Design Considerations for Rapid Prototyping
Below are some useful links that can serve as a guide to help you
design your parts for rapid prototyping. There are only a few basic
guide lines to follow to achieve the best possible part file that you
can. If you have any question if your part will grow or not please
ask your project manager and they will be able to answer any question
you may have.
|Typical SLA materials
do not work well with living hinges. A typical solution would
be to simulate the living hinge on the assembly by attaching
a piece of tape to the part. If the functionality of the living
hinge is crucial to the prototype we can utilize urethane casting
techniques or LS Nylon Materials. If needed, we can use a infiltrate on the nylon to increases the number of cycles that can be completed on the part. Please contact a project manager for details on this process.
Points, Knife, Edge, and Thread Design
|On occasion parts are designed with points
or knife edges in them. Current SLA technology cannot
produce these parts. They will round them off to a feature
size of .020 inches. The most common place is featured
if he found it in thread design. We advise that you do not
include threads in the design unless they are a course and
on large diameters. It is advisable to use taps or dies to
create and thread features. These features will be much more
functional than if they were designed into the CAD file.
The minimum feature size for SLA part is typically
.020 inches. However there are many variables to take
into consideration when designing these features. Some
of these variables are wall thickness, feature orientation,
feature function, and machine that the part will be grown on. If
you have any questions or concerns about any features of your
SLA part please bring this to the attention of your project
manager and he will abide you accordingly.
|Creating a hollow part is a good technique
to use to cut down on the volume of the prototype. This
is important because volume is one of the main factors that
play into the price of the prototype. A part with a lower
volume can be created quickly and more cost effectively.
For more information on hollowing techniques please contact your project maanger
Faceting & Stair stepping
Faceting and stair stepping happens on every SLA Model. This
occurs because the SLA model is grown in layers. If the layers
are further apart (.010") you will notice heavier stepping
on your parts. If the layers are closer together (.004")
then the stair stepping will be reduced and not be as noticeable.
Another factor that effects the surface finish of the SLA model
is Faceting. This is controlled by the output settings on your
3D CAD software. If you export a coarse setting the part will
appear to have many triangles over the surface Coarse Image , however if you export a part with fine
faceting the file may be to large and unmanageable Fine Image . The key is to fine the balance that will
take into consideration features and part size to give you the
best possible file.
|Text and logos follow the same rules as small
features do. If your text and/or logo is a important part of
the prototype please let your project manager know. The reason
is that some times the best orientation for the part to grow
is not the best for the logo. When possible keep spacing between
letter around .020" and try to use common fonts such as "arial" "tahoma" or "veranda" because
these are design to print clearly even at smaller sizes. Please consult your project manager if yo have concerns about your text growing.