A micrometer, sometimes known as a micrometer screw gauge, is a device incorporating a calibrated screw widely used for accurate measurement of components in mechanical engineering and machining as well as most mechanical trades, along with other metrological instruments such as dial, vernier, and digital calipers. Micrometers are usually, but not always, in the form of calipers. The spindle is a very accurately machined screw and the object to be measured is placed between the spindle and the anvil. The spindle is moved by turning the ratchet knob or thimble until the object to be measured is lightly touched by both the spindle and the anvil.
A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races.
Engineering tolerance is the permissible limit or limits of variation in:
- a physical dimension;
- a measured value or physical property of a material, manufactured object, system, or service;
- other measured values ;
- in engineering and safety, a physical distance or space (tolerance), as in a truck (lorry), train or boat under a bridge as well as a train in a tunnel ;
- in mechanical engineering, the space between a bolt and a nut or a hole, etc.
In mechanical engineering, a rolling-element bearing, also known as a rolling bearing, is a bearing which carries a load by placing rolling elements between two concentric, grooved rings called races. The relative motion of the races causes the rolling elements to roll with very little rolling resistance and with little sliding.
The Unified Thread Standard (UTS) defines a standard thread form and series—along with allowances, tolerances, and designations—for screw threads commonly used in the United States and Canada. It is the main standard for bolts, nuts, and a wide variety of other threaded fasteners used in these countries. It has the same 60° profile as the ISO metric screw thread, but the characteristic dimensions of each UTS thread were chosen as an inch fraction rather than a millimeter value. The UTS is currently controlled by ASME/ANSI in the United States.
American National Standard Pipe Thread standards, often called national pipe thread standards for short, are United States national technical standards for screw threads used on threaded pipes and pipe fittings. They include both tapered and straight thread series for various purposes, including rigidity, pressure-tight sealing, or both. The types are named with a full name and an abbreviation, such as NPT, NPS, NPTF, or NPSC.
Accurizing is the process of improving the accuracy and precision of a gun.
A screw thread is a helical structure used to convert between rotational and linear movement or force. A screw thread is a ridge wrapped around a cylinder or cone in the form of a helix, with the former being called a straight thread and the latter called a tapered thread. A screw thread is the essential feature of the screw as a simple machine and also as a threaded fastener.
A machine taper is a system for securing cutting tools or toolholders in the spindle of a machine tool or power tool. A male member of conical form fits into the female socket, which has a matching taper of equal angle.
A go/no-go gauge refers to an inspection tool used to check a workpiece against its allowed tolerances via a go/no-go test. Its name is derived from two tests: the check involves the workpiece having to pass one test (go) and fail the other (no-go).
An interference fit, also known as a pressed fit or friction fit, is a form of fastening between two tightfitting mating parts that produces a joint which is held together by friction after the parts are pushed together.
Gauge blocks are a system for producing precision lengths. The individual gauge block is a metal or ceramic block that has been precision ground and lapped to a specific thickness. Gauge blocks come in sets of blocks with a range of standard lengths. In use, the blocks are stacked to make up a desired length.
In machining, boring is the process of enlarging a hole that has already been drilled by means of a single-point cutting tool, such as in boring a gun barrel or an engine cylinder. Boring is used to achieve greater accuracy of the diameter of a hole, and can be used to cut a tapered hole. Boring can be viewed as the internal-diameter counterpart to turning, which cuts external diameters.
Nominal Pipe Size (NPS) is a North American set of standard sizes for pipes used for high or low pressures and temperatures. "Nominal" refers to pipe in non-specific terms and identifies the diameter of the hole with a non-dimensional number. Specific pipe is identified by pipe diameter and another non-dimensional number for wall thickness referred to as the Schedule. NPS is often incorrectly called National Pipe Size, due to confusion with the American standard for pipe threads, "national pipe straight", which also abbreviates as "NPS". The European and international designation equivalent to NPS is DN, in which sizes are measured in millimetres, see ISO 6708. The term NB is also frequently used interchangeably with DN.
The ISO metric screw thread is the most commonly used type of general-purpose screw thread worldwide. They were one of the first international standards agreed when the International Organization for Standardization (ISO) was set up in 1947.
Note: in this context, IT does not mean Information Technology, but it is an Engineering term.
In engineering and machining, an allowance is a planned deviation between an exact dimension and a nominal or theoretical dimension, or between an intermediate-stage dimension and an intended final dimension. The unifying abstract concept is that a certain amount of difference allows for some known factor of compensation or interference. For example, an area of excess metal may be left because it is needed to complete subsequent machining. Common cases are listed below. An allowance, which is a planned deviation from an ideal, is contrasted with a tolerance, which accounts for expected but unplanned deviations.
Tolerance analysis is the general term for activities related to the study of accumulated variation in mechanical parts and assemblies. Its methods may be used on other types of systems subject to accumulated variation, such as mechanical and electrical systems. Engineers analyze tolerances for the purpose of evaluating geometric dimensioning and tolerancing (GD&T). Methods include 2D tolerance stacks, 3D Monte Carlo simulations, and datum conversions.
In precision mechanics, fit refers to the degree of 'looseness' with which a shaft is inserted into a bored hole.
Preferred metric sizes are a set of international standards and de facto standards that are designed to make using the metric system easier and simpler, especially in engineering and construction practices. One of the methods used to arrive at these preferred sizes is the use of preferred numbers and convenient numbers, such as the Renard series and 1-2-5 series, to limit the number of different sizes of components needed.
