McGuire Glossary of Fastener Terminology

T - 11 terms

TAB - A type of lock washer designed with one or more tabs or notches to effectively lock a part in place, generally used where heat or heavy vibrations are a factor.

TC - Technical Committee

TEFZEL(R) (ETFE) (PLASTICS) - Ethylene-tetrafluoroethylene copolymer is a high impact material with properties similar to ECTFE. It is commonly used to manufacture pumps, valves, computer housings, and other electrical components.

THICK WAL - A style of part having a wall thickness of rounghly 14% of sthe counterbore diameter. Thick wall parts have higher installation loads and typically cn not be installed with spin-spin tools. Although they have narrower grip ranges than thin wall parts, they provide a higher level of performance.

THIN WALL - A style of part having a wall thikness of rouhgly 8% of the counterbore diameter. Thin wall parts haver lower installation loads sllowing them to be installed with spin-spin tools. They also have wider grip ranges than thick wall parts, but provide a lower level of performance.

THREAD FORM - Defined as the profile of an axial section through one complete pitch. Basic form for Unified National and M Profile threads is a 30 degree flank angle with a P over 8 truncation at the major diameter and a P over 4 truncation at the minor diameter. Design forms for internal and external threads are different from each other, maybe slightly different from the basic form and represent maximum material conditions.

THREADED INSERT - A metal fastener usukally threaded, that can provide a strong attachment point to a section of material. Threaded inserts can provide strong threads to soft materials such as platics or composites. Other stype of threaded inserts can be clinched or may utilize blind threaded rivet technology to provide strong threads in thin metal sheets. The use of threaded inserts eliminates the need for tapping or otherwise creating threads directly into the base material which may not offer the strength required or in some cases may be more costly.

TOP FEED - A method of automatic installation in which the fastener to be isntalled is presented automatically to the pulnch.

TORLON(R) (PAI) (PLASTICS) - Polyamide-imide possesses a combination of great mechanical strength, the ability to withstand radiation, usability from approoximately -300F to 500F, and resistance to most chemicals at room temperature. It is also flame retardant and gives off almost no smoke when burned. It is available in unreinforced grades and is readily machinable. This combination of assets makes it a good metal substitute for aerospace and electronic applications. It is commonly used for bushings, seals and distributors in engines and machinery.

TRANSFER DIE STAMPING - Transfer die stamping operations are the same as progressive die stamping operations except the sheet metal blank is separated early and transferred along a conveyor belt or similar structure.

TRIMMED-KNURL - When a knurl platform is knurled in screw machine work, the knurl rolls over or overhanges the platform. Knurls may be trimmed flush with the platform (-O S type nuts) trimmed to some value slightly greater than the platform height (-1 and -2 S Type nuts) or may be left untrimmed (type R retainlers).