Din 16742 - Tg5 ((free)) Guide

Understanding how Tolerance Group 5 (TG5) governs linear, angular, and wall dimensions protects designs from common tooling issues, component warpage, and assembly failures. What is DIN 16742?

The standard defines distinct tolerance groups—TG1 through TG7—each corresponding to the manufacturing precision required. This classification acknowledges that not all plastic parts are created equal; a simple cable clip does not require the same precision as an optical housing or a medical device component. By specifying a tolerance group, manufacturers can select the appropriate molding parameters, materials, and quality control measures.

. This means production and quality assurance are oriented toward higher dimensional stability than standard "normal" production. Application: It is frequently cited as the standard for Injection Moulding

stands for Tolerance Grade 5 within the DIN 16742 framework. It is classified as a "fine" tolerance for injection molded parts. In practical terms, TG5 sits exactly in the middle of the standard's capability range:

Using the same 50 mm example, positional tolerance under TG5 is approximately . This allows two snap-fit hooks located 50 mm apart to still align. din 16742 - tg5

Compared to the common TG6 (which is often used for standard engineering plastics), . Choosing TG5 means the toolmaker must maintain stricter controls over tool manufacturing, and the injection molder must manage process parameters (temperature, pressure, cooling) very tightly. Factors Affecting TG5 Tolerances

To successfully implement TG5, designers must consider the limitations of plastic injection molding:

Pekago and other major manufacturers often list as their standard for high-quality injection molding. It provides a balance between functional accuracy and production cost. Key characteristics of TG5 include:

Requires optimized cooling, precise processing, and often fiber reinforcement (e.g., PA6-GF30) to meet TG5. Production Impact of Specifying TG5 Understanding how Tolerance Group 5 (TG5) governs linear,

All tolerances in DIN 16742 are . If asymmetrical tolerances (e.g., fit dimensions) are required, they must be converted to a symmetrical tolerance field location by formally modifying the nominal dimension to the tolerance mean dimension C: 100-0.6 → 99.7 ± 0.3 .

Establishes rigorous quality control thresholds that minimize field failures. Challenges and Cost Drivers

: Tighter groups like TG5 are easier to achieve with amorphous resins (e.g., ABS, PC) that have low, predictable shrinkage than with semi-crystalline materials (e.g., PA66, POM). Dimension Type : DIN 16742 distinguishes between Tool-specific (W) Non-tool-specific (NW) dimensions: Tool-specific (W)

Understanding how TG5 relates to other common tolerance specifications is important: This classification acknowledges that not all plastic parts

DIN 16742-TG5 is widely recognized and applied across numerous industries that rely on high-quality plastic injection moulded parts, including:

by precision-focused suppliers (compared to TG7 or TG8, which are used for looser processes like Structural Foam Moulding). Achievability:

TG5 assumes (typically ±0.2% to ±0.5% absolute shrink depending on material).