Home / News & Blog / Abrasive Blog / Physical Properties of Abrasive Grains
1. Hardness: Resistant ability of abrasives when a compressive force is applied. Hardness are classified into scratch hardness and indentation hardness based on different modes of compressive force. Moh’s hardness belongs to the former, and knoop hardness to the latter. Generally, the higher the major chemical composition content in abrasives, the higher the hardness. Impurities affect abrasives’ hardness, which usually decreases with the increase in impurity content. However, hardness will get improved by right scope of TiO2in corundum.
2. Intensity: the material’s ability to withstand external load while resisting permanent deformation and fracture . It is an important indicator to measure carrying capacity of abrasives.
3. Toughness: resistant ability to fracture when grinding. Generally speaking，certain toughness can ensure abrasives products’ service life. The higher the toughness, the more unit grinding amount of metal. But excessive toughness of abrasives will affect their self-sharpening. The abrasive grains made by DOMILLadopts calcined treatment to improve abrasives’ toughness, bridge surface flaws, and increase tension during crushing process.
4. Bulk density: It is defined as the mass of many particles of the material divided by the total volume they occupy. The unit is g/cm3。 Different application has different requirement for abrasives’ bulk density. Coated abrasives use abrasive grains with lower bulk density, while bonded abrasives require abrasive grains with higher bulk density.
5. Particle density: the content of abrasives in per unit volume (the volume of open pores excluded). Unit i g/cm3. Particle density is an important index reflecting crystallinity and purity of abrasives. The particle density of corundum abrasive is usually within the range of 3.90 ~ 4.00 g/cm3, and it may fluctuates slightly with changes in particle sizes. Particle density refers to density without open pores, but including closed pores.
6. Particle shape: abrasives processed by roller dressing and processing method is sharp and pointed; Barmac processing method makes abrasivesblocky; When abrasives are processed by ball milling, they take on angular shapes. Different shapes of abrasives have different functions. Blocky particles are used for bonded abrasives while angular particles are suitable for coated abrasives.
7. Self-sharpening: the performance of abrasives products to maintain cutting capacity when new cutting edges are formed or passive abrasive grains fall off from bonding agents during grinding process. Excellent self-sharpening and high grinding efficiency result in faster wear of products.
8. Friability: generally, abrasives with small friability are mainly used for grinding large removal amount, such as snagging, cutting off, coping, etc., while abrasives with big friability are suitable for precision grinding and finishing grinding.
9. Thermal stability: the deformability of abrasive grains under influence of temperature; i.e. the performance of decomposition after materials go through drastic changes in temperature. The smaller the decomposition, the high the stability.
10. Thermal conductivity: the heat passing through per vertical unit area in unit interval under unit temperature gradient. λ=W/M.S.K (joule/meter.second.k)
11. Compressive strength: loading value of a single grain fracture under hydrostatic action. Unit: N. Measured by arithmetic average value of maximum vertical pressure(fracture pressure) that basic grains can withstand.
12. Specific surface area: the total surface area of abrasive grains per unit of mass, its unit is ㎡/g.
13. Loose abrasive: abrasive grains that can be used to grind or polish under loose state.
14. Fine powder sizing: frequently used sizing method of brown fused alumina are dry sizing and water sizing. The former includes sieving method and method of airflow; while the latter consists of flow-through and sedimentation.
