Tolerance

Definition

Tolerance refers to the permissible limit or limits of variation in a physical dimension, measured from a nominal value. It is crucial in design and manufacturing, as it determines how much deviation from a specified measurement is acceptable without affecting the functionality or performance of a part. Understanding tolerance is essential for ensuring that parts fit together correctly and function as intended, which connects deeply with precision input and constraints, as well as dimensioning techniques.

5 Must Know Facts For Your Next Test

1. Tolerance can be expressed in linear dimensions (like length), angular dimensions (like angles), and radial dimensions (like radius), making it versatile in application.
2. A tighter tolerance results in higher manufacturing costs due to the increased precision required during production, while a looser tolerance may reduce costs but can affect functionality.
3. There are different types of tolerances, such as unilateral (variation allowed in one direction) and bilateral (variation allowed in both directions), which affect how dimensions are interpreted.
4. The concept of 'stack-up' is important when dealing with tolerance; it refers to the cumulative effect of variations in dimensions from multiple parts that must fit together.
5. In engineering drawings, tolerances are often indicated using specific notation, and understanding these notations is essential for accurate communication between designers and manufacturers.

Review Questions

• How does tolerance influence the relationship between precision input and constraints in design?
  • Tolerance directly impacts precision input and constraints by defining the acceptable limits within which components must operate. When designing a part, engineers must consider how tight or loose these tolerances are to ensure that parts will assemble correctly without causing functional issues. Thus, establishing precise tolerances helps create constraints that guide manufacturing processes while maintaining product quality.
• What role does tolerance play in linear, angular, and radial dimensioning on engineering drawings?
  • In linear, angular, and radial dimensioning on engineering drawings, tolerance indicates the permissible variation for each dimension. This helps ensure that parts can be manufactured within acceptable limits without compromising their function. By clearly specifying tolerances alongside dimensions, designers communicate critical information that guides fabrication processes and quality control, ensuring parts fit and function together as intended.
• Evaluate the impact of different types of tolerances on manufacturing processes and product quality.
  • Different types of tolerances significantly affect manufacturing processes and overall product quality. For instance, tighter tolerances necessitate more advanced machinery and stringent quality control measures, potentially increasing production costs. Conversely, looser tolerances can simplify manufacturing but may compromise product functionality if components do not fit together properly. An effective balance must be struck to meet design requirements while maintaining cost efficiency and ensuring product reliability.

Related terms

Dimensional Accuracy: Dimensional accuracy is the degree to which the measured dimensions of a part conform to the specified dimensions, reflecting the precision of manufacturing processes.

Geometric Dimensioning and Tolerancing (GD&T): GD&T is a system for defining and communicating engineering tolerances using symbols, which helps ensure that parts fit together correctly while allowing for variations.

Fit:

Fit refers to the relationship between two mating parts, indicating how closely they match in size, which can be classified as clearance, interference, or transition fit.