Profile of a surface

Meaning and governing definition

Surface profile controls departure from the theoretically defined surface over the specified extent. Read the zone distribution and datum constraints together. KEYENCE: profile tolerances

In the fixed-frame example, an equal bilateral 0.14 mm zone permits −0.07 to +0.07 mm. Deviations of −0.06 and +0.08 mm fail the positive boundary. A different requirement that permits translating the nominal plane +0.01 mm produces residuals of −0.07 and +0.07 mm. Apply only the movement allowed by the drawing.

Read the drawing's governing standard and edition. ISO 1660:2017, edition 3, published February 2017 and confirmed 2022, gives profile-specification rules using the line/surface symbols defined in ISO 1101. ASME Y14.5-2018 (R2024) supplies a separate dimensioning and tolerancing framework. Similar symbols do not authorize mixing defaults, modifier meanings or datum rules between them. ISO 1660 record, ASME Y14.5 record

Establish the theoretical surface from the released dimensional/model definition. Identify the CAD revision, units and coordinate references used in inspection. A convenient mesh, nominal point set or unreleased model should not silently replace the authoritative geometry.

Zone width, distribution and extent

The tolerance value is the total zone width, not automatically a plus/minus value of that amount. In the equal bilateral case, half lies on each side of the nominal surface. PC-DMIS 2023.1 documents this default and distinguishes ASME unequal-distribution modifiers from ISO UZ/OZ options; similar functions do not make their notation equivalent. Interpret the actual indication under its governing framework. Hexagon: profile of a surface

For an explicitly assumed equal bilateral 0.20 mm zone, the permitted normal offsets are −0.10 to +0.10 mm. For a separately defined mathematical zone of the same width with center offset +0.05 mm, they become −0.05 to +0.15 mm. These are original interval calculations, not instructions for translating an ASME modifier into ISO notation. Define the positive normal/material direction and the specified zone center before using signed deviations.

Resolve which faces or region the indication controls. Do not expand a selected patch to every nearby face, or reduce a whole-surface requirement to one convenient trace. KEYENCE distinguishes surface profile, which addresses the entire specified surface, from line profile in a section. KEYENCE: surface versus line profile

A practical specification review should answer:

Datum constraints versus free fitting

Profile may be specified with or without datum references. In its named implementation, PC-DMIS fits measured surface data into profile zones while respecting the constraints imposed by referenced datums. Multiple considered features can require a simultaneous fit, rather than separate independent adjustments. Hexagon profile evaluation

The PC-DMIS 2023.1 datum guide explains primary, secondary and tertiary datum establishment with higher-precedence relationships preserved. Without datum references, its geometric-tolerance framework leaves translations and rotations unconstrained; each referenced datum constrains relevant freedoms. That is a software explanation of the constraint process, not permission to ignore the complete drawing or other applicable requirements. Hexagon: solving and using datums

An unrestricted alignment chosen only to improve the color map can remove an error that the datum-related requirement is intended to reveal. Conversely, locking arbitrary machine coordinates for a legitimately free profile evaluation can introduce an irrelevant placement penalty. Preserve the permitted freedoms and the datum construction in the measurement plan.

Original bounded evaluation example

Assume a planar nominal patch, a fully fixed evaluation frame, an equal bilateral 0.14 mm zone and exact normal deviations with extrema −0.06 and +0.08 mm. The allowed interval is −0.07 to +0.07 mm. The +0.08 mm point is outside it, although the peak-to-valley spread is only:

+0.08 − (−0.06) = 0.14 mm.

A zone that remains centered on nominal would need width 2 × max(0.06, 0.08) = 0.16 mm to contain those points. Thus comparing the spread alone with 0.14 mm would give the wrong answer for this fixed-center example.

Now assume a different requirement that permits translation of that planar nominal surface along its normal. Moving it +0.01 mm changes the residual extrema to −0.07 and +0.07 mm. The same points fit a 0.14 mm zone after that permitted translation. This is a candidate fit for the stated simplified case, not a general optimization or permission to translate a datum-fixed surface.

The example assumes exact points, known normals, no rotation, no other surfaces and no measurement uncertainty. It illustrates why fit freedoms and zone center must accompany a reported profile value; real acceptance still needs the specified evaluation and decision rule.

Sampling, geometry association and inspection

PC-DMIS illustrates how sparse points can underestimate the actual surface departure and requires correct nominal shapes and values for evaluation. A finite point set cannot by itself demonstrate every unsampled location. Hexagon: nominal and sampling requirements

Choose coverage for the surface's functional and manufacturing risks: curvature changes, edges, transitions, local waviness and inaccessible regions. Verify that the acquired data correspond to the intended nominal surface, especially near neighboring faces or sharp corners. Keep filtering, point rejection and excluded regions explicit. A dense colored rendering is not proof that the relevant regions were measured or associated correctly.

KEYENCE describes profile measurement and CMM approaches, while noting stylus access and contact-load limitations for its profile-system example. Select equipment and probing conditions for the part's geometry and compliance instead of assuming every contacting or optical workflow yields equivalent results. KEYENCE: measuring surface profile

For reproducibility, retain the drawing/model revision, nominal geometry, datum setup, allowed fit freedoms, zone distribution, measured extent, acquisition strategy, evaluation settings and software release. Report the measured result with applicable uncertainty and the agreed conformity rule. Investigate changed alignment or processing before treating a numerical difference as a physical change in the part.

Source scope

The cited Hexagon pages are PC-DMIS 2023.1, dated 8 March 2023. Their command behavior is not asserted for every software release. KEYENCE's live tutorials have no verified technical revision date here. Standards confirmation/reaffirmation dates are distinguished from technical editions. Interval arithmetic, the planar example and proposed inspection-record fields are original guidance.