3-D printing
Three dimensional (3-D) printing is one of the cornerstones of modern 'additive' manufacturing processes where an object is formed through the successive addition of just enough material to make it. Additive processes are those that join materials to make an object as with the layers of 3D printing rather than the subtractive processes of traditional machining using lathe, mill and drill which removes material. A worker starts with a large piece of material ( perhaps leather, wood or metal ) out of which the cuts drills or curves a much smaller product. He discards the excess material that is removed, most of which may never be reused. Additive processes allow a product which exists only as a CAD or data file on a computer to be output directly to a machine that will form the item entirely automatically and with minimal waste.3D printing technology
All 3D printing uses an additive process. The difference between thee most common technologies used in the industry are how the layers are built. Essentially, there are four main types of additive manufacturing that fall under the umbrella term 3D printing..
- selective laser sintering ( SLS)
- Fused deposition modeling ( FDM)
- inkjet 3-D
- Stereslithography (SLA)
Applications
Three dimensional printers help designers, developers and researches as their ideas can be made into digital designs and then printed in a short time. If adjustments are needed designs can be easily changed and then reprinted three dimensional printers can also be used to print new replica parts for machines or a specialized part required to adopt a current machines to a customers specific needs. The use of 3D printing is finding applications in many aspects of lie such as art, architecture, fashion design, interior design, engineering and prosthetic production etc.
potential footwear applications
3D printing technology is already used to create viable prototypes of new designs SLS and 3D inkjet printing can both be used to create durable (but non flexible) prototypes that can be passed around at a design meeting to view the aesthetics, colors and style of a shoe complete in every detail.
Previously, these concept shoes would have been either a simple drawing or a slow and carefully made model. It is easy to realize the savings in both time and effort and the advantage of having a three dimensional and tangible item that can be handled and assessed .
Models can be produced in a wide range of colors and materials of different texture can be simulated using the high resolution of 3D printing materials to recreate the wave and stitching of various fabrics..
It is now even possible create models that can be tentatively checked for fit the limitations or a full assessment being the rigidity of the material which be affect the comfortable ingress of the foot.
While it is possible to create a model of any type of shoe, particularly suit the production of rigid or stiff soled footwear - such as women's high -heeled shoes and student football boots. when rigid footwear is modelled, the printed results looks, fits behaves almost exactly like the production footwear, albeit it is more brittle and less durable.
Footwear that will be flexible when commercially produced can be modelled using these 3D printing methods in very intricate detail right down to stitching detail and apparent creases in the reproduction fabric, but will not flex or move like the real thing.
This opens up to designers the possibility of creating unique innovative footwear with designs so intricate as to preclude their manufacture by conventional means. These shoes could be both handled and warn even if they survive only one or two journeys up and down the catwalk. Some methods can create soft and flexible models that represent soling material, as well as whole shoes constructed from rubbery or pliable material.
It is surely will not be to long before complete shoes can be printed especially something simple such as a one piece, moulded type of footwear. This concept of footwear on demand is appealing to many and is likely to be one that has great commercially value. Customers could have their feet sent to a 3D printer that creates their exact size, taking into account he unique physical characteristics of their foot. This access to perfectly tailored footwear could mean a big improvement in performance particularly for those involved in sports. such an improvement could especially be seen if he materials used in the printing process could be customized to produce a level of flexibility that perfectly suited the weavers and their chosen sports.
Materials
In 3D printing, there are many materials can be used. The most commonly used materials are as follows:
a) General purpose plastics which are affordable durable and easily available for example acrylonitrile butadiene - styrene (ABS) and polylactic acid (polylactide) know as PLA.
b) high detail resin which can be used to produce intricate and detailed designs with a smooth surface finish.
c) SLS nylon used to make functional prototype from lasted sintered nylon.
d) Fibre reinforced resin for engineering parts said to be as strong as metal but at the price of plastic.
e) rigid opaque plastic, to make realistic prototype with high detail and accuracy.
f) Transparent plastic from which see through part can be printed.
g) Engineered polypropylene used to make durable prototype that behave and look like polypropylene.
h) Engineered ABS, for high precision designs and injection moulds with the toughness of ABS.
i) heat resistant plastics, with thermal resistant prototypes up to 80o C.
k) Industrial metals include graphene , carbon fibre, silicon, regolith, wood, glass, nylon, paper and cement polymer.
Advantages and disadvantages:
There are clean and definite benefits resulting from the use of 3D printing methods than traditional subtractive technologies. It is important to lander stand that 3D printing is still a developing technology. As such it comes with benefits, but it is still not at the level to take over from traditional footwear manufacturing methods.
Thee advantages of 3D printing are that complex design can be created without tools or moulds, which produces less waste. Designs can be customized and seen as physical prototype within a couple of hours due to the rapid speed of 3d printing.
However,, there are some drawbacks to using 3D printing. Although there are many materials available to use the choices are still limited compared to conventional product materials colors and finishes. The material also have a limited amount of strength and the process offers a lower level of precision. The main disadvantage is having higher costs for large production. This will improve as the price of pinners an raw materials continues to decrease while at the same time thee range of efficient production expected to increase.
1. Selective Laser Sintering (SLS)
In the selective laser sintering process, a digital CAD file output to a machine.. This directs a laser beam to move backwards and forwards over the surface of a bed of powder, fusing it into a solid form where it is hit by the laser. This process is repeated layer by layer with the powder bed being lowered by a fraction of millimeter after each layer is fused the fresh powder deposited on to and leveled by a sliding blade.
The advantage of the SLS process is that the item being created is both supported and increased by the bed of powder enabling shapes of highly complex geometry to be produced. SLS forms rigid, hard structures which are released from the powder bed at the end of the process. Unused powder is sifted and returned to the machine ready for the next batch of products to be made.
As the technology develops, an increasing variety of powdered substances are becoming available for use in SLS machines, in addition to the most commonly used plastic materials.
2. Fused deposition modeling (FDM)
Thee process that most people associated with the term 3D printing is used deposition modeling. FDM machines deposit from a heated nozzle a liquefied thermoplastic material that hardens almost immediately after extension. A micro-controllable gantry or work platform on which the end probe is formed is moved back add forth relative to the position of the dispensing nozzle, so that an object can be formed by the gradual building up of layers of material. A high-level of precision is possible allowing for creation of very delicate shaped, as each layer can be as fine as 0.05 mm.
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