Computer-aided design (CAD) is the use of a wide range of computer-based tools that assist engineers, architects and other design professionals in their design activities. It is the main geometry authoring tool within the Product Lifecycle Management process and involves both software and sometimes special-purpose hardware. Current packages range from 2D vector based drafting systems to 3D solid and surface modellers
CAD is used to design, develop and optimize products, which can be goods used by end consumers or intermediate goods used in other products. CAD is also extensively used in the design of tools and machinery used in the manufacture of components, and in the drafting and design of all types of buildings, from small residential types (houses) to the largest commercial and industrial structures (hospitals and factories).
CAD is mainly used for detailed engineering of 3D models and/or 2D drawings of physical components, but it is also used throughout the engineering process from conceptual design and layout of products, through strength and dynamic analysis of assemblies to definition of manufacturing methods of components.
CAD has become an especially important technology, within CAM, with benefits, such as lower product development costs and a greatly shortened design cycle, because CAD enables designers to lay out and develop their work on screen, print it out and save it for future editing, saving a lot of time on their drawings.
Computer-aided manufacturing (CAM) is the use of a wide range of Product Lifecycle Management computer-based software tools that assist engineers, Tool and die makers and CNC machinists, in the manufacture or prototyping of product components.
Traditionally, CAM has been considered as an NC programming tool wherein 3D models of components generated in CAD software are used to generate CNC code to drive numerical controlled machine tools.
Although this remains the most common CAM function, CAM functions have expanded to integrate CAM more fully with CAD/CAM/CAE PLM solutions.
As with other “Computer-Aided” technologies, CAM does not eliminate the need for skilled professionals such as Manufacturing Engineers and NC Programmers. CAM, in fact, both leverages the value of the most skilled manufacturing professionals through advanced productivity tools, while building the skills of new professionals through visualization, simulation and optimization tools.
Computer-aided engineering (often referred to as CAE) is the use of information technology for supporting engineers in tasks such as analysis, simulation, design, manufacture, planning, diagnosis and repair. Software tools that have been developed for providing support to these activities are considered CAE tools. CAE tools are being used, for example, to analyze the robustness and performance of components and assemblies. It encompasses simulation, validation and optimization of products and manufacturing tools. In the future, CAE systems will be major providers of information to help support design teams in decision making.
In regards to information networks, CAE systems are individually considered a single node on a total information network and each node may interact with other nodes on the network.
CAE systems can provide support to businesses. This is achieved by the use of reference architectures and their ability to place information views on the business process. Reference architecture is the basis from which information model, especially product and manufacturing models.
The term CAE has also been used by some in the past to describe the use of computer technology within engineering in a broader sense than just engineering analysis. It was in this context that the term was coined by Dr. Jason Lemon, founder of SDRC in the late 70's. This definition is however better known today by the terms CAM and PLM.
CAE areas covered include:
Stress analysis on components and assemblies using FEA (Finite Element Analysis);
Thermal and fluid flow analysis Computational fluid dynamics (CFD);
Kinematics;
Mechanical event simulation (MES).
Analysis tools for process simulation for operations such as casting, molding, and die press forming.
Optimization of the product or process.
In general, there are three phases in any computer-aided engineering task:
Pre-processing – defining the model and environmental factors to be applied to it. (typically a finite element model, but facet, voxel and thin sheet methods are also used)
Analysis solver (usually performed on high powered computers)
Post-processing of results (using visualization tools)
This cycle is iterated, often many times, either manually or with the use of commercial optimization software.
Machining process
Most machining progresses through four stages, each of which is implemented by a variety of basic and sophisticated strategies, depending on the material and the software available. The stages are:
Roughing
This process begins with raw stock, known as billet, and cuts it very roughly to shape of the final model. In milling, the result often gives the appearance of terraces, because the strategy has taken advantage of the ability to cut the model horizontally. Common strategies are zig-zag clearing, offset clearing, plunge roughing, rest-roughing.
Semi-finishing
This process begins with a roughed part that unevenly approximates the model and cuts to within a fixed offset distance from the model. The semi-finishing pass must leave a small amount of material so the tool can cut accurately while finishing, but not so little that the tool and material deflect instead of shearing. Common strategies are raster passes, waterline passes, constant step-over passes, pencil milling.
Finishing
Finishing involves a slow pass across the material in very fine steps to produce the finished part. In finishing, the step between one pass and another is minimal. Feed rates are low and spindle speeds are raised to produce an accurate surface.
Contour Milling
In milling applications on hardware with five or more axes, a separate finishing process called contouring can be preformed. Instead of stepping down in fine-grained increments to approximate a surface, the workpiece is rotated to make the cutting surfaces of the tool tangent to the ideal part features. This produces an excellent surface finish with high dimensional tolerances
A Lathe produces parts by "turning" rod material and feeding a single-point cutter into the turning material.
Cutting operations are performed with a cutting tool fed either parallel or at right angles to the axis of the workpiece. The tool may also be fed at an angle relative to the axis of the workpiece for the machinign tapers and angles. The workpiece may originally be of any cross-section, but the machined surface is normally straight or tapered.
Possible shapes
A variety of plain, taper, contour, fillet and radius profiles plus threaded surfaces.
Example parts
CNC turning can be used to create shafts, rods, hubs, bushes, pulleys, etc.
Advantages of CNC Turning
More cost effective than CNC Milling for appropriate shapes.
Specifications for CNC Turning
Material - most rigid materials including most metals and hard plastics Alternative machines - for short runs, mill. Tooling - CNC Turning requires only software program tooling. Reducing costs - minimize design elements.
Notes
As the turning process applies pressure to the material, weak shapes that may flex are not practical, such as long thin structures. Also, CNC turning generates a cut surface with a fine helical feed marks resulting from the rotation of the part and movement of the cutter.
CNC Milling
CNC milling is a cutting process in which material is removed from a block by a rotating tool. In CNC milling the cutting tool is moved in all three dimensions to achieve the desired cut shape.
Material is usually removed by both the end and the side of the cutting tool. In CNC milling the cutting tool usually rotates about an axis that is perpendicular to the table that holds the material to be cut. Cutting tools of various profile shapes are available including square, rounded, and angled. A wide variety of part shapes and geometries are possible.
Possible shapes
A wide variety of 2D and 3D shapes.
Example parts
CNC milling can be used to create engine components, custom and mold tooling, complex mechanisms, enclosures, etc.
Advantages of CNC Milling
Complex shapes from sheet or block material. Cost effective for short runs.
Specifications for CNC Milling
Material - most rigid materials including most metals and hard plastics Alternative machines - for 2D sheet shapes: Laser Cut, Turret Punch, Fixed Punch. Tooling - CNC Milling requires only software program tooling and in some cases work-holding jigs. Reducing costs - use corner radius 10% or more of the height (>0.2" recommended), avoid thin walls.
Notes
As the milling process applies pressure to the material, weak shapes are not practical, such as long thin shapes, and thin walls. Also, CNC milling generates a cut surface with a visible pattern resulting from the rotation and movement of the cutter.
Wire EDM Cutting
Wire EDM (electrical discharge machining) uses an electrically energized thin brass wire to slice through metal - including difficult-to-machine metals. Wire EDM creates intricate profiles. The Wire EDM machine uses rapid, controlled, repetitive spark discharges.
The workpiece must be electrically conductive. It is often possible to stack and cut workpieces simultaneously. The narrow kerf and dimensional accuracy make it possible to provide close-fitting parts. Workpiece thickness ranges from only a few thousands of an inch to several inches.
Possible shapes
Any simple or complex 2D shape - allows cutouts and thin walls, intricate openings and tight radius contours, both internally and externally.
Example parts
Punches, dies, stripper plates, gears.
Advantages of Wire EDM Cutting
Cutting intricate shapes and tight radius contours. Low cost when surface area of cut edge is small or quantity is low.
Specifications for Wire EDM Cutting
Material - Steel, super alloys, titanium, aluminum, brass, and most other metals. Alternative machines - Punch Fixed (for simple parts), Punch CNC (for thin sheets), Mill 3-Axis CNC (for simple shapes), Laser Cut (for longer runs of simple parts), Water Jet (for short runs of thick parts). Tooling - Wire EDM cutting requires only software program tooling. Reducing costs - reduce total cut length, minimize holes or provide a small gap connecting holes to the outer edge.
Notes
Wire EDM edges are smooth but matte. Typical surface finish is between 16 and 64 microinches. The edges of the finished work piece will have virtually no burrs. Kerf width 0.001 - 0.012". Sharp internal corners will be slightly rounded (~.008").
Material - most rigid materials including most metals and hard plastics 
Alternative machines - for short runs, mill.
Tooling - CNC Turning requires only software program tooling.
Reducing costs - minimize design elements.
As the turning process applies pressure to the material, weak shapes that may flex are not practical, such as long thin structures. Also, CNC turning generates a cut surface with a fine helical feed marks resulting from the rotation of the part and movement of the cutter.
Material - most rigid materials including most metals and hard plastics 
Alternative machines - for 2D sheet shapes: Laser Cut, Turret Punch, Fixed Punch. 
Tooling - CNC Milling requires only software program tooling and in some cases work-holding jigs.
Reducing costs - use corner radius 10% or more of the height (>0.2" recommended), avoid thin walls.
As the milling process applies pressure to the material, weak shapes are not practical, such as long thin shapes, and thin walls. Also, CNC milling generates a cut surface with a visible pattern resulting from the rotation and movement of the cutter.
Material - Steel, super alloys, titanium, aluminum, brass, and most other metals. 
Alternative machines - Punch Fixed (for simple parts), Punch CNC (for thin sheets), Mill 3-Axis CNC (for simple shapes), Laser Cut (for longer runs of simple parts), Water Jet (for short runs of thick parts).
Tooling - Wire EDM cutting requires only software program tooling.
Reducing costs - reduce total cut length, minimize holes or provide a small gap connecting holes to the outer edge.
Wire EDM edges are smooth but matte. Typical surface finish is between 16 and 64 microinches. The edges of the finished work piece will have virtually no burrs. Kerf width 0.001 - 0.012". Sharp internal corners will be slightly rounded (~.008").
