◆ Engineering Logic as CAD Rules

Rule-Based Geometry Creation That Thinks Like Your Engineers

Encode design intent, standards and decision logic directly into Siemens NX. CitiusKBE turns your engineering playbook into a living rule engine that builds, updates and validates 3D geometry automatically.

The Core Distinction

Parametric Modeling vs Rule-Based Geometry

Both automate CAD, but they solve different problems. Rule-based geometry creation handles decisions your engineers make in their heads, the ones that templates alone cannot capture.

Parametric Only Numbers-Driven

  • Geometry updates when dimensions change
  • Formulas link features mathematically
  • Works well for simple size variations
  • Cannot handle conditional design choices
  • Breaks when logic changes, not just values

Rule-Based Geometry Logic-Driven

  • Geometry adapts to conditions, not just numbers
  • Encodes engineering decisions (IF-THEN-ELSE)
  • Handles material, standard and feasibility rules
  • Validates design intent automatically
  • Scales across entire product families
Inside a CitiusKBE Rule

Anatomy of a Geometry Creation Rule

A well-designed rule captures inputs, conditions, geometry actions and validation. Here is a simplified view of how CitiusKBE structures rules inside Siemens NX.

// Rule: Select flange type based on pressure class
rule FlangeSelection (pressure, pipeSize, material) {
  // Condition block
  if (pressure >= 600) {
    flange.type = "welding neck";
    flange.face = "ring joint";
  } else if (pressure >= 150) {
    flange.type = "slip on";
    flange.face = "raised face";
  }
  // Geometry action
  createFlange(flange, pipeSize, material);
  // Auto-validation
  checkStandard("ASME B16.5");
}
Inputs Parameters the engineer supplies (pressure, size, material)
Conditions Engineering logic that makes the design decision
Geometry Action NX API calls that build the 3D feature
Validation Automatic standards and compliance checks
Six Categories of Rules

What Kinds of Rules Can Be Encoded?

CitiusKBE captures the full spectrum of engineering decisions your teams make every day, and embeds them into your Siemens NX environment.

R.01 · GEOMETRY

Geometry Creation Rules

Define how shapes, features and profiles are built based on inputs or product category.

IF diameter > 200 THEN use ribbed profile
R.02 · PLACEMENT

Feature Placement Rules

Position holes, slots, ribs and bosses based on geometric references or design intent.

hole.offset = plate.edge + (dia × 1.5)
R.03 · STANDARDS

Standards Compliance Rules

Enforce ISO, ASME, DIN, company and customer standards at the geometry level, not after the fact.

enforce("ISO-273", "hole tolerance")
R.04 · MATERIAL

Material Selection Rules

Auto-select materials and grades based on load, environment or application type.

IF temp > 400°C THEN grade = "A182 F22"
R.05 · VALIDATION

Validation & Check Rules

Verify dimensions, clearances, wall thickness and interferences the moment geometry is built.

checkClearance(bolt, neighbor, 3mm)
R.06 · MANUFACTURING

Manufacturing Feasibility Rules

Flag designs that violate DFM constraints, bend radii or tool-access requirements.

IF bendRadius < 2t THEN alert
Delivery Methodology

How CitiusKBE Builds Your Rule Engine

A structured five-stage process that transforms tacit engineering knowledge into a production-ready automation plug-in for Siemens NX.

Knowledge Elicitation

We interview senior engineers, review existing NX models and capture the undocumented design logic that drives your products.

Rule Modeling

Engineering decisions are formalized into structured rule sets with clear inputs, conditions, actions and validations.

NX Implementation

Rules are implemented using NX Open APIs, journals and our KBE framework, packaged as a native NX toolbar plug-in.

Validation & Testing

The rule engine is tested against historical designs to confirm it reproduces correct geometry across edge cases.

Rollout & Governance

Training, documentation and a rule-management framework ensure your team can evolve the logic as standards change.

Measurable Outcomes

What Rule-Based Automation Delivers

CitiusKBE customers consistently report these outcomes within the first two quarters of deploying rule-based geometry automation.

80%
Reduction in geometry creation time for rule-driven parts
95%
Compliance rate with corporate and customer standards
3x
Faster onboarding for junior design engineers
Where Rules Drive Design

Industry Applications of Rule-Based Geometry

Rule-based geometry creation delivers the biggest payoff in industries with strict standards, complex product families and repetitive design decisions.

Industry Typical Rule Applications Value Impact
Aerospace Bracket design, fastener patterns, stress-driven geometry, compliance checks High
Automotive / BIW Fixture layouts, clamp positioning, weld gun access, jig design rules High
Heavy Engineering Boiler tube layouts, pressure vessel nozzles, support structures High
Industrial Machinery Frame sizing, bolt patterns, cabinet layouts, mounting rules Medium
Piping & Plant Flange selection, pipe routing, support spacing, ASME compliance High
Tool & Die Die base rules, cavity layout, ejector pin positioning, shut-off logic Medium
Explore the Full Automation Stack

Related CAD Automation Capabilities

Rule-based geometry creation is one layer of CitiusKBE's automation platform. Explore the connected capabilities that amplify its impact.

Frequently Asked

Rule-Based Geometry Creation, Answered

Straight answers to the most common questions from CAD managers, engineering leads and design teams evaluating rule-driven automation.

What is rule-based geometry creation?

It is a CAD automation approach where engineering logic, design constraints and company standards are encoded as rules that automatically generate or modify 3D geometry. The rule engine decides how features are built, positioned and validated based on input conditions.

How is it different from parametric modeling?

Parametric modeling drives geometry through numeric parameters and formulas. Rule-based geometry creation adds conditional logic, IF-THEN-ELSE decisions, validation checks and design rules, so the model adapts intelligently to different scenarios, not just different numbers.

Does CitiusKBE support rule-based automation inside Siemens NX?

Yes. CitiusKBE builds rule-based automation plug-ins for Siemens NX using NX Open APIs, journals and Knowledge-Based Engineering frameworks, fully integrated with Teamcenter.

What types of rules can be encoded?

Geometry creation rules, feature placement rules, standards compliance rules, material selection rules, validation rules and manufacturing feasibility rules can all be captured and automated.

Can rules be updated when our standards change?

Yes. CitiusKBE structures rules in a maintainable format with clear inputs, conditions and actions. Your team can update individual rules through a governance framework without rebuilding the entire automation.

Who owns the rule engine after delivery?

You own it fully. The rule engine runs inside your NX environment as a plug-in, with full documentation and source ownership transferred to your team on project completion.

Turn Your Engineering Playbook Into a Rule Engine

Share one recurring design challenge with our KBE engineers. We will map the rules, estimate the automation scope and show you the expected time savings, at no cost.

Request a Rule Mapping Session