Demands strict process control and highly stable molding resins.
The sixth search for "ISO 20457 Tg5 pdf" returned some results.
| Tolerance Group (TG) | Typical Applications | | :--- | :--- | | | Packaging parts, simple containers, large-series consumer goods | | TG 4 | Precision parts: gears, functional elements requiring high dimensional stability | | TG 5 | Housing parts: enclosures for electronics, appliances, automotive interior components | | TG 6 | General technical parts with moderate precision requirements | | TG 9 | Rotomolded parts, which require wider tolerance zones due to process characteristics |
serves as the "standard" or baseline precision grade for plastic injection molded parts. It is the most commonly applied tolerance series for industrial and consumer plastic products where high precision is desired without the extreme manufacturing costs of high-precision grades like TG1-TG3. Core Function and Classification Iso 20457 Tg5
Specifying TG5 on a drawing requires defining accompanying parameters for valid measurement, such as the acceptance temperature (usually 23∘C23 raised to the composed with power cap C ) and measurement humidity.
Amorphous polymers (such as Polycarbonate (PC), ABS, or PMMA) inherently possess lower and more isotropic (uniform) shrinkage rates than semi-crystalline polymers (such as Polypropylene (PP) or Polyethylene (PE)). Adding glass fibers or mineral fillers further reduces shrinkage, making it significantly easier to meet TG5 criteria. 3. Process Control and Stability
The typical tolerance values associated with Tg5, which vary based on the nominal size of the dimension in question, are as follows: Demands strict process control and highly stable molding
Before any steel is cut, mold flow software should be utilized to simulate how the molten plastic will fill the cavity. This analysis helps engineers predict shrinkage, identify potential warpage, and ensure that the part will cool uniformly within the TG5 tolerance range. 3. Geometric Dimensioning and Tolerancing (GD&T)
Choosing the wrong tolerance group can have significant consequences. Selecting one that is too tight leads to high tooling costs, increased scrap rates, and unnecessary quality control efforts. A tolerance group that is too loose can result in parts that don't fit or function correctly.
: Extreme precision (expensive and difficult to maintain). TG4 : High precision (e.g., gears or precision wheels). It is the most commonly applied tolerance series
You will commonly find TG5 specified in industries where "plug-and-play" assembly is required without manual trimming or adjustment.
For TG5 to remain valid, parts must be measured under standard conditions (typically 23°C and specific humidity) to account for thermal expansion and secondary crystallization. Why Designers Choose TG5