is a term used for the process of taking computer information stored
in electronic files (usually 3d models), and making a three-dimensional
physical model by the use of special machines. These precision
machines interpret the computer information and actually "build"
a model which can be accomplished by several different processes.
There are many reasons why rapid prototyping is used, here are a few......
|1. Designs can be made quickly and
inexpensively, guaranteeing companies the best product possible, in the shortest time
||2. Save Money - Using rapid prototypes will
greatly reduce design time, production, & tool costs. Having a working model at the
time of quotes also greatly improves business for many companies.
|3. Catch Errors - Companies can save thousands
of dollars by discovering costly errors before the product goes into production.
||4. Sell Products - It always helps companies
to be able to show clients a working model 3-D model. Prototypes also allow sales teams to
pitch new products before they're manufactured.
|Stereolithography (SL) is
probably the oldest process of rapid prototyping available today. Stereolithography
uses an epoxy resin as the building material. Parts are built by directing a laser
in the shape of the part cross-sections over the surface of a vat of this liquid resin.
This pre-cures one slice of the part. The part is then lowered into the vat by the slice
distance (usually around .004"), and the liquid is "swept" smooth over the
top surface of the part by a blade. The next slice of the part is then traced with the
laser, and so on. The laser "cure depth" is set so that the consecutive layers
are cured into the preceding layers, providing a dense prototype. After the part is
finished building on the SL machine, it must have any support structures cut away, have
the excess resin on the "skin" of the part cleaned off, and then be cured in an
ultraviolet curing oven. There are some precautions when dealing with the uncured resin,
and it must be run in a well-ventilated area. The odors that are given off smell bad
and can be dangerous to the nervous system. Below are examples of test pieces that
were made using the SL process. On the right is a pic of an SL facility.
|Laminated Object Manufacturing (LOM)
is another process of prototyping. The LOM process uses paper or plastic
media (with ceramics and metals on the way soon), and works by laminating the slices of
material together and cutting out the cross-sections with a laser. Parts come out with a
wood-like texture and can be used as injection tools, concept models, or even casting
models. LOM currently is one of the largest RP process used for production
|Sanders Prototyping (also known as SP) was developed by Sanders
Prototype, Inc. in Wilton, NH. This process of prototyping fires wax microdroplets
from 2 ink-jets to build cross-sections of a part, much like a printer uses ink. The
droplets are printed into the cross section of the part in layers usually 0.0005"
thick, then a mill passes over the part to ensure the proper height is obtained. The
final part comes out as a "brick" of support and build material, which must be
placed into a solvent to carefully remove the support material. The SP process is more
popular with people who deal in small, intricate models (i.e. jewelers). Models built with
this machine tend to have higher accuracy and better surface finish than other processes,
however larger parts may take a long time to build. The finished parts can be used as
conceptual models, or may be shelled and cast for a usable part.