Part Defects

Under-Adhesion

18min

Under-Adhesion
A part is partially or completely detached from the platform during printing.
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How to Identify
Under-adhesion can be diagnosed as follows:
Part partially detaches from the platform
Look for areas not connected to the platform
Look for features not fully resolved at platform-adhered surfaces
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Part falls off the platform during printing
Look for the part in the cassette
Slices cured after the part fell off the platform will be on the window
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Part outline on the platform is incorrect after part removed
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Cause - Undercut﻿
Solution - Print Preparation or Part Design
Cause - Unvented volume﻿
Solution - Print Preparation or Part Design
Cause - Inconclusive
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Cause - Inconclusive
Cause - Asymmetrically oriented part﻿
Solution - Print Preparation or Part Design
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Cause - Small to large cross section later in the print﻿
Solution - Print Preparation or Part Design
Cause - Unvented volume﻿
Solution - Print Preparation or Part Design
Troubleshooting
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Process, Material, and Hardware Checks
If any of these conditions apply to your print, take the corrective action and reprint to see if the problem is resolved.
Review the Project Analysis﻿ in the Printer UI for blank slices.
If blank slices are present, repair the .stl file in a 3rd party repair program.
Review the first slice and verify that the part's surface is fully on the platform.
Update the model to have a flat base if that is the intention
Use the Snap to Platform﻿ feature in Carbon software to ensure that your part is on the platform.
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Release film reduces adhesion.
If you experience under-adhesion while using release film, try printing the build without film.
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Check the expiration date of your resin lot.
Ensure all two-part resin prints are completed within the resin's pot-life.
Ensure that one-part resins are emulsified. Invert bottle 5-6 times to distribute pigment.
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Verify the platform and cassette are cleaned properly, focusing on the platform surface, window, and all printer connection point
Verify platform and cassette are installed properly
M1/M2 Printers - Clean the platform's kinematic balls and clean & lubricate the kinematic pin mounts on the platform and cassette per monthly maintenance﻿
DO NOT bake parts on the platform which will cause misalignment of the kinematic balls.﻿
Reference cleaning and installation instructions for your printer: M1/M2 Printer﻿, M3/M3 Max Printer﻿, L1 Printer﻿.
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Diagnostics
If the above checks & actions did not resolve the issue or do not apply to your print, the following diagnostics may further inform what is causing the issue.
Print with a different platform and/or cassette
If the issue is resolved with another platform or cassette, reach out to Carbon Support for assistance with the problematic hardware.
Run an Alignment Squares Test﻿.
Print Preparation or Part Design Adjustments
The following solutions will address print or part-related causes of the defects. Choose among the suggested actions below and select the best approach for your application. Usually only one type of adjustment is needed.
Unvented volume
Reorient the part to vent the trapped volume
Small > large cross section change or an asymmetrical orientation
Place a larger cross section on the platform, aiming for the average cross section in the print
Obtain a more uniform cross section throughout the print
Move the part's center of mass closer to the platform
Supports may be needed with a new orientation.
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Unvented volume
Lift the part above the platform on supports to vent the trapped volume
Small > large cross section change or an asymmetrical orientation
Add supports to combat suction forces and to add more adhesion to the platform
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Unvented volume
Add vent holes in the part, at or near the platform, to vent the trapped volume
Reference DLS Design Guidelines﻿ for vent hole guidance.

Bevels/fillets at platform
Adjust base profile to vertical for a minimum of 1 mm
Extreme undercuts may require supports
Platform footprint
Increase footprint on platform for better adhesion 
Add structure to stabilize part against suction forces
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Reference Print Plan Adjustments﻿ for guidance on the following parameters:
﻿1 Pump Up Parameters﻿ 
To reduce suction forces
Platform Speed Parameters
Motor Up Speed
﻿5 Exposure Parameters﻿ 
To increase adhesion
Exposure Timing Parameters
Base Exposure Multiplier
Brightlining Parameters
All four parameters must be specified
Brightline Interior Exposure Time
Brightline Exterior Exposure Time
Brightline Border Thickness Pixels
Brightline Outer Borders
If problems persist, please reach out to Carbon Support.
Explanation & Causes
Explanation
Suction forces pulling down on the part are stronger than the adhesion of the part on the platform.
During normal printing, the suction forces and part adhesion are in balance. Under-adhesion occurs when either the suction forces are higher than normal or adhesion has been decreased.
Reference DLS Printer Dynamics﻿ for more information on suction forces.
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Causes
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Root Issue
Problem
Why Defect Presents
Base cross section
Missing first slice
A blank slice presents at the beginning of the print, restricting adhesion.
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Flat base not snapped to platform
The part is rotated slightly such that the platform cross section is too small to maintain adhesion.
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Undercut
When only a few slices have been cured, an undercut (filleted or beveled edge) can use suction forces to peel the cured slices off the platform.
EPU, FPU, and UMA are especially susceptible.
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Small to large cross section later in the print
Suction forces increase later in the print from large cross sections and the base cross section is not strong enough to overcome the force increase. 
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Asymmetrically oriented part
Suction forces can cause torque on asymmetrically orientated parts, rotating them off the platform.
Unvented volume
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A vacuum in an unvented cavity exacerbates suction forces.
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Root Issue
Problem
Why Defect Presents
Cleaning
Dirty platform
Part cannot properly adhere to the platform if pre-existing resin is present.
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Dirty cassette window
An improperly cleaned window can hinder the UV light required to cure the resin, reducing adhesion.
Misalignment
Improper seating
Platforms and cassettes may not seat properly if dirty or incorrectly installed, causing base slices to not fully adhere.
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Unlubricated kinematic pin mounts
M1/M2 Printers only
Unlubricated kinematic pin mounts are sticky, causing hardware to be misaligned. Misaligned hardware causes base slices to not fully adhere.
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Root Issue
Problem
Why Defect Presents
Expired
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Resin does not cure properly at the base, reducing adhesion.
Past pot-life
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Mixing
One-part resin not mixed
Pigment must be fully distributed in resin to cure properly at the base for full adhesion.
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Printing Stage
Parameter Type
Type of Adjustment
Why Defect Presents
1 Pump Up
Platform Speed
﻿Increase﻿
Increased Motor Up Speed increases suction forces
5 Exposure
Exposure Timing
﻿Decrease﻿
Adhesion is decreased with less UV exposure
5 Exposure
Brightlining
﻿Decrease﻿
Adhesion is decreased with less UV exposure
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Root Issue	Problem	Why Defect Presents
Base cross section	Missing first slice	A blank slice presents at the beginning of the print, restricting adhesion.
	Flat base not snapped to platform	The part is rotated slightly such that the platform cross section is too small to maintain adhesion.
	Undercut	When only a few slices have been cured, an undercut (filleted or beveled edge) can use suction forces to peel the cured slices off the platform. EPU, FPU, and UMA are especially susceptible.
	Small to large cross section later in the print	Suction forces increase later in the print from large cross sections and the base cross section is not strong enough to overcome the force increase.
	Asymmetrically oriented part	Suction forces can cause torque on asymmetrically orientated parts, rotating them off the platform.
Unvented volume		A vacuum in an unvented cavity exacerbates suction forces.

Root Issue	Problem	Why Defect Presents
Cleaning	Dirty platform	Part cannot properly adhere to the platform if pre-existing resin is present.
	Dirty cassette window	An improperly cleaned window can hinder the UV light required to cure the resin, reducing adhesion.
Misalignment	Improper seating	Platforms and cassettes may not seat properly if dirty or incorrectly installed, causing base slices to not fully adhere.
	Unlubricated kinematic pin mounts M1/M2 Printers only	Unlubricated kinematic pin mounts are sticky, causing hardware to be misaligned. Misaligned hardware causes base slices to not fully adhere.

Root Issue	Problem	Why Defect Presents
Expired		Resin does not cure properly at the base, reducing adhesion.
Past pot-life
Mixing	One-part resin not mixed	Pigment must be fully distributed in resin to cure properly at the base for full adhesion.

Printing Stage	Parameter Type	Type of Adjustment	Why Defect Presents
1 Pump Up	Platform Speed	Increase	Increased Motor Up Speed increases suction forces
5 Exposure	Exposure Timing	Decrease	Adhesion is decreased with less UV exposure
5 Exposure	Brightlining	Decrease	Adhesion is decreased with less UV exposure

Tears

Under-Supported Overhang

Under-Adhesion

How to Identify

Troubleshooting

Process, Material, and Hardware Checks

Slices

Release Film

Resin

Hardware

Diagnostics

Hardware

Print Preparation or Part Design Adjustments

Orientation

Supports

Design

Print Plan Adjustments

Explanation & Causes

Explanation

Causes