CAD is a computer-aided design system, i.e. a class of software for creating design documentation, 3D models, assemblies and technical drawings. To put it simply, CAD is a specific implementation of CAD for 2D and 3D design in mechanical engineering. Within a single project, an engineer can work with a 3D model, 3-6 standard projections of a part, a specification and files for transfer to production. A single change to a parameter, such as the diameter of a hole or the wall thickness, can automatically update the associated views, dimensions and tables without the need to redraw each element manually.
Unlike manual drafting, CAD does not work with individual lines but with a digital model in which geometry, dimensions and relationships are interconnected. This is particularly important in mechanical engineering, where a single part often has several versions, configurations and variants. For example, if the bearing mounting dimension is changed in a gearbox housing, the CAD system can update the model, drafting and specification within a single project. In this way, the designer can visualise the product’s logic even before it goes into production.
A CAD system differs from a hand-drawn or 2D drawing in that the engineer works not with individual lines, but with a parametric 3D model, where the geometry, dimensions, part drawings and specifications are all linked together. If you change a single parameter of a part in SOLIDWORKS – for example, the diameter of a hole or the wall thickness of a housing – the system can automatically update all views, sections, dimensions and specifications. With manual drafting or a simple 2D editor, each view would have to be checked and redrawn individually. This is precisely why parametric modelling reduces the need for duplicate edits and helps to prepare technical drawings for production more quickly. To make the difference clearer, let’s compare manual drafting and CAD based on criteria that are key for engineers.
| Criterion | Manual drafting/2D editor | CAD system |
| Speed of changes | Each projection must be edited separately | A single parameter can update the model, views and specifications |
| Number of errors | Higher risk of discrepancies between views | Fewer errors thanks to the link between the 3D model and drawings |
| 3D visualisation | The part must be visualised using 2D views | The product can be viewed in 3D even before manufacture |
| Transfer to production | Additional file preparation is often required | Data can be transferred to a CAM, CNC or PLM system |
A modern CAD system consists of modules that cover the entire process from the 3D model to the final design documentation. An engineer does not simply create the shape of a part, but works with a complete digital description of the product: geometry, assemblies, drawings, dimensions, materials and manufacturing data. This is particularly important in mechanical engineering, as a single change to the model can affect several parts, assemblies and specifications. To better understand the structure of a CAD system, it is worth breaking it down into its main working modules:
The CAD/CAM workflow is straightforward: CAD is responsible for designing the model, whilst CAM converts this model into machining data. For example, a designer creates a part’s body in CAD, after which a production engineer uses the geometry to prepare toolpaths on a CNC machine. This provides the company with a single digital workflow: model, drawing, specification, calculation and transfer to production without unnecessary manual duplication.
A machine-building company needs to switch to CAD/CAM to shorten the path from the initial idea for a part to the final design documentation. For example, when designing a gearbox housing, an engineer creates a 3D model, defines mounting locations, holes and stiffening ribs, and immediately generates the drawings. If the wall thickness or bore diameter needs to be changed, CAD updates the associated views and specifications without the need to manually redraw each view. For such tasks, the company should consider the SOLIDWORKS CAD solution, which offers convenient work with parts, assemblies, drawings and basic engineering checks. In practice, this offers several tangible benefits for design offices and production:
When CAD is used not in isolation but as part of a broader digital process, the organisation gains greater control over the entire product lifecycle. The designer views the model, the production engineer prepares data for CNC machining, the production team works with the latest version, and the project manager understands the current status of changes. If a company needs to integrate 3D design, calculations, PLM and engineering data management, solutions from Dassault Systèmes for design purposes may be the logical next step. This approach helps not just to draw faster, but to map out a clear path from the designer’s concept to production.
When choosing a CAD system for mechanical engineering production, you should consider how well it integrates with your actual workflow: from 3D modelling to drafting, calculation, approval and data transfer to the workshop. For mechanical engineering, it is important that the system supports parametric and hybrid modelling, handles complex assemblies and does not create unnecessary barriers between the designer, the process engineer and the production team. Before purchasing, it is best to assess not only the features but also future configuration, team training and technical support. That is why the first step could be a consultation on implementing a CAD system, where you can match the company’s requirements with the appropriate solution configuration. To ensure you make the right choice, check the basic criteria:
It is also worth considering industry-specific requirements: designing gearboxes, steel structures, process equipment or components for the aviation sector requires different sets of modules. If the CAD system is to operate not in isolation but within the company’s unified digital ecosystem, it is important to take a broader view from the outset: considering integration with PLM, version control, libraries of standard components and data transfer to production. For this approach, you might consider GEO-MENTOR’s industry-specific solutions, which help you select engineering tools tailored to specific processes, rather than an abstract list of functions.
CAD systems automate the design process, replacing manual drafting with parametric 3D modelling, where geometry, drawings, specifications and manufacturing data are interconnected. Instead of redrawing each view separately, the engineer modifies a model parameter and the system updates the associated elements. This reduces the number of errors in design documentation, simplifies data transfer between the design office and the workshop, and helps to move more quickly from the concept of a part to its manufacture.
CAD is a digital tool for creating drawings, 3D models and design documentation. In mechanical engineering, CAD helps to design parts, assemblies, housings, brackets, frames and fixtures. Unlike a conventional drawing, a CAD system maintains links between the model, views, dimensions and specifications. If the geometry of a part changes, related elements can be updated automatically within the configured project.
No, CAD does not replace the design engineer; rather, it eliminates some of the manual work. The system does not make technical decisions in place of the specialist. It helps to create geometry more quickly, check assemblies, produce part drawings and prepare data for manufacturing. Decisions regarding materials, tolerances, loads, manufacturability and safety are still made by the engineer in accordance with company standards and the technical specifications.
CAD is about design, whilst CAM is about production preparation. In CAD, the engineer creates a 3D model, technical drawings, assemblies and specifications. In CAM, a production engineer uses this model to generate toolpaths for a CNC machine. In other words, CAD answers the question “what are we manufacturing?”, whilst CAM answers “how exactly do we machine the part?” on specific equipment, taking into account the material of the specific workpiece.
STEP, IGES, DWG, DXF, STL and Parasolid are formats that are often required for the exchange of engineering data. STEP is useful for transferring 3D geometry between different CAD systems. DWG and DXF are often used for 2D drawings. STL is required for 3D printing and prototyping. Before choosing a CAD system, it is worth checking which formats are used by suppliers, the workshop, the CAM system and customers.
When changes to drawings take many hours, and errors between views carry through to production, it is time to make the switch. 3D CAD is particularly useful for assemblies, housing components, tooling, frames, mechanisms and products with multiple configurations. If a company frequently revises designs, transfers data to CNC machines or wishes to integrate PLM, a 2D editor is no longer sufficient to ensure a stable process.
