R... Glossary of Fastener and Fixing Terminology

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GLOSSARY           ALPHA LOCATOR  

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R CLIP

This is a bent wire spring clip shaped in the letter R, can be single or double coil.   Product 

REACH

Registration Evaluation Authorization and restriction of Chemicals regulations.  More Detail  

REBAR

RECESSED HEAD  

A screw head, having specially formed indentations or recesses central on the head, into which a suitably formed driver fits, generic names are Pozidriv® and Phillips®  

REDUCED SHANK BOLT  

A bolt whose shank diameter is smaller than the nominal diameter of the bolt, the shank diameter of such a bolt is approximately equal to the effective diameter of the thread.  Product

RELAXATION      

The loss of clamping force in a bolt that occurs typically without any nut rotation occurring. Commonly occurs as a result of embedment but can also be due to gasket creep, metal creep (at elevated temperatures), differential thermal expansion and stress relaxation.

RETAINING RING

A retaining ring is a fastener that holds components or assemblies onto a shaft or in a housing bore when installed in a groove. The exposed portion of the ring acts as a shoulder retaining the component or assembly. Product

RIBBED NECK BOLTS  

A  bolt with a serrated neck to prevent rotation.  Product

RIGHT HAND THREAD      

A screw thread that is screwed in by rotating clockwise. The majority of screw threads are right handed.

RILSAN

Rilsan is a coating for fasteners approved by the water authorities.  Detail

RIVET SOLID  

A headed metal fastener of some malleable material used to join parts, as metal plates, of structures and machines by inserting the shank through a hole in each piece and forming a head on the headless end. Product  

ROCKWELL HARDNESS TEST 

Forcing a cone-shaped diamond or hardened steel ball into the specimen being tested under standard pressure. The depth of penetration is an indication of the Rockwell Hardness. 

Hardness

ROLLED THREAD              

Rolled threads are formed by plastically deforming a steel blank rather than by cutting. The majority of standard fasteners have their threads formed by rolling. Most threads are rolled before any heat treatment operation.

Significant improvements in fatigue life can be achieved by rolling the thread after heat treatment, this improvement is due to compressive stresses being induced in the roots of the thread. Rolling the thread also generally improves the surface finish which can have a beneficial effect on fatigue life.

ROOT DIAMETER             

Identical to MINOR DIAMETER

ROUND HEAD  

Semi-elliptical top surface and flat bearing surface.  Product

RUN -OUT    

Run-Out is a term frequently interconnected with eccentricity. Normally run-out refers to the amount of run-out with the outside surface of one reference surface of a fastener in comparison with the outside surface of another surface reference on the component. As such, it does include eccentricity, angularity and bow. The amount of run-out is usually expressed in terms of Total Indicator Reading (TIR).

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