Friday, July 29, 2016

GD&T: The Path to Precision

GD&T: The Path to Precision
When an engineer sends a design to production, there is an area of the design where a feature or part is not clearly defined. Implanted in that area is the design’s zone of tolerance, also known as its limits of variation. The design can only tolerate a certain amount of deviation from that zone before material and money are wasted, time is lost, and productivity is diminished!

Don’t worry ― a solution to this quandary has been discovered. 

Manufacturers have found a systematic way to define and communicate tolerances through Geometrical Dimensioning and Tolerancing (GD&T). It uses symbolic language with rules and principles for engineering drawings and computer-generated 3-D solid models to explicitly describe nominal geometry and allowable variations. GD&T serves to research, refine, encode, and GUARANTEE the functions of machine part features.

For a "101" explanation of GD&T, read our previous blog entry called, Geometrical Dimensioning and Tolerancing (GD&T) 101, by clicking here.

GD&T Provides Countless Benefits
Manufacturers across the United States have found the benefits of GD&T to be profoundly immeasurable. Some of the major benefits are that it:
  • Provides a common language and concise technique for defining data production teams can easily utilize and understand, minimizing the risk of miscommunication and errors. 
  • Saves time and money by reducing the amount of scrap, rework, and costly drawing alterations. 
  • Minimizes the need for drawing notes to outline intricate geometry requirements on a component or assembly by using the program’s standard symbols. This accurately and quickly defines specific design, manufacturing and inspection requirements. 
  •  Securely joins logical and recognizable mechanical designs and processes.
  • Makes tolerances rounder, larger, and more realistic. Rounded tolerance zones provide more than 50% more tolerance than square zones, prompting augmented use, interchangeable parts, and functional design relationships.
  • Allows for continuous product improvements, line extensions and accessory development through its language.
  • Is supported by both national and international standards. A series of ISO standards meticulously archive the interpretation of each GD&T symbol and concept, assuring that assembled parts will be accepted.

GD&T Training Programs
There are various training programs offered to organizations that are designed to develop a comprehensive working knowledge of GD&T. These training programs provide the necessary coaching, materials and resources for manufacturers to effectively implement the system. Most GD&T training programs help manufacturers identify the:
  • Benefits of GD&T
  • Geometric characteristic symbols, their meaning, and method of inspection
  • Feature control frames and how to apply them on drawings
  • Application of modifiers and how they impact specified geometric tolerances

GD&T Gives Manufacturers a Competitive Edge
With proper training and application, manufacturers gain a superior ability over their competitors to reduce scrap, increase the versatility of parts, simplify inspection, increase exactitude of design, minimize replacement of parts, avoid recalls, and enhance efficiency. Manufacturers who use GD&T gain a competitive edge, as GD&T has brought an unprecedented degree of precision to the manufacturing of products! Additionally, GD&T usage has been increasing since the standard’s initial release in 1994. The ability to properly decipher specifications for quote purposes and product realization depends more and more on an organization’s ability to fully understand what the customer is saying in the Feature Frame GD&T symbols and codes.

Let the Michigan Manufacturing Technology Center Help
The Michigan Manufacturing Technology Center offers GD&T services and training to Michigan manufacturers. For more information, call 888.414.6682, visit or email Start reducing inadequacies in this imperfect world!

About Us
Since 1991, the Michigan Manufacturing Technology Center has assisted Michigan’s small and medium-sized businesses successfully compete and grow. Through personalized services fitted to meet the needs of clients, we develop more effective business leaders, drive product and process innovation, promote company-wide operational excellence and foster creative strategies for business growth and greater profitability. Find us at on the web at

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