1. What are cutting discs?
Cuttings disc are expendable tools used on angle grinders or stationary devices for cutting a variety of materials - from metal alloys (steel, stainless steel, aluminum), to wood, stone, concrete and other materials. They are round, thin and flat panels, like CD or DVD. They are basically divided into classical cutting discs using a synthetic resin as a binder and diamond discs.
They were invented because sometimes it was impossible to cut particular material or the procedure was too demanding regarding time or costs. Cutting discs on angle grinders allowed great mobility, ease of use and availability.
2. How are the cutting discs used?
Cutting discs are used by being installed on the angle grinder or a stationary device and then cutting required material like steel pipes, stainless steel rods, aluminum profiles, etc.
Unlike cutting with knife or scissors, in which case the cut parts connected together again obtain full length, cutting with cutting disc causes a reduction in the total length of the product. This happens because the cutting with discs actually removes material from a particular point to make a hole that will separate the product in pieces of desired length. If we take a thin hand sander and abrade the same place numerous time, we would get the same result. It means that cutting process is actualy extremely fast honing of material (several thousand revolutions per minute) on a very small area (0.8 to 3 mm).
It is important to note that this method of cutting creates a lot of friction that develops high temperature at the point of cutting and can lead to undesirable changes in structure and colors. In order to prevent this, it is advisable to use the disc as thin as possible, and cut carefully so the product wouldn't get warmed up.
3. Classic cutting discs with synthetic resin
In metal industry, cutting discs which are mostly used are the classic ones with synthetic resin as a binder. They are divided according to their purpose, so we distinguish between discs for cutting steel, stainless steel, aluminum, and stone.
They consist mainly of the following components:
steel ring - which enables firm and safe installing to the machine
label - contains all the important information related to the cutting disc
safety net - fiberglass net which prevents cracking of disc
cutting mixture - a mixture of corundum, binder and other materials
safety net - two safety nets is the standard for safety today
A cutting mixture is mostly made of aluminum oxide Al2O3, silicon carbide (SiC), and other special minerals.
4. Diamond cutting discs
Diamond discs are a completely different story. Their production technology, using diamonds, and the way of using discs makes them much more expensive than classic cutting discs.. It is clear that these are not discs completely made of diamonds, but they have cutting edge covered with a thin layer of diamond grains.
Diamond cutting discs were mainly used for cutting stone, concrete, reinforced concrete and asphalt, but with the development of technology they price became more available so they are used also for cutting ceramic, steel, stainless steel, plastic, etc ...
5. The influence of disc thickness on cutting
The thickness of disc has a crucial impact on speed and quality of cutting. In theory, you can also cut some material with grinding disc. The only question is how much power, time and material will you spend. (In the ideal case where angle grinder will not bounce or move to the left to the right during cutting).
The thinner disc is, the cutting is quicker and more accurate, less material is being used, likelihood of sparking is less and considerably lower temperatures are developed. Thickness of 3.00 mm was the standard for years. It was thick enough to withstand safety requirements and lateral straining, but also being thin enough for reasonable cutting. Since the standard grinding discs where manufactured in thickness from 6.00 to 12.00 mm, thickness of 3.00 mm for cutting disc proved to be ideal former production capabilities.
As technology of abrasives progressed, innovation began, so the thickness of cutting discs decreased to 2.5 mm, 1.9 (1.8) mm, 1.5 mm, 1 mm and 0.8 mm. Today, all discs produced by the leading European and world manufacturers are safe for use in any thickness, and there is no reason for the mistrust that still exists towards thin cutting discs. Two protective safety nets are minimum prescribed by European and world standards, but some manufacturers made a step further by producing discs with three safety nets..
The advantages of thin cutting discs (1.00 mm thick) as compared to the classic (3.00 mm thick)
- wearing off less material
- cut thickness from 1.05 to 1.3 mm versus 3.15 to 3.50 mm
- less vibrating
- less heating of material
- less sparks
- producing less odor
- faster cutting - higher productivity
- the worker does not need to use a lot of strength when cutting
- easier to control cutting
The advantages of the classic cutting blades (3.00 mm thick) as compared to thin cutting discs (1.00 mm thick)
- slightly longer lifetime (depending on the manufacturer)
- lower price
Lower prices of thicker dicss can depend on local factors - and these are primarily market requirements and policies of local suppliers. On the European market there is no difference between the price of thinner and thicker discs. If there is difference, it is in favor of thinner discs, which is logical as it is less material needed to produce it. Therefore, if someone wants to sell you thiner cutting discs at higher price - it is time to change the supplier.
The difference of 2 millimeters per cut it doesn't seem a lot at the first sight. But if someone makes 250-500 cuts a day, 200 days a year, you get a calculation that between 100 to 200 meters of pipes, profiles, rods, sheets of steel, stainless steel etc. per year is literally turned to dust.
6. Safety of cutting discs
Because of the strong centrifugal forces, discs must be manufactured according to strict safety requirements prescribed in standards EN 12413 - Safety requirements for bonded abrasive products and EN 13236 Safety requirements for superabrasives. Besides, leading manufacturers meet the additional requirements prescribed by the Organization for the safety of abrasives – OSA.
When working with cutting discs we should pay particular attention to handling them. Do not throw them or drop something on them. They are designed for maximum possible safety during operation, however, they are not indestructible. Before use a disc should be inspected visually for any cracks or chips. The cutting discs are spinning at the speed of 80 m / s, or little slower than the average speed of F1 cars. At that speed, each chip can cause serious life-threatening injuries.
We shouldn't kid ourselves - as in everything else, there are high-quality products and the ones of low quality. Lower price cutting discs is usually a consequence of worse contexture. The result can be rapid wearing of the discs, low quality of cut, difficult controlling, odors, increased sparking. Unfortunately, the safety of the disc itself is sometimes questionable. Cases where the disc bursted during work are not uncommon.
As with any other product, the balance should be found between the price and the quality. Joining the European Union, employers are obliged to provide safe working environment and safe tools for their employees.
7. Durability and quality of cutting disc
All cutting discs have their durability, so each manufacturer is obliged to print year when validity ends, clearly and indelibly on the cutting disc. It can vary from one up to the maximum of 3 years. It is not recommended to use cutting disc after the expiration date.
As for the quality of cutting disc, it is a very sensitive subject. There are various manufacturers, as well as different product lines of the same manufacturers with big differences in their prices and performance. Also some reputable manufacturers supply their cheapest lines from China – either they have a separate business units or some other companies work on their behalf. So be careful when you're buying discs and take enough time for proper testing. Good test could ultimately save you a lot of money and time.
It is important to know that nowadays, tools and technology are changing almost daily. You must have a time and a will to test new products on the market every few years.