Glossary

A V-bolt is a fastener with a V-shaped body and threads on both ends, designed specifically to clamp objects with angled or V-shaped profiles. Unlike the round or square shapes of a U-bolt, the V-bolt's design allows it to fit snugly over a triangular or angled surface, such as a structural beam or a bracket. It works by having its threaded legs pass through a mounting plate, with nuts then tightened to create a strong clamping force that secures the object in place and prevents it from slipping.

This specialized shape makes V-bolts an excellent choice for a variety of applications, particularly those involving mounting and bracing on angled surfaces. They are widely used in construction, for securing components to structures with V-shaped tops, and in telecommunications for mounting antennas and masts to poles. Their ability to provide a secure, non-slip grip on angled components makes them a reliable and versatile fastener in many industries.

A vented screw, also known as a vacuum or hollow screw, is a specialized fastener with a hole drilled through its center along its entire length. Its primary purpose is to eliminate "virtual leaks," which are pockets of trapped air and gas that can compromise a vacuum system. When a regular screw is used in a blind-tapped hole (one that doesn't go all the way through a material), air gets sealed in, which then slowly leaks out. The central hole of a vented screw provides a clear path for this trapped air to escape, allowing a vacuum chamber to be pumped down more quickly and completely.

This unique design makes vented screws essential in applications where a high-quality vacuum is critical. They are commonly used in scientific and medical equipment, semiconductor manufacturing, and aerospace systems where a clean, sealed, and pressure-regulated environment is required. By ensuring that no air is trapped, vented screws help maintain the integrity and performance of the vacuum.

A vernier caliper is a precision measuring instrument used to determine the exact dimensions of an object—such as length, diameter, thickness, or depth—with high accuracy. It consists of a main scale and a sliding vernier scale that work together to provide readings typically accurate to 0.02 mm (0.001 inch) or better.

The instrument features two sets of jaws: the larger jaws measure external dimensions (like the outer diameter of a bolt or shaft), and the smaller jaws measure internal dimensions (such as the inside diameter of a hole). Many models also include a depth probe that extends from the end of the caliper to measure the depth of holes, slots, or recesses.

The principle behind the vernier caliper is the Vernier scale, a secondary scale that allows the user to read between the smallest divisions on the main scale. By aligning the vernier scale marks with those on the main scale, the user can determine fractional measurements with very fine precision.

Vernier calipers are widely used in manufacturing, machining, mechanical engineering, metalworking, and quality control because they provide a reliable and versatile way to measure components without relying on electronic devices.

A vibration-damping mount (also called an anti-vibration mount or vibration isolator) is a mechanical component designed to absorb and reduce the transmission of vibration and shock between two connected parts—typically machinery and its supporting structure. These mounts are made from elastic materials such as rubber, neoprene, silicone, or specialized polymers that deform under dynamic loads to dissipate vibrational energy as heat.

When machinery operates—such as motors, compressors, pumps, or fans—it generates vibrations that can travel through its mounting points into the surrounding structure. Over time, this can lead to noise, wear, fatigue damage, and alignment issues. Vibration-damping mounts act as cushions or isolators that decouple the vibrating source from its base, protecting both the machine and the structure from these effects.

They come in many forms, including cylindrical mounts, sandwich mounts, conical mounts, and bonded rubber-metal assemblies, each designed to handle specific load directions and frequencies. Some advanced versions combine rubber elements with metal springs or hydraulic chambers to achieve better control over damping across a wide frequency range.

Vibratory loosening is the self-unscrewing of a threaded fastener like a bolt or screw due to vibrations. It's a progressive, two-step process: first, vibration causes microscopic movements within the joint, leading to a loss of the initial clamping force, or preload. Once that preload is weakened, any continued vibration can cause the fastener to gradually rotate, leading to a complete failure of the joint.

To prevent vibratory loosening, engineers use various methods to ensure the fastener remains secure. These include mechanical locking devices such as lock nuts, lock washers (like wedge-locking washers), and cotter pins that physically stop the fastener from rotating. Chemical solutions like threadlockers (adhesives that fill the gaps in threads) are also used. Most importantly, proper joint design and tightening the fastener to its correct preload are crucial, as a strong initial clamp is the best defense against this common cause of mechanical failure.

Video: Watch a Junker vibration test for bolted connections

Vickers Hardness (HV) is a measure of a material’s hardness determined using the Vickers hardness test. In this test, a diamond-shaped pyramid indenter is pressed into the material’s surface under a specific load. The size of the indentation left behind is measured under a microscope, and the hardness value (HV) is calculated based on the applied force divided by the surface area of the indentation.

This method is widely used because it can test very hard or very thin materials, and it works on metals, ceramics, and coatings. Vickers Hardness is expressed in units of HV (e.g., 450 HV), where higher numbers indicate harder materials. It’s commonly applied in metallurgy, fastener testing, aerospace, and quality control to evaluate wear resistance, strength, and material performance.

When referring to fasteners, viscosity usually comes up in the context of lubricants, coatings, or adhesives used with them.

Viscosity is the measure of a fluid’s resistance to flow. In fasteners, it matters because the thickness or flow characteristics of oils, greases, thread-locking compounds, or anti-seize coatings directly affect installation, torque, and long-term performance.

Lubrication & Torque: A high-viscosity lubricant (thicker) may stay in place better but can reduce accuracy in torque-tension relationships. Low-viscosity lubricants (thinner) spread more easily, reducing friction more consistently.

Threadlockers & Adhesives: Anaerobic adhesives like Loctite® are formulated with different viscosities—low-viscosity grades wick into pre-assembled threads, while high-viscosity grades fill gaps in looser assemblies.

Coatings & Corrosion Protection: The viscosity of protective coatings affects how evenly they cover a fastener and how well they resist dripping or running during application.

In short, viscosity determines how lubricants and adhesives behave on fastener threads, which directly influences torque, preload, and resistance to loosening.

Vulcanization is a chemical process used to strengthen rubber by adding sulfur (or other curatives) and applying heat. This process forms cross-links between the long molecular chains of raw rubber, transforming it from a sticky, soft material into one that is more durable, elastic, and resistant to heat, wear, and aging.

For fasteners and industrial uses, vulcanization is important in the production of rubber washers, seals, gaskets, O-rings, and vibration-damping components. Without vulcanization, natural rubber would deform easily, lose strength, and degrade quickly. With it, rubber parts can maintain consistent performance under mechanical stress, temperature changes, and chemical exposure.