Ceramic, Zirconia, Silicon Carbide, Aluminium Oxide Abrasive… Why?…
The world of abrasives can be ever so confusing. What happened to sandpaper?
Abrasives have been a part of our working life since the stone ages when a bit of sand was used to grind, flatten and smooth working surfaces and for many centuries animal skins were used for honing and sharpening knives and swords. Naturally available abrasives that have been used over the centuries include emery, garnet, walnut shell and even talc but today almost all abrasives used in the industrial world today may have begun as a naturally occuring ore but have been refined, hardened and purified to optimise their finishing characteristics.
The four main abrasive grains used today are:
Aluminium Oxide: A naturally occuring mineral which is refined in a refractory process to create a solid tough and blocky shaped abrasive. Through the refractory process several grades of aluminum oxide are made available, brown, pink and white being the most common.
White aluminium oxide is the most pure, it is also the toughest and most hard wearing. White aluminium oxide cuts well in hard wearing metal working applications and is used in products such as our JF4top material. JF4top is excellent for use on stainless steel finishing applications.
Pink aluminium oxide is a good general purpose aluminium oxide abrasive and is used in premium wood working products such as the KP947 paper wide belt products.
Brown aluminum oxide products would include products such as little bit softer and tends to be used in hand held applications such as our TF41 ’emery rolls’.
Zirconium Oxide (also called Zirconia): Significantly tougher than pink and brown aluminium oxide abrasives which makes zirconia grain well suited to high pressure machining and grinding applications. Zirconia grain also has a good heat resistance. Zirconia abrasives work best in the grit range 24 to 120 grit
Zirconia abrasives are commonly used in general steel fabrication shops where they have become the abrasive belt and disc of choice for the grinding and finishing of steel, they are also commonly used in stainless steel applications however some of the new ceramic abrasive products supplied by AFS are revolutionising metal grinding applications.
Although zirconia is tougher than aluminium oxide it will struggle to effectively grind mill scale.
Ceramic Grit Abrasives: Ceramic abrasives have a micro-crystalline habit and are more uniform in their structure than either aluminium oxide or zirconia abrasives. This micro-crystalline habit means they are able to breakdown in a controlled manner extending the range of available applications.
Strange as it may seen our new FX ceramic abrasives are proving to be revolutionary on aluminium castings, on mild steel mill scale, on stainless steel finishing and on a lot of the titanium alloys commonly used in aerospace applications.
It is important to note however that ceramic abrasives are particularly sensitive to heat and pressure which means that a correctly engineered process is essential to their successful use.
Silicon Carbide Abrasives: The natural mineral form of silicon carbide is long, thin and very sharp, so when thinking about silicon carbide abrasives think of a belt or disc covered in thousands of tiny but very sharp knives.
So why are silicon carbide abrasives not used everywhere? Because although they may be very sharp they are also more friable than the other main abrasive grits which means that they can break down more quickly.
All this means that silicon carbide abrasives are great when you need a clean bright cut (such as with our Tex Med S hand pad for graining stainless steel) or for cutting back laquers, or for polishing stone, but not very effective under high pressure grinding applications.