Glossary of Terms

Alphabetical Glossary of Technical Terms

This alphabetical glossary covers technical terms and terminology used throughout our website, including adhesives, Huck Rivets, Huck Bolts, sealants and silicones, as well as specialised product brands such as Xtralok®.

Bulge: Refers to the radial expansion of a rivet or rivet nut body during installation. As the fastener is installed, its body shortens and expands outward, creating a bulge that helps secure the joint.

Calliper: A measuring instrument with adjustable jaws used to accurately measure internal and external dimensions, thicknesses and, depending on the design, depth.

Closed End: A term used to describe a nutsert or rivet that is enclosed at one end, rather than being open or hollow throughout.

Countersinking: A drilling or machining process that creates a conical recess, allowing the head of a countersunk fastener to sit flush with the surrounding material.

Countersunk Head: A fastener head designed to sit flush with, or slightly below, the surrounding surface when installed in a correctly sized countersunk hole.

Curing: The process by which an adhesive or sealant develops its final properties, such as strength, adhesion and elasticity. Depending on the product, curing may involve a chemical reaction rather than simply drying. A surface that feels dry or has formed a skin does not necessarily indicate that the product is fully cured. Always refer to the manufacturer's technical data sheet for the correct curing time and conditions.

Dome Head: A rounded, curved fastener head that sits above the surface of the material after installation.

Flat Head: An alternative term sometimes used for a countersunk head, designed to provide a flush finish with the surrounding material. Terminology can vary depending on the fastener type.

Full Hex: A hexagonal-bodied nutsert with a shank that is predominantly hexagonal in shape and features a lead-in chamfer to assist with insertion. Designed for installation in a matching hexagonal hole, the hex-shaped shank provides improved spin-out resistance compared to half-hex and round-body nutserts.

Green Strength: The initial holding strength of an adhesive before it has fully cured. Good green strength can reduce the need for clamps and other supporting devices during assembly, potentially lowering production time and costs.

Grip Range: The range of material thicknesses, expressed as minimum and maximum values, that a fastener is designed to securely hold. It is important to note that the maximum grip range is not the overall length of the rivet or the shank length of the bolt.

Half Hex: A nutsert with a shank that is partly hexagonal and partly circular in shape. Designed for installation in a matching hexagonal hole, the hex-shaped section offers improved spin-out resistance compared to round-body nutserts.

Head: The upper portion of a fastener that may engage with an installation tool or assist in securing materials together. Common head styles include dome, truss, countersunk and other specialised designs.

High Tack: Refers to an adhesive's ability to grip or bond to a surface immediately upon contact. High-tack adhesives provide an initial hold that can help keep materials in position during assembly, even before the adhesive has fully cured.

Huck®: A registered trademark of Huck International, now part of Howmet Fastening Systems. Huck fastening technology was developed to address the problem of fasteners loosening under continuous vibration. In 1944, Louis C. Huck sketched the concept of a vibration-resistant lockbolt, laying the foundation for the famous Huck bolt.

Huck Bolts: A two-part fastening system consisting of a grooved pin and a collar. Unlike conventional nuts and bolts, Huck bolts are installed using a specialised industrial tool that swages the collar into the locking grooves of the pin, creating a permanent, vibration-resistant joint. Huck bolts are also commonly known as lockbolts.

Huck Rivets: The Huck Magna-Lok® is one of Australia's popular Huck rivets, valued for its extended grip range and ability to accommodate varying material thicknesses. This high-performance structural rivet features Huck's unique 360-degree internal locking mechanism, providing excellent resistance to vibration and helping prevent moisture ingress. Its wide grip range can reduce the number of rivet sizes required, helping minimise inventory, labour and installation costs.

Imperial: A system of measurement based on units such as feet, inches, pounds and gallons. Although Australia predominantly uses the metric system, imperial measurements are still commonly encountered in fastening applications. On this website, imperial dimensions may be represented by the double-prime symbol (″) or the abbreviation 'in' for inches.

Joint Sealant: A sealing product designed to fill and seal joints or gaps between different materials. Joint sealants help prevent the passage of moisture, air and dust while often allowing for movement between adjoining surfaces.

Knurled: A textured pattern of raised lines or ridges that can run horizontally, vertically, diagonally or in a criss-cross formation across a surface. On nutserts, the knurled or splined pattern helps the fastener grip the parent material during installation, providing improved torque and spin-out resistance compared to standard smooth-body nutserts.

Lab: Short for laboratory. A facility used for testing, experimentation, research and product evaluation.

Laboratory: A controlled environment equipped for conducting experiments, research, measurements and product testing.

Levelling Feet: Adjustable components used to stabilise and level furniture, machinery and equipment on uneven floors. They typically consist of a threaded shaft (stud) attached to a perpendicular base that acts as a foot. The threaded stud screws into a compatible threaded tube insert and can be independently extended or retracted until the attached item is level.

Mandrel: A shaft or pin used to support, shape or install a component. In nutsert installation tools, the threaded mandrel engages with the internal thread of the nutsert to facilitate installation. In blind rivets, the mandrel is the pin pulled by the installation tool to expand and secure the rivet body.

Maumac®: A registered trademark of Aerobolt Australia Pty Ltd, originating from the former business name Maumac Distributors.

Max. Grip: The maximum material thickness that a fastener is designed to securely hold. If the material exceeds this thickness, the fastener may not form correctly during installation, potentially resulting in an inadequate or insecure joint.

Metric: A system of measurement based on units such as millimetres, centimetres, metres, litres and kilograms. In fastening applications, the capital letter 'M' commonly identifies a metric thread size, such as M6 or M8, while 'mm' represents dimensions measured in millimetres.

Min. Grip: The minimum material thickness that a fastener is designed to securely hold. If the material is thinner than this specified value, the fastener may not form correctly during installation, resulting in reduced holding strength or an insecure joint.

Nose Assembly: A critical attachment used with Huck installation tools for installing pin-and-collar Huck bolts or structural rivets. Some compatible installation tools can accommodate different fastener types by changing the nose assembly to suit the specific fastener.

Nosepiece: The front component of a nutsert installation tool that supports and guides the mandrel during installation.

Nutsert: An internally threaded rivet nut designed to provide a secure female thread in thin or hollow materials where conventional nuts may be impractical. During installation, the nutsert body deforms to grip the parent material, creating a permanent threaded fixing point. Nutserts are available in a range of body styles, including smooth, knurled and hexagonal designs.

Open End: A term used to describe a nutsert or rivet with an open or hollow end, rather than a fully enclosed or sealed end.

Orlock® Rivet: Orlock® rivets secure materials on both sides of the application, offering high joint strength compared to some multi-grip structural rivets, although they have a more limited material grip range. Orlock® rivets are popular for their compact blind-side bulb, which helps resist pull-through and provides a secure fastening solution. Learn more in our structural rivet blog.

POP®: A registered trademark historically associated with blind rivets. The term 'pop rivet' is also widely used as a general description for blind rivets.

Pre-Bulbed: Refers to a threaded insert, such as a Plus Nut, where the initial bulb formation takes place during manufacturing. This design reduces the installation force required to set the insert. However, a pre-bulbed insert generally requires a larger mounting hole to accommodate the partially formed bulb.

Pull-Out: The axial force required to pull an installed nutsert out of its parent material. Pull-out resistance is an important performance characteristic when evaluating the strength and reliability of threaded insert installations.

Push-Out: The axial force required to push an installed nutsert out of its mounting hole in the direction away from the fastener head. Push-out resistance helps determine the security of the installed insert under applied loads.

Ribbed / Splined: A pattern of raised lines, ridges or grooves formed on the surface of a fastener. These features help the fastener grip the surrounding material during installation, improving resistance to rotation and spin-out.

Rivet Lad: Riley the Rivet Lad is Aerobolt's mascot.

Rivet Test Lab: Aerobolt's testing laboratory provides testing services for rivets, Rivnuts, rivet nuts, Nutserts, Huck bolts, sealants, adhesives and other fastening products.

Rivets: Mechanical fasteners used to permanently join two or more pieces of material. A typical blind rivet consists of two components: a tubular body and a pin known as the mandrel. During installation, a rivet tool pulls the mandrel through the rivet body, causing it to expand on the blind side of the material. This expansion creates a secure joint by clamping the materials together.

Rivnut: An internally threaded blind insert that provides a permanent female thread in thin or hollow materials where access to the rear of the application may be restricted. Rivnuts allow bolts or screws to be installed and removed while the threaded insert remains secured in the material. Rivnut is also identified as a registered trademark of Rivnut Fastening Systems Pty Ltd.

Rivtec®: A registered trademark of Rivtec Limited in New Zealand.

Sealant: A product used to fill and seal gaps, joints and openings between different materials. Sealants are commonly designed to prevent the passage of water, air, dust and other substances while accommodating movement between adjoining surfaces.

Shank: The portion of a fastener located beneath the head. Depending on the fastener type, the shank may be smooth, threaded, knurled, ribbed or otherwise shaped to suit the application.

Shear: A force acting across a fastener or material, typically perpendicular to the fastener's axis. Shear strength refers to the maximum shear stress a material or fastener can withstand before yielding or failing. Shear loads are common in applications where joined materials are subjected to opposing sliding forces.

Silicone: A flexible polymer-based material commonly used in sealants for construction, manufacturing and general-purpose applications. Silicone sealants are valued for their flexibility, durability and resistance to moisture and weathering. Most conventional silicone sealants are not paintable, so product compatibility should always be checked before application.

Slotted Shank: A term used to describe the slotted body of threaded inserts such as Plus Nuts and Jack Nuts. The slots allow sections of the shank to expand during installation, creating a cross-shaped blind-side bulb and accommodating a wider material grip range. Slotted-shank Plus Nuts may require higher installation forces due to their thicker walls. Some versions are pre-bulbed to reduce the installation load.

Spin-Pull: A nutsert installation method where a tool first rotates a threaded mandrel into the nutsert using low torque, then applies an axial pulling force to deform and secure the insert. Once the nutsert has been installed, the mandrel rotates in the opposite direction to disengage. This process is also known as spin-pull-spin. Compared to spin-spin tools, spin-pull tools can be more complex, heavier and more expensive, but they provide controlled installation through a direct pulling action.

Spin-Spin: A nutsert installation method that uses a rotating threaded mandrel to apply the force required to deform and secure the insert. In pneumatic spin-spin tools, an air motor drives the mandrel through reduction gearing, while a thrust bearing helps reduce friction during installation.

These tools are generally lightweight, economical and available with different gearing configurations. As the thread size increases, additional gearing can provide greater torque at the expense of installation speed. Stall torque can be adjusted by changing the air pressure.

Operation involves rotating the mandrel until the required setting torque is reached, then reversing the rotation to remove it from the installed nutsert. A serrated nosepiece may be used to help prevent the insert from rotating, although this can leave marks on the fastener head.

Spinning Out: Refers to the unwanted rotation of a fastener, particularly a threaded insert, within its mounting hole. This occurs when the insert fails to grip the surrounding material securely, preventing a bolt or screw from being tightened correctly.

Stroke: The distance travelled by an installation tool's piston during the fastener-setting process. Stroke length is an important factor in achieving the correct installation of certain rivets, nutserts and lockbolts.

Structural Rivets: High-strength rivets designed for demanding fastening applications. Unlike standard blind rivets, many structural rivets feature an internal locking mechanism that retains part of the mandrel within the rivet body after installation. This creates additional reinforcement within the fastener, helping increase joint strength and resistance to vibration.

Swage: A fastening process that permanently deforms a non-threaded collar into the locking grooves of a pin. Swaging is commonly associated with Huck bolts and other lockbolt fastening systems, creating a secure, vibration-resistant joint.

Tack: The ability of an adhesive to grip a surface immediately upon contact. Good tack allows components to be held in position during assembly, often reducing the need for additional supports or clamps. Tack differs from green strength, which refers to the initial strength of an adhesive bond before full curing.

Tensile: Refers to a pulling or stretching force applied to a material or fastener. Tensile strength is the maximum tensile stress that a material can withstand before failure.

Torque: The twisting or rotational force applied to an object, commonly associated with tightening nuts, bolts, screws and other threaded fasteners. Torque is typically measured in newton-metres (N·m).

Truss Head: A wide, shallow, rounded fastener head with a lower profile and larger bearing surface than a standard dome head. The wider head helps distribute the clamping force over a greater surface area.

Tube Threaded Insert: An internally threaded component designed to fit inside the end of a tube, commonly used in furniture, machinery and equipment that require adjustable levelling feet. The threaded tube insert provides a permanent female thread into which the adjustable foot's threaded stud is screwed. Together, the tube threaded insert and levelling foot form a two-part system that allows the height of the item to be adjusted as required.

Upset: A term used to describe the deformation or compression of a rivet or nutsert body during installation. This process creates a bulb or bulge that secures the fastener against the parent material.

Xtralok®: A registered trademark of Aerobolt Australia Pty Ltd. The Xtralok® brand is associated with a range of quality fastening products, including nutserts and multi-grip rivets, designed for reliable performance across various industrial applications.