Manufacturability of A20X printed lattice heat sinks

At a Glance

Metadata	Details
Publication Date	2024-12-20
Journal	Progress in Additive Manufacturing
Authors	Ganesh Chouhan, Prveen Bidare
Institutions	Sheffield Hallam University
Citations	4
Analysis	Full AI Review Included

Executive Summary

This research investigates the manufacturability and surface quality of compact Triply Periodic Minimal Surface (TPMS) lattice heat sinks fabricated from A20X aluminum alloy using Laser Powder Bed Fusion (LPBF).

Material and Method: A20X aluminum-copper alloy (enhanced with TiB₂ doping) was successfully printed using optimized LPBF parameters (200 W laser power, 88 J/mm³ energy density) to create intricate lattice structures within a compact 15 x 15 x 15 mm³ volume.
High Density Achieved: All printed heat sinks demonstrated excellent material quality, achieving a relative density exceeding 99.5%. The highest density recorded was approximately 99.7% (Diamond UC-10).
Superior Surface Area (SA): TPMS designs significantly outperformed conventional pin fin heat sinks (SA: 2344.94 mm²). The best TPMS designs (Unit Cell 5 group) achieved surface areas nearly double that of the conventional design.
Optimal Design for SA: The Split P lattice structure with a 5 mm unit cell (UC-5) yielded the largest surface area (5698.24 mm²). Cylindrical varying periodicity designs (CSUC) consistently showed higher SA than their uniform unit cell counterparts.
Surface Roughness: The Diamond lattice (UC-10) exhibited the smoothest surface (Ra: 0.3672 µm, Minimally rough). Seven out of the fourteen designs achieved Moderately rough surfaces (Ra 1.0-2.0 µm), suitable for thermal applications.
Manufacturability Defects: Common LPBF defects observed via SEM included partially melted particles, stair-case effects, balling, and dimensional inaccuracies, particularly on external hanging surfaces and boundary walls.

Technical Specifications

Parameter	Value	Unit	Context
Design Volume	15 x 15 x 15	mm³	Fixed volume for all heat sinks
Lattice Thickness	1	mm	Constant thickness of lattice struts
Base Thickness	2	mm	Constant thickness of heat sink base
Relative Density (Min)	> 99.5	%	Minimum density across all samples
Alloy Density	2.85	g/cm³	Density of A20X aluminum alloy
Tensile Strength (A20X)	~400	MPa	High strength characteristic of A20X
Laser Power	200	W	LPBF optimal process parameter
Scan Speed	1450	mm/s	LPBF optimal process parameter
Layer Thickness	30	µm	LPBF optimal process parameter
Energy Density	88	J/mm³	LPBF optimal process parameter
Powder Size Range	20-60	µm	Spherical, gas-atomized A20X powder
Largest Surface Area (SA)	5698.24	mm²	Split P (UC-5) lattice structure
Smoothest Roughness (Ra)	0.3672	µm	Diamond (UC-10) lattice structure
Rougest Roughness (Ra)	3.2294	µm	Schwarz P (UC-5) lattice structure
Roughness Target (Ideal)	1.0-2.0	µm	Moderately rough (achieved by 7/14 designs)

Key Methodologies

The study utilized a combination of additive manufacturing and advanced characterization techniques to assess the manufacturability of the TPMS heat sinks.

Design Generation: Five distinct TPMS lattice structures (Gyroid, Diamond, Lidinoid, Schwarz P, Split P) were designed using nTopology implicit modeling software, incorporating two unit cell sizes (5 mm and 10 mm) and cylindrical varying periodicity designs for comparison.
Additive Manufacturing (LPBF): Fabrication was performed using a Concept Laser M2 system in an Argon atmosphere (O₂ content maintained at 0.1%).
- Material: Spherical, gas-atomized A20X aluminum-copper alloy powder.
- Optimal Parameters: Laser power 200 W, scan speed 1450 mm/s, hatch spacing 52.5 µm, and layer thickness 30 µm.
- Build Orientation: All samples were printed with a 90-degree build orientation.
Relative Density Measurement: Samples were cut from the center, and micrographs were analyzed using ImageJ software to determine the percentage of defects (voids/porosity).
Surface Topography Analysis (Roughness): A high-resolution Alicona InfiniteFocus [IF-G4] optical profile meter was used for non-contact 3D surface mapping.
- Parameters Measured: Arithmetic mean deviation (Ra), root mean square roughness (Rq), and maximum height of the profile (Rz).
- Measurements: Three measurements were taken per sample, resulting in over 42 total measurements.
Microstructural Examination (Morphology): Surface morphology and defect analysis were conducted using a Jeol JSM-6060 Scanning Electron Microscope (SEM) equipped with an Oxford Inca energy-dispersive X-ray spectroscopy (EDX) system.

Commercial Applications

The successful fabrication of high-density, high-surface-area TPMS heat sinks from A20X alloy via LPBF is highly relevant to industries requiring lightweight, high-performance thermal management solutions.

Aerospace and Defense: A20X is a high-strength, low-density alloy ideal for lightweight, durable components. TPMS structures are critical for optimizing heat exchangers and structural components in aircraft and satellites.
Electronics Cooling: The compact size (15 mm cube) and significantly increased surface area (up to 2x conventional pin fins) make these lattices ideal for thermal management systems in modern, high-power electronic devices (e.g., laptops, compact servers, high-performance computing).
Automotive Industry: Utilization of lightweight A20X alloy for heat sinks and heat exchangers improves fuel efficiency and performance in electric and conventional vehicles.
Advanced Heat Exchangers: TPMS lattice structures, due to their architected, interconnected pore space and high surface area-to-volume ratio, are superior core structures for compact heat exchangers in various industrial processes.
Additive Manufacturing Optimization: The study provides critical data on the manufacturability of complex geometries (TPMS) using LPBF, guiding design rules for future additive manufacturing applications requiring high fidelity and minimal surface roughness.

Tech Support

Original Source

DOI: https://doi.org/10.1007/s40964-024-00923-3