designing for hp multi jet fusion: 10 tips you need to know · designing for hp multi jet fusion:...
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Designing for HP Multi Jet Fusion: 10 Tips You Need to Know
June 26, 2019Camille CaronAlex JuJames McCutcheon
1. Multi Jet Fusion Overview
2. 10 Tips
1. Minimums & Maximums
2. Orientation & Deformation
3. Feature Preservation
4. Design for Cleanability
5. Part Consolidation
6. Light Weighting
7. Text & Labelling
8. Caging & Packing
9. Repairing Models & Printability
10.Troubleshooting
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Webinar June 26, 2019Agenda
Multi Jet Fusion Overview
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Let’s talk
process
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Over 30 years of
HP Inkjetinnovation…
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What is Multi Jet Fusion?Technology Overview
Software and PluginsJob preparation and submission
HP Jet Fusion 3D Build Unit
Command CenterPrinter management
HP Jet Fusion 3D Printer HP Jet Fusion 3D Processing Station
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Multi Jet Fusion Manufacturing ProcessTechnology Overview
Fusion
Fused Fused FusedFused
Apply energyApply agentsMaterial Spreading
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Melting ProcessTechnology Overview
Energy
Pattern
Heat Signature
Visible spectrum
IR spectrum
white powder < melt
part > melt
200
190
180
170
160
150
140
130
120
110
100
˚C
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Let’s talk
tips and tricks
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Tip 1: Minimums & Maximums
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General PrinciplesMinimum and Maximum Feature Sizes
Upper Limits
• HP Jet Fusion 4200/5200:• Maximum build size is 380mm by
280mm by 380mm
• HP Jet Fusion 540/580:• Maximum build size is 332mm by
190mm by 248mm
• Solid, bulky parts may not print as well—consider hollowing them out if possible or adding internal lattice structures
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General PrinciplesMinimum and Maximum Feature Sizes
Lower Limits
• Minimum layer thickness is 0.08mm
• Recommended minimum feature thickness varies based on application and feature type
• Proportions also matter—0.4mm gaps work for spacing elements between 0.4mm and 1mm, but larger parts require larger gaps to disperse the heat
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Printed TestsFeature Sizing
Heights 0.1mm to 0.5mm
Heights 0.6mm to 1.0mm
Widths 1mm to 0.3mm
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Tip 2: Orientation & Deformation
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• Features printed in the XY plane and oriented to face the bottom of the build unit see a small degree of rounding and smoothing
• Features that benefit from this effect include fine details like:
• Text
• Small embossed or debossed features
• Holes and Pins
• Parts printed in the XY plane benefit mechanically from the entire layer fusing at once
Bottom FaceOrientation Guidelines
Bottom Face
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• Features printed in the XY plane and oriented to face the bottom of the build unit see a small degree of rounding and smoothing
• Features that benefit from this effect include fine details like:
• Text
• Small embossed or debossed features
• Holes and Pins
• Parts printed in the XY plane benefit mechanically from the entire layer fusing at once
Bottom FaceOrientation Guidelines
Bottom Face
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• Features printed in the XY plane and oriented to face the top of the buildunit see the sharpest edges and details
• However, parts printed in this orientation can have with a slightly rougher surface finish
Top FaceOrientation Guidelines
Top Face
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• Features printed in the XY plane and oriented to face the top of the buildunit see the sharpest edges and details
• However, parts printed in this orientation can have with a slightly rougher surface finish
Top FaceOrientation Guidelines
Top Face
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• Printing things sideways or oriented at a 30-degree angle provides the most even finish across the board
• Orienting parts at a 30 degree angle provides a good balance between sharp detail and smooth surfaces
Angled or Side FacesOrientation Guidelines
Side Face
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• Printing things sideways or oriented at a 30-degree angle provides the most even finish across the board
• Orienting parts at a 30 degree angle provides a good balance between sharp detail and smooth surfaces
Angled or Side FacesOrientation Guidelines
Side Face
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Avoiding WarpDeformation
• Thin and long parts can be prone to warp due to uneven shrinkage
• Parts with large, discrete changes in cross sectional area are prone to deformation, warp and overfusing
• These effects can be minimized by:
• Reducing the aspect ratio of long, thin parts
• Smoothly transitioning between thick and thin cross sectional areas
• Angled print orientation also helps fuse parts with quickly-changing thicknesses (like this tambourine) evenly, without warping.
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Tip 3: Feature Preservation
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Retaining ConcentricityFeature Preservation Guidelines
• To ensure that circular features such as holes remain concentric it is recommended that the print is oriented, so the circular feature lies in the XY plane
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Interface TolerancesFeature Preservation Guidelines
• For parts that are designed to fitted together after printing it is recommended that a minimum tolerance of ±0.2mm is used to ensure the parts can be combined
• For parts that are printed together it is recommended that a minimum tolerance of ±0.4mm is used to prevent features from fusing together
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Tip 4: Design for Cleanability
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Facilitating powder removal through complex assembliesImproving Gap Sizes and Openings
Creating cleaning flow
• Small gaps, and especially several small gaps, can be difficult and time consuming to thoroughly clean
• Larger gaps and elements allow easier powder removal
• You can also design in additional cut-outs, channels, and spaces to further facilitate powder removal via bead-blaster
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Custom tools for custom shapesPrinted Cleaning Tools
For long narrow parts
• Printing a chain inside to pull out helps knock out powder that is otherwise hard to reach
• Length, size, and style can be customized to your part
• Having the chain emerge from two ends makes for the easiest removal
For complex shapes
• Brush like tools can be printed separate from the part
• These make sure powder can be removed from even very deep, fine crevices that sandblasting alone can’t reach
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The benefits of easy accessPost-Print Assembly
Separation can speed things up
• You can also consider designing your part in separate pieces that can be assembled later
• This is best if you need small or no openings in the final assembly, that would prevent effective powder evacuation
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Tip 5: Part Consolidation
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Reduce assembly countConsolidating Parts
• As 3D printing allows for the manufacture of geometrically complex parts you can consolidate parts that were originally separate due to manufacturing constraints
• 3D printing allows for assembly complexity to be condensed into a single part
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Combine Moving PartsConsolidating Parts
• MJF technology allows for the in-situ printing of moving parts
• Complex geometries like fabrics and rotating interfaces can be printed fully assembled
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Tip 6: Light Weighting
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Reduce mass and minimize thermal buildupLattices Structures
• 3D printing allows for the creation of complex structures like lattices
• Mass reduction can be achieved by using lattice structures rather than solid features
• Additionally replacing solid printed areas with lattice structures can reduce thermal buildup in that area leading to reduced part warpage
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• The inbuilt complexity offered by 3D printing also allows for the manufacture of topology optimized designs
• Designs can be optimized such that material can be removed from areas that do not transfer loads –removing mass resulting in lighter, more efficient parts.
Remove unnecessary material
Topology Optimization
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Tip 7: Text & Labeling
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For labeling or customizing partsDesign for Readability
Proportion is key
• Ideal font size varies by typeface: Consider bolding a thin font, or increasing the size
• Text should be raised to a just-readable point. If it is too high, it can break off or be hard to clean. 1mm and less usually work well.
• Orientation will also impact readability.
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Tip 8: Caging & Packing
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Batching Parts for Unpacking and Processing
Caging
• Printing parts in cages make small pieces easier to unpack
• Cages can also be used for post-processing, such as conveniently sandblasting and dyeing parts in batches.
• Caging also allows for related components to be packed into a single unit allowing for easier part sorting during the powder removal process
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Populating Print BedsPacking
• Effective build packing can reduce part cost by increasing the number of parts in a build
• By considering the design of parts, packing density can be improved
• Consider adding draft angles to allow for parts to be nested
• Change the form/design of parts so they integrate together more easily
• Consider pre-nesting parts prior to using software to run auto-packing algorithms
• Inter-part spacing needs to be taken into consideration to reduce thermal build up. Larger parts should have increased spacings - this helps to avoid powder yellowing and overfusing of adjacent parts.
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Tip 9: Repairing Models & Printability
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Optimizing models for usePreparing Parts for Printing
Reducing file sizes
• Smaller files are easier to handle and submit for printers
• Make sure to post-process your files to remove unnecessary triangles. Many programs can be used to do this, ranging from Meshmixer to Magics to even Photoshop.
• Be careful not to over-reduce your files, or your part may print with an unintended faceted look
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Optimizing models for usePreparing Parts for Printing
Reducing file sizes
• Smaller files are easier to handle and submit for printers
• Make sure to post-process your files to remove unnecessary triangles. Many programs can be used to do this, ranging from Meshmixer to Magics to even Photoshop.
• Be careful not to over-reduce your files, or your part may print with an unintended faceted look
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Ensuring successful resultsRepairing Parts for Printing
The final step before printing
• Make sure your meshes are watertight and printable
• Many programs can be used to repair your STL, such as Netfabb, Magics, and HP SmartStream.
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Tip 10: Troubleshooting
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Thick white residue or parts stuck togetherOverfusing
Common causes and solutions
• If components that are supposed to move freely but are stuck, like for a chain, the gap size is likely too small and needs to be increased.
• If the white overfused portion is on the exterior of a part, it may have been packed too close to another large part. Try printing it again with more empty space around it.
• If the overfusing happens along a sharp straight line, you may have experienced the rare occurrence of a printhead issue. Troubleshoot the printer.
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• Sometimes, fine features printed facing up can experience some pitting, as in the HP logo coaster pictured. To avoid this, print parts sideways or at a 30-degree angle.
• Though MJF can print extremely fine features, those parts can be fragile and break if not designed properly. Thin connecting rings should have a small radius and connect small elements—otherwise, they may be vulnerable to breakage in sandblasting.
Issues that can impact fine elementsDetail Defects
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