Search results
Results from the WOW.Com Content Network
Engineering fits are generally used as part of geometric dimensioning and tolerancing when a part or assembly is designed. In engineering terms, the "fit" is the clearance between two mating parts, and the size of this clearance determines whether the parts can, at one end of the spectrum, move or rotate independently from each other or, at the other end, are temporarily or permanently joined.
For example, if a shaft with a nominal diameter of 10 mm is to have a sliding fit within a hole, the shaft might be specified with a tolerance range from 9.964 to 10 mm (i.e., a zero fundamental deviation, but a lower deviation of 0.036 mm) and the hole might be specified with a tolerance range from 10.04 mm to 10.076 mm (0.04 mm fundamental ...
Standard tolerance grades are a group of tolerances for linear sizes characterized by a common identifier. For SI measurements, a system of tolerance grades defined in ISO 286 is frequently used and identified by the letters IT followed by a number specifying how precise the requirements are, relative to the nominal size of a part.
Tolerance stackups or tolerance stacks are used to describe the problem-solving process in mechanical engineering of calculating the effects of the accumulated variation that is allowed by specified dimensions and tolerances. Typically these dimensions and tolerances are specified on an engineering drawing.
Example of true position geometric control defined by basic dimensions and datum features. Geometric dimensioning and tolerancing (GD&T) is a system for defining and communicating engineering tolerances via a symbolic language on engineering drawings and computer-generated 3D models that describes a physical object's nominal geometry and the permissible variation thereof.
A tolerance interval (TI) is a statistical interval within which, with some confidence level, a specified sampled proportion of a population falls. "More specifically, a 100× p %/100×(1−α) tolerance interval provides limits within which at least a certain proportion ( p ) of the population falls with a given level of confidence (1−α)."
To be sure that there will be enough clearance between the shaft and its hole, taking account of the tolerance, an allowance is intentionally introduced in the dimensions specified. The hole diameter might be specified as 10.03 mm with a manufacturing tolerance of ±0.01 mm ("plus-or-minus" 0.01 mm).
The tolerance values specified by the end-user are known as specification limits – the upper specification limit (USL) and lower specification limit (LSL). [2] If the process data plotted on a control chart remains within these specification limits, then the process is considered a capable process, denoted by C ^ p k {\displaystyle {\hat {C ...