Correct option is D
A
surface plate is primarily used for marking because it provides a
precisely flat and smooth datum surface or base. This ensures accuracy in marking operations, as the flatness and stability of the surface allow the workpiece to be positioned correctly and the marking tools to function precisely.
Characteristics of Surface Plates:
· Made from granite or cast iron to ensure durability and precision.
· Resistant to wear and thermal expansion, maintaining accuracy over time.
Applications:
· Used in inspection to check flatness, parallelism, and other geometric tolerances.
· Acts as a stable platform for scribing lines during marking processes.
