Layer adhesion remains a critical challenge in additive manufacturing, with delamination failures occurring at interfacial bonds that typically achieve only 20-80% of bulk material strength. These weak interfaces arise from insufficient molecular diffusion between layers, thermal gradients during solidification, and residual stresses that can exceed 10 MPa in some polymer systems.

The fundamental challenge lies in achieving molecular-level bonding between successive layers while maintaining dimensional accuracy and processing speed.

This page brings together solutions from recent research—including cross-layer mechanical anchoring systems, multihydrazide adhesion promoters, controlled thermal management during layer fusion, and stress-relieving substrate designs. These and other approaches focus on practical methods to enhance interlayer strength without compromising print quality or production efficiency.

1. Method for 3D Printing Multi-Layer Structures with Interlayer Cavities Filled by Transverse Rivets

DANA ITALIA S.R.L., 2023

A method for 3D printing multi-layer structures with improved interlayer adhesion to prevent delamination. The method involves creating cavities that cross multiple layers during printing and then filling the cavities with a second material to form rivets perpendicular to the layers. The rivets compress the surrounding layers as they cool and contract, increasing adhesion.

2. 3D Printed Green Body with Multihydrazide-Enhanced Layer Bonding

Hewlett-Packard Development Company, L.P., 2023

Improving the tensile strength of 3D printed green bodies to prevent damage during transportation and handling prior to fusing. The method involves selectively applying an adhesion promoter containing multihydrazide compounds like adipic dihydrazide to the binder fluid used in 3D printing. The multihydrazide adhesion promoter enhances the bonding between layers of particulate build material when forming the green body.

3. Layered Object Fabrication Method Utilizing Sub-Glass Transition Temperature Heating for Enhanced Interlayer Adhesion

SEIKO EPSON CORPORATION, 2021

Method for manufacturing a three-dimensional shaped object with high adhesion between layers without using solvents. The method involves shaping a first layer, cutting it, heating it to a temperature below the resin's glass transition temperature, and then shaping subsequent layers on top. The heating step increases adhesion between the layers.

4. 3D Printer Head with Nozzle-Integrated Layer Texturing Protrusions

SIGNIFY HOLDING B.V., 2019

Printing head for 3D printers that improves adhesion between layers of printed objects. The nozzle of the head includes a texturing member that protrudes from the main surface of the printed layer. These protrusions increase the contact surface area between layers, improving adhesion strength. The textured layer interfaces lock together better when subsequent layers are printed on top. The protrusions can be clamping features that grip the next layer.

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5. Method for Enhancing Interlayer Adhesion in Fused Material Extrusion via Temperature Differential Extrusion

SABIC GLOBAL TECHNOLOGIES B.V., 2018

A method to improve interlayer adhesion in 3D printed objects made by fused material extrusion, e.g., FDM. The method involves extruding adjacent layers at different temperatures. The temperature difference between layers should be at least 5°C. This sequence of alternating temperatures enhances bonding between layers to improve the overall strength of the printed object. The layers are fused together after extrusion to form the final article.

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6. Additive Manufacturing Feedstock with Removable Capsules for Interlayer Void Formation

Empire Technology Development LLC, 2017

A feedstock for additive manufacturing that enables strong interlayer bonding in 3D printed objects. The feedstock contains removable capsules that, when extracted after printing, leave voids on the surface of the solidified layer. The voids are then filled by the next layer's material, forming mechanical interlocks between layers. This provides enhanced adhesion compared to regular printing.

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7. A review of <scp>3D</scp> printing continuous carbon fiber reinforced thermoplastic polymers: Materials, processes, performance enhancement, and failure analysis

yaru zhang, wenkai zheng, yuzhong wang - Wiley, 2025

Abstract Fused filament fabrication (FFF) technology, recognized as a leading 3D printing method for the production of continuous carbon fiber reinforced thermoplastic polymer (CCFRTP) components, has garnered significant attention due to its design flexibility, independence from molds, and capability rapid prototyping complex structures. This paper presents comprehensive analysis review challenges associated with enhancing mechanical properties stemming interfacial bonding issues pore defects in 3D‐printed CCFRTP parts. Specifically, this study thoroughly examines modification techniques pertinent two critical constituents materials: resin matrix reinforcement. It also explores advancements FFF equipment specifically designed alongside current developments related impregnation processes. Furthermore, work introduces an evolution continuum path planning grounded principles structural lightweight while applying topology optimization create anisotropic The influence various process parameters on is analyzed systematically; additionally, processing strategies that incorporate auxiliar... Read More

8. Dynamic Boronate Ester Chemistry Facilitating 3D Printing Interlayer Adhesion and Modular 4D Printing of Polylactic Acid

wenjun peng, haiping xia, jingjun wu - Wiley, 2025

Abstract 3D printing, such as fused deposition modeling (FDM), is an advanced shaping technology, employing a layer‐by‐layer process to construct objects. However, the weak interlayer bonding restricts performance and functionality of FDM‐fabricated parts. Herein, boronate bond exchange utilized enhance mechanical strength enable modular 4D printing polylactic acid (PLA). Blending dynamic system endows PLA with improved adhesion welding capabilities. The blended filaments demonstrate excellent printability, 150% enhancement in Z‐axis strength, while nearly unchanged along X‐axis. Moreover, this enhanced facilitates assembly intricate structures, eliminating need for traditional 3D‐printed supports. Combined shape memory effects, diverse possibilities are demonstrated. This strategy highlights potential covalent bonds enhancing not only material but also intelligent designs.

9. Enhanced Performance 3‐D Printed PLA Parts through a Photo‐Initiator Mediated UV‐Curing

dylan jubinville, tizazu h mekonnen - Wiley, 2025

Abstract The fused deposition modeling or three‐dimensional (3D) extrusion fabrication of material parts from thermoplastics, including poly(lactic acid) (PLA) usually results in inferior mechanical performance due to weak inter‐layer bonding compared injection molded parts. In this work, a solvent‐free, effective, and inexpensive method is developed by incorporating photo‐initiators during 3D followed post‐process UV treatment improve the 3D‐printed PLA part's performance. This addresses key challenges printed parts, such as poor toughness sensitivity, while enabling its use high‐performance additive manufacturing (AM) processes. UV‐curing process enhances PLA's suitability for printing, supporting complex geometries custom designs enhancing crosslinking between adjacent chains, under exposure. solvent‐free nature aligns with sustainable manufacturing, strengthening role an eco‐friendly alternative petroleum‐based polymers. A standout result approach 64% improvement tensile properties photo‐initiator samples untreated PLA, achieved through UV‐curing. advanc... Read More

10. 3D Printer with Coordinated Dual-Head System for Integrated Hot Air Welding

GOVERNMENT OF THE UNITED STATES AS REPRESENTED BY THE SECRETARY OF THE AIR FORCE, 2025

3D printer with integrated welding capability to join 3D printed parts during printing. The printer has a movable hot air welding head in addition to the print head. The controller coordinates the movement of both heads to weld parts together as they are being printed. This allows creating complex 3D structures with joined sections made from different materials that can't be 3D printed alone. The hot air welding fuses the melted plastics together.

11. 3D Printing Method Utilizing Direct Layer Sintering with Gradually Increasing Energy Input

GENERAL ELECTRIC CO, 2025

Method for 3D printing without using a start plate by directly printing on the build platform. The method involves gradually increasing the energy level of the laser or electron beam used for powder melting as the layers are built. This allows sintering the powder without melting it, forming a strong build platform. The part is then printed on top of the sintered platform. The platform is removed after printing. This eliminates the need for a separate start plate and reduces build times.

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12. Three-Dimensional Printing Compositions with Saturated Coreactive Functional Groups for Controlled Curing and Shape Retention

PPG INDUSTRIES OHIO INC, 2025

Three-dimensional printing compositions with improved properties for additive manufacturing of objects. The compositions contain two coreactive components with functional groups that react with each other. At least one functional group in each component is saturated, without double bonds. This reduces viscosity and reaction rate compared to unsaturated functional groups. The saturated functional groups prevent excessive crosslinking during deposition, allowing better shape retention. The compositions can be used in 3D printing techniques like extrusion or inkjetting to build objects layer by layer. The saturated functional groups enable controlled curing and shape maintenance.

13. Device with Integrated Temperature Control, Pressing, and Gap Maintenance Mechanisms for Welding Dissimilar Additively-Manufactured Parts

NANJING UNIVERSITY OF AERONAUTICS AND ASTRONAUTICS, 2025

Device for heat control and accurate welding of dissimilar additively-manufactured parts. The device has a temperature control mechanism with a platform to hold the parts, cooling beneath the LMD part, heating beneath the SLM part, and protective gas spray. It also has a pressing mechanism to prevent deformation during welding. The platform moves, the pressing mechanism folds, and the heating head rotates to optimize welding quality. A supporting mechanism cleans and maintains gap between the parts during welding. This provides precise control of temperature, pressure, and gap during welding to mitigate distortion and improve joint quality in dissimilar additively-manufactured parts.

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14. Synthetic Scaffold with Mechanically and Chemically Tethered Layers for Enhanced Structural Integrity

HARVARD APPARATUS REGENERATIVE TECHNOLOGY INC, 2025

Enhancing the structural integrity of synthetic scaffolds used for tissue engineering to prevent delamination and failure during cellularization and implantation. The techniques involve tethering layers of the scaffold together mechanically and chemically during synthesis. This can be done by using gradient percentages of polymers in the fibers, incorporating support rings, and slowing electrospinning speed to place components mid-process. The tethering promotes bonding between layers and components to maintain scaffold integrity.

15. Inorganic Fiber Sizing Agent Comprising Cellulose Nanofibers and Resin with Variable Concentration

TAKEMOTO YUSHI KABUSHIKI KAISHA, 2025

Inorganic fiber sizing agent containing cellulose nanofibers and a resin to improve adhesion, falling prevention, and handling properties of fiber-reinforced composites. The sizing agent contains cellulose nanofibers in an amount of 10 ppm to 50,000 ppm by weight when applied to the fiber surface. This improves fiber-matrix adhesion by forming anchor points when the composite is cured, prevents fiber shedding, and enables smoother fiber handling compared to traditional sizing agents.

16. Laminated Body with Directly Bonded Plasma-Treated Fluorine-Based Resin and Metal Layers

OSAKA UNIVERSITY, 2025

Laminated body with high adhesion between a fluorine-based resin layer and a metal layer without using an intermediate layer. The adhesion is improved by performing a plasma treatment on the resin surface, stacking the metal directly on the treated resin, and heating/compressing without allowing the resin to expand excessively. The plasma treatment modifies the resin surface chemistry to increase adhesion. Controlling expansion prevents delamination due to resin tearing.

17. Investigation on delamination behavior of additively manufactured <scp>Kevlar</scp> and carbon composites subjected to <scp>Mode‐II</scp> loading conditions

kuldeep yadav, vikrant tiwari - Wiley, 2025

Abstract With increased design and manufacturing complexity of required components in various industries, additive composites shows great potential the production next‐generation lightweight structures. Fused filament fabrication (FFF) is one such method composite where are 3D printed by heating a material above its gel temperature depositing it on previously layers. The fabricated FFF known to be susceptible delamination owing weak interlayer adhesion. This experimental study an attempt understand underlying interlaminar phenomenon FFF‐printed end‐notched flexure (ENF) specimens subjected mode‐II loading conditions. industrial printer utilizing micro carbon fiber infused Nylon aka Onyx as base specimen material. Either Onyx, continuous fibers, or Kevlar fibers used interfacial materials for current study. In addition, ENF arms optimally reinforced with pre‐selected layers specimen. first category comprising three different interface configurations aims behavior other (Onyx//Onyx, Onyx//Kevlar, Onyx//carbon). On hand, second (Kevlar//Kevlar, carbon//carbon, Kevlar//carbon).... Read More

18. Stereolithographic Additive Manufacturing of Silicone Objects Using Photocurable Thiol-Alkenyl Silicone Composition

FORMLABS INC, 2025

Additive manufacturing of silicone objects using stereolithography (SLA) techniques. The method involves using a photocurable silicone composition with specific components like a thiol-containing silicone crosslinker, an alkenyl-containing silicone, and a photoinitiator. This allows well-defined 3D silicone objects to be printed using SLA printers, with improved properties compared to previous attempts. The thiol-ene silicone chemistry enables proper curing and avoids issues like oxygen inhibition and viscosity problems.

19. 3D Printing Device with Compression Unit for Post-Extrusion Layer Compaction

SEIKO EPSON CORP, 2025

3D printing device with improved void reduction in printed objects. It has a compression unit that applies pressure to the top layer after extrusion to compact the material and reduce voids. This prevents gaps between extrusions and between the top layer and substrate. The compression prevents voids that can weaken and anisotropize printed objects. The compression is done using a surrounding contact surface that compresses the top layer after extrusion.

20. Additive Manufacturing Powder with Alternating Reactant Coatings via Atomic or Molecular Layer Deposition

FORGE NANO INC, 2025

Additive manufacturing of metals and ceramics with improved flowability and sintering properties. The process involves coating the powder particles with alternating layers of reactants using atomic layer deposition (ALD) or molecular layer deposition (MLD). The coated particles are then used in additive manufacturing to create green parts. The ALD/MLD coatings improve green part flowability and green part sintering compared to uncoated powders. The coating thickness is around 0.2-5 nm. The coating composition can be metal oxides, metal fluorides, imides, polymers, etc. The ALD/MLD coating layers bond together during sintering to create a dense, cohesive part.

21. Enhancing <scp><i>Z</i></scp>‐direction strength of <scp>3D</scp>‐printed polylactide by embedding continuous carbon fibers

22. Polysiloxanes with Alkenyl and (Meth)acryloyl Functional Groups for Sequential Dual Curing

23. Activatable Material Comprising Polyvinyl Butyral and Thermoplastic Epoxy with Crosslinking Capability

24. Polyfunctional (Meth)acrylate Thioester Compound Derived from Polythiol for Enhanced Refractive Index and Adhesion

25. Thermoset Ink with Bismaleimide-Cyanate Ester Blend for 3D Printing via DLP and SLA

In order to achieve better inter-layer bonds in 3D printed objects, these techniques involve novel material combinations and printing processes that go beyond the initial layer formation. This opens up new applications and produces stronger printed parts.

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