Transcript
Printing with EOS SLS printer (selective laser sintering of nylon powder)
Introduction SLS printing has become one of the most popular technologies for building accurate and highly detailed parts for models, form exploration, and tool building. This document provides the basic description of the SLS printing process at Aarhus School of Architecture. The printer hardware is described, followed by the design guidelines for preparing a file to be printed, as well as sending the files to the 3D Lab, payment, and retrieval and post processing of the finished model. EOS Formiga P110 The EOS FORMIGA P 110 is an industrial 3D printer made by the German manufacturer EOS. The EOS FORMIGA P 110 is based on the LS (Laser Sintering) 3D printing technology developed by EOS. This 3D printing technique uses a fiber laser to melt and fuse fine plastic powder. Layer after layer the 3D object is built. We use the 0.1mm layer configuration—thus a sphere of 1cm diameter would be comprised of 100 layers.
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Table of contents 1. 1.1 1.2 1.3 1.4 2. 3. 4. 5. 6.
3D file guidelines Maximum size Minimum sizes Exporting the file Stepping phenomenon Price/payment Printing schedule/collection of models Delicate parts and unpacking Post-processing Useful links
Making your model
Checking
Expor6ng
Paying
Sending
Picking up
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1. 3D file guidelines 1.1 Maximum size: maximum size that can be printed is 190x240x340mm – an area of 30x40mm for heating coil. Download Rhino template for reference from: https://drive.google.com/file/d/0B8OiC3vTb_TSWlJfOXN6X1k3Wms/view?usp=sharing
1.2 Minimum sizes: Thin walls. 0.45 mm
If you are printing thin walls, they should not be thinner than 0.45mm or they can break when removing from the powder bed or removing excess dust. If you are printing fx large flat surfaces or open boxes, they may warp due to cooling down after being sintered at a high temperature. Consider thickening or adding stiffening by adding ribs bosses, and/or gussets your design in order to reduce the risk of warping. Wires. 0.8 mm
1.0 mm
When printing supported wires (length is greater than five times its width) they should not be thinner than 0.8mm. Unsupported wires – should be no thinner than 1.0mm.
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1.3
Embossed/engraved details. 2.0mm
2.0mm 0.5mm
0.5mm
Detail: a feature whose length is less than twice its width. Embossed details stick out from a surface, engraved details go into a surface. The minimum detail is determined by the printer’s resolution and should not be lower than 0.5mm in height and 0.2mm in width. If details are below minimum, they might not be correctly replicated. Escape holes. 2.0 mm
4.0 mm
Escape holes allow unbuilt material inside hollow products to be removed. If you are using one escape hole, the diameter of it should not be less than 4.0mm. When using 2 holes (required for products larger than 50x50x50mm), the holes should be no less than 2.0mm in diameter Clearance. 0.5 mm
Clearance is the space between any two parts, walls or wires. This should not be less than 0.5mm to ensure that the parts don’t melt together during sintering process. This would mean that fx mechanical parts won’t be able to move or intended gaps between features would be filled in. Fitting parts.
If you are printing two parts that will have to fit together(fx lid on a box), we suggest that you create a 0.1mm gap between them to create a snug but not too tight fit.
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1.4 Exporting the file. Ensure that you are working in “mm” units for your CAD file and export to “mm” as well. Before exporting your file for 3D print you have to be aware that it has to be ‘waterproof’. That means no open/naked edges. You can check this in Rhino by going to Analyze>Edge Tools>Show Edges. Also check for direction of surface normals and make sure they correspond with the outside/inside direction of the intended form. If the arrows point inwards, that means the geometry is read inside out and the surface normals need to be flipped. Also make sure that there no overlapping, intersecting shapes or surfaces. If there are, they should be trimmed or Boolean differenced. Mesh the object, then export the mesh to an STL file. Choose Tolerance 0,01mm, Binary 1.5 Stepping phenomenon Depending on the shape of your model and orientation in the print tray, you might see print lines, or “stepping” phenomena on your model, which is a natural artifact of 3D printing using the SLS process. SLS printing works by printing layer by layer, and while our layers are around 0.1mm thin, there is a “step” between each layer, much like a staircase. 2. Price/payment The price of the print is calculated according to the volume of your 3d model’s bounding box and is 0,25 kr/cm3. You can measure your bounding box by typing ‘bounding box’ in Rhino, choose ‘solid’ and then measuring ‘volume’. Remember to convert the number to cm, if you are working in mm. You then visit school’s webshop and pay the amount under 3D printing supplies http://shop.aarch.dk/depositum/3d_printing_supplies.htm Send your file together with the receipt to:
[email protected] 3. Printing schedule/collection of models Prints are scheduled to run every Monday and Wednesday. Send your files together with receipt no later than 16.00 on the printing days. Otherwise they will be printed on the next scheduled date. If the chamber is overfilled, we will fill it according to first come first serve concept. Your models are ready on the next printing date (fx all Monday jobs available on Wednesday and Wednesday jobs - Monday) You can collect them between 8.30-9.00 and 16.00-19.00 unless agreed otherwise.
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4. Delicate parts and unpacking Once the print is done in the machine, we will take it out from the powder cake in the unpacking station. From this point, the parts are taken for cleaning in the glass bead blaster and washed with tap water before they are available for collection. However, if the parts are very delicate, we might ask the student to be available during unpacking to assist in the process. 5. Post Processing All parts are printed in the white nylon powder. It is possible to post process your prints by sanding and/or painting. For painting you can use: -acrylic paint, water based -acrylic paint, solvent based -cellulose spray paint, solvent based -nail varnish, acetate solvent based or acrylic -oil paint You can also use primer coating in order to achieve smooth, shiny surfaces. Note that paint will add thickness to your model, so you might want to adjust you model before you print to accommodate that. Nylon dye can also be used, for example Dylon, etc. 6. Useful links Rhino Videos Introduction to Rhinoceros youtu.be/yPgMccdh8QU How to get your CAD model ready for print youtu.be/yuwJ89OgpWE Videos showing the settings for adjusting the export from Rhino to STL (start with 1, 2, etc. ) https://vimeo.com/channels/Rhinoprint3d NOTE: Look at this one 59:17 for more inside tips on the settings for meshing. https://vimeo.com/80478910 STL info from Rhino http://wiki.mcneel.com/rhino/stlinfo shells in Rhino V5 - https://www.youtube.com/watch?v=BSkzD35bamQ Rhino to 3D print tutorial from Sculpteo http://www.sculpteo.com/en/prepare-your-model-3d-printing-rhinoceros/ Shapeways guidelines: https://www.shapeways.com/materials/strong-and-flexible-plastic
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T-Splines (awesome tool to consider) sunglasses - https://www.youtube.com/watch?v=czTsFEkO8xI Geomagic Studio Constructing grids and nurbs surface from a scan http://support1.geomagic.com/link/portal/5605/5668/Article/1441/How-to-ConstructGrids-and-create-a-NURBS-surface-in-Exact-Surfacing Automatically creating a nurbs model http://support1.geomagic.com/ics/support/kbanswer.asp?deptID=5668&task=knowledge &questionID=1405 Faro Scanning Arm (ES model) http://www.faro.com/products/metrology/faro-scanarm/overview
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