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Basics of Tolerance 120

Shop Essentials Training

Class Information

Tooling U classes are offered at the beginner, intermediate, and advanced levels. The typical class consists of 12 to 25 lessons and typically requires at least two hours of instruction time.

Class Name:	Basics of Tolerance 120
Description:	This class explains the purpose of tolerances in manufacturing and describes how these tolerances are specified. Includes an Interactive Lab.
Prerequisites:	none
Difficulty:	Beginner
Number of Lessons:	12

Class Outline
Objectives The Importance of Measurements What Is Tolerance? Tolerance and Use Tolerance and Cost Tolerances for Various Operations Types of Tolerance Advantages of Limit Dimensions Tolerances for a Hole Surface Tolerance Dimensioning and Tolerance Summary

Class Objectives

Identify common tolerances in a manufacturing environment.
Define tolerance.
Identify how tolerance is determined.
Describe the impact of tolerance on cost.
Compare tolerances possible in machining operations.
Describe methods of describing tolerance.
Identify advantages of different tolerance methods.
Identify elements of tolerance for holes.
Describe elements of surface tolerance.
Identify the relationship between dimensions and tolerance.

Class Vocabulary
abrasive		A tool consisting of hardened grains that is used to machine, grind, or finish a workpiece.
accuracy		The exactness of a measurement produced compared to the desired result.
allowance		The intentional space left between a hole and the shaft inserted into it.
bilateral tolerance		A tolerance method using an equal plus and minus deviation from the specified dimension.
blueprint		A document containing all the instructions necessary to manufacture a part. The key sections of a blueprint are the drawing, dimensions, and notes.
casting		The process of pouring a liquid material into a mold until it cools into a solid form.
clearance		The difference between the largest permissible shaft and the smallest permissible hole.
dimensioning		The process of determining the desired measurement of a feature on a part.
drilling		The process of using a multi-point tool to penetrate the surface of a workpiece and make a round hole.
flaw		An unintentional surface irregularity that may be random or repeating, such as cracks or inclusions.
grinding		The use of an abrasive to wear away at the surface of a workpiece to achieve highly accurate measurements.
interference		A tight fit designed where the smallest permissible shaft is larger than the largest permissible hole.
lapping		An abrasive process that removes the last bit of unwanted material within a very tight tolerance.
lay		The overall direction of the pattern created by the production process.
limit dimension		A tolerancing method using an absolute maximum and minimum allowable dimension.
machining		The process of removing metal by producing chips through the use of cutting tools.
milling		The use of a machine to remove metal from the surface of a workpiece with a rotating multi-point tool.
precision		The ability of a process to repeat the same accurate measurement over time.
roughness		The inherent, fine, closely-spaced irregularities created by the production process.
surface tolerance		The allowable deviation in surface texture.
tolerance		The unwanted but acceptable deviation from a desired dimension. The tighter the tolerance, the greater the cost to manufacture the part.
tolerance limit		The expected range of measurements produced by a given operation.
turning		The machining process used to make cylindrical parts. Turning is commonly performed with a lathe.
unilateral tolerance		A tolerancing method using a deviation in only one direction, either plus or minus, from the specified dimension.
waviness		The repeating irregularities with spacing greater than roughness marks that result from machine deflections and vibration.