These dimensions are formed entirely within a single, solid block or moving segment of the mold tool. Because no mechanical shifting or opening occurs across this dimension during the injection cycle, variables are limited primarily to material shrinkage. Consequently, . Non-Tool-Specific Dimensions (NW)
: Crystalline materials (like Nylon) shrink and warp more than amorphous materials (like ABS or PC), which can push a part out of the TG5 range even if the mold is perfect.
When designing plastic components for industrial applications, achieving the right dimensional accuracy is critical for functionality, assembly, and cost-effectiveness. The standard (now often superseded by ISO 20457 ) serves as the definitive guideline for plastics molded part tolerances, classifying accuracy into different Tolerance Groups (TG).
Tolerance Group 5 (TG5) is a high-precision classification. It is typically specified for technical components that require exact fits and functional interfaces, such as gears, electronic housings, and automotive sub-assemblies. din 16742 - tg5
It is typically applied to structural housings, gears, snaps, and multi-component assemblies where interference fits must be avoided.
Small features (under 1mm) might have a tolerance of ±0.05mm.
." It was a sleek, polyamide component designed for a medical housing unit. His client had demanded , which meant the variations allowed were razor-thin—hardly the width of a human hair. These dimensions are formed entirely within a single,
Choosing the right tolerance group is critical because plastic behavior differs significantly from metal. Plastics are subject to high thermal expansion, moisture absorption, and shrinkage—factors that DIN 16742 addresses through its system of nine tolerance groups (TG1–TG9). What is Tolerance Group 5 (TG5)?
Selecting TG5 directly influences how a mold tool is engineered. Mold cavities are oversized to account for processing shrinkage. To safely hitting TG5 targets, engineers frequently leverage a strategy known as . Critical part features are intentionally designed "too small" on the plastic side, meaning the corresponding mold steel is left "too large". After first article inspection (FAI) samples are evaluated, the toolmaker removes tiny amounts of steel to dial in the perfect nominal dimensions. Tool-Specific (W) vs. Non-Tool-Specific (NW) Dimensions
DIN 16742 standardizes these fluctuations by breaking them down into ranging from TG1 (extreme precision micro-molding) to TG9 (coarse parts with highly unpredictable shrinkage). 🎯 Demystifying the TG5 Classification What is TG5? Tolerance Group 5 (TG5) is a high-precision classification
is often described as the "Standard" or "Fine" tolerance class for technical injection-molded parts. It sits in a sweet spot where high precision is achieved without the exponential cost increases associated with ultra-tight groups like TG1 or TG2.
Features formed within one half of the mold (e.g., inner diameter of a cavity).
: Always specify the standard and group on technical drawings (e.g., "General tolerances DIN 16742 – TG5"). Match Material to TG : Ensure your chosen resin (like ABS, PC, or Nylon