To calculate Bonus Tolerance, subtract the actual value from the feature’s fixed value, then multiply the result by the tolerance ratio. This calculation helps to determine the permissible variation allowed beyond the basic tolerance limit.
Bonus Tolerance Calculator
Enter any 3 values to calculate the missing variable
The Bonus Tolerance Calculator is indeed a very useful accessory. It comes with the function to find the additional tolerance allowed when certain conditions are met in geometric dimensioning and tolerancing (GD&T). Furthermore, the Bonus tolerance provides flexibility in manufacturing, especially for features like holes or slots.
The concept is based on the Maximum Material Condition (MMC) and Least Material Condition (LMC), allowing parts to meet specifications even with slight deviations. This helps reduce production costs and improve assembly accuracy.
Formula:
BT = (FV – AV) * TR
| Variable | Description |
|---|---|
| BT | Bonus Tolerance |
| FV | Feature’s Fixed Value |
| AV | Actual Value |
| TR | Tolerance Ratio |
Solved Calculations:
Example 1:
For a hole with a fixed value (FV) of 12 mm, an actual value (AV) of 11.5 mm, and a tolerance ratio (TR) of 0.2.
| Step | Calculation |
|---|---|
| Subtract actual value from fixed value | 12 – 11.5 = 0.5 |
| Multiply by the tolerance ratio | 0.5 × 0.2 = 0.1 mm |
Example 2:
For a slot with a fixed value (FV) of 15 mm, an actual value (AV) of 14.7 mm, and a tolerance ratio (TR) of 0.3.
| Step | Calculation |
|---|---|
| Subtract actual value from fixed value | 15 – 14.7 = 0.3 |
| Multiply by the tolerance ratio | 0.3 × 0.3 = 0.09 mm |
What is a Bonus Tolerance Calculator?
A Bonus Tolerance Calculator is a useful tool for engineers and machinists. The prime function of this calculator is to calculate the additional tolerance that can be gained when manufacturing parts with specified maximum material conditions (MMC).
Moreover, in situations where the actual size of a feature deviates from the MMC, the bonus tolerance offers additional flexibility in the positioning of the feature. In this way, this tool is especially significant in the calculation of position tolerance, which is essential for accurate assembly and fit.
To elaborate it more, when calculating the bonus tolerance for a hole, for example, if the hole size is larger than its MMC, the difference adds to the positional tolerance, allowing for more permissible variation. The concept of bonus tolerance is closely linked to the idea of least material condition (LMC) and ensures that even with slight variations in size, parts remain functional and compliant.
Final Words:
In a few words, utilizing a bonus tolerance calculator ensures precision in machining and manufacturing. It helps professionals account for dimensional variations, improving overall product quality and reliability.
