3D printing, also called additive manufacturing, is a process in which an object is made from a three-dimensional CAD file by depositing materials in layers. 3D printing can be used to produce all types of products like aeroplane parts, medical implants, artificial organs, novelty items, toys, sculptures, 3D figurines and much more.
There are several types of 3D printing - stereolithography (SLA), fused deposition modeling (FDM), selective laser sintering (SLS), digital light processing (DLP), multijet fusion (MJF), polyjet, direct metal laser sintering (DMLS), electron beam melting (EBM). Sometimes, rapid prototyping is confused with 3D printing techniques. But rapid prototyping is an application of 3D printing, which involves prototyping a part from a CAD file or better put as 3D printing is the process and rapid prototyping is the end result.
Based on the type of material, durability, surface finish, speed and cost, the 3D printing type is selected.
The process of 3D printing involves three steps:
- 3D modeling software: The object is designed with intricate details in the 3D model using CAD software. The software has the ability to allow for the tiniest, and precision designs. The CAD file is then converted into STL format.
- Slicing the model: Next, the model is sliced into hundreds or thousands of layers with a slicing software and sent off to the 3D printer via USB, WiFi or SD.
- Final process: In a 3D printer, a nozzle moves back and forth while dispensing the material layer-by-layer waiting for a layer to dry before adding the next.
3D printers are extremely flexible, accurate and fast to print rigid materials, and even strong industrial products.
Rapid prototyping is a process of fast fabricating or modeling or assembling a physical part using 3D CAD. The part is then manufactured using additive manufacturing technique or 3D printing. Rapid prototyping is highly beneficial for designers to visualize, design and develop the product before it goes for mass production. There are two types of prototypes - high fidelity where the design matches the projected end product, and low fidelity where the design does not exactly match with the end product.
Rapid manufacturing means the use of software and equipment to accelerate the manufacturing process. It is a broader term that encompasses moulding, CNC machining, vacuum casting, rapid tooling and more. With the help of various 3D printing techniques like selective laser sintering, stereolithography, laser melting, high resolution 3D objects can be created from CAD data.
3D printing offers a range of benefits which include:
Reduced wastage: 3D printing uses only the amount of material required for a particular part, thus making it more economical.
Strong and lightweight part: Plastic which is known best to produce lighter parts is one the widely used material. This is especially beneficial for aerospace and automotive industries that use lighter parts for fuel efficiency.
Better design complexity: 3D printing gives better design freedom to design and print complex geometries without any restrictions.
Speed, flexibility and customization: It is fast without having to create moulds like in the traditional process. Parts can be customized for mass production and printed on demand as the 3D design files are stored in virtual libraries. They can be edited any time saving costs on wastage and inventories.
A lot of industries like aerospace, automotive, education, robotics, fashion, medical, electronics, etc are using 3D printing.
3D printing technologies that are revolutionizing the manufacturing process are Fused Deposition Modelling (FDM), SLS, which are highly ideal for plastics and alumide, Stereolithography, Continuous Liquid Interface Production (CLIP), Digital Light Processing (DLP) that use photopolymerisation. Other 3D printing techniques include Electron Beam Melting (EBM), Direct Metal Laser Sintering (DMLS), and more.
Nylon, ABS, resin, polylactic acid or PLA, gold, silver, stainless steel, titanium, ceramics, PET/PETG, high impact polystyrene or HIPS, polycarbonate, polypropylene, PVA, etc. are some of the commonly used 3D printing materials.
Commonly referred to as SLA 3D Printing, stereolithography is an industrial 3D printing process that prints parts with highest details, tighter tolerance and smooth surface finish. This uses a technique called photopolymerisation wherein photosensitive liquid resin is hardened using a high-powered UV laser that creates the desired 3D shapes or objects.
SLA is an ideal choice for producing accurate and finely detailed parts with ultimate precision and water tightness and is adaptable with a wide range of materials.
SLA applications: Medical industry for making custom ear products, entertainment industry for video games, bespoke costumes and even special effects, digital dentistry, in education for exposing students to STEM concepts, and more.
SLS 3D printing provides high design freedom and accuracy, and produces parts with good isotropic mechanical properties and excellent tensile strength. The commonly used materials for SLS parts are polyamide, aluminum filled nylon (aluminide), glass-filled nylon, and carbon-filled nylon.
In the SLS process, a high-powered laser sinters the particles of polymer powder into a solid 3D model. SLS is used for rapid tooling, jigs and fixtures, moulds & casting patterns, transparent covers, optics, and more.
In Fused Deposition Modeling (FDM) 3D printing, also known as material extrusion, the printer melts material which is mostly plastic and extrudes it from a nozzle in single layers. Multiple layers of molten plastic are then fused to form 3D printed plastic parts. The parts from this plastic 3D printing are tough and rigid, low weight and high strength.
On the benefits side, FDM is economical, easy to operate with no chemical post-processing, supports plastics that are environment-friendly and produce parts that have complex geometries.
PolyJet 3D printing is ideal for precision prototypes and products that are smooth, accurate, intricate details, complex geometries and delicate features. Just like how inkjet printers jet ink drops onto papers for printing documents, PolyJet works by jetting liquid photopolymer onto a tray. These layers are then cured with UV light for producing 3D models.
This could be put as MultiJet meaning, with multiple jetting heads PolyJet printers can even jet photopolymers of different colours to print multi-coloured objects easily. It supports a wide range of materials and is used across all industries. For example, in the healthcare sector for joint replacements, orthodontic appliances, prosthetic limbs and more.
Metal 3D printing is an additive printing process that uses powdered metals and requires no contact tools and is managed entirely via laser beams. Here, a design is made on CAD and converted into .STL format. The design is then sliced and passed into the 3D printer. High-powered lasers are then passed to bind together the powder particles to form the 3D metal part. In the process, even layers of metallic powder are distributed.
Metal 3D printing is a type of additive printing based on laser technology that uses powdered metals. Some of the benefits of metal 3D printing include strong and robust finish, easy to customize or modify designs, ability to make ultra-complex parts and cavities which are impossible in traditional manufacturing and cost-effectiveness.
The most common types of metal 3D printing are Powder Bed Fusion which include Selective Laser Melting (SLM) and Electron Beam Melting (EBM), Direct Energy Deposition or also called Laser Material Deposition, Electron Beam Additive Manufacturing, Binder Jetting, Bound Powder Extrusion to name a few.
The metal 3D printing applications are huge. Many companies are looking at this option for its low volume and speciality parts. For instance:
- Producing functional metal prototypes so that engineers can evaluate and tweak the designs before they go into mass production
- Creating intricate brackets with thin, complex lattices. For instance, titanium brackets for satellites that are 25% lighter.
- Repair of aerospace and military equipment like turbine blades
- Manufacturing of innovative rockets
- Creating low-volume custom tools or instruments
- Mass production of wear-resistant parts at lower costs
There are many metal 3D printing materials available in the market. Some of the best ones are:
- Titanium: Lightweight, heat and chemical-resistant and strong
- Tool steels: High in hardness, high heat and abrasion resistant
- Iconel 625: A nickel-based super alloy which is strong and corrosion-resistant
- Stainless steel: extremely corrosion-resistant and high strength
- Cobalt: excellent temperature resistance, good mechanical properties and good corrosion-resistant
- Aluminium: Good dynamic properties, low weight, good thermal and mechanical properties
Metal 3D printing technology uses powder bed technology. Similar to 3D printing, this process involves:
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- First, a CAD design file is created
- It is converted into .STL and sliced into thin layers on the horizontal plane. It is then sent to a 3D metal printer.
- The printer uses laser to trace the shape across the metal powder
- The laser then heats up the powder to produce the metal part
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The process is gradual and additive.
Metal 3D printing technologies are:
• Powder Bed Fusion
Selective Laser Melting (SLM)
Electron Beam Melting (EBM)
• Direct Energy Deposition
Powder DED
Wire DED
• Binder Jetting
• Bound Powder Extrusion
Based on Powder Bed Fusion technology, Selective Laser Melting or SLM uses high-powered lasers to fuse metal layers into parts. Once the part is made, it is cut away from the build and post-processing work is done. The SLM 3D printed parts generally have a good precision, and are geometrically complex.However, it does require a significant post-processing work to achieve the perfect result.
Direct Metal Laser Sintering (DMLS) prints functionally rapid prototypes quickly. The 3D printer sinters each layer of the metallic powder with a laser to form a solid. Typically, the steps involved are:
• Model is created with CAD and then sliced and sent to the printer
• The printer is filled with the metal powder and heated to the temperature near the sintering range of the alloy.
• Thin layers of metal powder are dispensed onto the platform
• Laser then sinters the powder into solid forms.
• The sintering continues until the end product is produced.
Directed Energy Deposition (DED) is used across many industries like aerospace, oil & gas, marine, defence, etc. It is mainly used in repairing and rebuilding damaged parts. In DED, the material or the metal is melted into powder by either laser or electron beam and deposited onto the workpiece layer by layer. This additive manufacturing technology is called in different names like directed light fabrication, 3D laser cladding, laser deposition welding, rapid plasma deposition, and more.
In Binder Jetting, a liquid binding agent is deposited onto thin layers of the material which could be either metal, sand or ceramics, in layers until the part is completed. Binder Jetting 3D printers can print even more than 20 types of sand and ceramics; metals can be cured and sintered to achieve more than 97% density.
Metal casting or lost wax casting technology is a process where molten metal is poured into a mould cavity that has been created by a wax model, and cooled and extracted to produce metal shapes. Additive manufacturing and subtractive manufacturing could be said as a complementary technology for metal casting as 3D printing is ideal for low-volume casting jobs, facilitating greater design freedom.
A 3D model is a mathematical representation of 3D objects. 3D models are created for visuals for different industries like entertainment, 3D printing, virtual reality, video games, medical imaging, science, manufacturing and more.
To upload a 3D model design for 3D printing:
• Convert 3D file into STL format
• Slice the model with any slicing software
• Use your 3D printer
Another best alternative would be to choose an online professional 3D printing service depending on your need and budget.
3D STL files are the most commonly used format for 3D printing. sTL stands for STereoLithography or Standard Tessellation Language. The format describes the surface geometry of a 3D object and uses a series of triangles to reproduce the surface geometry of the model. STL files are simple and easy to handle.
PolyJet or Multi-jet modelling is a 3D printing technique where a plastic model is created in layers using a printhead that has several nozzles. The thermoplastics or the material are jetted as drops and polymerized by UV light. MJM 3D printing method is ideal for high-detailed, greater complexity plastic prototypes. There are no geometrical restrictions and it offers good surface quality.
PLA plastic or polylactic acid is a vegetable-based plastic material that uses cornstarch as a raw material.It is very popular in desktop 3D printing. Because it doesn’t require a heat bed and can be printed at lower temperatures, it is the best choice for extrusion-based 3D printers. PLA is renewable, biodegradable and very economical.
Injection molding is one of the common processes in manufacturing high-volume plastic parts. Better called as plastic injection molding, here the melted or molten plastic is injected into a mold cavity where it cools and hardens. Once cooled, the mold is removed and the plastic part is formed.
Advantages of injection molding are:
• Low labour costs: The process is fully automated
• Speedy production: Depending on the complexity and size of the mold, per cycle time could come to 15- 20 seconds.
• More material choice, less waste: Compatible with different polymer resins and multiple plastic materials could be used simultaneously. There is less wastage and any unused plastics can be recycled for future use.
• High-volume production: Ability to produce thousands of parts at a time