Before starting to talk about additive manufacturing let’s imagine we want realize a product, for example a handle for a car. During the design process could be necessary realize one or more prototypes to mount and try, so could be necessary pay money to realize a mold and pay for prototypes.
Finally, we can mount the handle in the car but…oops! Fingers do not pass!
So is necessary modify the mold, maybe realize another one because it is too much different from the new one. We need to spend more money to produce new prototypes hoping that them work, otherwise we start the loop again. Maybe is better use the handle as it is and enter and exit from the car by the car window…maybe the best choice is find a different technology/idea.
Additive manufacturing is a technology used to produce components using material deposition, layer upon layer, until the product is complete.
Nowadays is a well-known process and widely used in the automotive industry and elsewhere. It is entering gradually in our homes behalf small 3D printers sold in the shops.
How does this technology work? What are strengths and weaknesses?
There are many technologies that need different times and costs and different materials are used. The choice depends on the scope of the component.
SLA: stereolithography. A vat with a mobile platform is filled with a liquid photopolymer that harden when hit with the laser beam. After the first layer composed by cured polymer is completed, the platform is lowered to allow the curing of the second layer cf polymer. The loop is repeated until the part is complete, so it has a vertical construction.
SLM: The video below show how a product is made using Selective Laser Melting: the concept is the same case before, but in this case the vat is filled with a metal powder. There is a second vat with a mobile platform that lifts up when the first one moves down. The laser beam melt the powder on the primary vat to create the first layer, and when platforms move, a sweeping arm moves the powder from secondary vat to the primary one and the second loop can start.
3DP: in 3D printing a “printer” deposit a layer composed by a melted polymeric material behalf an extruder, like in the following video.
Strengths of additive manufacturing
The video shows immediately the first advantage: the technology allows to produce more than one part in the same time. Obviously this is function of the piece dimensions itself and vat dimensions, but mainly for few pieces this method allows to speed up the production time.
Another advantage is the possibility to realize very complex geometries, with undercuts, blind lightening, internal channels with any shape, not realizable with numerical control machining.
Another advantage, mainly on 3D printing, is flexibility and immediacy on prototype production: just create the 3D CAD model and print it.
Behind this simplicity there is a deep study of the method. For example the path followed by the extruder is not casual because in the successive layer it must not pass on a part too hot or cold, in order to avoid too strong thermal gradients.
In addition to reactivity in the realization of parts there is de possibility to create more than one variant for a single component, improving the product quality and reducing time to market.
From an economic point of view the possibility to realize components for production must be carefully evaluated. There is indeed a number of pieces beyond which the higher price of the mold is totally paid back, because the single component is cheaper than the same one produced using additive manufacturing; for example a piece made in polymeric material can be produced with injection molding or a 3D printing.
Concluding, additive manufacturing gives a boost in engineering design because allow producing very complex components o reduce the number of parts which a product is composed by. When the process is cost-effective it leads to revolutionize the way to design a component or a product.