THE FLAT-BOTTOM HOLE (FBH)

BH FLAT BOTTOM HOLES

Definition:

The flat-bottom hole (FBH) is machined to have a flat reflecting surface at the hole bottom. Flat bottom holes are similar to counter bores but do not include a center drill. These holes are designed to drill flat bottom blind holes for European-style hinges, etc. Flat bottom boring bits are also used for drilling large diameter thru-holes without the plug that is typical when using a hole saw.

SIDE-DRILLED HOLE - SDH

Definition:

The side-drilled hole (SDH) is typically a drilled hole, the side wall of which is used as the reflecting surface. Unlike the FBH, the bottom of a SDH serves no purpose. SDHs are often reamed after initial drilling. SDHs are often drilled in pipe walls at specified locations from the diameter, e.g.: 1/4T, 1/2T, and 3/4T. They can be drilled either longitudinally or circumferentially to the axis of the pipe. They can also be machined in plate, bar or other products. Primary use is Ultrasonic testing. Available in diameters from .010".

MICRO-SIZED HOLE

Definition:

The micro-sized hole (MSH) is a small diameter hole used primarily in Liquid Penetrant inspection. Hole diameter is normally 0.004 to 0.005", and hole depth is 0.008 to 0.010". These micro-sized holes meet the requirements of the U.S. Navy's NSTR-99 Rev. 2 (Qualification Examination Requirements for Nondestructive Test Personnel). They can be machined in welded plate, pipe, bolts, or any test prop. Also available in diameters and depths other than stated above.

CONCAVE RADIUS-BOTTOM HOLE

Definition:

The concave radius-bottom hole is machined with a concave radius at the hole bottom. Applications include ID pitting of tube or pipe for Eddy Current Inspection; and Liquid Penetrant test props. Available in diameters from 0.004".

CONVEX RADIUS-BOTTOM HOLE

Definition:

The convex radius-bottom hole is machined with a convex radius at the hole bottom. Available in diameters from 0.030".

IRREGULARLY-SHAPED PITS

Definition:

These holes and pits are machined in irregular configurations, not described above. Includes star-shaped, square holes, hex holes, and realistic pits. EDM pit electrodes can be cast from real pits and used to reproduce actual pits very accurately.