Digital Fabrication is a design and a type of a production process with a combination of 3D Modeling and CAD (Computing-Aided Design) with the additive and subtractive manufacturing.
Machines for Fabrication
- CNC Router: CNC or Computer Numerical Control includes proprietary software which interprets the 2D vector drawings or the 3D models which converts all the information to a G-Code which represents the CNC functions in the alphanumeric format.
The G-codes drives a machine tool, a powered mechanical device which is used for fabricating the components. CNC machines are being classified according to the number of axes they possess and they are specifically used in milling the materials like plywood, plastics, foam board, and metal at a fast speed and allows 4′ × 8′ (123 cm x 246 cm) sheets of material, including foam several inches thick, to be cut.
- Laser Cutter: It is type of machine that uses a laser for cutting the materials such as chip board, metal board and acrylic upto 3/8 inch (1 cm) thickness and it is bundled with a driver software which interprets the vector drawings which is produced by any number of CAD software platforms.
It helps in the modulation of the speed of the laser head, the intensity and the resolution of the laser beam and the objects which are cutted out of the materials with the help of laser cutter are used in the fabrication of physical models.
- 3D Printers: Various methods and technology are used by 3d Printers for the assemblance of physical versions of the digital objects. Desktop 3D Printers are useful in making small plastic 3D Objects with a use of roll of thin plastic filament, melting the plastic and then depositing it precisely to cool and harden.
- Fused Deposition Modeling: This is also known as Fused Filament Fabrication which uses a 3-axis robotic system, typically a thermoplastic as a single thin layer at a particular time and progressively builds a shape.
- Stereolithography: A high intensity light projector usually DLP (Data Loss Prevention) Technology is used with a photosensitive polymer resin which helps in projecting the profile of an object for building a single layer and curing the resin into a solid shape.
- Selective Laser Sintering: It uses a laser for tracing out the shape of an object at a finely powdered material which can be fused together with the help of application of heat from the laser and once the layer has been traced by a laser and the finished part is moved out of the way and a thin layer of the powdered material is spread, and the process is repeated. The materials which are used are alumide, steel, glass, thermoplastics (especially nylon), and certain ceramics.
- Powder Printers: It works same as SLS machine and the powders which are used can be cured, hardened or can be made solid with the help of the application of a liquid binder that is delivered via an inkjet printhead. The materials those are used are plaster of paris, clay, powdered sugar, wood-filler bonding putty, and flour, which are typically cured with water, alcohol, vinegar, or other combination.
Digital Fabrication Technologies
Digital Fabrication Technologies are divided into main classes:
- Subtractive Techniques
- Additive Techniques
I. Subtractive Techniques: It characterizes those reproduction methods that are based on the idea of producing the replica by carving a block of material, usually by a computer-controlled milling tool (CNC machinery).
Advantage of Subtractive Techniques: The main advantage of this technique is the availability of the wide range of the reproduction materials and the milling machine can operate on any of the material such as wood, stone and metal and these CNC Milling machines provides a very large workspace which is usually sufficient for the creation of the 1:1 replicas of life-size statues.
Subtractive Techniques are divided in two sub parts:
- 2.5D CNC Carvings
- 6-Axis CNC Carvings
2.5D CNC Carvings: It is the most common and economic devices that are able to carve bas-reliefs and they impose the limitations on the size of holes and the cuts which is depended on the size of the drilling tool.
2. 6-Axis CNC Carvings: These type of machines allows more degrees of freedom and they are able to rotate the drill all around the objects.
II. Additive Techniques: The four main additive Technologies are:
1. Fused Deposition Modeling (FDM): The processes of Fused Deposition Modeling are:
- In the FDM Devices, a thin filament of plastic is melted in a extruding head
- deposited to build the desired shape
- slice by slice on a moving platform
This type of approach requires a fairly simple machine as similar to the printing head of a 2D Printer.
The materials which is used is usually ABS or PLA as these type of materials are used for obtaining an artificial appearance to the printed objects which is undesirable for the CH uses. As depending on the quality of the device, the layered structure which is generated due to the deposition scheme can be little visible, so by using primer/filer, the surface can be smoothed and then paint it which makes the whole process less automatic and straightforward,
2. Laminated Object Manufacturing: It is based on the idea of cutting of the sheets with a blade and the slices of the objects to be fabricated from the sheets or a roll of a raw material and join them one on top of the other. At the end of this process of the fabricated objects, it is embedded in the raw material.
Different type of materials can be employed like paper, plastic or metal. If the paper is being used, colour can be added into the process. The cutting and the joining process may impose the several geometric constraints because of the removal of the unused materials that surrounds the fabricated objects.
3. Granular Material Binding (GMB): It is based on the very small particles that are deposited layer by layer on a descending platform and at each of the step; the topmost layer is selectively aggregated by a dedicated moving head.
- Use of Gypsum Powder and Liquid Binder: They are used on the selected location as like the internal sections of the objects which are being cutted from the current layer by using inkjet printer head.
Other material binding technologies include resin gels and a polymerizing agent that are used for the solidification of the gel. An alternative process is being used i.e. Laser Heat Source that can be used to drive a sintering process so that the solidification process can be done without melting over the metals or plastic powders and this technique is known as Selective Laser Sintering.
- Advantages of these techniques are that all the unbound granular materials remains together with the bound materials and it provides all the necessary support for all the overhanging structures.
4. Photopolymerization: It is the technique of the selective polymerization of a liquid resin which is being operated by the treatment of the resin with the UV light.
- Process of Photopolymerization: It proceeds by the process of layer by layer as the bottom most layer of the surface of the liquid resin is selectively polymerized by directly contacting it to the UV light either by a UV laser or by a digital projector.
A platform raises the already solidified resin as according to the FDM approaches these devices can only work on a limited set of materials and they still require a support structures for the given nature of the material.
Advantages of Digital Fabrication
- Computers figure out the manufacturing, saving time.
- Machines repeatedly produce identical products without error.
- Changing a product is as easy as changing the programming.
- Products are easily personalized.
- Personalized products are more treasured by customers, increasing sustainability.
- Products are locally made, resulting in low transportation costs.
- Computers program machines to create the product with as little material as possible, reducing waste.
- Complex products don’t cost more; computers do it all with ease.
- CNC and laser cutting are faster than regular manufacturing methods.