Increase Inter-Layer Bonding in 3D Printed Parts
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.
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.
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.
7. 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.
8. 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.
9. 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.
10. 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.
11. 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.
12. 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.
13. 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.
14. 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.
15. 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.
16. 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.
17. Polysiloxanes with Alkenyl and (Meth)acryloyl Functional Groups for Sequential Dual Curing
SAINT-GOBAIN PERFORMANCE PLASTICS CORP, 2025
Polysiloxanes with dual curability for 3D printing of silicone parts with improved properties. The polysiloxanes have both alkenyl and (meth)acryloyl functional groups. This allows sequential curing: UV-initiated polymerization of the (meth)acryloyl groups followed by thermal polymerization of the alkenyl groups. The sequential curing provides a resolved, isotropic material with improved mechanical properties compared to simultaneous curing of both groups.
18. Activatable Material Comprising Polyvinyl Butyral and Thermoplastic Epoxy with Crosslinking Capability
ZEPHYROS INC, 2025
Activatable material for baffling, adhering, and reinforcing components of articles like vehicles. The material has improved properties like high tensile modulus, strain to failure, and adhesion durability compared to existing materials. It contains polyvinyl butyral, a thermoplastic epoxy, carboxyl-terminated polymer adduct, and optionally other components like polymeric particles, mineral reinforcement, and epoxy resin. The material activates at higher temperatures to form a crosslinked network with improved mechanical properties when heated or exposed to certain conditions.
19. Polyfunctional (Meth)acrylate Thioester Compound Derived from Polythiol for Enhanced Refractive Index and Adhesion
MITSUI CHEMICALS INC, 2025
Composition, curable composition, cured product, molded body, and optical material with improved balance of refractive index, shrinkage, and glass adhesiveness. The key is using a specific polyfunctional (meth)acrylate thioester compound in the composition. This compound is made by converting thiol groups in a polythiol compound to a functional group and subjecting it to a β-elimination reaction. This results in a polyfunctional (meth)acrylate thioester compound that provides better refractive index, shrinkage, and adhesion when cured compared to other thioester compounds. The composition can contain a silane coupling agent, antioxidant, and light stabilizer.
20. Thermoset Ink with Bismaleimide-Cyanate Ester Blend for 3D Printing via DLP and SLA
NOGA 3D INNOVATIONS LTD, 2025
High-performance thermoset ink for 3D printing using digital light processing (DLP) and stereolithography (SLA) techniques. The ink contains a bismaleimide-cyanate ester blend that allows 3D printing of thermoset materials with excellent mechanical, thermal, and chemical properties. The bismaleimide provides crosslinking and the cyanate ester acts as a reactive diluent. The bismaleimide-cyanate ester blend enables 3D printing of thermosets with high retention of physical properties like strength and ductility.
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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