Practice Test Geeks(CNC) Computer Numerical Control Machinist Technical Practice Test
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Surface Finishing & Post-Processing Flashcards

6 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 6 Surface Finishing & Post-Processing flashcards as text

  1. What type of surface texture is produced by a ball nose end mill during 3-axis CNC contouring?

    Answer: Scallop-shaped cusps whose height depends on stepover distance

    A ball nose cutter leaves scallop-shaped cusps between passes; smaller stepover reduces scallop height and improves finish but increases machining time.

  2. Which operation is used to produce a very fine, flat reference surface on a workpiece that has already been rough milled?

    Answer: Surface grinding

    Surface grinding uses an abrasive wheel to remove small amounts of material, producing flat surfaces with tight parallelism and fine finish not achievable by milling alone.

  3. What is the purpose of 'honing' a bore after CNC machining?

    Answer: To correct minor out-of-roundness and produce a crosshatch finish for oil retention

    Honing removes small amounts of material with abrasive stones to correct bore geometry and produces a crosshatch pattern that retains lubricant in cylinder bores and bushings.

  4. A CNC part drawing specifies a surface finish of 63 Ra μin on a mating flange face. Which machining operation is most likely to achieve this directly?

    Answer: Fine face milling or finish turning at appropriate feeds

    Fine face milling or finish turning with appropriate feed and nose radius reliably achieves 32–63 Ra, which is the typical as-machined finish for functional mating surfaces.

  5. What is the main functional reason for specifying a specific surface finish on a sealing face (e.g., O-ring groove)?

    Answer: To ensure the surface is smooth enough to prevent fluid leakage past the seal

    Sealing surfaces must be smooth enough for the seal material (O-ring, gasket) to deform and fill any surface asperities, preventing leakage paths.

  6. Which of the following coatings is applied to cutting tools rather than finished parts to improve tool performance in CNC machining?

    Answer: TiN (titanium nitride) PVD coating

    TiN and similar PVD coatings (TiAlN, AlTiN) are applied to carbide and HSS cutting tools to increase hardness, reduce friction, and extend tool life.