ASME GDTP Senior Level study guide
ASME GDTP Senior Level · Work through your exam, one topic at a time.
The ASME GDTP Senior Level certification is a professional credential that recognizes advanced competence in Geometric Dimensioning and Tolerancing as defined by ASME Y14.5. It is intended for experienced designers, product definition engineers, manufacturing and quality engineers, inspectors, and GD&T trainers who must interpret and apply GD&T across complex drawings and inspection scenarios, and who are often the person others consult when a callout is ambiguous. The ASME GDTP Senior Level study guide has 10 sections and about 3,226 words.
01Fundamentals and Scope of GD&T per ASME Y14.5
ASME Y14.5 is a drawing-definition standard: it governs how geometric requirements are stated on an engineering drawing, not how parts are manufactured or measured. A candidate must know that the drawing is a legally binding contract, that dimensions and tolerances define the acceptable boundary of a part, and that GD&T exists to control variation in form, orientation, location, profile, and runout that plus/minus tolerancing cannot express cleanly.
357 words, about 2 min02Symbols, Terms, and Definitions
You must be able to define, without hesitation: feature, feature of size, datum feature, datum, datum reference frame, actual mating envelope, virtual condition, resultant condition, bonus tolerance, basic dimension, and the modifiers MMC, LMC, RFS, and free state. Each symbol in a feature control frame has a precise meaning: the geometric characteristic symbol, the tolerance value, the material condition modifier, and the datum references in order of precedence.
341 words, about 2 min03Datum Reference Frames and Datum Systems
A datum reference frame (DRF) is a coordinate system established by datum features that constrains the part in space. The primary datum constrains three degrees of freedom, the secondary two, and the tertiary one, for a total of six.
356 words, about 2 min04Form Tolerances and Controls
Form tolerances limit variation of a feature without reference to a datum. They are: straightness, flatness, circularity (roundness), cylindricity, and (for profiles) the form aspect of a profile control.
319 words, about 2 min05Orientation Tolerances and Controls
Orientation controls are perpendicularity, parallelism, and angularity. They limit the angle of a feature relative to a datum but not its location.
313 words, about 2 min06Location Tolerances and Controls
Location controls are position, concentricity, and symmetry (the latter two are largely deprecated in favor of position and profile in current practice, but you must know them). Position locates a feature of size relative to a datum reference frame using basic dimensions; the tolerance zone is typically a cylinder for holes and pins.
293 words, about 1 min07Profile Tolerances and Controls
Profile of a surface and profile of a line control form, orientation, location, and size (when the profile is a closed shape or the size is basic). Profile of a surface uses a tolerance zone of two parallel surfaces offset from the true profile; profile of a line uses two parallel lines in each cross-section.
326 words, about 2 min08Runout Tolerances and Controls
Runout controls the variation of a surface or feature as the part rotates about a datum axis. Circular runout controls variation in each cross-section; total runout controls the entire surface simultaneously.
297 words, about 1 min09Tolerance of Position and Bonus Tolerance / MMC-LMC Concepts
Position tolerance with material condition modifiers is the most heavily tested area. At MMC, the geometric tolerance is a fixed boundary (virtual condition); as the actual feature departs from MMC toward LMC, the allowable geometric tolerance increases by the amount of departure.
323 words, about 2 min10Application, Inspection, and Interpretation of GD&T on Drawings
This domain tests whether you can read a complex drawing, identify every requirement, and plan inspection. You must be able to trace a feature control frame to its datum reference frame, identify basic dimensions, determine the tolerance zone, and select the inspection method (CMM, functional gage, surface plate, optical comparator).
301 words, about 2 min