EFFECT OF PEG AND PVA BINDERS ON THE CNC MILLING OF HYDROXYAPATITE FOR BIOMEDICAL APPLICATIONS

Abstract

Hydroxyapatite (HAP) is widely used in biomedical and dental applications due to its unique properties. However, the machining process is important in giving attention to parameter materials and machines to produce a near-net shape for those implants with appropriate surface roughness. It is a challenge due to their high brittleness and hardness. In this context, understanding machining parameters and sample preparation is an essential factor in producing machinable HAP. In the present study, powder compaction with different binder content has been used to produce a sample for machining. This research prepares a sample by dry mixing, pressing, and sintering. HAP powder is granulated with water-soluble binders, Polyethylene Glycol (PEG), and Polyvinyl Alcohol (PVA) in amounts ranging from 1% to 4% by weight. PEG, as a soft binder, contributes to compaction, and PVA, as a hard binder, contributes to green strength. A CNC milling machine with an end mill cutter and constant parameters is used for machining. The samples were characterized using X-ray Diffraction (XRD) for phase identification, Scanning Electron Microscopy (SEM) for morphology, and a Surface Roughness Tester for surface roughness. XRD analysis shows that HAP with different binder ratios did not change the HAP structure. SEM analysis shows that different binder percentages create different surface properties, such as pore size and surface finish. HAP mixed with 4% PEG and 1% PVA (PEG4 PVA1) has a smooth surface finish after milling with a surface roughness (Ra) of 0.988 μm. Based on the machining outcome, it shows that a combination of binder and parameter machine can alter the surface finish and geometrical accuracy for biomedical applications.