Abrasive media development

As part of my doctoral research, I developed an entirely new polymer-based abrasive medium tailored for the Abrasive Flow Finishing (AFF) of metal additive manufactured components. The objective was to design a medium that is eco-friendly, economical, rheologically tunable, and capable of delivering high-quality finishing while overcoming the limitations of commercial AFF media.

The developed medium is based on a galactomannan polysaccharide carrier, a glycerol-based solvent, a borate cross-linked network, and silicon carbide abrasive particles. These ingredients form a three-dimensional polymer network that firmly holds abrasive particles and transmits controlled shear forces required for uniform material removal.

Extensive characterization confirmed the medium’s robustness and suitability for AFF:

• Rheology: The medium exhibits shear-thinning behaviour, meaning its viscosity decreases with increasing shear rate. This is essential for stable flow inside AFF fixtures and effective shearing of AM surface asperities.

• Morphology: SEM images showed a dense, pore-free structure with excellent adhesion between the polymer matrix and abrasive particles — ensuring consistent cutting action without cracking or separation.

• Chemical Stability: FTIR analysis confirmed strong cross-linking interactions between the polymer and the borate cross-linker, which enhances the mechanical strength and elasticity of the medium.

• Thermal Stability: TGA results demonstrated that the medium maintains its structural integrity at operational temperatures significantly better than comparable hydrogel-based media, with considerably lower weight loss during heating. 

The developed medium was produced in multiple viscosity grades, enabling optimization for different types of geometries:

• Higher viscosity: better for deep defect removal and stronger shearing action.

• Lower viscosity: useful for penetrating internal, narrow, or complex channels.

Overall, this abrasive medium provides a biodegradable, cost-effective, and customizable alternative to commercial AFF media, with performance validated across different metal AM components. It offers a scalable solution for industries seeking improved surface integrity, reduced post-processing cost, and greater control over finishing behaviour.