GD&T Surface Finish & Assembly Requirements 3

Question 1

A shaft and hole assembly uses an interference fit. Which surface finish condition on the shaft would MOST likely cause the interference to be less than intended?

Accepted Answer

Surface peaks (asperities) that are flattened during pressing

Answer

Surface that is too smooth

Answer

Surface that has deep valleys

Answer

A surface with a lay perpendicular to the shaft axis

Question 2

The 'lay' of a surface texture is best described as:

Accepted Answer

The predominant direction of surface marks or tool paths

Answer

The average roughness depth across the surface

Answer

The maximum waviness height on the surface

Answer

The spacing between surface peaks

Question 3

A drawing callout reads 'surface finish Ra 1.6 μm max'. A measured surface has Ra 1.2 μm. This surface is:

Accepted Answer

Within tolerance

Answer

Out of tolerance because it is too smooth

Answer

Only acceptable if Rz is also measured

Answer

Requires re-machining to reach Ra 1.6 μm

Question 4

Which GD&T symbol, when applied to a surface, requires every point on that surface to fall within two parallel planes separated by the tolerance value?

Accepted Answer

Flatness

Answer

Straightness

Answer

Profile of a surface

Answer

Parallelism

Question 5

In a bolted joint assembly, if the mating surfaces have excessive waviness (long-wavelength deviations), the primary risk is:

Accepted Answer

Uneven clamp load distribution and potential fatigue cracking

Answer

Increased friction during assembly

Answer

Higher surface roughness measurement

Answer

Improved sealing without a gasket

Question 6

A drawing specifies a surface profile tolerance of 0.05 mm bilateral. This means each surface point must fall within:

Accepted Answer

0.025 mm on each side of the true profile

Answer

0.05 mm above the true profile

Answer

0.05 mm below the true profile

Answer

0.10 mm total zone offset to one side

Question 7

When a surface finish symbol includes a value above the check mark line and a different value below it, they represent:

Accepted Answer

Maximum Ra and minimum Ra limits

Answer

Ra value and Rz value respectively

Answer

Roughness and waviness separately

Answer

Metric and inch equivalents