McGuire Glossary of Fastener Terminology

B - 20 terms

BACK FACE - In screw machine work, to face the back or cutoff end of a part after it has been cutoff while the work piece is held in the pickoff collet.

BACK WORK - General term applied to any operation done in the scree machine after the part has been cut off and is being held in the pick-off collet.

BARREL - Long cylindrical portion of a fastener. Most commonly used in reference to a cylindrical portion of a standoff. Also applied to the cylindrical portion of the type FE and PL locknuts. Sometimes applied to the cylindrical portion of Type B nuts

BELLEVILLE - Deliver the highest load capacity of all the spring washers and are very common in thermal expansion applications.

BENDING - Exactly as it sounds, bending is the process of twisting and flexing sheet metal or rod in a desired shape. Typically, pieces are bent around one axis into L-,U-, or V-shaped forms

BLACK OXIDE OR BLACKENING - A conversion coating for ferrous mateerials, stainless steel , copper and copper-based alloys, zinc, powdered metals, and silver solder. It is used to add mild corrosion resistance, for appearance and to minmize light reflection.

BLANK - A stud that has been headed but has not yet been thread rolled. A defective condition in which a part is supposed to contain a thread, but does not contain a thread.

BLANK DIAMETER - Sometimes referred to as the before rolled diameter. The diameter of the pin portion of a headed stud onto which threads will be rolled.

BLANKING - Blanking involves cutting pieces out of a piece of sheet metal using a die. It creates clean components, or blanks, that can undergo further processing by the stamping press or other machinery.

BLIND THREADED INSERT - Applies to an internal thread that does not go all the way through the product.

BLOW UP - A term used in screw machine work to indicate a change in external dimensions which occurs in thin wall parts when they are tapped.

BLOW-OUT (MOUNTING HOLE) - Panel material sheared away during a hole punch operation causing the die side of the panel to exhibit a larger diameter hole than the punch side.

BOTTOM FEED - Particular type of automatic installation tooling in which the part is automatically prsented onto the anvil.

BREAKLOOSE TORQUE - The amount of torque required to put into reverse rotation a fastener that is in the seated, clamped or tightened position. The torque is due to clamp load and not related to prevailing torque.

BREAKLOOSE TORQUE - The torque required to begin reverse rotation in a fastener that has not been seated. This will change with reuse - they are referred to as the "1st Off, 5th Off" torque. This torque is due to the locking element only and is considered a critical performance characteristic of a locking component.

BROACH - Term used to indicate the manufacture of a non-round hole. Also sometimes used as a noun to indicate the non-round hole. The square holes in type R retainers and the hex holes in type PL are produced by broaching.

BROACHING - The act of cutting a shape in any object by using a mandrel of a similar shape. As applied to fasteners, the way a knurled shank "broaches" its way into the mounting hole.

BUBBLE - The largest diameter portion of the locking feature on type LK nuts.

BULB - The largest diameter portion above the flange ontype SSC or SSA snaptop standoffs. Also sometimes used to mean the same as bubble on LK nuts.

BULB DIAMETER - The diameter of the bulb. When an insert is used near max grip the bulb diameter will be smaller than when the insert is used near min grip. Thick wall parts have historically been designed to provide a bulb diameter of 125% of shank diameter at max grip and 135% of shank diameter at min brip