Straight answers to the questions people ask most when choosing and using thin cutting discs and grinding discs for steel and stainless steel.
What is a slitting disc and what thickness should I choose?
A slitting disc is a thin cutting disc, used on an angle grinder to cut steel, stainless steel and other metals. Because it is thin, it cuts quickly, makes a narrow cut, wastes little material and generates less heat.
Thinner discs cut faster and cleaner, while thicker discs are more durable and resist side loads better. Choose the thinnest disc that suits the job and your level of control, and follow the manufacturer's instructions.
Why must a cutting disc for stainless steel be suitable for stainless?
Ordinary discs can leave iron, sulphur or chlorine behind on stainless steel, which can lead to rust spots and a loss of corrosion resistance. Discs made for stainless are made with very low levels of these contaminants.
If the job needs the stainless to stay clean, use a disc labelled for stainless steel only on stainless and do not use it on carbon steel.
How do I make a straight, clean cut?
Mark the line, clamp the work securely so it cannot move or close up on the disc, and start the grinder before you touch the work. Feed the disc into the work in line with its plane, with light, steady pressure, and let the disc cut at its own speed.
Keep the guard in position, and keep your body out of the line of the disc and sparks. A well supported, clamped job gives straighter cuts with less effort.
Can I twist or lever a thin cutting disc in the cut?
No. A thin cutting disc is designed to be loaded along its own plane, not sideways. Twisting, levering or bending it in the cut can make it jam or shatter, and fragments can cause serious injury.
If you need to change direction, withdraw the disc and start a new cut, or use a different tool. Do not use a thin cutting disc for grinding on its face or side. Check the label on the disc and the manual for your grinder to confirm what the disc is intended for.
What causes a cutting disc to break or shatter?
Common causes include side loading, pinching or jamming in the cut, dropping or damaging the disc, running it faster than its rated speed, using the wrong flanges, and using it after it has expired or been stored badly.
Inspect each disc before you fit it, use the correct guard and flanges, keep the cut unobstructed and wear eye and face protection. If a disc has been dropped or looks damaged, discard it.
What personal protective equipment is needed for cutting and grinding?
Wear eye protection with a full face shield, hearing protection, gloves, and clothing that covers your skin and will not catch fire easily. Sparks, dust and fragments can all be hazardous, and you may need a respirator when cutting some materials or in poorly ventilated places.
Your own risk assessment and the tool and disc makers' instructions set out what you must wear. Keep sparks away from flammable material.