CNC Ferrous & Non-Ferrous Material Properties 3

Question 1

What is the Brinell Hardness Number (BHN) test most suitable for measuring?

Accepted Answer

Large castings and forgings with coarse grain structures

Answer

The Brinell test uses a large steel or carbide ball indenter and is best suited for large, coarse-grained materials like castings and forgings.

Question 2

Which non-ferrous metal has the highest electrical conductivity among commonly used engineering metals?

Accepted Answer

Silver

Answer

Silver has the highest electrical conductivity of all metals, though copper is more commonly used due to cost.

Question 3

When machining copper, the main challenge is:

Accepted Answer

High work hardening rate and tendency to form built-up edge

Answer

Copper's high ductility causes it to smear and form built-up edge on cutting tools, requiring sharp tools and appropriate cutting fluids.

Question 4

D2 tool steel is classified as a:

Accepted Answer

High-carbon, high-chromium cold work tool steel

Answer

D2 is a high-carbon (1.5% C), high-chromium (11-13% Cr) cold work tool steel known for excellent wear resistance.

Question 5

Which stainless steel family is generally non-magnetic and cannot be hardened by heat treatment?

Accepted Answer

Austenitic stainless steel

Answer

Austenitic stainless steels (300 series) retain their FCC crystal structure at room temperature, making them non-magnetic and hardenable only by cold working.

(CNC) Computer Numerical Control Machinist Technical Practice Test

(CNC) Computer Numerical Control Machinist Technical Practice Test

CNC Ferrous & Non-Ferrous Material Properties 3