Definition

Noun: A type of fastener, specifically a screw, designed to be used either with a matching nut or by being threaded directly into a pre-tapped hole in a material. It is characterized by a slotted or recessed head (e.g., flat, pan, round) that is intended to be driven by a screwdriver or a corresponding driver bit.

Usage

A machine screw is a fundamental component in assembling metal parts, machinery, electronics, and other precision equipment. Unlike wood screws, which often have a tapered point and thread into softer materials, machine screws typically have a uniform diameter along their threaded length and require a pre-made threaded hole or a nut to create a secure, strong joint.

Examples

• The technician secured the access panel using four machine screws.
• You will need a 6-32 machine screw and a matching nut to attach this bracket.
• The assembly instructions specify that the components must be fastened with machine screws into the tapped holes on the chassis.

Advanced Usage

• Machine screws are often specified by their thread system (e.g., Unified National Coarse - UNC, Unified National Fine - UNF, or metric), diameter, length, and head type (e.g., flat head, pan head, socket head).
• In engineering drawings, a callout for a machine screw includes its specifications, such as "M4 x 0.7 x 12mm Socket Head Cap Screw," indicating a metric screw with a 4mm diameter, a 0.7mm thread pitch, a 12mm length, and a socket head.

Variants and Related Words

• Cap screw: Often used interchangeably with "machine screw," though sometimes specifically refers to a machine screw that is threaded into a tapped hole without a nut.
• Set screw: A type of machine screw, typically headless, used to secure an object within or against another object, often by applying pressure with its point.
• Socket head cap screw: A common type of machine screw with a cylindrical head featuring a hexagonal socket (Allen) drive.

Synonyms

• Fastener
• Bolt (Note: In precise terminology, a "bolt" is generally used with a nut, while a "screw" is used in a tapped hole. However, the terms are often used interchangeably in casual contexts, and some fasteners, like a machine screw, can function as either.)

Related Phrases

• To drive a machine screw: The action of turning the screw into place using a tool.
  • Use a #2 Phillips screwdriver to drive the machine screw.
• Machine screw thread: Refers to the specific helical ridge form cut into the screw.
  • This part has a machine screw thread to accept the fastener.

Noun

1. a screw used either with a nut or with a tapped hole; slotted head can be driven by a screwdriver