McGuire Glossary of Fastener Terminology

N - 67 terms

N-Designation - Designation used in structural bolting which indicates that the threads of, the bolt may be included in the shear plane of the joint. This designation refers to the usage of the bolt in the joint. It does not indicate a special bolt.

NAGARA - A smooth production flow, ideally one piece at a time, characterized by synchronization (balancing) of production processes and maximum utilization of available time. This includes overlapping operations where practical.

NAIL POINT - A sharp pyramidal point generally having a point angle of 30 to 45 degrees and produced by a pinching operation. It is designed for piercing wood or other resilient materials.

NAS DRAWINGS AND SPECIFICATIONS - Dimensional and material standards for aircraft fasteners developed by the National Aircraft Standards Committee. All drawings and specifications are prefixed by NAS.

NATURAL DRAFT - Taper on the sides of a forging, due to its shape or position in the die, that makes added draft unnecessary.

NATURAL FREQUENCY (FE) - The frequency at which a spring will freely vibrate once it has been excited.

NAVAL BRASS - A corrosion resistant metal containing 60 per cent copper, 39 1/4 per cent zinc and 3/4 per cent tin.

NAVAL BRONZE - Contains slightly more zinc than regular brass. Good for saltwater environments.

NEAR-NET-SHAPE FORGING - Forging components as close as possible to the required dimensions of the finished part.

NECK - (1) a specialized form of a portion of the body of fasteners near the head designed to perform a definite function, such as preventing rotation, etc., and (2) a reduced diameter of a portion of the shank of a fastener which is required for design or manufacturing reasons.

NECK DOWN - The name for the process by which a ductile metal elongates and reduces in cross sectional area once it has been stressed beyond its ultimate tensile strength.

NEEDLE POINT - A cone point of long length intended to perform a piercing function.

NEOPRENE WASHER (NAIL) - A nail with a neoprene washer to seal against moisture; often used for exposed applications such as flashing.

NESTED - Term used to identify a Smalley Flat Wire Compression Spring in a "Parallel" configuration, having a sinusoidal waveform. The wave contour in each 360 degree turn matches (nests), increasing the spring rate proportionally to the number of turns.

NESTING - (1) Grouping of identical or different parts in multiples within a workpiece to conserve material. (2) In packaging, stacking of parts whose shape permits one to fit inside another.

NESTING - The positioning of multiple pieces in a forging die design.

NET-SHAPE FORGING - Forging components on one or more sides to net shape requiring no further machining on at least one side, e.g. net forged gear with machined back face.

NEUTRAL SALT SPRAY TEST (NSS) - The purpose of the NSS is to observe corrosion of the pre-plate and/or breakdown of lifting of the top coat. The test takes place in a chamber for either 100 hours (Standard MIL spec.) or 336 hours (G.M. exterior spec).

NEWTON - A metric unit of force. One newton is equal to the force of gravity on one kilogram of mass.

NIB - A small perishable punch or die.

NIBBLE MARKS - Slight irregularities at the edge of the stock surface after progressive punching (nibbling) operations in a turret press.

NIBS - The raised projections on the underside of weld nuts. During welding into the sheet metal, the nibs melt and fuse to the sheet material.

NICKED THREADS - Nicks or indentations in threads can occur during the manufacturing process and during fastener transportation. In general, nicked thread problems tend to increase as the thread diameter increases and for fine pitches. There are acceptance tests for nicked threads that involve measuring the maximum torque required to drive a GO gauge down the thread. Examples of acceptance tests are SAE J123 and the Ford Motor specification WA990 1993. Nicks and indentations in threads are sometimes referred to as gouges.

NICKEL - A silver-white metal usually used as an alloy in steel, bronze, brass and cast iron. It tends to increase corrosion resistance and increases strength at both high and low temperatures. Nickel lowers the effects of work hardening thus helping to reduce the magnetism that can occur from cold forming.

NICKEL COPPER 400 - This alloy is approximately 70% Nickel and 30% Copper. It has excellent strength and corrosion resistance and is used in salt water marine and other chemical environments.

NICKEL PLATING - As an electro-deposit, this coating is used primarily when a decorative bright silver finish is desired. If high hardness and good chemical resistance are required, parts are often coated with electroless nickel. This has the advantage of being able to build thickness evenly on both the inside and outside of a part. Other than E-Coating, electroless nickel is one of the only coatings that will achieve total coverage. Other properties include excellent chemical resistance in a hard, durable finish. More decorative than zinc plating but does not provide the sacrificial protection.

NICKEL STEEL - Alloy steel containing nickel as its principal alloying element.

NITRIDING - A surface hardening process used on ferrous metals by heating the metal in contact with ammonia gas or other nitrogenous material, usually ammonia or molten cyanide of appropriate composition.

NITRIDING - Introducing nitrogen into the surface layer of a solid ferrous alloy by holding at a suitable temperature (below Ac 1 for ferritic steels) in contact with a nitrogenous material, usually ammonia or molten cyanide of appropriate composition. Quenching is not required to produce a hard case.

NITRIDING - A process of case hardening in which an iron-base alloy of special composition is heated in an atmosphere of ammonia or in contact with nitrogenous material. Surface hardening is produced by the absorption of nitrogen without quenching.

NITROCARBURIZING - Any of several processes in which both nitrogen and carbon are absorbed into the surface layers of a ferrous material at temperatures below the lower critical temperature and, by diffusion, create a concentration gradient. Nitrocarburizing is done mainly to provide an anti-scuffing surface layer and to in prove fatigue resistance. Compare to carbonitriding.

NITROCARBURIZING - Any of several processes in which both nitrogen and carbon are absorbed into the surface layers of a ferrous material at temperatures below the lower critical temperature and, by diffusion, create a concentration gradient. Nitrocarburizing is done mainly to provide an anti scuffing surface layer and to improve fatigue resistance, Compare with carbonitriding.

NO-DRAFT FORGING - A forged shape with extremely close tolerances and little or no draft, requiring a minimum of machining to produce the final part. Mechanical properties can be enhanced by this closer control of grain flow and retention of surface material in the final component.

NO-GO GAUGE - An inspection tool used to check a threaded part against allowed tolerances. There are ring gauges (for external threads) and plug gauges (for internal threads). A NO-GO gauge is designed to not thread on or into the part being inspected.

NOBEL METAL - A metal that does not readily tend to furnish ions, and therefore does not dissolve readily, nor easily enter into such reactions as oxidations, etc. The opposite of base metal. Examples of noble metals are silver, gold, platinum etc. Note: In order to avoid any confusion concerning the sign of electrode potentials, the words noble and base are often preferred because they are unambiguous.

NOMINAL DIAMETER - The diameter equal to the external diameter of the threads.

NOMINAL SIZE - The designation used for the purpose of general indemnification.

NON-FERROUS METAL - Metals or alloys without an appreciable amount of iron. Examples are aluminum, brass, copper, nickel, and titanium.

NON-MAGNETIC - Materials that have a maximum permeability of 2.0 (air=1.0) for a field strength of H=200 oersteds using a magnetic indicator per MIL-I-17214. Generally associated with the 18-8 stainless steel series.

NON-STANDARD FASTENER - A fastener which differs in size, length, material, or finish from established and published standards.

NON-THREADED FASTENER - A type of fastener that does not contain threads.

NON-VALUE ADDED - Those actions that the customer is not willing to pay for. Any activity that does not add value to the production or service.

NONDESTRUCTIVE INSPECTION - Any method of detection or measurement of the properties or performance capabilities of materials, parts, assemblies, or structures that does not impair the surface of internal integrity of the part.

NONFERROUS - Metals or alloys that contain no appreciable quantity of iron. Applied to such metals as copper, aluminum and brass

NONFILL (UNDERFILL) - Forging condition that occurs when the finish die impression is not completely filled with metal. Some causes are: improper distribution of metal in preforming operations such fullering, edging, and blocking; excessive removal of materials by chipping defects prior to finish forging; improper lubrication of die impression; low forging pressure; rough or uneven die finish; inadequate hammer or press capacity.

NORMALIZE - To remove internal stresses by heating a metal piece to its critical temperature and allowing it to cool very slowly.

NORMALIZING - A process in which an iron-base alloy is heated to a temperature above the transformation range and subsequently cooled in still air at room temperature.

NORYL(R) (PP3) (Plastics) - Modified polyphenylene ether is one of the more wildley known engineereing plastics and has gained UL and FDA approval for a broad spectrum of moldable and foamable grades. It has good impact strength at low temperatures and is resistant to many agents, including steam. It may be flurnished in either unreinforced grades and remains stable when processed. Yield stength or reinforced grades is comparable to aluminum. Typical end uses include computer and electric housings, automotive body parts, any piping.

NOSE ASSEMBLE/NOSE EQUIPMENT - A kit of parts fitted to an installation tool. The nose assembly must be matched to a specific fastener as it influences its installation and performance.

NOSE TIP - The interchangeable front-most part of a nose assembly. The nose tip must be matched to a specific fastener as it influences its installation and performance.

NOSEPIECE - The structural member of the installation tool that supports the head of the fastener during installation. With the head being supported and an axial load applied to the threads, the counterbore is placed in compression causing it to yield and create the bulb. For spin-spin tools the nosepiece has radial serrations to prevent the insert from rotating relative to the tool. Spin-pull tools have smooth nosepieces. The nosepiece is sometimes referred to as an anvil.

NOTCHING - Operation in which the punch removes material from the edge or corner of a strip or blank.

NOZZLE (GAGING) - The orifice in the air gage tooling that emits the air which blows against the part being measured. The diameter size of the nozzle is dictated by the air gage system used. The quantity and locations of nozzles are determined by the measurement applications.

NOZZLE DROP (GAGING) - The engineered distance that a nozzle is recessed below the surface of the air gage tool. Nozzle drop is governed by the air gage system. A deeper nozzle drop can provide longer wear life of the air gage tool.

NOZZLE DROP (GAGING) - The engineered distance that a nozzle is recessed below the surface of the air gage tool. Nozzle drop is governed by the air gage system. A deeper nozzle drop can provide longer wear life of the air gage tool.

NPV - An acronym representing net present value. This calculation considers cash flow, time and interest rate.

NUMBER OF TURNS(N) - The number of 360 degree turns of flat wire formed in a retaining ring or wave spring.

NUT - A nut is a block or sleeve having an internal thread designed to assemble with the external thread on a bolt, screw, or other threaded part. It may serve as a fastening means, an adjusting means, a means for transmitting motion, or a means for transmitting power with a large mechanical advantage and non-reversible motion.

NUT DILATION - Under load, the wedging action of the threads causes dilation of the nut resulting in an increase in the minor diameter of the nut; and reducing the effective shear areas of both the external and internal threads.

NUT SHEAR AREA - The cross-sectional area of the nut which would need to shear for a nut stripping failure to occur.

NUT THICKNESS - The overall distance from the top of the nut to the bearing surface, measured parallel to the axis of the nut.

NUTSERT® - Nutserts employs a different technology than other blind threaded inserts. A fracture point is designed into the insert causing the part to break into two separate parts when the installation load is applied. The exterior of the threaded portion has a taper which is forced into the counterbore causing it to expand radially against the wall of the mounting hole

NUVO DRIVE SYSTEM - #2NR (NUVO) drive is compatible with your #2R (Square Drive) recess. Dramatically reduces wobbling and stripping put, enabling single-handed operation. Designed to maximize torque transfer.

NUVO™ DRIVE SYSTEM - The drive recess which is compatible with #2 Robertson drive has rounded lobes, when used with Nuvo drivers dramatically reduce wobbling and stripping out, enabling single-handed operation.

NYLON - Nylon 6/6 is the most popular nylon material for fasteners. However, there are several different types of nylon for different fastening applications. Advantages of nylon fastener include light weight, good resistance to many chemicals and good for insulation. But the are some disadvantages and all must be considered in applications: Moisture, UV Resistance, Chemical Resistance, Temperature, Flammability and Strength.

NYLON - All grades posses toughness and resiliency and have a high fatique strength. Resistance to oils and hydrocarbon solvents is also good. Almost all formulations are also self-extinguishing and retain stable mechiancal properties at temperatures from -75F to above 225F. They are widely used for latches, cams, gears, and many other moving parts due to their excellent abrasion and impact resistance. Nylon is also available in a variety of cast forms and mobdylidenum disulphide filled grades (Nylatron(r) GS).

NYLON NAIL-IT - The body of a nylon nail-it is made from a polyamide resin thermoplastic mold injection material, the steel pin expander is a low carbon zinc plated steel. The body is hollow, one end is split and the other end has either a mushroom head, round head or flat head. The steel pin expander has threads on the point end and the head is slotted to accept a screwdriver.