Chapter J: J JSA

J

Symbol for joule. Symbol for moment of inertia.

japan

A hard, glossy, dark-colored varnish used on metallic objects. Japans are normally applied in successive applications and dried by baking in an oven at relatively high temperatures.

Japanese Standards Association

An international standards organization located at 1-24 Akasaka, 4-chome, Minato-ku, Tokyo 107, Japan. Sets the Japanese Industrial Standards (JIS) and publishes standards including metals and welding filler metals.

japanning

The process of applying a japan varnish to an object.

See also japan.

jewelry bronze

Alloys nominally containing 87.5% copper and 12.5% zinc.

jig

A work-holding device that places the workpiece in proper position and holds it securely. The jig can contain guides and hardened steel bushings for aligning, guiding, and supporting various cutting tools for drilling, reaming, tapping, etc. For comparison,

See also fixture.

jig borer

A machine (or a task of NC machining centers) for accurately locating, aligning, and boring hole in jigs, fixtures, dies, for centering, drilling, step boring, counterboring reaming, contouring, etc.

JIS

Abbreviation for Japanese Industrial Standards.

JIT

Abbreviation for just-in-time as in just-in-time manufacturing.

Jo blocks

Short for Johansson Gage blocks invented in 1895 by Carl E. Johansson in Sweden. Precision blocks made from hardened steel or other hard material. Considered the universal standard of precision measurement for science and industry throughout the world, they provide practical standards for measuring accurately in millionths of an inch, an impossible feat prior to their availability.

joggle

An offset surface consisting of two adjacent,...