NIMS CNC study guide
NIMS CNC · Work through your exam, one topic at a time.
The NIMS CNC credential is a industry-recognized certification for machinists who set up and run computer numerically controlled milling and turning equipment. NIMS awards credentials per duty area, so a candidate can earn recognition in CNC milling, CNC turning, or both, and stack those credentials with related machining certifications over time. The NIMS CNC study guide has 8 sections and about 2,799 words.
01Safety, Health, and Environmental Practices
Safety questions on NIMS-style exams test whether you can recognize a hazard and pick the control that matches it. Know the hierarchy of controls (elimination, engineering controls such as guards and interlocks, administrative controls, then PPE as the last line of defense).
337 words, about 2 min02Blueprint Reading, GD&T, and Drawing Interpretation
Start with the title block (units, material, part number, scale, revision) and the revision block, because a question may hinge on which revision is in effect. Recognize line conventions: visible (object), hidden (short dashes), center (long-short), phantom (chain), break, and section cutting-plane lines.
293 words, about 1 min03Precision Measurement and Inspection
A feature control frame reads left to right: geometric characteristic symbol, tolerance zone (diameter symbol if cylindrical), any material condition modifier, then datum references in order of precedence. Know the families: form (flatness, straightness, circularity, cylindricity), orientation (perpendicularity, parallelism, angularity), location (position, concentricity, symmetry), profile of a line and of a surface, and runout (circular and total).
608 words, about 3 min04Machining Fundamentals, Materials, and Cutting Tools
Cutting speed (SFM or m/min) is surface speed; feed is expressed per revolution, per tooth, or per minute. The core relationships are RPM = (3.82 × SFM) ÷ diameter in inches, and feed rate = RPM × number of teeth × chip load.
327 words, about 2 min05CNC Programming, G-Code, and CAM
Programs move between modal states (G90 absolute / G91 incremental, G20 inch / G21 metric, G17/G18/G19 plane selection) and one-shot commands. Know G00 rapid, G01 linear feed, G02/G03 circular interpolation with center offsets (I, J, K) or radius (R), and the convention that IJK are usually incremental from the start point to the arc center on most controls.
281 words, about 1 min06CNC Setup, Workholding, and Tool Setting
Workholding should follow 3-2-1 locating: three points establish the primary plane, two the secondary, one the tertiary - avoiding over-constraint that twists a part. Know vise technique (parallels, soft jaws, jaw lift, tapping the part down), fixture plates, clamps and strap support, chucks with proper jaw boring and grip length, collets, vacuum and magnetic chucks, and tombstones for multiple parts.
332 words, about 2 min07CNC Machine Operation and Production Control
Know the startup sequence: power up, verify air and coolant, home the axes if required, warm the spindle, load the program, confirm offsets, and check tool life counters. During production, monitor load meters, spindle sound, chip form, coolant flow, and finish; make offset changes in small, documented increments and record what changed and why.
305 words, about 2 min08Maintenance, Troubleshooting, and Process Improvement
Know the routine PM items: way lubrication and reservoir levels, way wipers and covers, ball screw and linear guide lubrication, coolant concentration and sump cleaning, chip conveyor and filtration, air line filters/regulators/lubricators, hydraulic oil and pressure, belts, spindle taper condition, and backup batteries for parameter memory. Spindle warm-up programs protect bearings and stabilize geometry.
316 words, about 2 min