Modelling / 3.5 /
Rapid Prototyping
Rapid Prototyping
Rapid prototyping is the production of a physical model of a design using three-dimensional CAD data. The growth in computing power has had a major impact on modelling with computer-aided manufacturing. Rapid software and hardware developments allow new opportunities and exciting new technologies to create dynamic modelling of ever-greater complexity. Models can be simulated by designers using software, tested and trialled virtually before being sent to a variety of peripheral machines for prototype manufacture in an ever-increasing range of materials. The ease of sending this digital data across continents for the manufacture of prototypes has major implications for data and design protection.
Laminated object manufacture (LOM) takes the sliced CAD data from a 3D model and cuts out each layer from a roll of material, using a laser or plotter cutter. These sliced layers are glued together to form the model, which is either built on a movable platform below the machine or on locating pins when using card. LOM is largely been discarded as better rapid prototyping techniques have become available.
This video highlights an older LOM technique using cutters
Stereolithography (SLA) (also known as optical fabrication, photo-solidification, solid free-form fabrication and solid imaging) is an additive manufacturing (or “3D printing”) technology used for producing models, prototypes, patterns and production parts.
SLA machines don’t extrude material onto a surface but instead start with an excess of liquid plastic, some of which is cured, or hardened by a laser to form a solid object.
SLA machines have four main parts:
A tank that can be filled with liquid plastic - photopolymer.
A perforated platform that is lowered into the tank.
An ultraviolet (UV) laser.
A computer to control the process.
Fused deposition modelling (FDM) works on an “additive” principle by laying down material in layers. A plastic filament or metal wire is unwound from a coil and supplies material to an extrusion nozzle that can turn the flow on and off. The nozzle is heated to melt the material and can be moved in both horizontal and vertical directions by a numerically controlled mechanism, directly controlled by a computer-aided manufacturing (CAM) software package.
The nozzle is heated when extruding plastic and metals and can be moved in both horizontal and vertical directions. New applications are being found for this type of rapid prototyping, including building houses out of concrete.
Selective laser sintering (SLS) is an additive manufacturing technique that uses a high-power laser (for example, a carbon dioxide laser) to fuse small particles of plastic, metal (direct metal laser sintering), ceramic or glass powders into a mass that has a desired 3D shape. Objects printed with SLS are most commonly made out of plastic powders, such as nylon, which are automatically dispersed in a thin layer on top of the build platform. A laser, which is controlled by a computer reading the CAD model tells the machine what to ‘print’. This traces a cross-section of the model into the powder, which then fuses together to form the model. SLS models can be extremely intricate and detailed, however, the machines and powders themselves can be very expensive.
SLS can produce highly detailed and complex models as well as full functional parts. This type of detail in not possible with most of the other forms of 3D printers