Basics Flashcards
7 cards from real CNC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Basics flashcards as text
What is 'chatter' in CNC machining and what is its primary cause?
Answer: Vibration between the tool and workpiece caused by resonance in the cutting system
Chatter is self-excited vibration where the cutting forces feed energy into the machine-tool-workpiece resonant frequency, producing poor surface finish and accelerated tool wear.
Which axis on a standard vertical machining center (VMC) controls the up-and-down movement of the spindle?
Answer: Z-axis
On a VMC, the Z-axis is the spindle axis and controls vertical (up and down) movement, determining depth of cut.
What is the recommended action when a CNC program encounters a tool that has exceeded its programmed tool life?
Answer: Replace or offset to a sister tool before resuming machining
Most CNC controllers support sister tool management, which swaps to an identical spare tool when the original exceeds its life limit, preventing scrap parts.
What does 'surface feet per minute' (SFM) describe in CNC cutting?
Answer: The velocity at which the cutting edge moves past the workpiece surface
SFM (or surface meters per minute in metric) measures the tangential speed of the cutting edge relative to the workpiece, and is the primary parameter for selecting RPM.
Why is it important to verify a CNC program using simulation software before running it on the machine?
Answer: It allows detection of tool collisions, gouges, and incorrect tool paths without risking the machine or workpiece
Simulation visually replays the tool path in a virtual environment, revealing crashes, gouges, missed features, and other errors before any metal is cut.
When referencing a CNC insert grade specification, what does the letter 'P' in the ISO classification indicate?
Answer: It is designed for machining steel and cast steel
In the ISO insert grade classification, 'P' designates grades formulated for cutting steel and cast steel, the most common application group.
What is the primary function of a tool presetter in a CNC environment?
Answer: To measure tool dimensions offline so length and diameter offsets can be entered before the tool is used on the machine
A tool presetter measures the exact length and diameter of each assembled tool offline, allowing accurate offsets to be loaded into the controller before machining begins.