3D Printing Common Technologies

3D Printing Technologies (3D Hubs)

Introduction

Choosing the most suitable 3D Printing technology can be a challenge, a wide range of technologies and materials are available which means that in most cases more than one technology is viable, but each has pros and cons and can give you different options in finishing and post processing.

In order to know which technology to use, you should have a basic understanding about the most common 3D Printing Technologies

One of the oldest technologies of 3D printing. It utilizes a photo-polymer resin that undergoes a chemical reaction causing it to solidify when exposed to light with a certain wave length.

Polymerization techniques are most suitable for producing fine detailed parts and a smooth surface finish. Jewelry and dental applications utilize this technology on daily basis.

Depending on the source of light, Photo-polymerization can be done using different techniques.

1. Photo-polymerization Based Technologies

Resin based system 3D Printed Jewelry model 

A.   Stereo-lithography (SLA) uses a clear tank filled with photo-polymer resin. Using a moving point laser, the cross-sectional area of the required model is solidified.

Since the laser is required to pass by each point that needs to be cured, the printing speed is directly affected by how big is the surface area to be cured.

After a layer is solidified the platforms moves up lifting the model and allowing a new layer of resin to flow underneath it and repeating the process layer by layer, we get our solid model.

The solid part is then cured by UV light to enhance its mechanical properties.

B.   Direct Light Processing (DLP) Using almost the same technique of SLA, DLP utilize a light projector to project a single image of each layer curing all the layer at once. Resolution of DLP is dependent on the resolution of the projector (Pixel size).

DLP is faster than SLA (in some cases) because it cures the whole layer at once instead of a laser passing the cross-sectional area to be cured.

Another technique of DLP is using LCD or LED instead of a projector to cure the resin

SLA & DLP 3D Printing Process

Powder based technologies produce solid parts using metal or plastic powders. A thermal source is used to fuse the powder particles one layer at a time.

After fusion of each layer, the platform moves down and a mechanism is used to lay a thin layer of powder on top of the parts and then the process is repeated to fuse another layer resulting in the final solid part submerged in unfused powder.

Powder based technologies allow us to design complex geometry since the product does not need support

Both Plastic and metal parts produced with powder-based technologies have high mechanical properties which allow them to be manufactured as final products.

The limitation of these technologies’ centers around the surface roughness, internal porosity of the solid model and the cost of such technologies is relatively high.

The main difference in powder-based technologies is the heat source and material.

2. Powder Based Technologies

Final solid part submerged in un-fused powder.

SLS 3D Printing Process

3.Fused Deposition Modeling (FDM)

The most used, cheapest and easy to use 3D Printing technology out there. FDM uses extrusion technology to create a solid part.

A string of solid thermoplastic polymer (Filament) is fed to a hot end which raise the temperature of the filament to the melting point, then a nozzle is used to extrude the material at precise locations (Based on gcode). The filament is then solidified when cooled down creating a solid part layer by layer.

FDM uses a wide range of materials like PLA, ABS, PET and Nylon. It’s used on a wide scale to produce plastic prototype and sometimes functional parts.

4.Binder Jetting

Like SLS a powder is used as raw material in Binder Jetting 3D Printing, but instead of sintering using heat soured, droplets of colored binder are dropped using a nozzle (the same way 2D printing works) binding the particles of powder together.

After each layer the platform drops down and a thin layer of powder is laid on top of the part and the process is repeated producing what is called a green part.

The green part is then coated or submerged in an infiltrant to improve mechanical properties.

 

Binder Jetting is often used for producing colored parts and products that do not require high mechanical properties like architecture models.

FDM 3D Printing Process

Binder Jetting full color product

Binder Jetting 3D Printing Process

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