Rapid Prototyping Basics

For those in the design world, the idea of rapid prototyping is not a new concept; prototypes of every new design must be produced to validate and test before a finalized version will proceed to mass production. With the emergence of additive manufacturing technologies, commonly known of as 3-D printing, the speed of prototyping has started to rapidly increase over the past few years. While CNC machines were used extensively, for prototyping (in subtractive manufacturing), they are losing ground to additive processes because of the flexibility they offered in 3D printing. CNC machines are limited in the types of parts it can produce, due to the restriction of; tooling available, setup required, and/or the number of axis around which the workpiece can be rotated around. However, in 3D printing, we are able to see a virtually limitless set of geometric options that can be produced, as well as an incredibly short turnaround time. First, we will look at the basics varieties of 3D printing; liquid, solid, and powder, the different types have a variety of

Types of Additive Layer Manufacturing Systems

Based on the type of raw material used for rapid prototyping, additive layer manufacturing processes can be classified as follows:

Liquid Based Additive Layer Manufacturing

Liquid printing systems begin with a supply of raw material in the liquid phase and using a high energy electron or laser beam to process and cure the material into the final, solid part. Stereolithography Apparatus (SLA) is an example of a liquid base system.

Solid Based Additive Layer Manufacturing

These systems start with solid raw material, which often comes in thin wires, and use electron or laser beams to melt the material into the required shape and place. The following systems are examples of solid based additive manufacturing systems: Fused Deposition Modeling (FDM), Multi-Jet Modeling, and Laminated Object Modeling

Powder Based Additive Layer Manufacturing

This type of system uses laser or electron beam heat to melt fine powdered material into the required shape. Common powder based systems include: Selective laser Sintering (SLS) or Selective Laser Melting (SLM)

Processing Steps for Rapid Prototyping

Much like in traditional prototyping, engineers will begin in a 3D modeling program to create a CAD model of the part they wish to create, however, the biggest differences are in how the material is produced. In rapid prototyping, we use an STL file (Standard Triangulation Language) to create a number of individual 2-dimensional cross-sections which add together to create the final part. Many 3D printers can combine multiple types of materials, either as the manufacturing or support material, these different materials can serve as supports or be layered to give additional strengths or properties where needed.  To finalize we can hit start and walk away while the prototype is printing, an operator is only needed for any post processing and taking the final products off of the trays.

Advantages of Rapid Prototyping

• Decreased set-up and overall product manufacturing time.
• Decreased manufacturing cost.
• No need of make patterns, molds or tooling.
• Minimize costly mistakes.
• Allows production of complex geometry.
• Easy to learn and quick to implement.
• Zero material waste.

Disadvantages of Rapid Prototyping

• A rapid prototyping system may cost up to 1.5 million US dollars (although less expensive machines are becoming more common).
• Some skilled labor is required to manage the materials and machine.
• Post processing may be required.
• Parts have poor mechanical properties compared to steel.
• Part size is limited to machine work tray.
• Parts can only be manufactured one at a time.

Prototyping Fun

The rapid reduction in cost and increase in technology over the last five to ten years has done a great job of bringing the idea of manufacturing into schools and homes. With printers small and affordable enough for almost anyone to own one, the number of people experienced and interested in prototyping has continued to rise. Almost every day there are new releases of ideas and innovations that are utilizing 3D printing to speed up the production and testing. With the continual rise of this technology we have seen examples of people 3D printing items which a few years back were thought impossible:

• Firearm components
• Quick replacement parts for machines – for when you know the specifications but can’t get an OEM part in quickly
• 3D printing all of the gears and frame for a new 3D printer!