Creo

PTC Creo (formerly Pro/ENGINEER) pioneered parametric feature-based modelling. Learn its modelling philosophy, relations, family tables, top-down skeletons, flexible modelling, and simulation/generative tools.

Pro/ENGINEER, launched in 1987, introduced the parametric, feature-based, history-driven modelling now standard in all mainstream CAD. Its successor Creo is widely used in heavy machinery, industrial equipment, consumer products and defence.

Creo is known for robust relations and family tables, strong large-assembly and top-down tools, and integration with Windchill PLM.

An analogy

Relations in Creo are like spreadsheet formulas living inside the model: dimensions become cells that can depend on each other.

Feature-based modelling

Datum planes, sketches, extrudes, revolves, sweeps, blends, holes, rounds, shells, drafts and patterns form a model tree. Creo emphasises strong references and intent — sketches are always fully constrained via 'weak' and 'strong' dimensions.

Relations and parameters

User parameters (LENGTH, MATERIAL, PART_NO) and relations link dimensions, control patterns and even suppress features conditionally. Parameters flow into BOMs and drawing notes.

Family tables and top-down design

Family tables create standard parts (bolt series, profile sizes) from one generic model. Skeleton models and published geometry drive large assemblies from a master layout, so changes propagate coherently.

Flexible modelling, simulation and generative design

Flexible modelling edits geometry directly without history (useful for imported models). Creo Simulate/Ansys-powered simulation, Generative Topology Optimisation and Additive Manufacturing extensions support design-to-print workflows. Windchill manages revisions and change processes.

Formulas

• Relation: d1 = d0 / 2
• Conditional relation: IF d0 > 80 … ELSE … ENDIF
• Pattern spacing: d5 = (d0 − 2·edge) / (p6 − 1)

Worked example: Relation-driven plate

Given: LENGTH = 100 mm (relations above)

Find: Width, thickness, holes, spacing, mass.

• d1 = 50, d2 = 10
• LENGTH > 80 → 4 holes
• Spacing = (100 − 20)/3 = 26.7 mm
• Mass ≈ 100 × 50 × 10 × 7.85 × 10⁻⁶ = 0.39 kg

Answer: 50 × 10 mm, 4 holes at 26.7 mm, ≈ 0.39 kg

Worked example: Instance count

Given: Bolt family: 5 diameters × 6 lengths

Find: Instances.

• 5 × 6 = 30 instances from one generic

Answer: 30 standard parts

Part relations

/* Plate driven by LENGTH parameter */
d0 = LENGTH
d1 = LENGTH / 2            /* width */
d2 = LENGTH / 10           /* thickness */

IF LENGTH > 80
   p6 = 4                  /* holes in pattern */
ELSE
   p6 = 2
ENDIF
d5 = (LENGTH - 20) / (p6 - 1)   /* hole spacing, 10 mm from each end */

MASS_EST = LENGTH * d1 * d2 * 7.85e-6   /* kg, steel */

Relations are evaluated at regeneration; parameters like LENGTH can also drive family-table instances and drawing notes.

Common mistakes

• Wrong: Hard-coding values that should be linked. — Right: Use parameters and relations to capture intent.
• Wrong: Creating separate models for every size. — Right: Use family tables for standard-part series.

Applications

• Industrial machinery: Tractors, mining equipment, pumps (large assemblies, top-down).
• Consumer & medical: Products with plastic parts, mechanisms and variants.
• Aerospace & defence: Configuration-managed designs with Windchill.

Key takeaways

• Parametric feature modelling pioneer.
• Relations and parameters encode intent.
• Family tables for standard parts.
• Skeletons for top-down large assemblies.

Going further

• Pro/PROGRAM: Feature-level programming to include/exclude features based on inputs.
• Mechanism dynamics: Creo mechanism analysis with motors, springs and contact.
• Model-based definition: Creo MBD annotates 3D models with semantic PMI for downstream CMM and CAM.