A machine screw is often described as small diameter bolt. Like a bolt or hex head cap screw, it features a straight, untapered shank and a blunt end, but it is usually driven with a screwdriver instead of a wrench. External machine thread runs entire length of shank.
Most commonly used to fasten metal to metal, a machine screw is designed to be inserted into a prethreaded hole or mated with a nut (in which case it may be called a stove bolt). Because application thread sizes vary, it is especially important to select the right machine screw to meet your specific requirements.
Features a relatively tall head with cylindrical sides; can be flat or rounded on top.
Head may be slotted for driving with a screwdriver or unslotted for driving with a socket or wrench.
Features a countersunk head with a low-profile, rounded top that protrudes slightly above the surface.
Is a disc with a chamfered outer edge and short cylindrical sides that resembles a frying pan; has a slightly larger diameter than a round head.
Special hex shape with or without center pin is ideal for use anywhere you're concerned about vandalism or theft.
Designed for use in permanent applications. Installs with a standard slotted screwdriver; requires special tool for removal.
Unique design thwarts tampering, yet allows easy installation and removal with spanner tool.
Star-shaped drive with six rounded points for maximum transfer of torque; provides a high level of security without sacrificing accessibility.
Brass—alloy of copper and zinc that resists rust and moderate atmospheric corrosion. Not high in strength, but is durable and conducts electricity. Often used for appearance. Nonmagnetic.
Carbon Steel—contains only carbon and residual amounts of other impurities. Magnetic and malleable; can be cast or wrought.
Nylon—used extensively in electronics applications. Nonconductive, durable, and ductile material. Resists heat, corrosion, and nonacidic chemicals. Has excellent insulating properties, but dimensions can be affected by moisture absorption.
Polycarbonate—a tough, versatile thermoplastic characterized by high-impact strength, low weight, and flexibility. It provides excellent insulation in electrical applications.
Stainless Steel—contains a minimum of 12% chromium for exceptional resistance to extreme environmental conditions. Properties are highly anticorrosive. Not affected by scratching; however, not as strong as common alloy steels. Mildly magnetic.
18-8 Stainless Steel—contains approximately 18% chromium and 8% nickel. Provides excellent protection against rust and corrosion. The material of choice for prolonged outdoor use or exposure to salt spray and chemical fumes. Mildly magnetic.
Steel—the most common fastener material. Available in these types:
The information contained in this article is intended for general information purposes only and is based on information available as of the initial date of publication. No representation is made that the information or references are complete or remain current. This article is not a substitute for review of current applicable government regulations, industry standards, or other standards specific to your business and/or activities and should not be construed as legal advice or opinion. Readers with specific questions should refer to the applicable standards or consult with an attorney.
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