Chapter Four · failure evidence
What Laser Sintering & Ablation got wrong, from 60 dissertations
The records evaluate various laser sintering, ablation, and additive manufacturing processes across metallic, ceramic, and polymeric materials. Many attempts encountered structural cracking, excessive thermal damage, melt pool instability, lack of fusion, redeposited debris, or inferior processing speeds compared to mechanical and lithographic alternatives. These records come from PhD theses at 19 institutions, 2021 to 2026. Each links to its thesis. They were extracted by language models reading the full text, so treat each as a lead to read, not a verdict.
Laser processing performed slower or produced worse structural precision than conventional mechanical or lithographic techniques
Laser sintering and ablation frequently exhibited lower throughput, greater geometric variation, or higher roughness than baseline methods such as mechanical drilling, micromilling, and electron beam lithography. In several applications, laser direct writing also suffered from reduced resolution, excessive cycle times, and elevated leakage current.
Lost to a baseline
Parallel line laser sintering resulted in ~70% corner-to-center variation, performing worse than standard thermal sintering (17%) and IPL sintering (5.4%).
Inkjet-Printed Conductive Electrodes: Design, Fabrication, and Characterization · YorkSpace
Lost to a baseline
Biopsy time was lower (P<0.001) using a microblade compared to laser biopsy
Assessment of laser-assisted micromanipulation procedures in a commercial bovine in vitro production laboratory Assessment of Laser-assisted micromanipulation procedures in a commercial bovine in vitro production laboratory in the UK · University of Nottingham Repository
Considered and rejected
Considered and rejected: Laser ablation from metallic foil rejected due to material waste from subtractive processing and lower throughput compared to additive printing.
Considered and rejected
Considered and rejected: Rotary laser-cut PTFE tubes for HSAs rejected in favor of DLP 3D printing due to loose manufacturing tolerances and extrusion variance
Function Follows Form: An Exploration of Robotic Embodiment through Geometry · MIT
Tried and failed
excimer laser ablation micromachining applied to fused silica cavity fabrication. Outcome: too slow. Reason: produced excessive surface roughness and required prohibitive sequential processing times for millimeter-scale cavity milling
The Development Of A Fingertip Implantable Mems Tactile Sensing System · Penn
Tried and failed
increasing pulse duration in pulsed laser processing applied to single-pulse laser drilling of superalloys. Outcome: worse than baseline. Reason: lower peak power reduced energy efficiency while longer cycle times increased drilling cost
Investigation of productivity, energy efficiency, quality and cost for laser drilling · Cranfield
Lost to a baseline
Laser ablation bone removal rate of ca. 2.88 mm3/min was ~165x slower than conventional drilling (477 mm3/min) for equivalent volume removal, with significantly higher cumulative heat exposure
Bone: A study of machining-induced damage and the role of interstitial fluid · University of Nottingham Repository
Considered and rejected
Considered and rejected: Rejected PDMS, laser cutting, and 3D printing for microfluidics in favor of desktop CNC micromilling on thermoplastics to prevent material leaching and resolution limits.
Lost to a baseline
Capacitive pressure sensor sensitivity of laser-sintered hybrid device (0.028 %/N) was lower than fully FDM printed counterpart (0.087–0.092 %/N) due to particle intermixing increasing dielectric permittivity in FDM
3D printing of elastomeric mechanical sensors designed for human motion monitoring · EPFL
Considered and rejected
Considered and rejected: Rejected laser recrystallization of poly-Si for M3D integration due to higher thermal budget (>400°C vs <250°C for IWO) and 10,000x higher leakage current (10pA/μm vs 1fA/μm)
Energy-efficient On-chip Deep Neural Network (DNN) Inference and Training with Emerging Non-volatile Memory Technologies · Georgia Tech
Tried and failed
direct-write laser rastering applied to patterning polymer thin films. Reason: produced irregular and nonuniform through-holes compared to mask-assisted patterning
Active Micro-/Nano-Structures for Electromechanical Actuation · MIT
Lost to a baseline
Visible meta-optics fabricated with laser direct-write (HiRes) exhibited lower resolution and patterned shell-like artifacts compared to electron beam lithography (JEOL JBX6300FS).
MEMS-integrated Alvarez Metalenses and Large-area Meta-optics · ResearchWorks
Lost to a baseline
KrF excimer laser ablation achieved etch rates almost an order of magnitude lower than XeCl (308 nm) laser ablation on CVD diamond reported by Ageev
Excimer laser machining of CVD diamond · Iowa State
Excessive laser thermal input caused unintended melting, charring, and material breakdown
High laser power, low scanning speeds, and intense ultrafast pulses caused severe heat accumulation that melted delicate microstructures and charred polymer or paste matrices. These thermal excesses also produced bubbling, bulging hole profiles, substrate cracking, and loss of fine features.
Tried and failed
selective laser sintering with high thermal input applied to polymeric solid dispersion powder beds. Outcome: unstable. Reason: low laser speed and high bed temperature caused excessive energy density and complete powder bed melting
Expanding the processing space for amorphous solid dispersions · UT Austin
Tried and failed
Below-bandgap femtosecond laser writing applied to suspended semiconductor nanostructures. Reason: Nonlinear absorption caused structural melting and ablation of suspended cavities even at low pulse energies.
Formation, integration, and control of semiconductor spin-defects in electronic and photonic devices · Harvard
Tried and failed
increasing laser pulse energy for particle acceleration applied to laser-driven microparticle acceleration. Reason: direct ablative heating and optical saturation caused particle fracture or melting rather than higher velocity
Tried and failed
ultrafast laser structuring of polymer particles applied to polystyrene microspheres. Reason: low melting point caused thermal damage and melting rather than deep ablation
Considered and rejected
Considered and rejected: Rejected below-bandgap femtosecond laser writing because multi-photon absorption delivered excessive instantaneous power that melted suspended nanostructures.
Formation, integration, and control of semiconductor spin-defects in electronic and photonic devices · Harvard
Considered and rejected
Considered and rejected: Rejected using a constant 500 W laser power across all 10 layers for thin wall fabrication due to excessive heat accumulation and remelting of previous layers reducing deposition efficiency.
Tried and failed
laser cutting thin polymer adhesive sheets applied to microfluidic channel and electrode cavity patterning. Reason: low laser power caused incomplete cutting while high power or low speed caused thermal burnout
Design and Fabrication of Microfluidic Electrochemical Sensor for Lead Detection in Drinking Water · YorkSpace
Tried and failed
high-power pulsed laser machining with spiral toolpath applied to chemical vapor deposition diamond drilling. Reason: excessive thermal stress and ablation induced bulging hole profiles and substrate cracking
Advances in Instrumentation for Dynamic Nuclear Polarization & Magic-Angle Spinning NMR · MIT
Tried and failed
laser sintering at high power and speed applied to dispensed conductive silver paste traces. Reason: excessive thermal input charred and embrittled the conductive traces
Computational Fabrication and Assembly for In Situ Manufacturing · MIT
Considered and rejected
Considered and rejected: Rejected printing 3D dielectric microstructures directly on top of metal vias/traces because direct laser absorption heats the metal and violently disrupts the print.
Novel entangling gates and scalable trap designs for trapped-ion quantum computing · Scholars' Bank
Tried and failed
CO2 laser cutting applied to thin silicone elastomer sheets. Reason: Photothermal ablation caused thermal buckling and edge charring, leading to channel misalignment and fluid leakage
Tried and failed
Single-exposure high-intensity ultrafast laser photopolymerisation applied to 3D optical metamaterial microfabrication. Outcome: unstable. Reason: High laser intensities triggered avalanche photopolymerisation, causing uncontrolled bubbling, porosity, and loss of microscale features
Insufficient laser power or scan penetration caused incomplete melting and lack of fusion
Operating below required energy density thresholds or scanning at excessively high speeds prevented complete melting and adequate curing depth. This resulted in loose sintering, track boundary lack-of-fusion porosity, uncured subsurface material, and failed material ejection.
Tried and failed
low power with reduced hatch spacing applied to laser powder bed fusion. Outcome: worse than baseline. Reason: Lack-of-fusion porosity at meltpool boundaries caused brittle cleavage despite achieving finer grain size
Digital Twins for Accelerated Qualification in Additive Manufacturing · Virginia Tech
Tried and failed
low repetition frequency laser processing applied to metal powder bed fusion. Reason: energy density threshold required for complete melting was not reached, causing only loose sintering
Tried and failed
sub-threshold multi-pulse laser forward transfer applied to thick polymeric microstructures. Reason: insufficient laser fluence caused localized material ablation instead of mechanical propulsion
Laser-Induced Forward Transfer of Functional Microdevices · EPFL
Tried and failed
selective laser melting with short exposure time applied to aluminum alloy additive manufacturing. Reason: insufficient energy input from large melt cross-section and short exposure time caused lack of fusion
Characterization of Heat Exchange for Additively Manufactured Components · YorkSpace
Tried and failed
laser ablation for microvia drilling applied to polymer dielectric build-up layers. Reason: insufficient laser energy prevented full dielectric ablation in small diameter via holes
Heterogeneous Integration for High-Speed mm-Wave Communication · Georgia Tech
Tried and failed
low pulse energy annular laser ablation applied to tissue microbiopsy harvesting. Reason: energy density below threshold failed to reliably eject intact tissue samples
Laser beam shaping for surgery and microbiopsy · UT Austin
Tried and failed
pulsed laser deposition at low pulse energy applied to oxide thin film deposition. Reason: insufficient laser fluence caused non-uniform island growth rather than continuous layer-by-layer film growth
Epitaxial Strain of Rare-Earth Nickelates on STO Using Pulsed Laser Deposition · UT Austin
Tried and failed
laser powder bed fusion at low power applied to refractory metals. Reason: laser power below threshold failed to achieve complete melting regardless of normalized enthalpy
Development of Materials for Extreme Environment Applications by Laser Powder Bed Fusion · MIT
Tried and failed
low-power laser thermal sintering applied to conductive silver paste traces. Reason: laser power was insufficient to reach the required curing temperature
Computational Fabrication and Assembly for In Situ Manufacturing · MIT
Tried and failed
High-speed laser sintering applied to conductive silver paste traces. Reason: Fast scan speeds limit thermal penetration depth, leaving subsurface material uncured regardless of applied power
Computational Fabrication and Assembly for In Situ Manufacturing · MIT
Tried and failed
selective laser melting at low power applied to thermoelectric powder sintering. Reason: laser power was insufficient to heat the melt pool above the required sintering temperature
Numerical Analysis of the Melt Pool Kinetics in Selective Laser Melting Based Additive Manufacturing of M g2Si Thermoelectric Powders · Virginia Tech
Thermal stress and expansion mismatches caused substrate distortion, cracking, and part detachment
High residual stresses and thermal expansion mismatches during laser processing induced severe warpage, substrate cracking, and delamination. These stresses also led to recoater blade collisions, brittle cleavage, and base plate separation in additive manufacturing builds.
Tried and failed
laser powder bed fusion additive manufacturing applied to fine internal channels and thin-walled features. Reason: feature resolution limits caused internal channel blockage and thin-wall cracking during fabrication
Considered and rejected
Considered and rejected: Rejected Wolfmet selective laser melting due to brittleness, surface defects, and structural detachment.
Imaging near-field compton backscattered X-rays using Pinhole and coded masks · Cranfield
Tried and failed
Selective laser melting substrate bonding across energy densities applied to single layer metal powder deposition. Reason: laser scans failed to adhere to the base plate, causing part displacement during recoater blade passage
Tried and failed
laser powder bed fusion additive manufacturing applied to sub-millimeter thin wall fabrication. Reason: residual stress and thermal warpage caused recoater-part collisions below 500 µm feature sizes
Considered and rejected
Considered and rejected: Laser cutting and continuous welding were rejected in favor of EDM wire cutting and pulse-spot welding to minimize residual stress and edge material degradation.
Novel Permeance–Based Equivalent Circuit Model for Improved Performance Prediction of Traction Induction Motors in Electric Vehicles · Scholarship at UWindsor Institutional Repository
Tried and failed
laser milling thin microwave dielectric substrates applied to millimeter-wave reconfigurable patch antennas. Reason: Laser micromachining caused substrate cracking and degradation in thin laminates, degrading bandwidth and polarization performance
mm-Wave Reconfigurable Antenna Systems for 5G Applications · Georgia Tech
Tried and failed
laser powder bed fusion on dissimilar substrates applied to copper-steel dissimilar metal printing. Reason: thermal expansion coefficient mismatch caused severe thermal accumulation, substrate distortion, and interfacial cracking
Tried and failed
laser ablation of conductive coatings applied to silicone elastomer membranes. Outcome: worse than baseline. Reason: laser thermal energy caused localized substrate surface stiffening, preventing recovery of original mechanical compliance
Multifunctional Dielectric Elastomer Actuator for in vitro Cell Mechanostimulation · EPFL
Tried and failed
direct laser ablation patterning applied to hydrogel scaffolds prior to shrinkage. Outcome: unstable. Reason: ablated structural features lacked mechanical integrity and collapsed during subsequent dehydration
Implosion Fabrication: Rethinking 3D Nanofabrication from First Principles · MIT
Ablation debris redeposition and recast layers caused groove blockage and surface defects
Laser ablation produced ejected particulate and recast accumulation that clogged micro-grooves and created uneven, damaged hole edges. These redeposited materials also formed raised lips that prevented direct bonding and degraded optical components via plume contamination.
Considered and rejected
Considered and rejected: Rejected complex multi-directional femtosecond laser raster patterns in favor of a simplified pattern to decrease ablated debris redeposition and wall taper.
Understanding Degradation Mechanisms of Metallic Alloys in High-Temperature Molten Salt Environments · Georgia Tech
Considered and rejected
Considered and rejected: Rejected upright reflected light microscopy on the femtosecond laser setup in favor of an inverted design to reduce debris re-deposition during laser ablation.
Multifunctional Polymer Fiber Probes for Biomedical Application · Virginia Tech
Tried and failed
static micro-beam pulsed laser surface ablation applied to metal surface micro-structuring for hybrid joining. Outcome: worse than baseline. Reason: Low scan speeds and small beams caused recast accumulation, groove blockage, and internal voids.
Theoretical and Experimental Investigation of Ultra High-Strength Joining in Steel-Short Fiber Reinforced Composites · Georgia Tech
Tried and failed
single-step laser ablation applied to substrate cavity micromachining for direct bonding. Reason: laser ablation created a raised redeposited edge lip that disrupted wafer direct bonding
The Development Of A Fingertip Implantable Mems Tactile Sensing System · Penn
Tried and failed
laser drilling apertures applied to stainless steel substrates. Outcome: worse than baseline. Reason: produced imprecise, damaged, and uneven crater-like edges compared to mechanical drilling
Coherent charge dynamics in molecules on the attosecond to few-femtosecond timescale · Imperial
Tried and failed
UV laser ablation of microvias applied to high-melting-point dielectric polymer films. Reason: High melting temperature caused irregular via shapes, excessive debris, and severe post-clean film thinning
Design and Demonstration of Mechanical and Electrical Reliability of 1-micron Redistribution Layers · Georgia Tech
Tried and failed
semi-additive processing with through-dielectric vias applied to ultra-low-k polymer interconnect redistribution layers. Reason: Laser debris, non-uniform electroplating, and seed-etch dielectric damage compromised via-containing conductor lines
Reliability Assessment and Demonstration of Ultra-low-k Dielectric Materials for Advanced Interposers · Georgia Tech
Considered and rejected
Considered and rejected: Operating at variable laser power settings, rejected to prevent fourth-parameter confounding, thermal lensing, mode instability, and plume debris optical contamination.
A Process-Development Framework for UV-Laser Through-Silicon Via Drilling in Semiconductor Packaging · JScholarship
Melt pool instabilities, keyholing, and plasma plume interference disrupted additive deposition
High peak power densities and gas interactions triggered plasma bursts, keyhole vaporisation, and chaotic melt pool transitions in directed energy deposition. These instabilities resulted in severe undercut, droplet oscillations, wire deviation, nozzle clogging, and lack of fusion.
Tried and failed
laser-leading hybrid energy source with wire feeding applied to metal additive manufacturing. Outcome: unstable. Reason: high surface tension and lack of arc detachment pressure caused low droplet detachment frequency and rippling
High deposition rate wire based additive manufacture of Ti-6Al-4V. · Cranfield
Tried and failed
hybrid plasma arc and laser additive manufacturing applied to titanium alloy wire deposition. Outcome: unstable. Reason: extremely narrow wire-to-workpiece distance tolerance causing severe wire stabbing or large droplet oscillations
High deposition rate wire based additive manufacture of Ti-6Al-4V. · Cranfield
Tried and failed
reducing laser beam spot size with wire feed applied to laser additive manufacturing. Outcome: unstable. Reason: Excessive peak power density caused plume interference, wire deviation, and lack-of-fusion defects.
Tried and failed
focused laser beam for secondary melt pool reshaping applied to wire directed energy deposition. Outcome: unstable. Reason: small spot sizes exceeded keyhole threshold causing metal vaporisation, severe undercut, and spatter
Bead shape control using multi-energy source (mes) for wire-based directed energy deposition (ded) process. · Cranfield
Tried and failed
argon shielding gas in laser powder bed fusion applied to stainless steel additive manufacturing. Outcome: unstable. Reason: induced plasma bursts and laser beam wandering, causing chaotic transitions between keyhole and conduction melting regimes
Lost to a baseline
At 600 W laser power in copper LPBF, enhancing solid-phase absorptivity (Asolid ×10) formed more lack-of-fusion defects along track edges than baseline because liquid could not wet the wider melt pool prior to solidification.
Considered and rejected
Considered and rejected: Rejected high-density parameter sets with low traverse rates and high laser powers due to excessive nozzle balling and clogging.
DIRECTED ENERGY DEPOSITION PROCESSING OF ALPHA-BETA, NEAR-ALPHA, AND BETA TITANIUM ALLOYS · DalSpace
Left open by the authors
Problems the authors named and did not get to.
Left open
Determine selective laser melting parameters to control the sub-grain cell geometry of 316L stainless steel. Blocker: Requires a selective laser melting (SLM) metal 3D printing lab and experimental characterization equipment (e.g., SEM).
Microstructural Deformation Mechanisms and Optimization of Selectively Laser Melted 316L Steel · Virginia Tech
Left open
Mitigate microcracks and intermetallic disconnections in selective laser melted Finemet soft magnetic alloys. Blocker: Requires additive manufacturing lab equipment (selective laser melting machine) and material characterization tools.
Selective Laser Melting of Finemet Soft Magnetic Material · Virginia Tech
Left open
Determine whether small thermal shock cracks heal post-scanning during final densification sintering of 8-YSZ. Blocker: Requires a physical materials laboratory, sintering furnace, laser flash sintering apparatus, and characterization equipment (e.g., SEM).
Control of selective laser flash sintering of yttria-stabilized zirconia · UT Austin
Left open
Perform high cycle and low cycle fatigue testing and crack propagation analysis on 3D printed gradient 316L stainless steel specimens. Blocker: Requires selective laser melting 3D printing equipment and physical mechanical/fatigue testing apparatus
3-D Printing, Characterizing and Evaluating the Mechanical Properties of 316L Stainless Steel Materials with Gradient Microstructure · Virginia Tech
Left open
Optimize selective laser melting parameters and analyze substrate positioning to reduce density variation in Finemet alloy parts. Blocker: Requires a selective laser melting physical apparatus and Finemet alloy powder to perform experimental builds
Selective Laser Melting of Finemet Soft Magnetic Material · Virginia Tech
Left open
Apply selective laser sintering to directly process binderless low-temperature phase ceramics like boehmite to initiate phase transitions and particle necking. Blocker: Requires physical selective laser sintering (SLS) apparatus and ceramic powder materials (boehmite).
Indirect selective laser sintering of ceramics · UT Austin
Left open
Study elongated cell, melt pool, and grain formation during selective laser melting of 316L stainless steel. Blocker: Requires a selective laser melting 3D printer and microscopy/metallurgical characterization equipment.
3-D Printing, Characterizing and Evaluating the Mechanical Properties of 316L Stainless Steel Materials with Gradient Microstructure · Virginia Tech
Left open
Evaluate residual stress and texture of LPBF Fe-Si alloys (>6 wt% Si) using alternative scan strategies to achieve crack-free parts. Blocker: Requires a Laser Powder Bed Fusion (LPBF) additive manufacturing machine, metal powders, and physical characterization equipment (e.g., XRD/EBSD).
Optimisation of silicon content in Fe-Si alloys processed via Laser Powder Bed Fusion for an additively manufactured soft magnetic core Laser Powder bed fusion of Fe-Si alloys and · University of Nottingham Repository
Left open
Test additively manufactured SLM pool boiling surfaces with spherical re-entrant cavities across varying geometric parameters. Blocker: Requires selective laser melting (SLM) additive manufacturing and experimental pool boiling testing apparatus
Characterization of Heat Exchange for Additively Manufactured Components · YorkSpace
Left open
Apply additive manufacturing microstructural control methods to Ti-based, CoCrMo, and Al alloys for tailored tribological properties. Blocker: Requires selective laser melting (SLM) additive manufacturing equipment, specialized metal alloy powders, and characterization tools (SEM, EBSD).
Additive manufacturing: Towards alloys with spatially defined tribological properties · Imperial
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