Dimensioning parts that will be bent In which type of dimensioning scenario must the drafter explicitly account for bend allowances and bend deductions because the part will be formed rather than left flat?

Difficulty: Easy

Correct Answer: Sheet metal

Explanation:


Introduction / Context:
When parts are formed by bending, the flat pattern length differs from the simple sum of leg lengths due to material stretching and compression around the neutral axis. Drawings must account for this via bend allowance or bend deduction to ensure the finished dimensions are correct.



Given Data / Assumptions:

  • The component will be made from sheet stock and bent into shape.
  • Material thickness, inside bend radius, and bend angle are known or specified.
  • Manufacturing requires a flat pattern that develops to the finished shape after bending.


Concept / Approach:
Sheet metal dimensioning includes formulas for bend allowance, bend deduction, or K-factor–based neutral axis placement. These capture the extra material needed (or to be removed) around each bend so net dimensions match the design intent after forming.



Step-by-Step Solution:

Identify bend locations, angles, and radii.For each bend, compute bend allowance using inputs: thickness, radius, and angle.Sum straight lengths and add/subtract allowances or deductions to get the flat pattern.Annotate the drawing with bend notes and necessary process details.


Verification / Alternative check:
Prototype or use CAM software with a validated material K-factor to compare predicted finished sizes with actual bends. Adjust allowances in the drawing as needed.



Why Other Options Are Wrong:

  • Angular / Datum / Tolerance: These are general dimensioning constructs and controls, but they do not specifically address forming effects and bend compensation.


Common Pitfalls:
Ignoring bend relief at corners or using a generic K-factor for all materials can lead to cracked bends or dimensional errors.



Final Answer:
Sheet metal

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