While draft angles are not strictly a tolerance, they are critical for achieving TG5 reliably.
| Feature depth (mm) | Recommended draft (per side) | |--------------------|-------------------------------| | 0 – 10 | 0.5° – 1.0° | | 10 – 30 | 1.0° – 1.5° | | 30 – 100 | 1.5° – 2.0° | | Over 100 | 2.0°+ |
TG5 allows minimal drafts if surfaces are polished, but too little draft increases wear and variability.
Challenge: A 64-pin ECU connector housing required pin alignment within 0.08 mm for wave soldering.
Approach: Initially specified TG5 for all dimensions. After mold flow analysis, only the pin grid array (PGA) zones were mapped to TG5. The outer shell was relaxed to TG4.
Result: Tool cost reduced by 18%. First-pass yield reached 97% (vs 82% if full TG5). The housing passed 95°C thermal shock testing.
Lesson: Selective TG5 application is smarter than blanket tolerancing.
If you specify TG5, you are demanding the tightest plastic tolerances possible. This feature eliminates most standard injection molders—only those with high-end moldmaking (tolerances < 0.005 mm on cavities) and fully automated process monitoring can reliably hold TG5.
Title: Precision in Motion: An Analysis of DIN 16742 Tolerance Class TG5
Introduction
In the realm of modern manufacturing, injection molding stands as one of the most versatile and widely used processes for producing plastic components. However, the physical properties of polymers—such as shrinkage, thermal expansion, and moisture absorption—present unique challenges when it comes to dimensional accuracy. Unlike machined metal parts, which can often achieve exact specifications, plastic parts require standardized tolerance systems to ensure interchangeability and functional reliability. This is where DIN 16742 comes into play. As the German standard for dimensional tolerances and acceptance conditions for plastic molded parts, it provides a framework for engineers and suppliers to agree on quality. Specifically, Tolerance Class TG5 represents a critical balance within this standard, offering a mid-range level of precision that is applicable to a vast array of industrial applications.
The Framework of DIN 16742
To understand the significance of TG5, one must first understand the structure of DIN 16742. The standard categorizes tolerances into two main groups: dimensional tolerances (for length, width, height) and form tolerances (for flatness, straightness, etc.). These tolerances are not arbitrary; they are based on the nominal size of the dimension and are grouped into "Tolerance Groups." din 16742 - tg5
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.
Defining Tolerance Class TG5
TG5 falls in the middle of the standard spectrum, situated between the highly precise lower groups (TG1–TG3) and the looser, general-purpose higher groups (TG6–TG7).
TG5 is often characterized as a "Fine" or "Medium-Precision" tolerance class. It is stricter than general commercial molding standards (like TG6 or TG7) but does not demand the extreme, costly controls required by High Precision (TG1–TG2).
In the context of the standard’s tables, TG5 specifies a permissible deviation that is significantly tighter than what might be acceptable for a disposable item, yet achievable without exotic tooling or specialized environment controls. For example, on a nominal dimension of 100mm, the tolerance range in TG5 would be narrow enough to ensure good fitment with mating parts, but wide enough to account for the natural variability of the injection molding process.
Application and Suitability
The selection of TG5 is highly strategic. It is the default choice for functional components that require a degree of reliability and fitment but do not fall into the category of high-precision instrumentation.
Material Considerations
A unique aspect of DIN 16742 is that tolerance groups are often correlated with material behavior. TG5 implies the use of materials that offer moderate stability.
If a manufacturer were to specify TG1 for a semi-crystall
DIN 16742 TG5 refers to a specific "Tolerance Group" (TG) within the German standard for injection-molded plastic part tolerances. While is the most common standard for general industrial parts,
represents a more precise accuracy requirement typically used for high-quality technical components. Deep Mould Key Characteristics of TG5 Precision Level : TG5 is classified as an "Accurate" "Precision" While draft angles are not strictly a tolerance,
production level. It is tighter than the standard TG6 but less extreme than the tool-room limits of TG3 or TG4. Application
: It is often specified for "hard" plastic components or multi-component parts where a more accurate fit is needed (e.g., snap-fits or bearing housings). Cost vs. Accuracy
: Achieving TG5 requires more intensive process monitoring and higher-quality tooling, which generally increases production costs compared to TG6. www.makrolar.eu Factors Affecting TG5 Compliance
The ability to maintain TG5 tolerances depends on several manufacturing variables outlined in the standard: Material Shrinkage
: 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)
: Dimensions formed within a single mold half; these typically allow for tighter tolerances. Non-tool-specific (NW)
: Dimensions affected by the opening/closing of the mold or moving parts (like sliders), which require larger tolerance ranges. Super-Ingenuity Implementation Recommendations
For technical guidance on applying this standard, designers often use tools like the PolTolerances Software
, which helps calculate specific values based on material and part geometry. www.makrolar.eu Design Note
: When using TG5, it is recommended to define "steel-off" positions on drawings to allow for final mold adjustments after the first trial (FOT). Standard Updates : Note that was largely harmonized with the international standard
, so you may see both referenced on modern engineering drawings. specific ±mm values for TG5 across different nominal dimension ranges?
The DIN 16742 standard is a widely used German engineering guideline for determining tolerances of plastic moulded parts. Within this standard, Tolerance Group 5 (TG5) represents the baseline or "standard" level of precision for industrial applications. Understanding DIN 16742 - TG5 TG5 allows minimal drafts if surfaces are polished,
Precision Level: TG5 is considered the standard precision category. It is often applied as a general tolerance across various plastic materials, such as ABS or PC+ABS, to ensure a balance between manufacturing cost and part quality.
Tolerance Range: While the exact numerical deviation depends on the nominal dimension of the part, TG5 typically allows for general tolerances in the range of ±0.1 mm to ±0.5%.
Purpose: Using TG5 allows engineers to define acceptable variations without having to specify tolerances for every single dimension on a drawing, simplifying the design process and setting clear expectations with manufacturers.
Status Update: Note that DIN 16742 was officially withdrawn and superseded by the international standard DIN ISO 20457:2020-03. Comparison of Tolerance Groups
Tolerances in DIN 16742 are categorized based on the required precision and manufacturing process: TG1 to TG3: Extreme precision parts. TG4: High-precision parts. TG5: Standard precision applications (baseline).
TG6: Coarse parts where looser tolerances are acceptable (often used for standard thermoplastics).
TG7 to TG9: Very coarse parts where shrinkage is high or unpredictable. Key Implementation Advice
Material Influence: Shrinkage properties of different polymers (e.g., PP vs. ABS) will affect how easily TG5 is achieved.
Mold-Fixed vs. Non-Mold-Fixed: When citing this standard, you should specify whether the dimension is mold-fixed (within one half of the tool) or non-mold-fixed (crossing the parting line), as this changes the expected tolerance.
Alternative Processes: While primarily for injection moulding, TG5 is also a common target for vacuum casting and some CNC post-processing workflows.
Are you looking to apply these tolerances to a specific material or a particular manufacturing process like injection moulding? Vacuum Casting | FACTUREE – The Online Manufacturer
The TG5 specification within DIN 16742 refers to a particular type of tool holder interface. The nomenclature can vary, but TG5 typically denotes a specific design or performance criterion that tool holders must meet. This could involve the geometric accuracy of the tool holder, its balancing class, or its material composition. The exact requirements of TG5 are detailed within the DIN 16742 standard and are designed to ensure compatibility, precision, and reliability in high-speed machining applications.