An angle grinder, also known as a side grinder or disc grinder, is a handheld power tool used for grinding (abrasive cutting) and polishing. Although developed originally as tools for rigid abrasive discs, the availability of an interchangeable power source has encouraged their use with a wide variety of cutters and attachments. Angle grinders are standard equipment in many metal fabrication shops and on construction sites. They are also common in machine shops, along with die grinders and bench grinders.
Angle grinders typically have an adjustable guard and a side-handle for two-handed operation. Certain angle grinders, depending on their speed range, can be used as sanders, employing a sanding disc with a backing pad or disc. The backing system is important to prevent the disk from breaking during use. Some manufacturers sell products specifically marketed as right-angle Sanders; these may be either electric or pneumatic.
The 115mm refers to the diameter of the grinding disk which is mounted on the end of the grinder spindle. There are many different types and sizes of grinding disks available but the most popular size for general purpose grinding is 115mm in diameter with a 22mm hole in the centre which fits onto the spindle of most commonly available angle grinders.
The vast majority of 115mm grinding disks are made from aluminium oxide which is suitable for most metals including steel but not stainless steel or titanium. For these materials you need to use silicon carbide disks instead which are more expensive but will last much longer when used on stainless steel or titanium.. Aluminium oxide disks are usually white in colour while silicon carbide disks are usually black or greenish-black .
When choosing a new grinding disk always make sure that it is compatible with your particular model of angle grinder by checking the maximum speed rating printed on both the disk and your angle grinder . If in doubt always go for a lower speed rated disk as using one