Chapter B: B BZN

B

B

Symbol for the element boron.

Ba

Symbol for the element barium.

Babbit metal

A general term for a group of soft alloys widely used as cast, machined, or preformed bimetallic bearings in the form of a thin coating on a steel base. The main types contain antimony, lead, lead-silver, lead-bronze, cadmium, tin, or arsenic, and small percentages of copper and bismuth. High grade alloys consist of tin, copper and antimony; low grade alloy is made from lead, copper, and antimony. Trade names include Bearite , Bearium . Discovered in 1839 by Isaac Babbitt, a Boston goldsmith, they have good bonding characteristics with the substrate metal, maintain oil films on their surfaces, and are nonseizing and antifriction.

See also arsenical lead babbitt.

back, file

The convex side of a file having the same or similar cross-section as a half-round file.

backlash

(1) Wear in gear, screw mechanism, or other moving parts that can result in lost motion, slippage, or end play causing vibration; (2) a possibly dangerous reaction involving the sudden release of potential energy of a body in motion when the body stops, usually causing the body to quickly reverse directions. Down milling on milling machines require a backlash eliminator.

back rest

In turning and grinding, a tool used to support slender work.

back taper

The slight decrease in diameter from point to back in the body of the drill.

bactericides

Pesticides or chemical agents that are destructive to bacteria and used to retard...