the vat itself. 3DPrinterNotes:ME308LAdvancedManufacturingProcesses (By:AthiqAhamedKhazi) P a g e 4 | 10 Selective Laser Sintering (SLS): Essentially works on the same principle as SLA, but rather than using resin, a powder is used. A laser heats up the powder to just below melting temperature causing it to sinter. Then a roller comes along and rolls another layer of powder on top only for the laser to sinter it too. Essentially each layer is stuck together because the laser heats them up enough to fuse, but not too much to cause them to melt.  Digital Light Processing (DLP): This method works in much the same way SLA work, where the difference is instead of using a UV laser to cure resin that make up your 3D model, a light build is used. Like with SLA, DLP has less visible layers compared to other process such as FDM / FFF, but DLP is also faster at curing the resin than SLA due to its ability to create a single layer on one digital images, whereas with SLA the UV laser (a single dot) has to trace out the object layer. 3DPrinterNotes:ME308LAdvancedManufacturingProcesses (By:AthiqAhamedKhazi) P a g e 5 | 10 Binder Jetting ( MIT Technology): Binder Jetting is a family of additive manufacturing processes. In Binder Jetting, a binder is selectively deposited onto the powder bed, bonding these areas together to form a solid part one layer at a time. The materials commonly used in Binder Jetting are metals, sand, and ceramics. Binder Jetting is used in various applications, including the fabrication of full-color prototypes (such as figurines), the production of large sand-casting cores and molds and the manufacture of low-cost 3D printed metal parts. Benefits & Limitations of Binder Jetting: The key advantages and disadvantages of the technology are summarized below: - Binder Jetting produces metal parts and full-color prototypes at a fraction of the cost compared to DMLS/SLM and Material Jetting respectively. Binder Jetting can manufacture very large parts and complex geometries, as it is not limited by any thermal effects (e.g. warping). The manufacturing capabilities of Binder Jetting are excellent for low to medium batch production. Limitations: - Metal Binder Jetting parts have lower mechanical properties than DMSL/SLM parts, due to their higher porosity. - Only rough details can be printed with Binder Jetting, as the parts are very brittle in their green state and may fracture during post processing. 3DPrinterNotes:ME308LAdvancedManufacturingProcesses (By:AthiqAhamedKhazi) P a g e 6 | 10 - Compared to other 3D printing process, Binder Jetting offers a limited material selection. (For more info: https://www.3dhubs.com/knowledge-base/introduction-binder-jetting-3dprinting/#:~:text=Binder%20Jetting%20is%20a%20family,come%20in%20a%20granular%20fo rm.)  Continuous Liquid Interface Production (CLIP):  Selective Deposition Lamination (SDL) FDM Print Quality Factors to Consider  Nozzle size affects resolution / print quality  Weight of layers may squeeze lower layers and deform print  Warping caused when plastics such as PLA & ABS cool after heating  Missing layers are common when the printer fails to provide the correct amount of plastic  Stringing happens when some material drops from the nozzle onto unwanted parts of the print   Nozzle blockage is common More mechanical and software tinkering / calibration for optimal printing SLA Print Quality Factors to Consider  Consistently creates higher resolution prints with fewer flaws  Creates more accurate prints (closer in dimensions, shape and size to the actual CAD file)  Less force applied to model during print (improved surface finish) 3DPrinterNotes:ME308LAdvancedManufacturingProcesses (By:AthiqAhamedKhazi) P a g e 7 | 10  As resin is photo-curable by UV light, long terms exposure to sunlight can reduce models mechanical strength.  Resin is sticky and completed prints need to be cleaned out with alcohol to remove stickiness  Printing from the “top down” means the model’s height cannot be greater than the depth of resin in the vat.  Tied to purchasing resin from manufacturer (currently no too few third party suppliers)  Post-finishing required – removal of support structures after print FDM vs SLA Printing Times FDM Standard Setting: 0.3-1.7 in/hr SLA Built In Rate: 0.3 – 0.7 in/hr   FDM vs SLA: Materials, Colours & Availability  Like any machine there are running costs, and for 3D printers the main one is consumables (essentially the materials needed to create the 3D print). One of the advantages that FDM has over SLA is the variety of materials and colours that are on offer, general lower cost of the materials, and just as importantly the variety of third party consumables (ability to shop around). Having said that one advantage SLA has over FDM is the accuracy of prints that can be used for anatomical regions of patients and for accurate prototyping for businesses to access design and functionality of their product or for advertising the final product. One of the major disadvantages of SLA however is the limited choice of resins which cannot be exchanged between printers… essentially (at least for the time being) each manufacturer will design their resin vat to fit only their printer(s).  With SLA, the resin is quite expensive compared to equal quantities you get with filaments, not to mention a limitation of materials & colours too and you are (at least for the time being) tied to purchasing the resin from the same company you bought the printer from. However there are different types of resin available for purchase to allow your final prints to have different physical properties. 3DPrinterNotes:ME308LAdvancedManufacturingProcesses (By:AthiqAhamedKhazi) P a g e 8 | 10 3D Printer Filament Material Types (FDM): Overview Filament Type Colour Variety Printing Temp. (°C) ABS Yes 230 – 240 PLA Yes 180 – 220 PLA and ABS are the 2 most common FDM desktop printing materials. Both are thermoplastics, meaning they enter a soft and mouldable state when heated and then return to a solid when cooled. Via the FDM process, both are melted and then extruded through a nozzle to build up the layers that create a final part. ABS (Acrylonitrile Butadiene Styrene) :is a common thermoplastic well known in the injection molding industry. It is used for applications such as LEGO, electronic housings and automotive bumper parts. PLA (Polylactic Acid): is a biodegradable (under the correct conditions) thermoplastic derived from renewable resources such as corn starch or sugarcane. It is one of the most popular bioplastics, used for many applications ranging from plastic cups to medical implants. ABS and PLA are both adequate for many prototyping applications. ABS is often preferred due to its improved ductility over PLA. With a higher flexural strength and better elongation before breaking, 3D printed ABS can be employed for end use applications whereas PLA remains popular for rapid prototyping when form is more critical than function. Surface finish and post processing: The nature of printing with FDM means that for both ABS and PLA, the print layers will be visible after printing. ABS typically prints in a matte finish while PLA is semi-transparent, often resulting in a glossier finish. Acetone is often used in post processing to smooth ABS, also giving the part a glossy finish. ABS is regularly machined after printing and can easily be sanded. PLA can also be sanded and machined, however greater care is required. Heat resistance: For high temperature applications, ABS (glass transition temperature of 105°C) is more suitable than PLA (glass transition temperature of 60°C). PLA can rapidly lose its structural integrity and can begin to droop and deform, particularly if under load, as it approaches 60°C. 3DPrinterNotes:ME308LAdvancedManufacturingProcesses (By:AthiqAhamedKhazi) P a g e 9 | 10 Biodegradability: PLA is stable in general atmospheric conditions and will biodegrade within 50 days in industrial composters and 48 months in water. ABS is not biodegradable, however it is recyclable. PLA is regularly used for the production of food related items, however confirmation by the filament manufacturer that it is safe to do so is recommended. Rules of thumb: - - ABS and PLA are the most common desktop FDM printed materials and are typically similar in cost. ABS has superior mechanical properties but is harder to print with compared to PLA. ABS is best suited for applications where strength, ductility, machinability and thermal stability are required. ABS is more prone to warping. PLA is ideal for 3D prints where aesthetics are important. Due to its lower printing temperature is easier to print with and therefore better suited for parts with fine details Print Materials: By default, the CubePro can print PLA and ABS print material. Each material has unique benefits and you can guide your selection based on the properties your part requires. PLA This is a hard plastic that has a low environmental impact. It is derived from renewable, starch-based resources. It is recommend using PLA when printing extra-large parts on CubePro as it is a more stable print material. PLA is the optimal support material for industrial ABS parts. PLA has the ability to dissolve away in caustic soda solutions supported by an ultra-sonic tank. ABS This is a well-known plastic known for its strength and industrial properties. As a build material, ABS is good for both small and large parts. ABS works well as a support material for extra-large PLA parts. INF Infinity Rinse-Away is a water soluble material that allows you to print your part with rinse-away supports Compatible with PLA and nylon. Print complex parts with intricate patterns and suspension in space. 3DPrinterNotes:ME308LAdvancedManufacturingProcesses (By:AthiqAhamedKhazi) P a g e 10 | 10 NYL Nylon is a strong, flexible and durable material that prints detailed parts. Excellent material for prototyping, small-run manufacturing and parts requiring secondary operations. INF is the optimal support material for nylon parts. Please Note: Please go through MSDS ( Material Safety Data sheet) of PLA & ABS before using them. FDM 3D Printer Design Considerations: There are several key components in this requiring many design trade-offs among the various options. Filament: Filament typically comes on spools (for open source printers) or, in some cases, in proprietary cartridges. Printers need to have some means of getting filament off the spool by allowing the filament to turn on a spindle or a lazy-susan-type tray. In some cases, this is part of the frame or attached to it; in other cases, the filament rests on a lazy susan next to the printer. Frame: The frame of a printer needs to be stiff and sturdy for the prints to build up accurately. If the frame is sloshing around, it is unlikely that you will be able to have an accurate print. Various types of aluminium, extruded rails typically make up frames. Laser-cut or 3Dprinted joints typically make up the rest of the frame. Build Platform: Every 3D printer needs to have a flat surface to build the print. This surface is commonly called the build platform, or sometimes just the platform or bed. Some printers have a heated platform to allow printing of materials that need to be kept warm during building. Others just have a glass or other plate that needs to be covered with tape of some sort to ensure that the first layer of the print will stick. The printer has a heated platform covered with Kapton high-temperature tape. The one in is unheated and covered with blue painter’s tape to allow printing of a plastic called PLA (polylactic acid). Extruder Design: The extruder is the part of the printer that melts and moves the filament. The extruder has several parts. One is an extruder drive mechanism, which is a motor and a mechanism that pushes the filament into the hot end. The hot end in turn is comprised of a heater, a nozzle, and a sensor (a thermistor) to sense how hot the bed is. You can see two extruders 3DPrinterNotes:ME308LAdvancedManufacturingProcesses (By:AthiqAhamedKhazi) P a g e 11 | 10 on the printer which is a dual-extruder machine capable of printing objects out of two materials. Bowden and Direct-Drive Extruders: There are many different extruder designs, which fall into two major categories. A directdrive extruder has a motor and drive gear pushing the filament right next to the hot end. A Bowden extruder has a drive gear that is separated from the hot end with a guide tube. The main reason for using a Bowden extruder is that it moves the heavy motor away from the nozzle, which can make the part of the extruder that is moving a lot lighter. This can allow for faster printing speeds, but at the cost of a more complex extrusion system. Retraction: When the printer is creating a layer, there are holes and filled areas. Some of the holes can be made by having the nozzle zip around the edge of the hole. Sometimes, though, it is necessary to stop extruding across a gap in the layer. In that case the extruder has to retract the filament. The drive gears need to be able to pull filament back as well as push it forward to make this work. How much to retract during a print is something a user can set during the process of slicing a model into layers Retraction has a strong effect on print quality. Nozzles: The nozzle is one of the most critical pieces of the printer and one of the more delicate ones. The holes are tiny and easily clogged. To a degree, the nozzle material and quality define what materials your printer can safely melt and therefore print. Good-quality nozzles can handle polycarbonate, nylon, and other higher-temperature. Plastics. The nozzle is part of the hot end, which includes the nozzle, the heater block, the thermal break (barrel), and, in many designs, a heat sink to cool the top part of the thermal break. Some designs depend on the insulating properties of high-temperature plastics or, occasionally, ceramics (at the cost of being able to extrude higher-temperature materials). Moving Parts: 3D printers need to move some combination of the extruder and the build platform to be able to create objects. They achieve this with a combination of stepper motors attached to drive screws or cable, belt, or other systems attached to pulleys. A stepper motor is a precise, brushless, direct current (DC) motor that moves the shaft in predefined angular steps. Motors for 3D printers typically have 200 steps per revolution. The stepper motor is then coupled to a drive screw (like the z-axis motors for the printer or to a belt or cable. 3DPrinterNotes:ME308LAdvancedManufacturingProcesses (By:AthiqAhamedKhazi) P a g e 12 | 10 Safety: 3D printers need to be treated with respect because of the machine-tool aspects of their personalities. In general, use common sense and follow manufacturer’s instructions. Here are a few things to also consider: The hot end is as hot as the inside of an oven baking a cake, and heated platforms can be pretty hot too. Take the same precautions as you would when dealing with any other hot surfaces and do not grab the nozzle or swipe excess filament off with your finger. - The printer is a moving robot. Do not stick fingers into it when it is operating. - Keep the area around your printer well ventilated, but remember to draw air away from it; - Do not leave your printer unattended, and be sure you are able to hear it while it is running. - Bad mechanical noises are typically the first sign that something has gone wrong. 3DPrinterNotes:ME308LAdvancedManufacturingProcesses (By:AthiqAhamedKhazi) P a g e 13 | 10