CNC Cutting Tool Geometry & Selection 5

Question 1

What does the ISO tolerance class 'M' mean in an insert designation code?

Accepted Answer

The insert has a standard tolerance on the inscribed circle and thickness

Answer

In the ISO insert code, tolerance class 'M' specifies a particular range of dimensional tolerances for the inscribed circle diameter and insert thickness.

Question 2

A thread milling cutter is preferred over a tap for which scenario?

Accepted Answer

Threading thin-walled or large-diameter holes where tap breakage risk is high

Answer

Thread milling is safer in large or thin-walled features because the small cutter cannot break catastrophically inside the part like a large tap can.

Question 3

Which drill geometry feature is designed to reduce thrust force during drilling?

Accepted Answer

Web thinning (point thinning)

Answer

Web thinning reduces the chisel edge width at the drill point, which significantly lowers the axial thrust force needed to penetrate the material.

Question 4

In CNC milling, 'climb milling' differs from 'conventional milling' primarily in:

Accepted Answer

Whether chip thickness decreases or increases from entry to exit

Answer

In climb milling chips start thick and thin out; in conventional milling chips start thin and grow thick — this affects cutting forces, finish, and tool life.

Question 5

PVD (Physical Vapor Deposition) coatings on carbide inserts differ from CVD coatings in that PVD coatings:

Accepted Answer

Are applied at lower temperatures preserving edge sharpness

Answer

PVD coatings are deposited at lower temperatures (around 500°C vs 1000°C for CVD), allowing sharper edge geometries to be maintained without substrate distortion.

(CNC) Computer Numerical Control Machinist Technical Practice Test

(CNC) Computer Numerical Control Machinist Technical Practice Test

CNC Cutting Tool Geometry & Selection 5