The use of 3D CAD (computer aided design) in fast fabrications of physical parts, models or assemblies is known as rapid prototyping. Using additive manufacturing, or 3D printing as it is better known, completes the parts’, models’ or assemblies’ creation process. A prototype is said to be one of high fidelity if the intended finished product is a close match to the design, as contrasted to a prototype with remarkable difference with the finished product which is termed a product with low fidelity. You can read more about rapid prototyping here.
In Rapid prototyping, a number of technologies are involved. The most common of these technologies is an additive manufacturing that employs layering. Beyond this are other technologies which include high-speed machining, molding, casting and extruding. Although the most commonplace process of rapid prototyping is additive manufacturing, prototypes have equally been created by other very conventional processes.
Some of these processes used include:
- Compressive – a process where semi-solids or liquid materials are forced into their desired shapes before solidification. This is exemplified in casting, molding or compressive sintering.
- Subtractive – this is a process where blocks of materials are carved into their desired shapes by the use of milling, turning or grinding.
A Designer’s Solution
Rapid prototyping became the preferred option for product designers who were seeking a means of quick manufacturing of prototype representative parts. In the process of manufacturing, its ability to aid the design, production and visualization of representative parts prior to mass production makes it very attractive to designers, manufacturers, investors as well as customers. Originally, it was a solution applied to the automobile industry with regards to the creation of scale models and parts, but for a while now, it has also been applicable to a variety of applications cutting across numerous industries ranging from aerospace right unto the medical.
Another use of rapid prototyping is in rapid tooling. This is a situation where a part is made by the process and is then applied as a tool in the remaining process. An example of this is like in the making of sensor wedges or mold plugs that are used during a process.
Rapid Prototyping Types
There are different types of Rapid Prototyping. Below is listed some of the various types of rapid prototypes in use.
Vat Photopolymerization or Stereolithography (SLA)
The history of commercially available 3D printing cannot be told without this type of RP (rapid prototyping) as it was the first method to be successfully employed commercially. It is fast as well as affordable. It makes use of an immersion of a photosensitive liquid that is solidified in layers by the employment of ultraviolet light controlled by a computer.
Material Jetting or Fused Deposition Modelling (FDM)
The majority of 3D desktop printers of a non-industrial nature make use of this easy-to-use, inexpensive type. A thermoplastic filament spool is employed as a melting material inside the barrel of a printing nozzle. The ensuing liquid plastic goes on to be laid in layers as directed by a deposition program run from a computer. The results that were earlier recorded by this method produced weak products with poor resolution. However, there is fast improvements going on with the process; also, being cheap and fast still makes it attractive to product developers.
Selective Laser Sintering (SLS)
A powdered material is heated and sintered with the aid of a laser to make a prototype, built layer-on-layer from a bed of powder. This is used for plastic and metal prototyping. It should be noted though that the parts’ strength is not to be compared to that of the SLA which is much better. Furthermore, the finished product’s surface usually comes out rough and in need of a secondary work to achieve a proper finish.
Powder Bed Fusion or Selective Laser Melting (SLM)
This is preferred in the making of complex and high-strength parts. SLM is often used in the automotive, defense, aerospace and medical industries. This fusion process based on a powder bed, makes use of a metal powder in a very fine state. This fine powder is melted in a manner that produces layers which is used subsequently in producing prototypes or parts for production by the aid of electron beams or high-powered laser. In RP, the usual SLM materials deployed for use are aluminum, titanium, alloys of cobalt chrome and stainless steel.
Sheet Lamination or Laminated Object Manufacturing (LOM)
This is another inexpensive process, though in sophistication it comes behind SLS or SLM. However, it is not the most suitable for conditions that demand high levels of accuracy. Thin laminates are built up by LOM. These have been cut accurately by the use of laser beams or by some other cutting device that produces CAD pattern designs. The part is completed after every layer delivered is made to bond on top of previous ones.
With this process, it is possible to print multiple parts at once. It should be noted though that the parts made using this process do not have the same strength as those made with SLS. Just like with many other processes, powder beds are also used here. Micro-fine liquid droplets are sprayed on the powder bed with the aid of nozzles, and this results in a bonding of the powder particles. These bonded powder particles form parts’ layers. A roller is then used for compacting the layers, and the process repeats with the laying down of another powder layer. An oven is finally used to finish the process where it cures the part by burning away any binding agent used and bringing about a fused and coherent part.
Digital Light Processing (DLP)
Bearing some similarities with SLA, this process also employs resin polymerization. However in curing, a more standard source of light is used than is used with SLA. Though a cheaper and faster technique than the SLA, having supporting structures alongside after-building curing are necessary. There is another version where the parts, without using layers, are continuously pulled out of a vat. While the pulling is going out, the part crosses a barrier of light which on interaction changes its configuration and recreates the plastic into the intended cross-sectional design.
It would be good that you understand the reasons why a lot of producers will always opt for RP. It is an immense advantage to be able to have a view of a product, complete with knowing how it works, quite before the product is manufactured. Making use of a rapid prototyping machine shop gives a further advantage of being able to do corrections and improvements in the design. The great thing is that all this can happen in a matter of few days or at the most few months. This particular benefit makes it possible for presentations of an intended product to be made with an actual copy, giving opportunity for customer or investor input.
The other advantages include the facts that it yields very precise copies of intended products. Secondly it is actually very cheap, as it requires much less labor and helps in the elimination of costly errors at manufacturing. Lastly, it is remarkably very fast, given you the ability to have your samples in very short periods of time.