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Precision Machining

Experienced Worker Assessment Blueprint

Specific Competencies and Skills Tested in this Assessment:

Written Assessment:

Administration Time: 3 hours
Number of Questions: 195

Areas Covered:

7% Organization and Shop Practices
14% Measurement/Inspection/Shop Math
11% Interpretation of Blueprints/Design Activities
7% Benchwork/Application of Technical Information
7% Precision Grinding Machines
10% Lathes
2% Power Saws/Drill Presses
10% Milling
8% Tool Technique/Machine and Tool Maintenance
5% Electrocutting-Discharge Machines (EDM)/Metallurgical Processes and Heat Treatment
18% CNC Programming/Preparation/Operations
1% CNC Programming Using a CAM system

Sample Questions:

The proper tool for removing a broken tap is the 

  1. tap extractor
  2. chisel
  3. punch
  4. scriber 

Of the following, the most versatile layout tool is the 

  1. surface gauge
  2. combination set
  3. hermaphrodite caliper
  4. vernier height gauge 

The process of forming horizontal or diamond-shaped serrations on the circumference of a workpiece is 

  1. facing
  2. knurling
  3. boring
  4. kneading 

Which of the following is not part of the dividing head? 

  1. index crank
  2. index plate
  3. sector arms
  4. arbor support 

Information retained by a CNC system until new information replaces it is said to be

  1. Interpolated
  2. Digital
  3. Random
  4. Modal

Performance Assessment:

Administration Time: 4 hours

Number of Jobs:

Areas Covered:

48% Millblock Workholding and tooling setups, selection of cutting tools, selection of appropriate feeds and speeds, milling workpiece square to size, milling slot, milling angle, deburring, drill cross holes, safety procedures, cleanup and care of tools and equipment, tramming the head, indicating the vise, width square to length, pattern of holes, size of drilled hole, overall finish and quality of work. 

32% Adapter Arbor Setup for 30° angle and 45° chamfer, setup and cutting procedure of relief groove and threading, thread measurement, safe work habits, proper workholding methods chosen to maintain concentricity, metal removal rate, proper geometry on tool bits, setup for taper turning, surface finished on turned diameters, accuracy of machined lengths and square shoulders. 

20% CNC Programming

Sample Job:

Mill Block

Estimated Job Time: 1 hour and 45 minutes

Participant Activity: Following industrial safety rules, the participant will machine the block on the milling machine according to the specifications give on the drawing provided in each