“A” SHEET METAL SCREWS \u2013 Sheet metal screws with (a) sharp-pointed ends; (b) fewer threads per inch than type AB screws: and (c) deeper threads with better gripping power than type AB. The Industrial Fasteners Institute incorrectly labels type A an “obsolete” thread though it is universally pre\u00acferred in 18-8 stainless over type AB, especially by the marine industry.
“AB” SHEET METAL SCREWS \u2013 Sheet metal screws with pointed ends similar to type-A screws and thread dimensions similar to type-B. Type AB screws are seldom used in stainless.
AN \u2013 Stands for Air Force-Navy.
ANSI \u2013 Stands for American National Standards Institute. ASME \u2013 Stands for American Society of Mechanical Engineers.
ANSI\/ASME NOMENCLATURE (B1.1 AND ALL) \u2013 The “B” numbers are standards set by ASME regarding various aspects of fasteners. The most common number, B1.1, deals with dimensions and thread tolerances; B1.2 with gages and their use; B1.3 with various systems for gaging threads; B1.7 with definitions of terms.
ASTM \u2013 Stands for American Society for Testing and Materials.
ASTM 193-194 \u2013 ASTM 193 are chemical and physical specifications for hex head cap screws, studs, and bolts made of steel and stainless steel. ASTM 194 refers to nuts. The commonly used stainless is called grade 8, referring to 304 material to certain specifications, and grade 8M referring to 316 material. The major differences between ASTM and commercial stain\u00acless fasteners are: (a) 304 material must be used for manufacturing grade 8, not simply 18-8; (b) ASTM 193-194 generally refers to heavy hex heads and heavy nuts, though semi-finished hex heads and finished nuts may be sup\u00acplied with the permission of the buyer; (c) cold formed material will require carbide solution treatment or annealing to reduce hardness to meet ASTM requirements.
AGE HARDEN \u2013To use modified heat treatments at various temperatures over a period of time to harden and strengthen a fastener.
AIRCRAFT QUALITY \u2013 Fasteners made with a particularly high level of attention in manufacture and inspection.
ALLOY STEEL \u2013 A mixture (or alloy) of ordinary steel added to other metals besides carbon with the specific purpose of attaining certain characteristics such as higher strength. A few exceptions to this definition exist, however, so that a chromium content above 4% is not considered alloy steel and above 12% is considered stainless steel.
ALUMINUM \u2013The most abundant metal in the earth, aluminum is blueish and silvery-white, very light, malleable, and ductile with high heat and electrical conductivity. It is non-magnetic and one-third the weight of steel with good corrosion resistance against certain chemicals and acids but weak resis\u00actance against other elements such as sea water.
ANNEAL – To heat metal in order to lower its hardness. The term anneal refers to the heat treatment given all 300 series stainless and most 400 series stainless by a steel mill after the raw material has been completed but before fasteners are manufactured. Anneal also refers to the heat treatment given 400 series stainless fasteners after their manufacture (also called hardening and tempering) to lower hardness and increase toughness, For example, fasteners of 410 stainless may score over 200,000 psi after manu\u00acfacture and be too brittle. By annealing at 1000 degrees F. tensile strength would decrease to 125,000-150,000 psi; annealing the same material to 500 degrees F. would bring tensile to 160,000-190,000 psi.
AUSTENITIC \u2013 Refers to 300 series stainless, the most popular of the stainless alloys accounting for 85%-90% of stainless fasteners sold. Named for Sir Robert Williams Austen, an English metallurgist, austenitic stainless is a crystal structure formed by heating steel, chromium, and nickel to a high temperature where it forms the characteristics of 300 series stainless steel. An “AUSTENITE” is a molecular structure where 8 atoms of iron surround one atom of carbon, thus limiting the corrosive effects of the carbon. Auste\u00acnitic fasteners have the highest level of corrosion resistance in the stainless family, cannot be hardened by heat treatment, and are almost always non\u00acmagnetic. Sometimes heat and friction in cold-forming can cause austenitic stainless to take on slight magnetism. but the corrosion-resistant properties remain the same.
The most popular of austenitic grades is known generically as “18-8 stainless” and includes grades 302, 302HQ, 303, 304, 305, and XM-7. Typi\u00accal industries using 18-8 fasteners include: food, dairy, wine, chemical, pulp and paper, pharmaceutical, boating, swimming pool, pollution control, elec\u00actronic, medical and hospital equipment, computer, textile.Type 316 stainless has added nickel and especially molybdenum. The molybdenum (called cooly) sharply increases corrosion resistance to chlo\u00acrides and sulfates, including sulfurous acids in the pulp industry. It has supe\u00acrior tensile strength at high temperatures compared to 18-8. Besides pulp and paper, typical industries using 316 are: photographic and other chemi\u00accals, ink, textile, bleach, rubber.
Exotic metals in the 300 series include 309,310,317,321, and 347. With superior corrosion resistance at elevated temperatures, these metals are used for furnace parts, high temperature containers and processing equip\u00acment, aircraft parts such as collector rings, exhaust systems, and equip\u00acment for very corrosive compounds of sulfuric, nitric, citric, and lactic acids. Their usage compared to 18-8 and 316 is very low.
“B” \u2013 Referring to sheet metal screws, type-B indicates a blunt point with more threads per inch and smaller thread depth than type-A screws.
BEARING SURFACE \u2013The part of a fastener such as the washer face of a nut or under the head of a machine screw that actually comes in contact with the part it fastens.
BEVEL\u2013 A small slant, usually describing a flat washer which is square and thicker on one side than the other. The slant of the bevelled washer can offset a slanted surface, so that a bolt going into the bevelled washer may be parallel to the floor or ground.
BINDER HEAD \u2013 Old term for pan head, “binder” has now come to mean “binding” head screws rather than pan.
BLANK \u2013 A fastener where one or two stages of manufacturing have been performed, but the fastener has not been finished.
BOLT VERSUS SCREW \u2013 Though some manuals spend pages trying to differentiate between a bolt and a screw, any difference is dubious at best and Star uses the terms interchangeably. For hex head, a bolt does not have a washer face under the head while a cap screw does.
BRASS \u2013 The most common alloy of copper, brass is about two-thirds copper, one-third zinc. It is non-magnetic with good strength and toughness, high electrical conductivity, and an attractive lustrous finish. It has good corrosion resistance but not in salt water. Brass is commonly used by the electrical and communications industries, builders hardware, and some ma\u00acrine applications.
BROACH \u2013 Using sharp edges to cut material and push it away, broach usually refers to the socket drive on socket screws.
CAPTIVE SCREW \u2013 Where the shoulder of a screw is perceptibly smaller in diameter than the threaded portion (technically the minor diameter or less).
CARBIDE PRECIPITATION \u2013 Carbon that breaks loose from its bond within the stainless solution when material is heated between 800-1400 degrees. Under severe corrosive conditions, it can result in extra oxidation and sur\u00acface corrosion. See Solution Annealed.
CARBON \u2013 Adds strength to stainless steel, but also lowers corrosion resistance. The more carbon there is, the more chromium must be added, because carbon offsets 17 times its own weight in chromium to form car\u00acbides, thus reducing the chromium available for resisting corrosion.
CARBON STEEL\u2013 Ordinary steel with no significant additions besides carbon.
CERTIFICATE OF COMPLIANCE \u2013 A certification that a fastener meets the description or standard to which it was sold.
CHAMFER \u2013 A slight rounding on the end of a fastener or the edges of a hex nut for ease of assembly or smoother appearance.
CHEESE HEAD \u2013 Old term for fillister head in United States; similar to fillister in metric sizes.
CHROMIUM \u2013 A blue-white metal, chromium is the most important element providing corrosion resistance in stainless steel. By adding 12% chromium to ordinary steel, stainless steel is formed. Chromium offsets the corrosive effects of carbon found in steel and is the primary factor in the ability of stainless to form a passive film on its surface providing corrosion resistance.
CLASS 1A \u2013 Solution annealed in finished condition to meet ASTM A193 specification.
COARSE THREADS \u2013 Proponents of coarse threads claim: (a) coarse threads exhibit a better fatigue resistance; (b) coarse threads are more tolerant to handling and shipping; (c) coarse threads assemble and disassemble quicker and easier; (d) coarse threads tap better into brittle materials.
COLD FORMING or COLD HEADING or COLD WORKING \u2013When fasten\u00acers are produced without heating or small heat below the recrystallization temperature (so the raw material bond of stainless remains unchanged) by pressing metal wire against various dies at high speed to form a fastener’s head or basic shape. Cold working causes an increase in tensile strength and hardness (known as work hardening) and a decrease in ductility.
CONDITION A \u2013 Means that fasteners are usually solution annealed.
CONDITION B \u2013 Means strain hardened to meet certain minimum tensile requirements.
COPPER \u2013 A reddish metal that is an excellent conductor of heat and elec\u00actricity. It is malleable, ductile, and non-magnetic with low to average strength and good corrosion resistance. Brass and silicon bronze, composed mainly of copper, gain their strength from the addition of other metals, such as silicon.
CREEP STRENGTH \u2013 A measure of the resistance of fasteners to stress under elevated temperatures. At higher temperatures, a fastener can change in dimension under the same load, and that is called creep. Creep can cause the loosening of fasteners as temperature increases.
CREVICE CORROSION \u2013 Refers to joints and crevices in a fastener as\u00acsembly where lack of oxygen caused by limited space or by surface grease prevents the passive film on stainless from forming.
CUT THREADING \u2013 Forming threads on a fastener by cutting away and actually removing the unneeded metal.
DEB URR \u2013To remove chips, burrs, or other imperfections through a sec\u00acondary operation such as grinding.
DISCONTINUITIES \u2013 A variety of small or large disfigurations in a fastener such as pits (slight depressions on the surface), toolmarks, voids (small cracks), laps, folds and seams (slightly bunched or folded material at cor\u00acners of a fastener), and inclusions (a slight non-metallic impurity in the metal). Minor discontinuities are permissible in both commercial fasteners and those made to various MS and other specs.
DRAWING \u2013 Where raw material shaped like wire is pulled through a die to reduce its diameter to that needed for the particular fastener being manufac\u00actured.
DUCTILITY \u2013 The ability of a fastener to deform before breaking (for ex\u00acample, an elastic would be more ductile than a diamond). Ductility is a mea\u00acsurement similar to elongation.
“18-8 ” \u2013 300 series stainless steel having approximately (not exactly) 18% chromium and 8% nickel. The term “18-8” is used interchangeably to char\u00acacterize fasteners made of 302,302HQ,303,304,305,384, XM7, and other variables of these grades with close chemical compositions. There is little overall difference in corrosion resistance among the 18-8 types, but slight differences in chemical composition do make certain grades more resistant than others against particular chemicals or atmospheres. “18-8” has supe\u00acrior corrosion resistance to 400 series stainless, is generally non-magnetic, and is hardenable only by cold working.
ELONGATION \u2013 Stretching a fastener to the point that it breaks. The per\u00accent of elongation at rupture (same as measure of ductility) is determined by dividing the total length after stretching to the original length. Elongation de\u00accreases as strength and hardness increase.
ELECTRICAL CONDUCTIVITY \u2013 Metals carry electric currents with vary\u00acing capacities. As a relative guide to the conductivity of different metals, with electrolytic copper rated at 101 under the International Annealed Copper Standard, at 68 degrees F.,18-8 stainless rates is rated at 5; silicon bronze 651 at 12; and brass at 27.
ETCH \u2013 A chemical process that cleans and brightens aluminum after heat treatment.
EXTRUDING \u2013 When cold forming produces a fastener before threading with two different diameters.The portion with the larger diameter is the shoul\u00acder; the smaller portion will be roll threaded. In the extruding process, a manufacturer starts with raw material equal to the shoulder diameter and pushes part of it through a die, reducing the diameter of the portion which will later be roll threaded.
F593, F594 \u2013 F593 is a specification for stainless hex head cap screws; F594 is for stainless nuts. Compared to regular stainless fasteners, F593 and F594 call for: (a) tensile requirements about 20% higher than that of commercial 18-8 or stainless hex caps and nuts to MS specifications (MS35307-8. MS34649-50); (b) both a minimum and a maximum tensile and hardness requirements while commercial and MS fasteners do not have a maximum; (c) chemical requirements that are somewhat bizarre, eliminating many commonly used mixtures of 300 or 18-8 stainless while allowing others.
The copper requirements of F593-4 permitting 3%-4% for some grades and no copper for others are senseless.
FATIGUE \u2013 Metal failure due to stresses that push first in one direction and then another. Fatigue Corrosion is caused by repeated stress in a corrosive atmosphere and is generally not associated with stainless.
FATIGUE STRENGTH \u2013 Measures the endurance of a fastener by showing the load it can accept without breaking under repeated load cycles.
FERRITIC \u2013 Comprising less than 5% of stainless fasteners, mainly type 430, it is magnetic and not hardenable by heat treatment.Though containing no nickel, ferritic stainless has a high chromium content providing greater corrosion resistance than martensitic stainless but much less than austen\u00acitic. It is mainly used by the automotive and building industries for decorative trim, architectural hardware, handrails, moldings on various products.
FINE THREADS \u2013 Proponents of fine threads claim: (a) fine threads are stron\u00acger in tension because of their larger tensile stress area; (b) because of their larger minor diameters. fine threads develop higher torque and shear strengths; (c) fine threads tap better into thin walls and more easily into hard materials; (d) fine threads require less torque to develop equivalent preloads, since they offer more resistance to vibration.
FIT \u2013 Normally referring to threads, fit is a measure of the tightness of mating parts.
FRETTING CORROSION \u2013 Occurs when vibration causes a stainless fas\u00actener to continually rub against another surface. resulting in the passive oxide film on stainless rubbing off. Fretting corrosion might occur in high tensile fasteners such as martensitic stainless.
FULL BODY DIAMETER \u2013 When the shoulder of a fastener equals the outside or major diameter of the threaded portion.
GALLING (ALSO CALLED SEIZING) \u2013 When two metals or fasteners stick together and cannot be easily loosened. In tightening fasteners, for example, pressure builds on threads as metals rub against each other, and the pas\u00acsive film preventing corrosion on stainless may not form due to lack of oxygen. Heat contributes to galling caused by high speed fastener installa\u00action. A reduced wrench speed can help. Thread lubrication is the most effec\u00active treatment for galling.
GALVANIC CORROSION \u2013 An accelerated degree of corrosion occurring when two different metals are in contact with moisture, particularly sea water. All metals have what is termed a specific electric potential, so that low level electric current flows from one metal to another. A metal with a higher position in the galvanic series will corrode sacrificially rather than one with a lower position, meaning stainless, for example, will corrode before gold.The further apart the metals on the chart, the more electric current will flow and the more corrosion will occur. No serious galvanic action will occur by combining the same metals, only dissimilar ones.To prevent galvanic corrosion, use insu\u00aclation, paint or coatings when separating dissimilar metals; or put the metal to be protected next to a metal which is not important in the assembly, so it can corrode sacrificially.
GIMLET POINT\u2013A threaded cone point usually having a point angle of 45\u00ac50 degrees.
GRIP \u2013The unthreaded part of a fastener.
HARDNESS Normally stated in terms of Rockwell or Brinell scale of mea\u00acsurement, hardness shows resistance of a fastener to rough marks and abrasions, can indicate yield strength and brittleness, and has a direct rela\u00actionship to tensile strength in alloy steel fasteners. However, for stainless, brass, and silicon bronze, the correlation between hardness and tensile or yield is tenuous with no definite relationship.
Case-hardening uses surface heat treatment on ferrous material to cause a harder outside surface than the center. Through-hardening hardens the entire fastener. Bright hardening calls for heat treatment without oxygen, so no oxides are formed on the material surface.
HEADER POINT \u2013 A chamfer at the end of a fastener formed at the time of heading but before threading.
HEAT TREATMENT \u2013 Heating often combined with cooling at controlled temperatures in order to strengthen and harden a fastener.
HOT FORGING \u2013 Heating metal to red-hot temperatures or temperatures above the recrystallization point to soften it before shaping a fastener. Hot forging is primarily used when the diameter of the metal is too large for cold forming or the quantity required is too small to economically set up a cold-forming machine.
HYDROGEN EMBRITTLEMENT\u2013 Hydrogen trapped under the surface of a fastener can later cause ruptures. It is generally associated with carbon and alloy steels, not stainless. There may be no external signs of corrosion before a break occurs.
IFI \u2013Stands for Industrial Fasteners Institute.
IN-PROCESS SAMPLING \u2013 Random samples of fasteners taken at differ\u00acent process points in the manufacture for testing comformance.
ISO \u2013 Stands for International Organization for Standardization.
INTERGRANULAR CORROSION \u2013 A technical term describing corrosion at grain boundaries (various outside portions) of a fastener. It can occur when fasteners are heated above 800 degrees during use, such as welding, which changes the chromium-carbon bond in stainless, thus allowing in\u00accreased oxidation and corrosion. To prevent intergranular corrosion, low carbon stainless should be used, or material should be annealed and quenched after exposure to elevated temperatures, so the carbon is put back into an austenitic stainless bond.
JAM NUT \u2013 A thinner nut that is “jammed” against another nut to prevent loosening.
KNURL \u2013 A rough or decorative surface on part of a fastener.
LEAD \u2013 A heavy malleable ductile metal that increases machineability.
LEFT HAND THREAD \u2013 Opposite of commonly used fasteners. With left hand thread, a nut would be tightened on a bolt by turning it counterclock\u00acwise.
LIQUID PENETRANT TEST \u2013 Dipping fasteners into a dye and then view\u00acing under ultraviolet light to look for cracks.
LOT \u2013 A particular size of fastener processed from the same raw material heat and same production process.
LOT SAMPLING\u2013 Random samples taken from the same lot of fasteners for quality inspection. Maximum lot size for inspection purposes should not exceed 250,000 pieces; thus, lots over 250,000 would require additional samples.
MS \u2013 Stands for Military Standards. The overriding characteristic of MS fasteners compared to commercial products is the extensive inspection and lot traceability for MS, guaranteeing the chemical, physical and dimensional qualities. While commercial fasteners may look similar and happen to pass many tests given MS products, the commercial fasteners lack the pedigree of guaranteed quality for chemical, physical and dimensional aspects that users who order MS fasteners rely on.
MACHINEABILITY \u2013 Same as free machining. Refers to the malleable char\u00acacteristics of metal when cutting or forming on screw machines.
MAGNETISM \u2013 As related to stainless fasteners. 300 series stainless is non-magnetic in its raw material condition. Cold working can sometimes induce traces of magnetism in 300 series, depending on the severity of cold working and chemical composition of the stainless. A rise in magnetism is related to an increase in tensile strength and work hardening caused by the heat and friction of cold forming and does not reduce corrosion resistance or cause any molecular change in austentic raw material. A higher portion of nickel can increase stability in stainless, thus decreasing work hardening and any possibilities of magnetism. Brass and silicon bronze are non-mag\u00acnetic. Many stainless specs including MS hex head cap screws allow 2.0 magnetic permeability which translates to low\/medium magnetism. Magnetic permeability of 1.0 translates to a very slight, glancing magnetism.
MAGNETIC PERMEABILITY test simply determines the level of magnetism. MAJOR DIAMETER \u2013 Largest or outside diameter of the screw threads.
MANGANESE \u2013 A non-magnetic metal which improves strength and hardness.
MARTENSITIC \u2013 Comprising approximately 5% of stainless fasteners, martensitic refers mainly to stainless types 410, 416, and 420. Named for Robert Martens, a German metallurgist, martensitic grades have a high carbon content which reduces corrosion resistance but allows a sharp in\u00accrease in tensile strength after heat treatment. Because of its high tensile strength, martensitic stainless is used for highly stressed parts such as control rod mechanisms, valves, shafts and pump parts. Martensitic stain\u00acless is magnetic, contains no nickel, loses toughness in very cold tempera\u00actures, and may have a tendency to become brittle. Its corrosion resistance is not as good as austentic or ferritic stainless, so martensitic fasteners are used in mild atmospheres.
MILLED FROM BAR (ALSO CALLED MACHINING) \u2013 Made on a screw ma\u00acchine or lathe by cutting material away from the original piece of metal. It is used for manufacturing very large diameters which cannot be cold formed and for small quantities where it would not be economical to set up cold forming equipment. However, machining can interrupt the grain of metal causing a lessening in tensile and fatigue strength.
MINOR DIAMETER \u2013The inside or smallest diameter of the screw threads.
MOLYBDENUM \u2013 Nicknamed moly, molybdenum is a metal added to 316 stainless steel, sharply increasing its corrosion resistance to chlorides and sulfates, especially various sulfurous acids in the pulp industry. Molybdenum helps reduce hardness and increase tensile strength at higher tempera\u00actures. Molybdenum is also added to Marutex\u00ae self-drilling screws made of 410 stainless to significantly increase corrosion resistance.
MONEL \u2013 Invented by the International Nickel Co. and composed basically of two-thirds nickel, one-third copper, monel has good strength, excellent corrosion resistance against salt water and in high temperatures, and is very expensive.
MUNTZ \u2013 A form of brass with about 60% copper.
NAVAL BRONZE (ALSO CALLED NAVAL BRASS) \u2013 Basic brass with a small addition of tin for added corrosion resistance against salt water.
NAS \u2013 Stands for National Aerospace Standards.
NICKEL \u2013 A metal added to 300 series stainless to provide corrosion resis\u00actance, increased strength in both high and low temperatures. and increased toughness in low temperatures. Nickel lowers the effects of work hardening, thus reducing traces of magnetism caused by cold forming and making material flow more freely in manufacturing. The addition of nickel to stainless prevents stainless from becoming brittle at sub-zero temperatures and in\u00accreases its high temperature properties.
NON-FERROUS \u2013 Metals without iron. Brass and silicon bronze are nonfer\u00acrous; stainless is often characterized as non-ferrous, but that is not correct.
NYLON \u2013 Light and low in strength compared to metal fasteners, nylon is non-magnetic, good for insulation, and corrosion resistant against many chemicals,
OVEN HEAD \u2013 Old term for truss head.
PASSIVATING \u2013 A very confusing term, since the common usage has taken on a different meaning than the technical definition. In Star’s experience, users (including engineers) of commercial fasteners seldom mean the old technical terminology. Technically, passivating is not cleaning but is a pro\u00access of dipping fasteners into a nitric acid solution to rapidly form a chromium oxide on the surface of the material, creating a passive film that protects stainless from further oxidation (see Passive Film). The purpose of passivat\u00acing is to remove both grease left from manufacturing and traces of steel particles which may have rubbed off manufacturing tools onto the fastener. In common commercial parlance (meaning non-military and aerospace), pas\u00acsivating means cleaning to users, and the terms “passivating” and “cleaning” are used interchangeably. A wide range of cleaning methods using different mixtures containing nitric, phosphoric and other acids or simply exposing cleaned stainless fasteners to air for a period of time will result in a “passi\u00acvated” condition. For fasteners that have been properly cleaned, it is impos\u00acsible to determine the method of cleaning or passivation that was used. AN\/ MS\/NAS fasteners sold by Star have been cleaned, descaled, and passi\u00acvated to the applicable engineering specifications.
PASSIVE FILM \u2013The major characteristic of stainless is its ability to form a thin layer of protection called a “passive film” on its outside surface. This film results from a continual process of low-level oxidation, so oxygen from the atmosphere is needed for the passive film to exist. Once formed, it prevents further oxidation or corrosion from occurring. Even if chipped or scratched, a new passive film on stainless will form.
PHOSPHORUS \u2013 A non-metallic substance that lowers the rate of oxidation, thereby helping resist corrosion.
PICKLING\u2013 Removing surface impurities by using chemicals.
PILOT POINT\u2013 Similar to a “B” point, a pilot point is a small (perhaps 1 \/8″-1\/ 4″) unthreaded blunt portion at the end of a sheet metal or drive screw.
PITCH \u2013 The distance between two adjacent threads measured at the out\u00acside diameter of the threads.
PITCH DIAMETER \u2013 Approximately in-between the major and minor diameters.
PITTING CORROSION \u2013 Pitting indicates deep corrosion in localized spots on a fastener. Dirt or grease on certain portions of a fastener may block oxygen from that surface, thus impeding the passive film which protects stainless from corrosion.
PRECIPITATION HARDENED STAINLESS STEEL \u2013 Type 630 stainless, little used, expensive and not sold as commercial products, it combines corrosion resistance of 300 series stainless with high tensile strength of 400 series.
PROOF LOAD \u2013 A test load that a fastener must undergo without showing significant deformation. It is usually 90% of yield strength.
QUENCH \u2013To cool suddenly and rapidly after heating.
REDUCTION OF AREA \u2013 A measurement like elongation which is related to the tensile strength of a fastener. While elongation measures the length of a fastener stretched to its breaking point compared to its original length, re\u00acduction of area measures the diameter of a fastener just before breaking compared to its original diameter.
ROLL THREADING \u2013 Forming threads on a fastener by pushing or rolling dies against the fastener without any removal of metal. Roll threading. as opposed to cut threading. hardens the material making the threads stronger.
ROOT DIAMETER \u2013 Refers to the minor diameter on screws or the major diameter on nuts.
SAE \u2013 Stands for Society of Automotive Engineers.
SCALE \u2013 A discoloring or oxidation on the surface of hot forged fasteners.
SCREW MACHINE \u2013 Cutting and removing material in order to form a fastener.
SECONDARY OPERATIONS \u2013 Less important than the major steps of heading or cold forming fasteners, secondary operations include grinding, polishing,drilling.
SEMI FINISHED HEX CAPS \u2013 The normally sold variety of stainless hex head cap screws, semi finished have the same dimensions as a finished fastener but with generally greater tolerances.
SHEAR STRENGTH \u2013 Measured by the push or pull against the side of a fastener until the fastener breaks (for example, moving an object continually against the side of a screw that is protruding from a wall). As a rule of thumb, shear strength is two-thirds of tensile strength. Double Shear Strength is applying a load against a fastener in two places causing the fastener to break into three pieces.
SILICON \u2013 A non-metallic substance that adds strength and toughness to copper to help form a bronze alloy.
SILICON BRONZE \u2013 An alloy made of 95%-98% copper plus a small amount of silicon added for strength. Small amounts of manganese and aluminum may also be added for strength, and lead may be added for machineability.Silicon bronze is non-magnetic with a high degree of thermal conductivity and high corrosion resistance against sea water, gases, and sewage. It is often used by the utilities industry for pole line hardware and switchgear equipment. mine sweeping, sewage disposal equipment, food machinery, marine applications, plumbing and liquid handling. Surprisingly, silicon bronze is only a low to moderate conductor of electricity, though it is a better conductor than stainless.
SOLUTION ANNEALED (SAME AS CARBIDE SOLUTION ANNEALED) \u2013A process of heating and removing carbide precipitants (carbon that has broken loose from its stainless steel solution) by heating raw material or a finished fastener to over 1,850 degrees and cooling it quickly, usually in water, so carbon content goes back into the stainless solution.
STAINLESS STEEL \u2013With the addition of 12% chromium to iron, stainless steel is formed. The chromium protects the iron against most corrosion or red-colored rust; thus the term “stainless” steel. The ability of stainless to form a thin layer of protection on its outside surface, called a “passive film”, is its most important characteristic in preventing corrosion (see Passive Film).
The overriding purpose of stainless steel is to provide corrosion resis\u00actance against: (a) atmospheric conditions such as carbon dioxide, moisture, electrical fields, sulfur, salt, and chloride compounds; (b) natural and artifi\u00accially produced chemicals (c) extremes of weather where cold tempera\u00actures cause brittleness and hot temperatures reduce strength and increase corrosion. For more information, see Austenitic, Martensitic, Ferritic, and Precipitation Hardening. When iron or ordinary steel are exposed to air, the oxygen in the air combines with iron to form iron oxide known as rust. When stainless steel is exposed to air or oxygen, a thin layer of film, chromium oxide. forms on the surface. If this film is broken, it will quickly reform if enough oxygen is present.
STAMPING \u2013 Punching out parts with dies, usually referring to flat washers. STOVE HEAD \u2013 Old term for truss head.
STRAIN HARDENED \u2013 To increase hardness and strength by (a) cold working of raw material by a steel mill or (b) cold forming by a fastener manufacturer, The standards for strain hardened material vary with different specifications. Cold forming by a fastener manufacturer can sharply in\u00accrease tensile strength and hardness, so that ordinary material from a steel mill may often be used. However, fasteners that are milled from bar will decrease in strength and hardness, so that raw material would need to be strain hardened by a steel mill before milling the fasteners.
STRESS CORROSION \u2013 Occurs when corrosion causes a highly stressed part (one that is pushed to its maximum tensile strength) to crack. Except for heat treated 400 series stainless, stress corrosion does not normally apply to austenitic stainless, brass, or bronze, since these metals are relatively ductile and not normally used for high tensile operations.
SULFUR \u2013 A non-metallic substance found in large quantities by itself or combined with other elements to form sulfates and sulfides. It improves machineability and helps cool material and prevent galling, but its presence lowers the corrosion resistance of stainless.
TANTALUM \u2013 A gray ductile metal with a high melting point and excellent corrosion resistance against certain chemicals.
TAP \u2013To put internal threads in a hole or in a nut. TAP BOLT \u2013 Fully threaded bolt.
TEMPER \u2013To heat material after hardening to a temperature of perhaps 1000 degrees F. and allow to cool naturally in order to soften material and make it less brittle. Or to heat to a lower temperature of possibly 500 degrees F. to relieve stress in metal without affecting the hardness.
TENSILE STRENGTH \u2013 A common measure to compare the strength of a fastener. It is the load needed to pull the fastener apart.
THREADS \u2013 Class 1 threads are a loose tolerance. Class 2 threads com\u00acprise 90% of stainless fasteners and are normal commercial tolerance. Class 3 threads have a stricter tolerance and tighter fit such as socket cap and set screws. No definite relationship exists between tensile strength and tight\u00acness or looseness of fit. The symbol “A” added to threads, such as 2A, means external threads (screws), and “B” means internal (nuts).
With the exception of 10\/32 diameter. which is extremely popular, coarse thread comprises 90-95% of hex head cap screws and hex nuts sold in 18\u00ac8 stainless, and perhaps 98% of other stainless items including machine screws and socket products. Coarse threads are deeper than fine threads with fewer threads per inch, so coarse threads may have greater protection against thread stripping, better tap in brittle materials, and better fatigue resistance. while fine threads may have better fit in thin-walled materials, higher torque strength, and increased tightness during vibration.
TIN \u2013 A malleable and ductile metal which increases strength, hardness and corrosion resistance against salt water when added to brass alloys.
TITANIUM \u2013 A silvery gray metal with high corrosion resistance against salt waters, chlorides, and many acids. It is strong, though lightweight, and very expensive.
TORQUE OR TORSION STRENGTH \u2013 Torque is the force used in twisting, such as tightening a fastener. Torsion strength is the amount of force needed to twist a fastener apart. Both measures consider the amount of pressure applied to the fastener and the length of the wrench used in the application.
TOUGHNESS \u2013 A fastener’s capacity to accept various impacts and shocks.
TUMBLING \u2013To flip fasteners around like clothes in a dryer in order to clean fasteners and increase the shininess of stainless. Soap or a cleansing solu\u00action are often added.
UN, UNR \u2013 Indicates “unified” screw threads to “inch” dimensions used in the U.S. as distinguished from metric dimensions.
UNJ \u2013 A type of threads originating around the 1950’s with a more rounded fit in order to prevent cracks, reduce loosening due to vibration and slightly increase strength. Possessing a tighter fit, UNJ thread depth is smaller than the usual UN standards with the minor diameter of external threads on screws and internal threads on nuts both increasing. UNJ is used in critical applications by the aerospace and automotive industries.
UNDERSIZE BODY OR REDUCED BODY DIAMETER \u2013Where the shoulder of a fastener equals the pitch diameter or less, which means the shoulder is smaller than the outside diameter of the threads. It would indicate that a fastener was not extruded during its manufacture.
WASHER FACE \u2013 A circular rim on the underside of the head of a bolt or on one side of a nut with the purpose of providing a flat bearing surface for the bolt or nut to sit on. A smooth washer face takes away any burrs or imperfec\u00actions caused by the manufacturing process.
WORK HARDENED \u2013 An increased level of hardness caused by cold form\u00acing fasteners. Too much work hardening may cause a slight degree of magnetism in austenitic stainless.
YIELD \u2013The resistance to a load pulling on the middle of a fastener until the fastener shows permanent deformation.
YIELD STRENGTH \u2013The amount of pressure required to cause permanent deformity.<\/p>\n\n\n\n
Inspection & Approval Certificates : C\/W Certificate (Calibration Works Certificate) EN 10204 3.1 \/ DIN 50049 3.1 \/ ISO 10474 3.1 Mill Test Certificate,
ISI Mark, BIS Certified, NACE HIC TM-0284 \/ NACE MR-0103 \/ NACE MR-0175 \/ ISO 15166, CE Marked, European Pressure Equipment Directive
PED-2014\/68\/EU, AD-2000-WO, ASME Boiler & Pressure Vessel Code Section-II Part A Edition 2019, API 6A (American Petroleum Institute),
with EN 10204 3.2 Certificate duly Certified & Approved by IBR (Indian Boiler Regulations), LR Class (Lloyd\u2019s Register), GL (Germanischer Lloyd),
BV (Bureau Veritas), DNV (Det Norske Veritas), ABS Class (American Bureau of Shipping), SGS, TUV, RINA, IR Class (Indian Register of Shipping),
NORSOK Approved Standard M-630, M-650 Rev.3<\/p>\n\n\n\n
If you have any requirement of above items, please feel free to contact us<\/p>\n\n\n\n
Regards,<\/p>\n\n\n\n
CONTACT PERSON :<\/strong><\/p>\n\n\n\n MUKESH SHAH ROLEX METAL DISTRIBUTORS CHAIRMAN \u2013 chairman@rolexmetals.com “A” SHEET METAL SCREWS \u2013 Sheet metal screws with (a) sharp-pointed ends; (b) fewer threads per inch than type AB screws: and (c) deeper threads with better gripping power than type AB. The Industrial Fasteners Institute incorrectly labels type A an “obsolete”<\/p>\n
Director
Mobile No. 0091 \u2013 9820292499
Email \u2013 marketing@rolexmetals.com<\/strong><\/p>\n\n\n\n
57-A Khatargalli
Thakurdwar
Mumbai \u2013 400 002 India
0091-22-23858802
0091-22-23823963
0091-22-23898724
marketing@rolexmetals.com
www.rolexmetals.com<\/strong><\/p>\n\n\n\n
MANAGING DIRECTOR \u2013 managingdirector@rolexmetals.com
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WEBMASTER \u2013 webmaster@rolexmetals.com
CUSTOMER CARE \u2013 customercare@rolexmetals.com<\/p>\n","protected":false},"excerpt":{"rendered":"