Effect of PMMA pore former on mechanical strength and performance of glass fibre metal-bonded porous diamond blocks with Cu–Sn–Ti solder alloys

To develop a metal-bonded diamond tool that does not require frequent dressing during grinding, a novel glass fibre metal-bonded porous diamond block is proposed. The effect of the content percentage and particle size of polymethyl methacrylate (PMMA) pore formers on the porosity of porous diamond blocks was investigated. The Vickers hardness and bending strength of the porous blocks with and without diamonds were tested. Wear tests were performed on the porous diamond blocks. The results show that an increase in the PMMA content (1.75–9.45 wt%) caused an increase in the porosity (2.8 %–22.9 %) and a decrease in the bending strength (8.6 %–71.9 %) and Vickers hardness (22.1 %–54.3 %), compared to those of the blocks without PMMA. An increase of PMMA size (20–40 μm diameter) caused an increase in the porosity (2 %–11.6 %), and a decrease in the bending strength (34.1 %–42.7 %) and Vickers hardness (23.7 %, 40.5 %), compared to those of the blocks without PMMA. However, excessively large PMMA particles (50–70 μm diameter) caused a decrease in the porosity and an increase in the bending strength and Vickers hardness. Increasing the porosity of the diamond blocks appropriately can reduce the need for frequent dressing and enhance the SiC removal rate. However, excessive porosity tends to accelerate diamond wear, leading to a decrease in the SiC removal rate.