MT08 Lesson04: Liquid-Based Additive Manufacturing Technologies

liquid-based additive Manufacturing Technologies five vat photopolymerization VP stereo lithography SLA Digital Light processing DLP continuous Digital Light processing cdlp six material jetting MJ Nano particle jetting npj drop on demand DOD s binder jetting BJ binder jetting BJ that photopolymerization VP vat polymerization uses a vat of liquid photopolymer resin out of which the model is constructed layer by layer an UltraViolet UV light is used to cure or Harden the resin where required whilst the platform moves the object being made downwards after each new layer is cured as the process uses liquid to form objects there is no structural support for the material during the build phase unlike powder based methods where support is given from the unbal material in this case support structures will often need to be added resins are cured using a process of photopolymerization Gibson and all 2010 or UV light where the light is directed across the surface of the resin with the use of motor control mirrors grinda 2009 where the resin comes in contact with the light it cures or hardens stereo lithography SLA also known as vat photopolymerization or resin printing is an additive manufacturing am process that utilizes a laser beam to cure liquid resin layer by layer to create three-dimensional objects it is widely considered one of the most accurate and highresolution AM Technologies available advantages of SLA high accuracy and resolution SLA produces Parts with exceptional detail and smooth surface finish making it ideal for applications requiring intricate features and Aesthetics wide range of materials SLA offers a variety of resins with different properties like strength flexibility and biocompatibility Catering to diverse applications transparent and translucent materials SLA offers unique capabilities for creating transparent or translucent Parts rapid prototyping SLA offers relatively Fast Printing speeds compared to some other AM Technologies making it suitable for rapid prototyping iterations limitations of SLA higher cost per part SLA materials and machines can be more expensive compared to some other AM Technologies impacting the cost per part limited build volume build volumes of SLA machines tend to be smaller compared to other AM Technologies postprocessing requirements SLA Parts often require post-processing steps like cleaning and support removal adding time and effort resin safety some resins used in SLA can be harmful if not handled properly requiring appropriate safety precautions applications of SLA prototyping SLA is widely used for creating High Fidelity prototypes for various Industries including Automotive medical and consumer goods jewelry and dental models SLA is used for creating intricate jewelry molds and high Precision Dental models medical devices SLA is used to produce medical models surgical guides and even some functional medical devices Art and Design SLA enables the creation of detailed figurines models and artistic objects overall SLA is a valuable am technology for applications requiring high accuracy smooth surface finish and a wide range of material options however its higher cost and potential limitations in build volume and postprocessing needs should be considered when choosing the most suitable am technology for specific projects the build process Digital model 3D CAD software is used to create a digital model of the desired object slice preparation the model is sliced into thin horizontal layers by software generating instructions for the SLA machine resin vat a vat containing liquid photosensitive resin is placed in the SLA machine laser beam a computer controlled laser beam scans each layer of the sliced model on the surface of the resin vat curing the laser beam cures solidifies the resin wherever it strikes creating the first layer of the object platform descent the build platform holding the partially formed object descends slightly into the resin vat repeat steps four to six are repeated until all layers are cured building the entire object layer by layer postprocessing the printed object is removed from the build platform clean to remove excess resin and possibly cured further under UV light Digital Light processing DLP Digital Light processing DLP is an additive manufacturing am technology similar to stereo lithography SLA but uses a different approach to curing photosensitive resin here's a breakdown of the DLP process and its key characteristics advantages of DLP faster printing speeds DLP generally offers faster printing speeds compared to SLA due to its ability to cure an entire layer at once using the projected image lower cost per part DLP can be a more cost effective option compared to SLA especially for larger production runs due to faster printing speeds and potentially lower material costs large build volume DLP systems can offer larger build volumes compared to SLA machines allowing for the production of bigger Parts limitations of DLP lower resolution while still capable of producing high quality Parts DLP generally offers slightly lower resolution compared to SLA due to the nature of light projection and pixel size on the DMD chip limited material selection the material options for DLP might be narrower compared to SLA although the range of available materials is constantly expanding applications of DLP prototyping DLP is widely used for creating functional prototypes and models with good detail and faster printing speeds compared to SLA manufacturing DLP can be used for small batch production of various parts particularly where larger build volumes are required Dental applications DLP is used to create Dental models surgical guides and even some custom Dental Prosthetics consumer goods DLP can be used to manufacture various consumer goods such as figurines jewelry molds and even some electronic components comparison with SLA both SLA and DLP are versatile AM Technologies for creating objects from photosensitive resins however they have some key differences curing method SLA uses a point-by-point laser beam for curing while DLP projects an entire layer image onto the resin using a DMD chip speed and cost DLP generally offers faster printing speeds and potentially lower cost per part especially for larger volumes resolution SLA offers slightly higher resolution and smoother surface finish compared to DLP material options SLA typically offers a wider range of material options including specialized resins for specific applications overall DLP is a valuable and costeffective am technology it offers rapid printing speeds larger build volumes and is suitable for various applications from prototyping to small batch production however its slightly lower resolution and potentially narrower material selection compared to SLA should be considered when choosing the most suitable am technology for specific projects the build process Digital model similar to SLA a 3D CAD model is used to create the object design slice preparation the model is sliced into thin layers by software generating instructions for the DLP machine resin vat a that containing liquid photo poly resin is placed inside the DLP machine digital microm mirror device DMD a central component of DLP is a DMD this chip consists of millions of tiny individually addressable mirrors light projector a projector shines light onto the DMD layer by layer curing the software controls the DMD tilting each individual mirror on or off this selectively reflects the light from the projector projecting the desired image of each layer onto the surface of the resin in the vat cures each layer Point by Point using the laser beam requiring the image to be scanned across the entire layer curing the exposed areas of the resin cure solidify due to their photosensitivity forming the first layer of the object platform descent the build platform holding the partially formed object descends slightly into the resin vat repeat steps 5 to 7 are repeated until all layers are cured building the entire object layer by layer postprocessing similar to SLA the printed object undergoes postprocessing like cleaning and support removal continuous Digital Light processing cdlp is an additive manufacturing am technology derived from DLP Digital Light processing it offers a unique approach to curing photosensitive resin leading to faster printing speeds and potentially Improv Park quality compared to standard DLP the key difference with DLP lies in how the layers are cured DLP cures each layer Point by Point using the laser beam requiring the image to be scanned across the entire layer cdlp projects an entire image of the complete layer onto the resin using the DMD chip this image can continuously expose the entire layer simultaneously leading to faster curing times advantages of CD LP faster printing speeds The Continuous curing approach of cdlp allows for significantly faster printing speeds compared to standard DLP particularly for larger objects and thicker layers potentially improv Park quality cdlp can potentially offer improved part quality due to reduced layer cure time minimizing shrinkage and warping issues that can occur in slower curing processes potential for larger build volumes some cdlp systems offer larger build volum volumes compared to standard DLP machines limitations of cdlp limited availability cdlp technology is still relatively new hence the number of commercially available cdlp machines is currently lower compared to standard DLP systems material compatibility not all DLP resins are compatible with cdlp due to the differences in curing Dynamics potential challenges with fine features The Continuous curing approach might pose Challen es for achieving extremely fine features and high resolutions compared to standard DLP applications of cdlp rapid prototyping cdlp is well suited for rapid prototyping applications where quick turnaround times are crucial low volume production cdlp can be used for small batch production of Parts especially when faster printing speeds are desired applications requiring good dimensional accuracy the potential for improved part quality due to reduced cure time makes cdlp suitable for applications where dimensional accuracy is critical overall cdlp is a developing am technology offering promising benefits in terms of speed and potentially improved Park quality however its limited availability material compatibility and potential challenges with fine features should be considered when choosing the most suitable am technology for specific needs the build process Digital model similar to SLA a 3 CAD model is used to create the object design slice preparation the model is sliced into thin layers by software generating instructions for the DLP machine resin vat a vat containing liquid photopolymer resin is placed inside the DLP machine digital microm mirror device DMD a central component of DLP is a DMD this chip consists of millions of tiny individually addressable mirrors light projector a projector shines light onto the DMD layer by layer curing the software controls the DMD tilting each individual mirror on or off this selectively reflects the light from the projector projecting the desired image of each layer onto the surface of the resin in the vat projects an entire image of the complete layer onto the resin using the DMD chip this image can continuously expose the entire layer simultaneously leading to faster curing times curing the exposed areas of the resin cure solidify due to their photosensitivity forming the first layer of the object platform descent the build platform holding the partially formed object descends slightly into the resin vat repeat steps 5 to 7 are repeated until all layers are cured building the entire object layer by layer postprocessing similar to SLA the printed object undergoes post-processing like C cleaning and support removal both cdlp and DLP utilize similar core principles but differ significantly in their curing approach curing method cdlp cures entire layers simultaneously while DLP cures each layer Point by Point speed cdlp offers significantly faster printing speeds compared to DLP part quality cdlp has the potential for improved part quality particularly regarding dimensional accuracy material options cdlp currently has a potentially narrower range of compatible materials compared to DLP availability cdlp systems are currently less widely available compared to standard DLP machines step by step the build platform is lowered from the top of the resin vat downwards by the layer thickness a UV light cures the resin layer by layer the platform continues to move downwards and additional layers are built on top of the previous some machines use a blade which moves between layers in order to provide a smooth resin base to build the next layer on after completion the vat is drained of resin and the object removed technical info the SLA process has a high level of accuracy and good finish chew at all 2010 but often requires support structures and post curing for the part to be strong enough for structural use the process of photopolymerization can be achieved using a single laser and Optics blades or recating blades Gibson and all 2003 Passover previous layers to ensure that there are no defects in the resin for the construction of the next layer the photopolymerization process and support material may have likely caused defects such as air gaps which need to be filled with resin in order to achieve a highquality model typical layer thickness for the process is 0.025 to 0.5 mm chew at all 2010 postprocessing Parts must be removed from the resin and any excess resin fully drained from the vat supports can be removed using a knife or sharp Implement care must be taken not to contaminate the resin and the appropriate safety precautions must be taken methods for removing resin and supports include the use of an alcohol rinse followed by a Water Rinse the processing may be lengthy as parts may require additional scrubbing to remove material fully finally Parts can be dried naturally or by using an air hose UV light is often used as well for a final post cure process to ensure a highquality object machine example machine 3D Systems procs 950 Max part weight 450 kg area 1,500 mm XB 750 mm x 550 mm materials the vat polymerization process uses Plastics and polymers polymers UV curable photopolymer resin resins viset range 3D Systems advantages high level of accuracy and good finish relatively quick process typically large build areas object 1,000 1,000 by 800x 500 and Max model weight of 200 kg disadvantages relatively expensive lengthy post processing time and removal from resin limited material use of photo resins often requires support structures and post curing for parts to be strong enough for structural use material jetting MJ material jetting creates objects in a similar method to a two-dimensional inkjet printer material is jetted onto a build platform using either a continuous or drop on demand deal OD approach material is jetted onto the build surface or platform where it solidifies and the model is built layer by layer material is deposited from a nozzle which moves horizontally across the build platform machines vary in complexity and in their methods of controlling the deposition of material the material layers are then cured or hardened using ultraviolet UV light as material must be deposited in drops the number of materials available to use is limited polymers and waxes are suitable and commonly used materials due to their viscous nature and ability to form drops nanoparticle jetting npj is a patented additive manufacturing am technology developed by xjet it utilizes a unique approach employing nanop particles suspended in a liquid to create highquality ceramic and metal Parts advantages of mpj high resolution and smooth surface finish npj offers exceptional resolution and smooth surface finish particularly for ceramic Parts making it suitable for applications requiring intricate details and Aesthetics wide range of materials npj can handle various ceramic and metal materials including multimaterial printing capabilities within the same build faster printing speeds mpj can offer faster printing speeds compared to some other ceramic and metal AM Technologies like selective laser centering SLS or selective laser melting slm water soluble support material mpj utilizes a water soluble support material simplifying the removal process and minimizing post-processing steps limitations of mpj limited availability mpj technology is currently offered by only one company xjet limiting user options and potentially impacting cost due to less competition newer technology as a relatively new technology mpj is still under development and the long-term performance and material properties of printed Parts require further exploration potentially higher cost due to limited competition and the unique technology involved npj systems and materials might have a higher cost compared to some other AM Technologies applications of npj prototyping npj is well suited for creating High Fidelity ceramic and Metal protot types with intricate details and smooth surfaces manufacturing mpj can be used for small batch production of ceramic and metal Parts particularly for applications requiring high resolution and multimaterial capabilities jewelry and dental applications mpj has the potential for creating intricate jewelry pieces and dental crowns with high detail and smooth finishes Aerospace and medical npj is being explored for applications in Aerospace space and medical Fields due to its ability to produce complex ceramic and metal Parts with specific properties overall npj is a promising am technology offering unique advantages in terms of resolution multimaterial capabilities and potentially faster printing speeds however its limited availability newer technology status and potentially higher cost should be considered when choosing the most suitable am technology for specific projects the build process Digital model similar to other AM Technologies a 3D CAD model is used to design the desired object slicing the model is sliced into thin layers using software nanoparticle inks the process utilizes inks containing Nano particles of the desired material ceramic or metal suspended in a liquid carrier inkjet print heads multiple inkjet print heads deposit the nanoparticle inks onto the build platform layer by layer select deposition the print heads precisely deposit the inks based on the slic model data building up the desired shape centering once a layer is deposited it undergo a centering process centering applies heat and or pressure causing the Nano particles to fuse together forming a solid layer of the desired material layer by layer building the process repeats depositing and centering each layer until the entire object is complete postprocessing the printed object undergoes post-processing steps like support removal and cleaning drop on demand DOD principle unlike continuous inkjet CJ printing which uses a continuous stream of ink with droplets being deflected as needed DOD technology only dispenses a drop of ink when required this precise control allows for efficient ink usage and the creation of high resolution prints inkjet print heads DOD printers employ specialized print heads equipped with numerous tiny nozzles each nozzle has a heating element or a piso electric crystal in thermal DOD the heating element creates a small bubble that expands pushing a tiny drop of ink out of the nozzle in pyo electric Dodd the crystal vibrates when an electrical signal is applied creating pressure that forces a drop of ink out advantages of DOD high resolution precise drop placement allows for creating intricate detail and sharp text making DOD suitable for applications requiring High Precision wide material compatibility dood printers can work with various inks including UV curable inks solvent-based inks and biocompatible inks catering to diverse printing needs efficient ink usage since ink is only dispensed when needed DOD technology offers efficient material utilization reducing waste and potentially lowering printing costs faster printing speed speeds compared to CJ printing DOD systems can achieve faster printing speeds due to the ability to control individual drops and avoid deflection mechanisms limitations of DOD potential for clogging the tiny nozzles can be susceptible to clogging if not properly maintained or if using inks with incompatible particles limited build volume dood printers often have smaller build volumes compared to other 3D printing Technologies like fuse deposition model moding fdm cost while DOD printers offer efficient ink usage the initial cost of the printer itself might be higher compared to some other Technologies applications of DOD prototyping DOD printers are well suited for creating highresolution prototypes with fine details printing on various materials DOD technology can be used to print directly onto various materials like textiles Plastics and even food items depending on the used printed Electronics DOD is used in the development of printed Electronics where functional electronic circuits are directly printed onto a substrate packaging and labeling DOD printers are used for highquality printing on packaging materials and product labels overall DOD technology offers excellent printing quality material versatility and efficient ink usage however it's potential for clogging limited build volume and potentially higher initial cost should be considered when choosing the most suitable printing technology for specific applications the build process Digital model as with various other 3D printing Technologies the process starts with a 3D CAD model of the desired object or design slicing the model is sliced into thin horizontal layers by slicing software generating instructions for the dod printer printing process material preparation The Chosen material often in the form of a liquid or gel is loaded into the appropriate cartridge or reservoir of the dod printer jetting and positioning the dod print head equipped with numerous tiny nozzles precisely controls the deposition of material droplets based on the slice layer data this control can be achieved through thermal DOD heating elements within the nozzles create tiny bubbles that push out droplets piso electric DOD piso electric crystals vibrate creating pressure that forces out droplets layer by layer building each layer is built upon the previous one with precise positioning of material droplets forming the desired shape curing or solidification depending on the material and application UV curable materials exposure to UV light solidifies the deposited droplets solvent-based materials the solvent evaporates leaving the material solidified binder jetting a a separate binding agent solidifies the deposited material particles post-processing once the entire object is printed post-processing steps might be needed depending on the material and application this could involve removing support structures if used cleaning or washing the printed object additional curing or finishing steps EG heat treatment surface treatment step by step the print head is positioned above build platform droplets of material are deposited from the print head on a Surface where required using either thermal or piso El electric method droplets of material solidify and make up the first layer further layers are built up as before on top of the previous layers are allowed to cool and Harden or are cured by UV light postprocessing includes removal of support material technical info material jetting builds objects in a similar method to a two-dimensional ink jet printer multiple materials can be used in one process and the material can be changed during the build stage material is jetted onto the build platform surface in droplets which are formed using an oscillating nozzle droplets are then charged and positioned onto the surface using charg deflection plates this is a continuous system which allows for a high level of droplet control and positioning droplets which are not used are recycled back into the printing system drop on demand DOD is used to dispense material onto the required surface droplets are formed and positioned into the build surface in order to build the object being printed with further droplets added in new layers until the entire object has been made the nature of using droplets limits the number of materials available to use polymers and waxes are often used and are suitable due to their viscous nature and ability to form drops viscosity is the main determinant in the process there is a need to refill the reservoir quickly and this in turn affects print speed unlike a continuous stream of material droplets are dispensed only when needed released by a pressure change in the nozzle from thermal or piso electric actuators thermal actuators deposit droplets at a very fast rate and use a thin film resistor to form the droplet the piso electric method is often considered better as it allows a wider range of materials to be used the design kinds of a typical DOD print head changes from one machine to another but according to atad typically include a reservoir ceiling ring Paso elements and silicon plate with nozzle held together with high temperature glue postprocessing support material can be removed using a sodium hydroxide solution or water jet due to the high accuracy of the process technology the level of postprocessing required to enhance the properties is limited and the functional and aesthetic qualities of a part are largely determined during the printing stage straty polyjet technology cures the material using UV light and therefore no post curing process is needed machine example machine obj 500 conx 3 build area 490 by 390x 200 mm layer thickness layer thickness 16 microns no of colors 46 materials the material jet process uses polymers and Plastics polymers polypropylene HTP PS pmma PC ABS hips EDP advantages the process benefits from a high accuracy of deposition of droplets and therefore low waist the process allows for multiple material parts and colors under one process this advantages support material is often required a high accuracy can be achieved but materials are limited and only polymers and waxes can be used binder jetting BJ the binder jetting process uses two materials a powder-based material and a binder the binder acts as an adhesive between powder layers the binder is usually in liquid form and the build material in powder form a print head moves horizontally along the X and Y AIS of the machine and deposits alternating layers of the build material material and The Binding material after each layer the object being printed is lowered on its build platform due to the method of binding the material characteristics are not always suitable for structural parts and despite the relative speed of printing additional post-processing see below can add significant time to the overall process as with other powder-based manufacturing methods the object being printed is self-supported within the powder bed and is removed from the Unbound powder once completed the technology is often referred to as 3dp technology and is copyrighted under this name step by step powder material is spread over the build platform using a roller the print head deposits the binder adhesive on top of the powder where required the build platform is lowered by the model's layer thickness another layer of powder is spread over the previous layer the object is formed where the powder is bound to the liquid Unbound powder remains in position surrounding the object the process is repeated until the entire object has been made technical info the binder jetting process allows for color printing and uses metal polymers and ceramic materials the process is generally faster than others and can be further quickened by increasing the number of print head holes that deposit material the two material approach allows for many different binder powder combinations and various mechanical properties of the final model to be achieved by changing the ratio and individual properties of the two materials the process is therefore well suited for when the internal material structure needs to be of a specific quality layers of build material often in granular and powder form are held together using the adhesive binder the print head deposits The Binding material in micro amounts and the powder material is used in creating most of the overall object Mass a heated build chamber can help to speed up the printing process by increasing the viscosity of the materials Che at all 2010 postprocessing the overall process time is extended as it requires the binder to set and the part is often allowed to cool in the machine to fully solidify to achieve a high quality finish Gibson atall 2010 postprocessing is often required to make the parts stronger and give the binder material better mechanical and structural properties Gibson at all 2010 machine example Machine Spectrum z500 layer thickness 0.089 to 0.203 mm print speed two layers SL minute materials Metals stainless steel polymers ABS PA PC Ceramics glass all three types of materials can be used with the binder jetting process advantages Parts can be made with a range of different colors uses a range of materials metal polymers and Ceramics the process is generally faster than others the two material method allows for a large number of different binder powder combinations and various mechanical properties disadvantages not always suitable for structural parts due to the use of binder material additional post-processing can add significant time to the overall process

2025-01-12 09:42

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