Composite Position Tolerance — Layered Control for Hole Group Location

Core Concept

•First line: controls the position and orientation of the entire hole group relative to the primary datums. 

•Subsequent lines: only constrain the spacing and orientation between holes within the group.

Tolerance Frame Structure

•One position tolerance symbol, followed by multiple rows of tolerance values and datum references. 

•The last row may be datum‑independent.

Application
Used where hierarchical control of a feature group’s position, orientation, and internal spacing is needed. It enables flexible tolerance allocation—balancing function, manufacturability, and cost

Composite Position Tolerance: Principles & Application

Control Logic

•First Row: Controls overall position and orientation of the feature group. 

•Subsequent Rows: Constrain only internal spacing and orientation within the group.

Tolerance Frame Structure

•Single position symbol followed by multiple rows of tolerance values and datums. 

•Final row may be datum‑independent.

Application

Used for hierarchical tolerance control of feature groups (e.g., holes, pins). Enables flexible tolerance allocation that balances functional needs, manufacturability, and cost.

Summary: Composite Position Tolerance in DTAS 3D

•Clarity through Simulation – DTAS 3D visually demonstrates the meaning and behavior of composite position tolerances, eliminating interpretation ambiguity. 

•Multi‑Row Tolerance Frames – Supports definition of layered controls (e.g., overall hole‑group location + internal spacing) with precise design‑intent expression. 

•Tolerance‑Zone Behavior – Simulates how different rows of the tolerance frame constrain feature variation, faithfully reflecting the GD&T hierarchy.