Different types of 3D Printing Process: Part -3 and 3D Printing Materials
By: Aditya Gonella
Tags: Innovation, Technology, 3D Printing, Additive Manufacturing, Tech

let's discuss the last two 3D printing processes and understand them.

DIRECT ENERGY DEPOSITION 3D PRINTING:

Next is the direct energy deposition (DED) 3d printing technology, which constructs parts by directly melting materials and deposits them on the workpiece, layer by layer. This additive manufacturing technique is mostly used with metal powders or wire source materials. While this process can be definitely used to manufacture new parts, it is typically used for repairing and rebuilding damaged components. Other popular terms of DED like laser engineered net shaping, directed light fabrication, direct metal deposition, Laser Deposition Welding (LDW), and 3D laser cladding.

A typical DED 3D printer consists of a nozzle mounted on a multi-axis arm inside a closed frame. This deposits melted material onto the workpiece surface, where the material solidifies. The process is similar to the metal extrusion 3D printing technique, but the nozzle in DED can move in multiple directions, with up to five different axes compared to only three for most FFF machines.

SOURCE: https://www.lboro.ac.uk/media/wwwlboroacuk/external/content/research/amrg/vat-process.jpg



DED’s ability to control the grain structure of a part makes it a good solution for the repair of metal parts. And also, typically, DED machines have high material deposition rates. Some DED processes can achieve a speed of up to 11 kg of metal per hour (Sounds pretty fast right!). With DED, powders or wires can be changed or mixed to create custom alloys for better parts. But on the downside, the parts product tends to have low resolution and poor surface finish. This will need some secondary machining that will add time and cost to the overall process.

SHEET LAMINATION 3D PRINTING:

The Sheet Lamination (SL) 3D printing manufacturing technique, also known as Laminated Object Manufacturing (LOM) consists of superpositioning several layers of material composed of foil in order to manufacture an object. Each foil is cut to shape with a knife or laser in order to fit the object’s cross-section. Layers are coated with adhesive and successively glued together layer by layer, similar to other 3D printing processes. These 3D printers are based on LOM (laminated object manufacturing) technology and produce parts made with a combination of PVC (PolyVinyl Chloride) which produces models which are inexpensive at a very low cost. This technique is mainly used to produce objects in a highly detailed resolution.

SOURCE: https://www.lboro.ac.uk/media/wwwlboroacuk/external/content/research/amrg/Direct%20Energy%20Deposition%20-%20process.jpg

Yes! Now you know the basics of major core technologies involved in 3D printing. In the next one, we will see about various 3D printing materials, their properties, and their applications in detail.

Having learned the basics and foundation, let us now dive deeper into the 3D printing process. As mentioned earlier, there are different kinds of materials that can be used, but, how do we choose the best for our project? What properties to look for? — These are the quick questions that come to us when we want to work with 3D printing. This section helps you to find the answers!

SELECTION OF MATERIALS FOR 3D PRINTING AND THEIR PROPERTIES:

Materials are usually graded into 3 categories- mechanical performance, visual quality, and process. We further break down these categories into the following to paint a clear picture:

1. Ease of printing

2. Visual quality

3. Max stress

4. Elongation at break

5. Impact resistance

6. Layer adhesion(isotropy)

7. Heat resistance.

POLYLACTIC ACID (PLA):

It is the most widely used polymer for 3D printing. It provides very good visual quality. It is a rigid and fairly strong material, but is brittle and has less toughness due to which it snaps and does not bend. It also has a low thermal resistance and tends to warp in hot environments. This makes the material well suited for non-mechanical applications that need low toughness and low heat resistance. But it’s a fantastic choice for general printing applications or prototyping. ABS ( ABS is an abbreviation for Acrylonitrile Butadiene Styrene, it is an impact-resistant thermoplastic and amorphous polymer.) is being used for a long time and is in use even now because of its advantages over PLA.

Advantages:

1. Biodegradable

2. Odorless

3. Good UV resistance.

Disadvantages:

1. Low humidity resistance

2. Can’t be glued easily

ACRYLONITRILE BUTADIENE STYRENE (ABS):

ABS is another majorly used polymer and is usually picked over PLA when higher temperature resistance and higher toughness are required.ABS is not significantly stronger when compared to PLA, however, it is tougher so it will flux more before it fractures and thus performs better under impact. ABS is a little less glossy than PLA and can also be easily centered and painted. You can give it an acetone vapor bath and completely smooth the printout. This material tends to warp when it’s not evenly heated. So a closed chamber is strongly encouraged. Not all printers can print with this material at these higher temperatures. So, we need to check on the printer before we choose this material for higher temperatures.

Advantages:

Can be post-processed with acetone vapors for a glossy finish

2. Can be post-processed by using sandpaper and painted with acrylics

3. Acetone can also be used as a strong glue

4. Good abrasion resistance

Disadvantages:

1. UV sensitive

2. Odor while printing

3. High fume emissions

POLYETHYLENE TEREPHTHALATE (PET):

PET is a form of polyester that’s molded into water bottles and other packing material. PET is not nearly used as widely as PLA or ABS but provides some very unique opportunities for 3D printing. It is a tougher material than PLA, similar to ABS. So it provides some flexibility for fracture, It has a higher heat resistance than PLA but not as high as ABS. Visually, it’s glossy. There are a wide variety of opaque and transparent PET filaments that allows us to give a unique touch to our model. PET is not that difficult to print with, but compared to PLA, it leaves some stringing on the print. PET does not warp as ABS does, so it does not need an enclosure to operate. You can print PET reliably on any printer that has a higher temperature range and a heated bed.

Advantages:

1. Can come in contact with foods

2. High humidity resistance

3. Recyclable

4. Good abrasion and chemical resistance

Disadvantages:

This material is that it is heavier than PLA and ABS.

NYLON:

Nylon is widely used as an engineering polymer and has various functional applications. Nylon is significantly stronger than ABS, PETG, and PLA. It’s also very tough, has high impact resistance, and has a good thermal resistance. It also has a very low coefficient of friction. There is a wide range of colors to select the color of nylon filament from. While painting may not work well for nylon, Its challenges are in printing it. Nylon is very hygroscopic, tending to absorb moisture from the air. All polymers absorb moisture, but nylons are high absorbents. Nylon must be kept dry or be dry before printing. To achieve this, many people use a food dehydrator for multiple hours before and during the print. Well, printed adhesion can be difficult also as nylon warps much like ABS. To print nylon, your printer will need to maintain higher print temperatures, have a heated bed, an enclosure, for desired results with nylon.

Advantages:

1. Good chemical resistance

2. High strength

Disadvantages:

1. Absorbs moisture

2. High fume emissions

THERMOPLASTIC POLYURETHANE (TPU):

TPU and TPE filaments are more commonly known as flexible materials. They are not commonly used but have significant advantages. They have very high impact resistance and will not fracture like most other polymers. These materials are extremely soft. These materials are often used in parts that need to be flexible. One important thing about TPUs and TPEs is that we need to use less infill in places where we want more flux.

Advantages:

1. Good abrasion resistance

2. Good resistance to oil and grease

Disadvantages:

1. Difficult to post-process

2. Can’t be glued easily

POLYCARBONATES:

Polycarbonate is naturally clear but can be made opaque. Polycarbonate is the strongest of the materials that we’ve discussed. It Not only is somewhat ductile, but it also has good impact resistance. Polycarbonate is essentially a much stronger version of ABS. Printing polycarbonate is very difficult. It does stick to anything easily and will readily warp. Much like nylon, polycarbonate is extremely hygroscopic and needs to be dried before and during printing to ensure the part comes out correctly.

Advantages:

1. Can be sterilized

2. Easy to post-processing processes like sanding

Disadvantages:

1. It is UV sensitive.

Based on all this data we can choose the best material for our 3D printing based on our requirements and the properties of the materials.

And summing up all the information, here is a picture to help us visualize better!

An easy representation of the 3D printing materials and their characteristics

SOURCE: https://s3-eu-west-1.amazonaws.com/3dhubs-knowledgebase/Which-FDM-3D-printing-plastics-is-best-for-my-application/chemistry-comparison.png

Hoping that you got an idea of the parameters on which the printing material should be selected. And in the next blog, we are going to discuss the printing conditions to be followed before and after 3D Printing.

Meet you in the next part of my 3D Printing-Series!!🙂