Computer Aided Design, or CAD, is a powerful tool with countless applications in the product development space. It is essential in the design, prototyping, and manufacturing steps in the development process. Learning how to use CAD takes time and experience, and there’s a specific engineering mindset that goes into modeling parts and assemblies. Here are some good design practices we’ve developed over the years to make our models optimized and effective.
There are multiple CAD platforms, each with its own interfaces and capabilities. At Synectic, our engineering team uses SolidWorks, an industry standard CAD software that makes sharing files easy among clients and partners. We’ll reference CAD practices and features specifically in the context of SolidWorks in this article, but much of the thought process behind these design principles is applicable across all software.
Core principles of good CAD design
When we talk about good design practices, we are referring to models that are:
- Easy to edit and iterate without having to redesign the entire model. This practice saves time and effort later, reducing the need for additional work if you have to make edits to dimensions down the road.
- Easy for other engineers to follow. Engineers often work collaboratively on projects, which requires sharing parts and assemblies among the team. Be mindful of this when designing models and make your work easy to follow, update, and interact with other components.
- Easy to fabricate. When designing models, keep in mind the fabrication technique you’ll use to create the physical part. Some features simply can’t be made with certain fabrication techniques. This will differ depending on the design stage you’re working on, whether that’s fabricating prototypes or designing for manufacturing.
We’ll walk through the specifics of each of these to better understand what to keep in mind when designing a part.
Thinking ahead: designing for future edits and iterations
Creating a part that is easy to edit and iterate upon begins with design intent. Design intent refers to how your model behaves when its dimensions are modified. Capturing your design intent from the beginning allows you to have a clear idea of the way your model should function and behave, and the way that different dimensions should be related to each other.
- Dimension for editing: If you anticipate an aspect of your design that you’ll likely need to change, plan for that and link other dimensions to it as well. This way, when you update one dimension, the model will rebuild smoothly.
- Planes and reference geometry: Lay the model out in a way that makes sense in terms of the planes and reference geometries. If the part needs to be symmetrical, center it around one of the planes. This can also help if you are going to use the part in a larger assembly later.
- Symmetry: Using symmetry and midplanes within your design helps you avoid having to do the same work twice. You can use symmetric relations to ensure that when you update one side of the model, the other side updates automatically, keeping dimensions consistent.
- Parametric Modeling: If you’re working with a part that needs specific dimensions in order to be compliant with a larger assembly, use dimension constraints to ensure that these stay constant throughout the design process. You can also link parameters within the model if you have dimensions that need to be related to each other.
Let’s look at an example. Here is a sketch of a shape that will be used to create a part later. We can see that, depending on where you define the dimensions, changing the height updates the model in different ways. In both cases, the same dimension is changed, but a different updated sketch is generated. You can choose where to define these dimensions based on the design constraints and needs of your model.
Height = 40mm
Dimension: base length
Dimension: angle
Height = 50mm
Dimension: base length
Dimension: angle
Defining different dimensions changes the way the model updates when the height is changed.
Structuring your design tree for efficiency
You can use the design tree to document how your model is created and communicate that with collaborators. If you’re new to CAD, the design tree is a representation of each of the sketches and features used to create the model. The design tree outlines each component in sequential order, making it easy to see what is dependent on prior sketches and features.
In order to use the design tree effectively, create your features in an order that makes sense. Be mindful of parent- child relationships, which determine the order that features are rebuilt when the part is edited. By understanding which features are dependent on which sketches, you can understand how the model will change if a single sketch is updated. All of these will vary based on each unique design, but creating these relationships intentionally will keep your model simple and easy to follow.
Helpful hint
When receiving a new part from someone, use the roll back bar to see how the part was created and hide features if needed. Here’s a walkthrough of how we can use the design tree to understand how a complex part was created.
Using the roll back bar can help you understand the deisgn tree. It shows you how the model is built and give you a sense of the different features and what design components they depend on.
Building smarter sssemblies in CAD
Creating assemblies in SolidWorks requires just as much thought as creating new parts. These can be very helpful in determining how parts will interact when combined into a functioning system. Here are things to keep in mind when working with assemblies:
- Mates: Use mates to constrain how each part interacts with others, but don’t over-constrain your model. If your final design will allow motion, reflect that in the assembly with the correct number of degrees of freedom.
- Interference and collision detection: These built-in SolidWorks features can help you ensure enough clearance between parts. You can also make sure that there are specific tolerances that reflect what you would like to see in your physical model.
Helpful hint
When sharing assemblies, use the Pack and Go feature to avoid leaving referenced parts behind.
Designing CAD models for real-world manucaturing
When designing parts in SolidWorks, one mistake we often see is designing a part that is not manufacturable. It’s one thing to create a model on the computer with all of the necessary components for your design, but fabricating the physical model requires additional insight about manufacturing processes and capabilities.
The way you fabricate your part determines the features you can realistically achieve in a physical model. Simply put, certain manufacturing processes cannot produce certain features designed with CAD software. For example, designing for injection molding requires draft angles, and if you include undercuts, it will be impossible to remove the part from the mold.
Keeping these things in mind throughout the design process will allow you to include the necessary features for your design and omit design choices that are not compliant with the fabrication process you are using. Though this may require some problem-solving and alternative design methods, it will also help you avoid having to do additional work later to make the model work with your desired fabrication process.
CAD collaboration tools and techniques
Sharing parts and continually iterating on parts that are part of larger assemblies can be difficult to navigate, especially when multiple team members are making changes. You can use the following two techniques in SolidWorks to streamline this process and make collaborative work easier.
Product data management (PDM)
PDM is a feature built into SolidWorks to help with model management and sharing. You can think of SolidWorks PDM as a library where, when you have several different parts as part of a larger assembly, one team member can only edit a part if they check it out in their name. When they check the part back in, changes are reflected for everyone on the team, updating the part and the assembly. This tool manages all file changes and automatically updates, notifying team members of changes and reducing confusion that may arise from multiple people making edits to a part at the same time.
Product data management (PDM)
This is a technique in which you design a master model first and then break it up into smaller components to work on as separate parts.
Take a car, for example. When designing a car, you have an idea of how the outside of the car should look and the general shape and size of the final product. Using a master modeling technique, you can create the outer shape and then section that larger design into smaller parts (doors, hood, etc.) to be worked on separately.
This technique is helpful because changes made to the master model are propagated through the rest of the parts. This helps to ensure that features are consistent and shared across each component when collaborating on a project.
Helpful hint
Rename features and sketches within the design tree to clearly communicate what you’re referring to with others sharing the model. Group features in folders to maintain organization and clarity.
Practical CAD tips to boost efficiency
Here are a few tips that can help streamline your CAD process:
- Shortcuts: Use keyboard and mouse shortcuts within the platform to quickly access frequently used tools. Some engineers use “M” to quickly access the measure tool or right-click and drag to access frequently used sketch tools. These can be configured based on your personal preference and are fully customizable to streamline your workflow.
- Evaluate: measurement and evaluation tools in SolidWorks help you measure your design to ensure it is compliant with your desired dimensions.
- Built-in features: SolidWorks includes several built-in tools that create features automatically based on your input parameters. For example, instead of having to manually design your own snap hook, you can use the built-in feature to generate it. Some other helpful features to check out include Fill Pattern, Hole Wizard, and more.
- Reference Measurements: having a physical measurement tool nearby to reference while you work helps visualize smaller features
Translating CAD skills across platforms
We discussed earlier how there are many different CAD software platforms, and each company chooses to use one that fits their preference. However, many of the skills you learn on one platform can be translated well. Learning to use new CAD software is a lot like learning a new coding language if you already know how to code. If you understand how if statements, for loops, and conditionals work, transitioning from C to Python is an adjustment, but it isn’t like learning something from scratch.
The same thing applies when going from SolidWorks to Creo or Fusion. Features might be named differently, and there might be a learning curve in navigating the program’s mechanics, but the thought process remains the same. Good design practices are universal regardless of the platform you choose to use, which is all the more reason to develop and practice this highly universal skill.
Building better products through smarter CAD design
CAD skills are highly versatile and essential across the product development cycle. When using CAD to create models, it’s always important to keep in mind the good design practices that we discussed to make your models easy to edit, share, and fabricate. Laying out intentional design intent, using collaborative features within the platform, and understanding production processes will help create models that are functional and ready for collaboration and production. Mastering these techniques doesn’t happen overnight, but every project offers the chance to refine your approach and work smarter. Regardless of your experience, starting out with these design practices in mind will lay a solid foundation that will optimize the efficiency, effectiveness, and professionalism of your models as you work through the design process. The more intentional you are in your modeling process, the more value CAD will bring to your product design.
About Synectic Product Development: Synectic Product Development is an ISO 13485 certified, full-scale product development company. Vertically integrated within the Mack Group, our capabilities allow us to take your design from concept to production. With over 40 years of experience in design, development, and manufacturing, we strive for ingenuity, cost-effectiveness, and aesthetics in our designs.
