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


Acorn Die
A form of threading die for use in screw machines. The cutting portion resembles an acorn.

Acorn Nut
A blind tapped hex nut with an acorn shaped top. Provides sealing for projecting threaded parts.

Age Hardening
A process of aging that increases hardness and strength, and ordinarily decreases ductility. Age hardening usually follows rapid cooling or cold working.

American Standards
Dimensional standards for fasteners, etc., developed by the American Society of Mechanical Engineers. (ASME)

AMS
Aeronautical Material Specifications are material and process specifications for aircraft components conforming to established engineering and metallurgical practices in the aircraft industries. They are developed by the SAE aeronautics committee. All specifications are prefixed by 'AMS'.

AN
Dimensional standards for aircraft fasteners developed by the Aeronautical Standards Group. All drawings are prefixed by 'AN'

Angle of Head
In countersunk heads, the included angles of the conical underportion or bearing surface, usually 82 or 100 degrees.

ASTM
Standards developed by the American Society for Testing and Materials.

Balls
Used in 'quick release pins' where permanent assemble and disassemble action tales place. Provides a reliable holding fastener.

Barrel Nut
An internally threaded screw having a slotted head.

Bent Bolt
A cylindrical rod having a thread at one end and the other end bent to some desired conformation; also a bent cylindrical rod having threads at both ends.

Bevel
A surface not at right angles to the rest of the piece.

Binding Head
Rounded top surface and slightly tapered sides. The bearing surface is flat with annular undercut optional.

Blind Rivet
A rivet designed for use where only one side of the work is accessible.

Blunt Start
The removal of the partial thread at the entering end of thread.

Body of Bolt or Screw
Also designated grip. The blank portion of the bolt or screw which is between the thread and the head.

Bolt Blank
A headed rod or bar intended for a subsequent threading operation.

Bolt End
A headless rod threaded at one end and assembled with a square nut, designed to be welded or otherwise fastened to a part or structure.

Brinell Hardness Test
A method of determining the hardness of metallic materials by applying a known load to the surface of the material through a hardened steel ball of known diameter. The diameter (or depth) of the resulting impression in the metal is measured. The Brinell hardness number is taken as a quotient of the applied load divided by the area of the surface im...

Broaching
A generating process whereby metal is removed with a multiple-point tool, usually a bar, with tooth height increasing from the starting end. When the broach is pulled or pushed through or over the work, each tooth removes a clip of uniform thickness, in contrast to a milling cutting tooth which removes a wedge-shaped chip.

Burnish
To smooth or polish by a rolling or sliding tool under pressure.

Button Die
Small adjustable dies for screw machines and similar work, supported in a ring holder.

Cap Nut
A blind tapped hex nut with an acorn-shaped top. Provides sealing for projecting thread parts.

Cap Screws
Term used to describe hexagon head, slotted head, square head and socket head cap screws.

Captive Screws
Where the shank above the threaded portion is undercut lower than the threaded portion.

Carbide
A compound of carbon with one or more matallic elements.

Carbide Tools
Tools with cutting points of tungsten, tantalum or other alloys of sintered carbides.

Carbon Steel
Any steel made by combining carbon with iron.

Carriage Bolts
A round or flat head bolt with a square neck to prevent rotation. Used in wood assemblies.

Case Harden
Hardening a ferrous alloy so that the outer portion or case is made substantially harder than the inner portion or core. Typical processes used for case hardening are carburizing, cyaniding, carbonitriding, nitriding, induction hardening, and flame hardening.

Casting
1. A term applied to the act of pouring molten metal into a mold. 2. The metal object produced by such pouring.

Castle Nut
A hexagon nut having a cylindrical portion at the end opposite to the bearing face, with opposed slots in this portion which are parallel to the axis, designed for insertion of a cotter to secure the nut in place when used with a drilled fastener.

Centerless Grinding
Grinding the outside or inside diameter of a round piece not mounted on centers.

Chamfer
(v) To bevel a sharp external edge. (n) A beveled edge.

Chasing Threads
Cutting screw threads by moving a tool along the axis of the work to be threaded.

Chatter
Rough or unsatisfactory surfaces on work. It is usually caused by a slight jumping of the tool away from the work or of the work away from the tool.

Check Nut
A double chamfered hexagon machine screw nut Class 3B fit. (AN 316).

Chip
The metal removed by a tool.

Chuck
Device for holding work in machine tools.

Class of Thread
Class of threads are distringuished from each other by the amount of tolerance or tolerance and allowance specified. Classes 1A, 2A, and 3A apply to external threads, and Classes 1B, 2B and 3B apply to internal threads.

Clevis
U-shaped shackle for connecting a rod to a pin.

Clevis Pins
A headed dowel pin with a drilled shank that accepts a cotter pin. Used as a fastener where more than temporary holding actions is required. (ASA B 5.20-1958).

Clinch Nut
A nut having a pilot which, after insertion in a hole, is clinched or staked in place to prevent rotation.

Cold Heading
Forcing metal to flow cold into dies to form thicker sections and more or less intricate shapes. The operation is performed in specialized machines where the metal, in the form of a wire or bar stock, may be upset or headed in certain sections to a larger size and, if desired, may be extruded in other sections to a smaller diameter than the stock w...

Cold Swaging Process
A method of reducing or forming steel or other material while cold, by drawing to a point or reducing the diameter, as may be required.

Cold Work
To deform metal stock by hammering, forming, drawing, etc., while the metal is at ordinary room temperature.

Columbium
A metal which may be added to chrome-nickel stainless steel to improve its welding and general heat-resistant qualities, by preventing carbide precipitation.

Companion Flanges
Shaft attached collars of 18-8 stainless steel into which a threaded piece may be joinedd. Has standard I.P.S. threads.

Comparator
A device for inspecting screw threads and outlines by comparing them with a greatly enlarged standard chart.

Cone Point
A point in the form of a cone, commonly having an included angle of 90 degrees or 118 degrees when applied to set screws.

Copper Steel
When any minimum copper content is specified, the steel is classed as copper steel. The copper is added to enhance errosion resistance of the steel.

Corrosion
Gradual chemical or electrochemical attack on a metal by atmosphere, moisture or other agents.

Cotter Pin
Used as a locking device in clevis pins, castellated nuts and slotted nuts with drilled bolts. Ends available in various types such as 'extended mitre end', etc.

Counterbore
(v) To enlarge a hole to a given depth. (n) 1. The cylindrical enlargement of the end of a drilled or bored hole. 2. A cutting tool for counterboring, having a piloted end of the size of the drilled hole.

Countersunk Head
A head, the underside of which is beveled to fit a flaring hole. The bearing surface of other types of heads is generally perpendicular to the body axis.

Crest
That surface of the thread which joins the flanks of the thread and is farthest from the cylinder or cone from which the thread projects.

Crest Clearance
As in a thread assembly, the distance, measured perpendicular to the axis, between the crest of a thread and the root of its mating thread.

Crest Truncation of Thread
The distance, measured perpendicular to the axis, between the sharp root and the cylinder or cone which bounds the root.

Cup Point
A point in the form of a cone, commonly having an included angle of 90 degrees, with a conical depression in the end commonly having an included angle of 118 degrees. The contact area is a circular ridge which has considerable holding power with slight penetration, applied to set screws generally.

Deburring
The removal of burrs by a secondary operation such as grinding.

Deep Drawing
Forming shapedd articles or shells by forcing sheet metal into a die.

Die
1. One of a pair of hardened metal blocks for forming, impressing, or cutting out a desired shape. 2. (thread). A tool for cutting external threads. Opposite of tap.

Die Casting
A very accurate and smooth casting made by pouring a molten alloy usually under pressure into a metal mold or die.

Die Chaser
The separate cutting tools used in die heads, which actually cut the screw threads.

Dog Point
A cylindrical extension, or pilot, of diameter smaller than the minor diameter of the thread, commonly equal to about D/2 in length, with a conical section between it and the thread; usually used as a pilot in assembling or as the end of a set screw projecting into a fairly deep hole or slot.

Double End Stud
Threaded at both ends with standard Class 2A threads to take nut assembly.

Dowel Pins
Used as a holding pin with chamfered on one end. Drilled headed dowel pin (clevis pin) used - frequently removed fastener.

Dowel Screw
Both ends have Gimlet points, threaded similar to a Lag Bolt. The center section has a plain unthreaded shoulder. Used in joining two wooden members such as a leg to a table top.

Drill
(v) To sink a hole with a drill, usually with a twist drill. (n) A pointed cuttiniig tool rotated under pressure.

Drilled Head or Shank
Used in AN Bolts and Machine Screws, etc.

Drive Screw
A piloted, multiple threaded screw with a large helix angle, used for permanent applications. It forms a mating thread as it is hammered or pressed into a prepared hole.

Driver Head
A head, on a bolt or screw, designed for driving the fastener by means of a tool other than a wrench, such as a screw driver.

Drop Forging
Forming metal, usually under impact, by compression within dies designed to produce the required shape.

Elevator Bolt
A flat, plain, circular countersunk head bolt with a square neck to prevent rotation.

Endurance Limit
The maximum stress that a metal will withstand without failure during a specified large number of cycles of stress.

Escutcheon Pin
A piece generally used to join a plate or shield, to cover or protect softer or more delicate materials or actions.

Expansion Bolt
A combination of a 'lag bolt' and an internally threaded split sleeve, designed for fastening to stone or concrete by inserting a sleeve into a hole in the concrete and expanding to a tight fit in the hole by turning the lag both with a wrench.

Eyebolt
A bolt having a head in the form of an open or closed anchor ring, or of a flattened and pierced section, with or without a collar or shoulder under the head.

Face
To machine a flat surface perpendicular to the axis at rotation on a lathe.

Fatigue Strength
The stress to which a metal can be subjected for a specified number of cyclic changes of stress.

Feather Key
A parallel key fastened in either the shaft or in the hub of a member sliding on it. When fastened in the shaft, it must be long enough to hold or drive the sliding member in any of its positions on the shaft. When in the sliding member the key need only be as long as the hub.

Fillet
A rounded filling of the internal angle between two surfaces.

Fillister Head
Rounded top surface, cylindrical sides, and a flat bearing surface.

Fin
A thin projecting rib.

Fin Neck Carriage Bolt
A plain, circular, oval head bolt with two oppositely located fins to prevent rotation.

Finished Hexagon Bolts
A washer faced or chamfered bearing surface with a close body tolerance.

Fit
The general term used to signify the range of tightness which may result from the application of a specific combination of allowances and tolerances in the design of mating parts. See 'Class of Thread'

Flat Head
Flat top surface and a conical bearing surface.

Flex-Loc*
When used as a stop or lock nut, the locking threads of the slotted top press inward against the bolt, lifting the nut upward and causing the remaining threads to bear against the lower surface of the bolt threads. (*TM)

Following Flank
The flank of a thread opposite to the leading flank.

Forge
To shape metal while holt and plastic by a hammering or forcing process. Dies used in process.

Form of Thread
The profile of a thread in an axial plane for a length of one pitch.

Free Machining
The property that makes machining easy because of the forming of small chips, a characteristic imparted dto steel by sulfur, etc.

Full Annealing
Annealing a ferrous alloy by austenitizing and then cooling slowly through the transformation range.

Full-Size Body
The body of a bolt or screw which has a diameter between the minimum and maximum limits of the major diameter of the thread.

Galvanize
To treat with a bath of lead and zinc to prevent rusting

Gimlet Point
A taper-threaded point; applied to wood screws, Type A tapping screws, lag bolts, etc.

Grind
To finish or polish a surface by means of an abrasive.

Grip
The unthreaded portion of a bolt or screw.

Half Dog Point
The same as a dog point but half as long; used on short screws for the same purposes as the dog point, but in a shallower hole or slot.