Comparing Rapid Prototyping Technologies

 Comparing RP Technologies: ''Which one should I use?''

The  following review allows you to do a close-up comparison  of the 6 most common Rapid Prototyping technologies in Australia and New Zealand.

FDM

Objet 3D

SLA

SLM

SLS

Z-corp

 

FDM - Fused Deposition Modelling

FDM is a layering process, it uses a filament of actual thermoplastic that is melted and extruded through a tiny nozzle.  The nozzle draws the 2D cross-section of the part and then criss-crosses inside to fill in the volume. 

FDM's strength is...well, strength!  Since you are working with an engineering thermoplastic, the material properties are better than other rapid prototyping processes.  However, due to voids and imperfections in interlayer adhesion, it does not match the strength of the base engineering resin.  Therefore, if you require engineering prototypes for functional testing, you are better to use Rapid CNC or Rapid Plastic technologies to provide you with more accurate results.

FDM's weakness is resolution and accuracy of small features.  This is primarily why ARRK does not offer it as a service. 

 

Objet 3D Printing  (Polyjet)

Objet is a newcomer to the rapid prototyping industry.  However, it is gaining ground rapidly for concept modelling applications.  It uses multiple jets to deposit UV-curable liquid in remarkably thin layer thickness, which gives the models great Z axis resolution. 

Objet's strength is its ability to reproduce fine detail definition and it's wide range of hard and soft rubber-like materials, with a medical graded material option.  Objet's weakness is that these materials are functionally limited and not suitable for high impact or heat testing.

 

SLA - Stereolithography Apparatus

SLA technology uses an optical configuration, with a UV laser solidifying epoxy liquid layer-by-layer.  This process is suitable for both small, detailed parts or large parts, with machines available containing build platforms up to 1800x800x800mm in size.

SLA technology has been around for a long time and consequently a lot of time and money has been spent in improving the mechanics of the material.  Whilst the flexural strength of SLA material has improved, SLA prototypes still have limited functionality and not suitable for high temperatures or impact tests. 

SLM -Selective Laser melting

SLM is an additive metals manufacturing technology with a presence in medical Orthopaedics and Dental through to Aerospace and high technology engineering and electronics sectors.

The process uses a high powered laser to fuse fine metal powders together layer by layer direct from CAD data to create functional metal parts. After each layer a powder recoater system deposits a fresh layer of powder in thicknesses ranging from 20 to 100 microns. The system uses commercially available gas atomised metallic powders to produce fully dense metal parts in materials including Titanium, Stainless Steel, Cobalt Chrome and Tool Steel.

SLS - Selective Laser Sintering

SLS has been in existence for many years.  It builds models layer-by-layer with a bed of thermoplastic powder.  Each layer of fresh powder is sintered (slightly melted) together using a high-power laser.  Then a fresh layer of powder is rolled onto the surface so that the process can be repeated for the next cross-section. 

SLS parts are typically very strong and exhibit material properties that come close to the base material.  They are an excellent choice for parts requiring strength and toughness, and can be used in high temperature tests.  The weakness of SLS is its inability to do fine details and its coarse surface finish.

Z-Corp

Z-Corp is a 3D printer for concept modelling.  The print heads jet out a binder onto a bed of powder in multiple layers to form 3D parts.  One unique feature of some Z-Corp machines is their ability to make multi-coloured parts directly in the machine using coloured binders. 

The materials used are starch based and once the model is built they are dipped into a glue to strengthen the surface.  Despite this, the parts remain fairly fragile and thin wall-sections easily crumble and break.