For instance, the environment is very extreme in aerospace parts such as turbine blades and requires good fitting. Here, Geometric Dimensioning and Tolerancing ensure this kind of blade keeps its correct orientation and location relative to other components for reliable function under stress.
4. Reduced Waste and Rework
When the design intent is ambiguous, manufacturers eu data occasionally create parts that do not fulfill functional requirements. These parts are then either scrapped or have to be reworked at great expense.
GD&T reduces this risk by clearly defining the acceptable tolerance zones for each feature, reducing the possibility of producing defective parts. This, in turn, leads to higher efficiency and less wasted material.
To understand how GD&T works, one first needs to understand its basic principles. Those are usually referred to by the acronym SLOF, meaning Size, Location, Orientation, and Form.
These four elements are controlled with specific GD&T symbols and a feature control frame defining acceptable tolerances.
Let's explore each below.
1. Size
In this context, size refers to the physical dimensions of a feature, which could be the diameter of a hole or the length of a cylinder. This is typically controlled using traditional ± tolerances, but in GD&T, other geometric controls often influence the size.
2. Location
The location of a feature is described as where it is in space relative to the other features of the part. The most common symbol used in GD&T that controls location is True Position. This allows features to be properly placed in relation to others, such as drilling a hole in the correct place.
3. Orientation
Orientation refers to how a part or feature is angled in space relative to another feature. Common orientation controls include Parallelism , Perpendicularity and Angularity , which ensure that features are aligned as required. For example, GD&T may ensure that two surfaces are perpendicular to each other to prevent issues during assembly.