GD&T Surface Finish & Assembly Requirements 2

Question 1

On a drawing, the surface texture symbol with a horizontal bar beneath it indicates:

Accepted Answer

Material removal is prohibited

Answer

A horizontal bar beneath the surface texture symbol means material removal by machining is NOT permitted on that surface.

Question 2

Which Ra value represents the smoothest surface finish?

Accepted Answer

Ra 0.8 μm

Answer

Ra 0.8 μm has the smallest average roughness value, making it the smoothest of the listed options.

Question 3

A bearing bore drawing specifies a surface finish of Ra 0.4 μm and a flatness tolerance of 0.02 mm. What is the correct interpretation?

Accepted Answer

Both the surface finish and flatness must independently be met

Answer

Surface texture and geometric tolerances are independent requirements; both must be satisfied simultaneously.

Question 4

In an assembly where a gasket seals between two flanges, which surface finish parameter is MOST critical for sealing performance?

Accepted Answer

Rp (maximum peak height)

Answer

Rp (maximum peak height) is critical for sealing because high peaks can puncture soft gaskets and prevent a proper seal.

Question 5

A profile of a surface tolerance applied all-around a part also controls:

Accepted Answer

Size, form, orientation, and location of that surface

Answer

Profile of a surface is a comprehensive tolerance that simultaneously controls size, form, orientation, and location when datums are referenced.

(GD&T) Geometric Dimensioning and Tolerancing Certification Practice Test