SolidWorks 2011 Parts Bible - Matt Lombard [62]
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.
Identifying 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:
• 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.
Cross-Reference
Chapter 11 discusses configurations and feature suppression in depth.
• Insert Part. This SolidWorks technique enables you to use one SolidWorks part as the starting point for a second part. For example, the as-cast part has all the features to make the part, but it is inserted as the first feature in the as-machined part, which adds the cuts required by the machining process.
Creating multiple versions
Sometimes size-based versions of parts have to be created or versions based on additional features. If these are simple, they can also be handled with configurations, but you need to plan this flexibility in advance.
Creating a Simple Part
You need to practice some of the skills you will learn on simple parts. Chapter 2 introduced the tools and features you will use, and this chapter teaches you how to string the simple features together intelligently. In this section, I'll show you how to build the simple part shown in Figure 4.1. While the shape is simple, the techniques used and discussed here are applicable to a wide variety of real-world parts. The discussion on how to model the part contains information on some of the topics you need to understand in order to do the work.
FIGURE 4.1
A simple machined part
Deciding where to start
Deciding where to start can be more difficult than it sounds, especially for new users. For this reason, I will go through some sample parts and discuss possible starting points. Figure 4.2 shows the first part. For reference, all of these parts are found on the DVD included with this book.
FIGURE 4.2
Deciding where to start
When you are trying to decide how to model geometry in SolidWorks, you should be thinking of a 2D shape and a process. You typically create prismatic shapes by using an Extrude feature and round shapes by using a Revolve feature. Features can also add material (boss) or remove material (cut). Obviously, your