Some materials, like Nylon, require moisture conditioning before final measurement.
To consistently achieve TG5 tolerances, injection molders must use high-quality tooling and exercise steady control over the injection molding process. The Tolerance Hierarchy (TG1 – TG7)
Smaller dimensions (under 6 mm) might feature tolerances within ±0.05 mm.
In the medical device industry, precision, reliability, and quality are paramount. The production of medical devices requires a high level of accuracy, consistency, and control to ensure the safety and efficacy of the final product. To achieve this, manufacturers must adhere to stringent standards and guidelines that govern the design, development, production, and testing of medical devices. One such standard is ISO 20457 TG5, a critical specification that has gained significant attention in recent years. Iso 20457 Tg5
: For a deep dive into how these grades are applied in practice, Makrolar provides a comprehensive PDF guide on tolerancing for plastic moulded parts according to ISO 20457.
for medium-to-large features) without forcing unneeded tool precision.
Within this standard, the tolerance grade represents a critical balance between high precision and production feasibility. This article explores what ISO 20457 TG5 means, when to use it, and how it impacts the design and manufacturing process. What is ISO 20457? In the medical device industry, precision, reliability, and
: Dimensions affected by the moving parts of the mold, such as parting lines, slides, or core pulls. These require wider tolerances due to mechanical clearances. Application Examples for TG5
A key contribution of ISO 20457 is its success in shifting the industry away from "fear tolerances" — specifying unnecessarily tight tolerances that drive up costs without providing any functional benefit — toward a more realistic, achievable, and cost-effective approach.
Variations in thickness cause uneven cooling, leading to internal stresses and warpage that break TG5 limits. Use coring or ribs to reduce thick sections. Draft Angles and Ejection Incorporate generous draft angles (typically 1∘1 raised to the composed with power 2∘2 raised to the composed with power One such standard is ISO 20457 TG5, a
As a part cools inside the tool, internal residual stresses cause warping. For TG5, the permissible variance typically spans
Device housings, laptops, and household appliance components.
Excellent structural integrity, especially when reinforced with glass fibers.
What or polymer blend are you planning to use?
Understanding where TG5 sits relative to other groups helps engineers avoid over-specifying tolerances, which increases production costs unnecessarily. Feature / Metric TG3 (Commercial) TG5 (Precision) TG7 (Ultra-Precision) Consumer goods, toys, housings Automotive sensors, medical gears Aerospace instrumentation, fiber optics Cost Profile Moderate Increase ( Exponential Increase ( Tooling Wear Impact Metrology Required Standard calipers / Micrometers CMM (Coordinate Measuring Machine) Optical / Vision measuring systems Design and Manufacturing Best Practices for TG5