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Allmetal Screw Products
Category: General technical and industrial > Glossary of fastener terms
Date & country: 14/08/2008, US
Words: 297


Hanger Bolt
One endd is gimlet pointed and has a wood screw thread. The other end consists of a coarse machine screw thread. The center section is unthreaded.

Hardenability
In a ferrous alloy, the property thaet determines the depth and distribution of hardness induced by quenching.

Hardening
A method of heat treating metals by heating to a temperature within, or above, the critical range, holding at that temperature for a given time, and then cooling rapidly, usually by quenching in oil or water.

Hardness
Resistance to plastic deformation by indentation, penetration, scratching or bending.

Head
The preformed, enlarged end of a bolt, screw, pin, or rivet, provided with a bearing surface which is usually either flat or conical.

Head Marking
Used to identify the material used in a fastener such as a bolt or cap screw. The marking is either raised or indented to specifications.

Header Point
A chamfer point, usually of 45 degrees included angle, forming by a die at the time of heading and prior to threading.

Heat Treating
An operation involving the heating and cooling of a metal to obtain certain desirable conditions or properties.

Height of Thread
The distance, measured perpendicular to the axis, between the major and minor cylinders or cones, respectively.

Heli-Coil
Coil of wire used as an insert to accept a screw or bolt and adding holding power by forcing itself between the fastener and the walls of the recess when the fastener is driven in.

Hexagon Head
Flat top surface with hexagonal sides andn with a flat bearing surface. (Six Sides)

Hexagonal
A recessed hexagon socket in the headd of a cap or set screw to add greater tightening and loosening power. Used with a Hex key wrench. (See Hexagon Head)

Hook Bolt
A 'bent bolt' having the unthreaded end bent to form a hook, such as a round bend, square bend, right-angle bend, or acute-angle bend hook bolt.

Hot Forming
Working operation such as bending and drawing sheet and plate, forging, pressing, and heading, performed on metal heated to temperatures above room temperature.

Immunize
To remove small particles of iron or grit from the surface of stainless steel by pickling in an acid solution.

Impact Test
A test to determine the energy absorbed in fracturing a test bar at high velocity. The test may be in tension or in bending, or it may properly be a notch test if a notch is present, creating multiaxil stresses.

Included Angle of Thread
The angle between the flanks or the thread measured in an axial plane.

Incomplete Thread
On straight threads, that portion at the end having roots not fully formed by the leadd or chamfer on threading toolss:

Ingot
Steel formerly in a molten state, transferred to an ingot mold to solidify.

Interference Fit
A thread fit having limits of size so prescribed that an interference always results when mating parts are assembled.

Internal Thread
A thread on the internal surface of a hollow cylinder or cone.

Iron
Primarily the name of a metallic element. In the steel industry, iron is the name of the product of a blast furnace containing 92 to 94 percent iron. Other names for blast furnace are pig iron and hot metal.

Jackson Head
A machine screw with a small oval head. (Trimmed oval head).

Jam Nut
(1.) A second nut forced or jammed against the main nut to prevent loosening. (2.) A thin nut.

Key
A small block or wedge inserted between shaft and hub to prevent circumferential movement.

Keyslot
The recess cut for Woodruff keys produced by sinking a milling cutter of the right diameter and width into a shaft.

Keyway
A groove or slot cut to fit a key. A key fits into a key seat and slides into a keyway.

Knurl
A roughened surface produced by contact with a wheel which forces metal above the surface while making indentations below the surface.

Lag Bolt
A fastener having a square head, with a gimlet or cone point, and a thin, sharp, coarse-pitch thread, designed for insertion in wood or other resilient materials and producing its own mating thread.

Lead Error
A variation in the distance between the threads of a screw.

Left-Hand Thread
A thread is a left-hand thread, if, when viewied axially, it winds in a counter-clockwise and receding direction. All left-hand threads are designated LH.

Length of Fastener
The length of a flat bearing surface fastener is the distance, in a line parallel to the axis, from the bearing surface to the extreme point. The length of a countersunk head fastener is the distance, in a line parallel to the axis, from the largest diameter of the bearing surface to the extreme point.

Lentil Head Screw
Obsolete term for oval head screw.

Liquid Honing
A metal finishing process by forcing a stream of liquid, in which a very fine abrasive is suspended, against the surface to be finished.

Lock Nut
A nut which, in addition to serving the purposes of an ordinary nut, has a special means for gripping a threaded member so that a relative rotation between the nut and the threaded companion member is prevented in use.

Machineability
Relative ease or difficulty in forming.

Magnaflux
A magnetic method of determining surface and subsurface defects in metals.

Major Diameter
On a straight thread, the diameter of the coaxial cylinder which would pass through the crests of an external thread or the roots of an internal thread.

Master Gage
A thread-plug gage which represents the physical dimensions of the nominal or basic size of the part. It clearly establishes the minimum size of the threaded hole and the maximum size of the screw at the point at which interference between mating parts begin.

Maximum Material Limit
The maximum limit of size of an external dimension or the minimum limit of size of an internal dimension.

Mechanical Properties
Those properties of a material that reveal the elastic and inelastic reaction when force is applied, or that involve the relationship between stress and strain; for example, the modulus of elasticity, tensile strength and fatigue limit.

Micro-Inch
One millionth of an inch. Used in measuring imperfections of surface finishes.

Milling Process
A machining process whereby a surface is generated with a rotating toothed cutter. Each tooth takes an individual chip.

Minor Diameter
On a straight thread, the minor diameter is the diameter of the coaxial cylinder which would pass through the roots of an external thread.

Monel
A corrosion resisting metal consisting essentially of two-thirds nickel and one-third copper.

MS Specifications
(Military Standard)

Nail Point
A sharp pyramidal point of approximately 30 degrees or 45 degrees included angle.

NAS Drawings and Specifications
Dimensional and material standards for aircraft fasteners developed by the National Aerospace Standards Committee. All drawings and specifications are prefixed by 'NAS'.

Naval Brass
A corrosion resisant metal containing 60 per cent copper, 39 1/4 per cent zinc and 3/4 per cent tin.

Neck
A portion reduced in diamter between the ends of a shaft.

Nickel
A silver-white metal usually used as an alloy in steel, bronze, brass and cast iron. It tends to increase corrosion resistance.

Nifriding
A surface hardening process used on ferrous metals by heating the metal in contact with ammonia gas or other nitrogenous material.

Nipple
A short piece of threaded pipe used to connect two fittings.

Non-Ferrous Metal
Metals or alloys without an appreciable amount of iron. Examples are aluminum, brass, copper, etc.

Non-Magnetic
Steels with sufficient quantities of manganese or nickel to render the steel non-magentic. 18-8 (300 series chrome-nickel steel) is non-magnetic when annealed. Type 316 is non-magnetic in all conditions. (See pg. 156 of the Data Book).

Normalize
To remove internal stresses by heatinig a metal piece to its critical temperature and allowing it to cool very slowly.

Nut
A metal block (solid nut) or sleeve having an internal thread made to assemble with the external thread on a bolt, screw, or other threaded part. It may be a fastening means, an adjusting means, a means for transmitting motion, or a means for transmitting power with large mechanical advantage and nonreversible motion.

Nylon Fasteners
Fasteners made of a material that has a low dielectric constant and relatively high tensile strength, enabling it to resist high voltage at commercial frequencies. It can also operate at continuous temperatures as high as 250 degrees F. Any temperatures above has an effect to oxidize material. Electric and electronic equipment manufacturers are fin...

One-Way Head Screw
A round head screw which is slotted but has side clearances at diagonally opposite sides of the slot so that the screw can be driven only in the direction of assembly, designed for preventing tampering.

Open Washer
A washer with one side open so as to be removed or put under a nut without removing the nut.

Oval Binding Head Screw
Obsolete term for a truss head screw.

Oval Head
Rounded top surface and a conical bearing surface with an included angle usually of 82 degrees.

Oval Point
A rounded end which is used, particularly for set and adjusting screws, to apply pressure without cutting action.

Oven Head Screw
Obsolete term for truss head screw.

Pan Head
Flat top surface rounded into cylindrical sides, and a flat bearing surface. The recessed pan head has a rounded top surface blending into cylindrical sides and a flat bearing surface.

Passivate
A process of surface treatment for neutralizing stainless steels. A n oxydizing solution, such as nitric acid is applied to the surface. This strengthens the normal protective film which helps in resisting corrosion. It also removes any foreign substance which might cause local corrosion.

Pattern Nuts
Special nuts usually furnished in plain or chamfered face unless otherwise specified, and threads are unified Coarse or unified Fine, Class 2B. (also small and extra small)

Peening
The stretching of metal by hammering or rolling the surface.

Phillips Recessed Head
A type of screw drive having a cross recess with a wide center opening, steep walls and a blunt conical bottom. Permits easy and rapid entrance of the 4-winged driver.

Physical Properties
Those properties familiarly diiscussed in physics, including those descriabed under mechanical properties; for example, density, electrical conductivity, co-efficient of thermal expansion.

Pinch Point
A sharp conical point, usually of 45 degrees included angle, formed by a pinching operation.

Pipe Caps
A cap that threads onto a pipe (like a nut) to seal one end.

Pipe Fittings
The term applying to all forms of connecting parts which join pieces sof pipe together.

Pipe Plugs
A short piece of threaded pipe, Slotted, Square Head or Socket, used to close up one end of a fitting.

Pipe Screw Thread
American Standard pipe threads are tapered 1 inch in 16, or 3/4 inch per foot. They are 60 degree threads, of National form with flat or rounded top and bottom.

Pitch
The distance, measured parallel to its axis, between corresponding points on adjacent thread forms in the same axial plane and on the same side of the axis.

Pitch Diameter
On a straight thread, the diameter of the coaxial cylinder, the surface of which would pass through the thread profiles at such points as to make the width of the groove equal to one-half of the basic pitch. On a perfect thread this occurs at the point where the widths of the thread and groove are equal.

Pitch Line
A generator of the cylinder or cone of a screw thread specified in the definition of pitch diameter.

Plain Sheared Point
The end of a fastener cut approximately flat and square to the axis, without chamfer.

Planer Head Bolt
A bolt havinig a large low square head, designed for insertion in T-slots of planer, shaper, or milling machine tables.

Plate
The electro-chemical coating of a metal piece with a very different metal.

Polish
To make smooth or lustrous by friction with a very fine abrasive.

Precipitation Hardening
Hardening caused by the precipitation of a constituent from a supersaturated solid solution.

Precision Machine Screws
Slotted machine screws, milled from bar, cut thread, and are machined finished Class 3A fits.

Process Annealing
Heating a ferrous alloy to a temperature close to, but below, the lower limit of the transformation range and then cooling, in order to soften the alloy for further cold working.

Punch
(v) To perforate by pressing a non-rotating tool through the work.

Quench Hardening
Hardening a ferrous alloy by austenitizing and then cooling rapidly enough so that some or all of the austenite transforms to martensite.

Quenching
Rapid cooling. When applicable, the following more specific terms should be used: direct quenching, fog quenching, hot quenching, interrupted quenching, selective quenching, spray quenching, and time quenching.

Ream
To finish a drilled or punched hole very accurately with a rotating lfuted tool of the required diameter.

Reamer
Tool used for englarging holes previously formed by drilling or boring.

Recessed Head
A screw head, having specially formed indentations or recesses centered on the head, into which a suitably formed driver fits.

Relief
The amount one plane surface of a piece is set below or above another plane, usually for clearance or for economy in machining.

Ribbed Neck Carriage Bolt
A plain, circular, oval head bolt with a serrated neck to prevent rotation.

Right-Hand Thread
A thread is a right hand thread if, when viewed axially, it winds in a clockwise and receding direction.

Rivet
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.

Rivet Bolt
A bolt designed as a substitute for rivets, having a button head, a ribbed shank, a UNC thread, or a special thread such as a Dardalet thread or Lok-Thread (TM).

Rockwell Hardness Test
A measure of hardness by determining the depth of penetration of a pentrator into the specimen under certain fixed conditions of test. The penetrator my be either a steel ball or a diamond sphero- conical penetrator. The hardness number is related to the depth of indentation and the higher the number the harder the material.

Rod Ends
The ends of connecting rods which fit over crank pins or cross head pins.

Roll Threading
Applying a thread to a bolt or screw by rolling the piece between two grooved die plates, one of which is in motion, or between rotating grooved circular rolls.

Rolled Point
The point frequently produced by the cupping of the last 1 to 1 1/2 threads by the thread roling pressure. This type of point is not produced intentionally but is considered as an alternative form of the plain sheared point.