CNC Safety Standards & Maintenance Practices 3

Question 1

Which ANSI standard governs safety requirements for machining centers and automatic tool-change systems?

Accepted Answer

ANSI B11.8

Answer

ANSI B11.8 specifically addresses safety requirements for drilling, milling, and boring machines, including machining centers with ATC systems.

Question 2

A CNC machine's axis drive produces unusual grinding noise during rapid traverse. The most likely cause and correct action is:

Accepted Answer

Ball screw or linear guide degradation; stop and schedule maintenance

Answer

Grinding during rapid traverse typically indicates ball screw or linear guide wear, requiring immediate maintenance to prevent catastrophic axis failure.

Question 3

When should a CNC operator perform a machine home (reference) position check?

Accepted Answer

At the start of each shift and after any emergency stop or collision

Answer

Reference position must be verified at shift start and after any event that could shift encoder or limit switch calibration, such as E-stops or collisions.

Question 4

What is the correct disposal method for used CNC cutting fluid (coolant) containing metal fines?

Accepted Answer

Follow EPA and local regulations for industrial waste disposal

Answer

Used metalworking fluid with metal fines is a regulated industrial waste requiring disposal per EPA 40 CFR Part 262 and applicable local environmental regulations.

Question 5

The purpose of a CNC machine's overtravel limit switch is to:

Accepted Answer

Stop axis movement before a mechanical crash into end-of-travel

Answer

Overtravel limit switches are hard-wired safety devices that cut axis drive power to prevent the machine from driving a carriage into its mechanical end stop.

(CNC) Computer Numerical Control Machinist Technical Practice Test

(CNC) Computer Numerical Control Machinist Technical Practice Test

CNC Safety Standards & Maintenance Practices 3