Intersecting Surfaces and Burrs
Wherever inside surfaces intersect, burrs are often produced as indicated by the arrows in the top half of the part shown in Figure 1.
If these burrs will interfere with the use of the part, they can be eliminated by specifying a corner break or radius as shown in the lower half of Figure 1.
A radius of .005″ maximum produces a corner sharp enough for nearly all applications, such as at ”A”, a sealing seat, but is somewhat more expensive to produce. A chamfer in the .015″ range is a more common practice.
Burrs at the intersection of a cross drilled hole and a center hole are often removed by the reamer which is used to “size” the hole. Burrs which will not interfere with the use of the component and those which have to be removed should both be covered by a note. Unless absolutely necessary, a note to “Remove All Burrs” is wasteful.
Cutting off a drilled part often turns a burr at “B” as shown in Figure 2A. An inside chamfer at the cutoff end (See Figure 2B) minimizes the cutoff burr and rarely interferes with the use of the part. A drilled hole can be chamfered from the inside, and the resulting cutoff burr at “C” in Figure 2C rarely interferes with the use of the piece.