Technical Articles

What is EN ISO 14405-2:2021?

EN ISO 14405-2:2021 is an international technical standard that provides guidelines for specifying and verifying geometric tolerances in engineering drawings. Geometric tolerancing is crucial in determining the allowable variation in form, profile, orientation, location, and runout of features on a part or component.

Key Features of EN ISO 14405-2:2021

The standard introduces several important concepts and definitions to facilitate accurate communication and interpretation of geometric tolerancing requirements. Here are some key features:

Datum Reference Frame (DRF): This defines a coordinate system used to establish the relationship between features and their tolerances on a part. It includes primary, secondary, and tertiary datums that serve as reference points for measurement and inspection.

Modifiers: Modifiers such as MMC (Maximum Material Condition) and LMC (Least Material Condition) are used to define the allowable limits of a feature's size within the specified tolerance zone.

Basic Dimensions: These are core dimensions used to calculate the tolerance values and determine the level of control required for a specific feature.

Benefits of Using EN ISO 14405-2:2021

Implementing EN ISO 14405-2:2021 offers several advantages for manufacturers, designers, and quality control professionals:

Improved Communication: The standard ensures clear and precise communication of geometric tolerancing requirements, reducing misunderstandings and errors during production and inspection processes.

Enhanced Design Understanding: Engineers can accurately interpret and apply geometric tolerances, resulting in better-designed parts that meet functional requirements.

Reduced Production Costs: By specifying tolerances correctly, manufacturers can optimize production processes, reduce scrap rates, and avoid costly rework or rejected parts.

Interchangeability: The standard promotes interoperability between different engineering organizations by providing a common language for defining geometric tolerances.


EN ISO 14405-2:2021 is a vital technical standard that facilitates accurate communication and specification of geometric tolerances in engineering drawings. By adhering to this standard, businesses can achieve improved product quality, increased productivity, and cost savings. It is essential for professionals in the manufacturing and design industries to familiarize themselves with the key concepts outlined in EN ISO 14405-2:2021 to ensure effective implementation and compliance.



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