A chamfer is a small oblique surface, most often inclined at 45°, that replaces the sharp edge between two faces. It differs from a fillet or radius, which is a rounding. It is dimensioned by its two sides or by one side and an angle: “1 × 45°” denotes a chamfer 1 mm on a side, inclined at 45°.
It is produced on a lathe or by milling with a conical cutter or chamfering tool, which can also break the edges of a hole. A countersink, made to seat a countersunk-head screw, is a conical chamfer at the mouth of a drilled hole. In sheet and plate work the word has a second meaning: the weld bevel is the preparation of the edges of the parts, V or X shaped, that allows full weld penetration; it is made when cutting, often by plasma, or on a bevelling machine. MIG-MAG welding requires this preparation on thick sections.
A chamfer has several functions. It removes cutting edges and protects hands. It guides a shaft into a bore or a screw into a tapped hole. It prevents chipping and crack initiation on sharp edges, and it improves coating adhesion: paint or powder coating thins out on a sharp edge and protects poorly against corrosion. A chamfer or radius shown on the drawing also acts as a deburring instruction. When machined, it falls under the CNC machining capability; when prepared for welding, under welding and plate fabrication.
In a quote request. Dimension the functional chamfers (size and angle) and add a general note for the other edges, for example “edges broken 0.3 mm”. If the drawing refers to ISO 2768, it also provides tolerances for chamfers and edge radii: the ISO 2768 tool helps you read the tolerance classes.