ASME B18-12 pdf free download
ASME B18-12 pdf free download GLOSSARY OF TERMS FOR MECHANICAL FASTENERS
1 INTRODUCTION1.1 Scope
This Standard is a summary of nomenclature andterminology currently used to define and/or describemechanical fasteners，related characteristics，and themanufacturing processes that produce these products.Utilization of these terms by manufacturers and consum-ers is intended to reduce or eliminate confusion andserve as a sound basis for communication.
(a) Primary Operations. Mechanical fasteners areproduced by forming or screw machine operations.Forming is generally scrapless and, depending uponsize,may produce fasteners at rates exceeding 50opieces per minute. Screw machining,although moretightly toleranced,is significantly slower and generatesscrap because it involves the removal of material.b) Secondary Operations. Fasteners generally un-dergo several secondary operations or processes suchas thread rolling,heat treating,or plating.
(c) Fastener. A fastener is a mechanical devicedesigned specifically to hold,join，couple,assemble,or maintain equilibrium of single or multiple compo-nents.The resulting assembly may function dynamicallyor statically as a primary or secondary componentof a mechanism or structure. Based on the intendedapplication, a fastener is produced with varying degreesof built-in precision and engineering capability , ensuringadequate，sound service under planned,preestablishedenvironmental conditions.
(d) Bolts，Studs,Screws，Nuts，Washers.Rivets，Pins,and Custom Formed Parts. These items are the generalproduct families in which mechanical fasteners are bestclassified. Within each product family are numeroustypes that may have a name conforming to the technicallanguage of a national standard or alternately may havea name that has its origins in commercial or marketingnomenclature often taken from its intended application.Such names，for example，include the “stove bolt”and”carriage bolt.”Because mechanical fasteners are usedin just about every mechanical assembly, they necessar-ily have been designed to meet a broad range ofapplications from watch and computer assembly to thespace shuttle design. The names given to fasteners appear to be as limitless as the designer’s imagination.While many fasteners may look alike,they generallyhave defined engineered capabilities based upon theirintended application.
1.2 Referenced Documents
In the development of this Standard,a number ofterms were written based upon language found inmore than 230 standards and other publications of thefollowing organizations:
a) American Society for Testing and Materials(ASTM),100 Barr Harbor Drive,West Conshohocken,PA 19428-2959
b)The American Society of Mechanical Engineers(ASME)，Three Park Avenue，New York，NY10016-5990
(c) Industrial Fasteners Institute (IFD),1717 EastNinth Street，Suite 1105，Cleveland,OH 44114-2879(d) Society of Automotive Engineers (SAE)，400Commonwealth Drive，Warrendale，PA 15096-00O1
2TERMINOLOGY
2.1 Basic Fastener Terminology
2.1.1 comnercial fastener: manufactured to pub-lished consensus standards and stocked by manufactur-ers or distributors.
2.1.2 compression fastener: a fastener whose primaryfunction is to resist compressive forces.
2.1.3endurance limit or endurance strength: themaximum alternating stress that a fastener can withstandfor a specified number of stress cycles without failure.2.1.4 headed fastener: a fastener having one endenlarged or formed.
2.1.5 headless fastener: a fastener，either threadedor unthreaded, that does not have either end enlarged.2.1.6 high strength fastener: a fastener having hightensile and shear strengths attained through combina-tions of materials，work-hardening, and heat treatment.
These fasteners usually have a tensile strength in excessof 120,000 psi.
2.1.7 lockpins and collars: a headed and externallygrooved mechanical device designed for insertionthrough holes in assembled parts. A cylindrical collaris swaged into the external groove as the lock pin ishydraulically tensioned. Collars are either smooth boredor may contain a fit-tab. An optional flange providesa built-in washer.
2.1.8 mechanical properties: identify the reaction ofa fastener to applied loads. Rarely are the mechanicalproperties of the fastener those of the raw materialfrom which it was made. Properties such as tensileand yield strengths,hardness,and ductility will varywidely,depending upon choice of manufacturing meth-ods and metallurgical treatments.
2.1.9 modified standard: a part that is standard withone or more of its features or characteristics slightlychanged. Such a part is normally ordered to a customer’sprint is used by that customer in a particular application,but the part is such that any interested manufacturercan produce it.
2.1.10 nonstandard fastener or special fastener: afastener that differs in size,length,configuration, mate-rial, or finish from established and published standards.2.1.11 physical properties: inherent in the raw mate-rial and remain unchanged, or with only slight alterationin the fastener following manufacture. Such propertiesare density, thermal conductivity, and magnetic suscepti-bility.
2.1.12 Part ldentifying Nunber (PIN): a 21-charactercode that identifies an ASME B18 manufactured productby specific characteristic fields such as fastener familyidentification,B18 standard identification,fastener styleor type, thread series,nominal diameter, nominal lengthor dimensionalother characteristics，material and treat-ment,plating， coating,and passivation and specialfeatures relevant to the fastener product.
2.1.13 precision fastener: manufactured to closedimensional and geometric tolerances.
