Chapter 4: Creating Simple Parts, Assemblies, and Drawings ......................................................
What is the manufacturing method?
Modeling for the casting process is very different from modeling for the machining process.
When possible, the process should be evident in your modeling. There are times when you will
not know which process will be used to create the part when you start to create a model. If you
are simply making an initial concept model, you may not need to be concerned about the pro-
cess. In these cases, it may or may not be possible to reuse your initial model data if you need to
make a detailed cast part from your non-process-specific model. Decisions like this are usually
based on available time, how many changes need to be made, and a determination of the risk of
making the changes versus not making the changes as well as which decision will cost you the
most time in the long run.Sometimes it makes sense to allow someone else to add the manufacturing details. A decision like
this depends on your role in the organization and your experience with the process compared with
that of other people downstream in the manufacturing process. For example, if you are not familiar
with the Nitrogen Gas Assist process for molding polypropylene, and you are modeling a part to be
made in that process, you might consider soliciting the help of a tooling engineer or passing the
work on to someone else to add engineering detail.Best Practice
As engineers, we are typically perfectionists. However, there always needs to be a balance between perfection
and economy. Achieving both simultaneously is truly a rare event. Still, you should be aware that problems left
by the designer for other downstream applications to solve (such as machining, mold making, and assembly)
also have an impact on the time and cost of the project.
The best practice in this case is a judgment call. When faced with assembling a model sloppily or remodeling it
perfectly, I usually choose to remodel because doing it the second time is always faster. In addition, if addi-
tional changes are required, you do not need to struggle with the sloppily assembled model. You can easily
copy sketches from one part to another, while keeping the old part open as you build the new part. As a result,
you may be surprised how quickly things go. n
Will there be secondary operations?
When working with any manufacturing process, some secondary processes are generally required.
For example, if you have a cast part, you may need to machine the rough surface to create a flat
face in some areas. You may also need to ream or tap holes. In plastic parts, you may need to press
in threaded inserts.SolidWorks includes special tools you can use to document secondary operations:l Configurations. This SolidWorks technique enables you to create different versions of a
part. For example, one configuration may have the features for the secondary operations
suppressed (turned off) and showing just the part as cast, while the other configuration
shows the part as machined.