MAS.865 2018 How to Make Something that Makes (almost) Anything

[MAS.865](../../) > [Design Tools](../) > generative, declarative, evolutionary ## Molding --- ### Manufacturing #### 1. Blow molding Blow molding (BrE moulding) is a manufacturing process by which hollow plastic parts are formed: It is also used for forming glass bottles. In general, there are three main types of blow molding: extrusion blow molding, injection blow molding, and injection stretch blow molding. The blow molding process begins with melting down the plastic and forming it into a parison or in the case of injection and injection stretch blow moulding (ISB) a preform. The parison is a tube-like piece of plastic with a hole in one end through which compressed air can pass. The parison is then clamped into a mold and air is blown into it. The air pressure then pushes the plastic out to match the mold. Once the plastic has cooled and hardened the mold opens up and the part is ejected. The cost of blow moulded parts is higher than that of injection – moulded parts but lower than rotational moulded parts. #### 2. Powder metallurgy Powder metallurgy (PM) is a term covering a wide range of ways in which materials or components are made from metal powders. PM processes can avoid, or greatly reduce, the need to use metal removal processes, thereby drastically reducing yield losses in manufacture and often resulting in lower costs. Powder metallurgy is also used to make unique materials impossible to get from melting or forming in other ways. A very important product of this type is tungsten carbide (WC). WC is used to cut and form other metals and is made from WC particles bonded with cobalt. It is very widely used in industry for tools of many types and globally ~50,000t/yr is made by PM. Other products include sintered filters, porous oil-impregnated bearings, electrical contacts and diamond tools. #### 3. Compression molding Compression Molding is a method of molding in which the moulding material, generally preheated, is first placed in an open, heated mould cavity. The mold is closed with a top force or plug member, pressure is applied to force the material into contact with all mold areas, while heat and pressure are maintained until the molding material has cured. The process employs thermosetting resins in a partially cured stage, either in the form of granules, putty-like masses, or preforms. Compression molding is a high-volume, high-pressure method suitable for molding complex, high-strength fiberglass reinforcements. Advanced composite thermoplastics can also be compression molded with unidirectional tapes, woven fabrics, randomly oriented fiber mat or chopped strand. The advantage of compression molding is its ability to mold large, fairly intricate parts. Also, it is one of the lowest cost molding methods compared with other methods such as transfer molding and injection molding; moreover it wastes relatively little material, giving it an advantage when working with expensive compounds. #### 4. Extrusion Extrusion is a process used to create objects of a fixed cross-sectional profile. A material is pushed through a die of the desired cross-section. The two main advantages of this process over other manufacturing processes are its ability to create very complex cross-sections, and to work materials that are brittle, because the material only encounters compressive and shear stresses. It also forms parts with an excellent surface finish.[1] Drawing is a similar process, which uses the tensile strength of the material to pull it through the die. This limits the amount of change which can be performed in one step, so it is limited to simpler shapes, and multiple stages are usually needed. Drawing is the main way to produce wire. Metal bars and tubes are also often drawn. Extrusion may be continuous (theoretically producing indefinitely long material) or semi-continuous (producing many pieces). The extrusion process can be done with the material hot or cold. Commonly extruded materials include metals, polymers, ceramics, concrete, modelling clay, and foodstuffs. The products of extrusion are generally called "extrudates". #### 5. Injection moulding Injection moulding BrE or Injection molding AmE, is a manufacturing process for producing parts by injecting molten material into a mould. Injection moulding can be performed with a host of materials mainly including metals, (for which the process is called die-casting), glasses, elastomers, confections, and most commonly thermoplastic and thermosetting polymers. Material for the part is fed into a heated barrel, mixed (Using a helical shaped screw), and injected (Forced) into a mould cavity, where it cools and hardens to the configuration of the cavity.[1]:240 After a product is designed, usually by an industrial designer or an engineer, moulds are made by a mould-maker (or toolmaker) from metal, usually either steel or aluminium, and precision-machined to form the features of the desired part. Injection moulding is widely used for manufacturing a variety of parts, from the smallest components to entire body panels of cars. Advances in 3D printing technology, using photopolymers which do not melt during the injection moulding of some lower temperature thermoplastics, can be used for some simple injection moulds. Parts to be injection moulded must be very carefully designed to facilitate the moulding process; the material used for the part, the desired shape and features of the part, the material of the mould, and the properties of the moulding machine must all be taken into account. The versatility of injection moulding is facilitated by this breadth of design considerations and possibilities. #### 6. Lamination Lamination is the technique of manufacturing a material in multiple layers, so that the composite material achieves improved strength, stability, sound insulation, appearance or other properties from the use of differing materials. A laminate is a permanently assembled object by heat, pressure, welding, or adhesives. #### 7. Rotational molding Rotational Molding (BrE moulding) involves a heated hollow mold which is filled with a charge or shot weight of material. It is then slowly rotated (usually around two perpendicular axes), causing the softened material to disperse and stick to the walls of the mold. In order to maintain even thickness throughout the part, the mold continues to rotate at all times during the heating phase and to avoid sagging or deformation also during the cooling phase. The process was applied to plastics in the 1940s but in the early years was little used because it was a slow process restricted to a small number of plastics. Over the past two decades, improvements in process control and developments with plastic powders have resulted in a significant increase in usage. Rotocasting (also known as rotacasting), by comparison, uses self-curing resins in an unheated mould, but shares slow rotational speeds in common with rotational molding. Spin casting should not be confused with either, utilizing self-curing resins or white metal in a high-speed centrifugal casting machine. #### 8. Spin casting Spin casting, also known as centrifugal rubber mold casting (CRMC), is a method of utilizing centrifugal force to produce castings from a rubber mold. Typically, a disc-shaped mold is spun along its central axis at a set speed. The casting material, usually molten metal or liquid thermoset plastic, is then poured in through an opening at the top-center of the mold. The filled mold then continues to spin as the metal solidifies or the thermoset plastic sets. #### 9. Transfer molding Transfer molding (BrE moulding) is a manufacturing process where casting material is forced into a mold. Transfer molding is different from compression molding in that the mold is enclosed [Hayward] rather than open to the fill plunger resulting in higher dimensional tolerances and less environmental impact.[1] Compared to injection molding, transfer molding uses higher pressures to uniformly fill the mold cavity. This allows thicker reinforcing fiber matrices to be more completely saturated by resin.[1] Furthermore, unlike injection molding the transfer mold casting material may start the process as a solid. This can reduce equipment costs and time dependency. The transfer process may have a slower fill rate than an equivalent injection molding processes. #### 10. Thermoforming Thermoforming is a manufacturing process where a plastic sheet is heated to a pliable forming temperature, formed to a specific shape in a mold, and trimmed to create a usable product. The sheet, or "film" when referring to thinner gauges and certain material types, is heated in an oven to a high-enough temperature that permits it to be stretched into or onto a mold and cooled to a finished shape. Its simplified version is vacuum forming. In its simplest form, a small tabletop or lab size machine can be used to heat small cut sections of plastic sheet and stretch it over a mold using vacuum. This method is often used for sample and prototype parts. In complex and high-volume applications, very large production machines are utilized to heat and form the plastic sheet and trim the formed parts from the sheet in a continuous high-speed process, and can produce many thousands of finished parts per hour depending on the machine and mold size and the size of the parts being formed. ### Process - Plastic processing ( [process](https://www.youtube.com/watch?v=qn16JtE_vLc)) - Injection Molding( [process](https://www.youtube.com/watch?v=b1U9W4iNDiQ)) - Injection Molding with 3D Printing ([process](https://www.youtube.com/watch?v=Ens_f2eSXYU)) ### Prototyping #### In House Casting - Investment Casting - [High Temp Resin using tin](https://formlabs.com/blog/metal-miniatures-3d-printed-pewter-casting-molds/) - Lens Molding Techniques ([survey](lens.pdf) ) #### Soft Robotics Open source toolkit:<a href="https://softroboticstoolkit.com/home"> Soft Robotics Toolkit</a> Fabrication: <a href="https://softroboticstoolkit.com/book/pneunets-fabrication">molding</a> <a href="https://www.youtube.com/watch?v=dgHQ15zjkhY">3D printing</a>   Popular materials: <a href="https://www.smooth-on.com/product-line/ecoflex/">Ecoflex</a> <a href="https://www.smooth-on.com/tb/files/ECOFLEX_SERIES_TB.pdf">[bulletin]</a> <a href="https://www.smooth-on.com/product-line/dragon-skin/">DragonSkin</a> <a href="https://www.smooth-on.com/tb/files/DRAGON_SKIN_SERIES_TB.pdf">[bulletin]</a> Latex Polyurethane rubber   Cool state-of-the-art developemnt: <a href="https://www.youtube.com/watch?v=RyFRfFPV9xI">3D printed jump robot</a>  <a href="https://www.youtube.com/watch?v=bC1WFU4G-WU">Camouflage</a> <a href="https://www.youtube.com/watch?v=E8YwpECaHdw">Light guided cyborg ray</a> <a href="https://www.youtube.com/watch?v=2DsbS9cMOAE">walk, crawl</a> <a href="https://www.youtube.com/watch?v=EXkf62qGFII">earthworm</a> <a href="https://www.youtube.com/watch?v=F6vSHmHw1gw">transparent gel</a> <a href="https://www.youtube.com/watch?v=q2Q-taHAo7Q">vine-line, growing robot</a>  <a href="https://www.youtube.com/watch?v=gdoQvQzPiZY">human-soft-robot interaction</a> <a href="https://www.nature.com/articles/s41467-017-00685-3">Self inflated in high temperature by mixing elastomer with ethanol</a>   Works from Tangible Media group: <a href="https://tangible.media.mit.edu/project/aeromorph/">AeroMorph</a> <a href="https://tangible.media.mit.edu/project/autoinflatables/">Auto-inflatables</a> <a href="https://tangible.media.mit.edu/project/pneui/">PneUI</a>