Madhawa's Blog

i'm Madhawa Ranga following BSc. in Materials Science and Engineering at the University of Moratuwa.

Rapid Prototyping April 25, 2009

This is a facinating and a latest technology used for prototype manufacturing.
I thought of sharing some info related to this because, most people don’t know what this is.
University of Moratuwa has a Rapid Prototyping machine brought from Germany about 8 months ago, with the funds of national Science Foundation and Induastrial Development Authority, and now sharing it with the industry at a conciderable price. It is very usefull tool for designers who want to make prototypes of their designs (like vehicle, new type of phone casing, engine parts, new shape of a computer mouse, etc) before going to the production process. it is quick, low cost and easy. No need of making moulds, struggling with machines, can produce very complex shapes. All aredone through the computer and feeding the data to the machine.

Below are some details I got from the internet.

Rapid prototyping is the automatic construction of physical objects using solid freeform fabrication. The first techniques for rapid prototyping became available in the late 1980s and were used to produce models and prototype parts. Today, they are used for a much wider range of applications and are even used to manufactureproduction quality parts in relatively small numbers. Some sculptors use the technology to produce complex shapes for fine arts exhibitions.

Rapid prototyping takes virtual designs from computer aided design(CAD) or animation modeling software, transforms them into thin, virtual, horizontal cross-sections and then creates each cross-section in physical space, one after the next until the model is finished. It is aWYSIWYG process where the virtual model and the physical model correspond almost identically.

With additive fabrication, the machine reads in data from a CAD drawing and lays down successive layers of liquid, powder, or sheet material, and in this way builds up the model from a series of cross sections. These layers, which correspond to the virtual cross section from the CAD model, are joined together or fused automatically to create the final shape. The primary advantage to additive fabrication is its ability to create almost any shape or geometric feature.

The standard data interface between CAD software and the machines is the STL file format. An STL file approximates the shape of a part or assembly using triangular facets. Smaller facets produce a higher quality surface.

The word “rapid” is relative: construction of a model with contemporary methods can take from several hours to several days, depending on the method used and the size and complexity of the model. Additive systems for rapid prototyping can typically produce models in a few hours, although it can vary widely depending on the type of machine being used and the size and number of models being produced simultaneously.

Some solid freeform fabrication techniques use two materials in the course of constructing parts. The first material is the part material and the second is the support material (to support overhanging features during construction). The support material is later removed by heat or dissolved away with a solvent or water.

Traditional injection molding can be less expensive for manufacturing polymer products in high quantities, but additive fabrication can be faster and less expensive when producing relatively small quantities of parts.

Rapid prototyping is now entering the field of rapid manufacturing and it is believed by many experts that this is a “next level” technology.[citation needed]

(from Wikipedia)

Mainly there are 4 main technologies used for rapid prototyping.

Prototyping technologies Base materials
Selective laser sintering (SLS) Thermoplastics, metals powders
Fused deposition modeling (FDM) Thermoplastics, eutectic metals.
Stereolithography (SLA) photopolymer
Laminated object manufacturing (LOM) Paper

But 2 more are there

Electron beam melting (EBM) Titanium alloys
3D printing (3DP) Various materials

A youtube video on RP.

Read more on RP,
Go to RP home page >>>

from these technologies the RPM in the University of Moratuwa use the Stereolithography technique with the use of a UV reactive photo polymer.

The RPM in University of Moratuwa can produce models with the maximum dimensions of 25,25,25 cm in volume. The machine is in the Engineering Design Center at the University of Moratuwa, and anyone interested or want a job to be done, can call the Design center and ask for shedules and prices.


One Response to “Rapid Prototyping”

  1. mathisha Says:

    Thanx madhawa.. this was a big help.

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