Conceptual Understanding: The growth in computing power has had a major impact on modelling with computer-aided manufacture. 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 sending 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 manufacture of prototypes has major
implications for data and design protection.
Stereolithography (SLA)
(uses laser or UV light to set plastic liquid)
It is a form of 3D printing using a liquid bath of resin combined with an ultraviolet laser. The ultraviolet light hits the liquid hardening it to form the structure of the object being printed. The base plate of the bath then moves down allowing more liquid to flow over the previously hardened liquid the same process can be repeated until the object being printed has been completed. The ‘Sweeper’ seen in the image to the right just helps even out the height of the bath every time the laser fires.
Laminated object manufacturing (LOM)
It 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.
Fused deposition modelling (FDM)
(Same as school makerbot and Flashforge)
Uses an “additive” principle by laying down materials in layers.
Plastic/metal is unwound from a coil and sent to an extrusion nozzle that can turn the flow on and off.
The nozzle is heated to melt the material, nozzle moves in horizontal and vertical directions by a numerically controlled mechanism (CAM).
Selective laser sintering (SLS)
(uses laser to set plastic powder or metal)
is an additive manufacturing technique that uses a high-power laser (for example, a carbon dioxide laser) to fuse small particles of materials such as plastic, metal (direct metal laser sintering), ceramic or glass powders into a mass that has a desired 3D shape.
Advantages and Disadvantages of Rapid Prototyping
Advantages
-Decrease development time
-Decrease costly mistake
-Increase the number of variants of a product (since each printed model takes less time to produce, the time saved can be used to develop more ideas, thus increase productivity).
-Increase product complexity (more complex and difficult shapes can be modelled, which would perhaps not be possible with hand. For eg. sculpting out an accurate sphere in a material).
-Increase effective communication (since the model is tangible, various aspects of the design would be easier to explain to others, as compared to CAD.
-Models can also be tested, which probably would be only possible through artificial simulation for CAD designs, and thus unlike prototypes, this would only give an approximate idea).
-Rapid Prototyping can provide with concept proof that would be required for attracting funds (easier to explain, aesthetics can be focused on)
Disadvantages
-Some people are of the opinion that rapid prototyping is not effective because, in actual, it fails in replication of the real product or system.
-It could so happen that some important developmental steps could be omitted to get a quick and cheap working model. This can be one of the greatest disadvantages of rapid prototyping.
-Another disadvantage of rapid prototyping is one in which many problems are overlooked resulting in endless rectifications and revisions.
-One more disadvantage of rapid prototyping is that it may not be suitable for large sized applications.
-The user may have very high expectations about the prototype's performance and the designer in unable to deliver these.
Discuss the types of Rapid Prototyping systems and list the key features: