CAD — Computer-Aided Design

CAD (Computer-Aided Design) is software used by engineers, designers and architects to create, modify, analyse and document designs as precise 2D drawings or 3D models. It replaces manual drafting with digital geometry that can be edited, dimensioned, reused and shared. In a manufacturing context, CAD is the origin of the product definition: the geometry and specifications created in CAD feed downstream activities such as the engineering bill of materials, manufacturing planning and, via CAM, the programming of machine tools. CAD data is typically governed within PLM and connected to ERP so that engineering and business systems stay aligned.

What CAD does

CAD lets a designer build an accurate digital representation of a part, assembly or structure. Modern mechanical CAD is predominantly parametric and feature-based: dimensions and relationships are defined as editable parameters, so changing one value updates the model and its associated drawings consistently. Output includes 3D models, 2D production drawings with dimensions and tolerances, and data for analysis. CAD spans many disciplines, from mechanical and product design to electrical and electronic layout, and architecture and civil engineering, each with specialised tools and standards.

CAD in the engineering toolchain

CAD rarely stands alone; it is the first stage of a connected toolchain often grouped under the CAx family:

• CAE uses the CAD model for simulation and analysis, such as stress or flow.
• CAM derives tool paths and machine instructions from the geometry for production.
• PLM manages CAD files, versions, releases and the engineering BOM across the product lifecycle.
• Digital twin concepts build on CAD geometry to represent a physical product virtually.

This chain means the quality and structure of the original CAD model influence everything downstream, from simulation accuracy to manufacturability.

CAD and the ERP system

While CAD lives in the engineering domain, its output must reach the commercial and production systems. The engineering bill of materials defined alongside the CAD model is transferred, usually through PLM, into the manufacturing BOM and master data used by ERP for material requirements planning, purchasing and costing. Keeping the two worlds synchronised is a recurring integration challenge: part numbers, units, materials and revision states must be consistent so that what engineering designs is what purchasing buys and production builds. Integration approaches range from manual hand-off to automated PLM-to-ERP interfaces that propagate released structures and engineering changes.

Practical considerations

Selecting and operating CAD involves more than the modelling tool itself. Organisations consider interoperability and neutral exchange formats so that designs can be shared with customers and suppliers using different systems, data management to control versions and prevent uncontrolled file copies, and standards for modelling and drawing so that designs are consistent and reusable. As design data becomes the master source for manufacturing and increasingly for digital-twin and simulation use, disciplined CAD data management, governed through PLM and linked to engineering change management, becomes as important as the geometry-creation capability itself.

Related Topics

• PLM
• Engineering change management
• Bill of materials