This article is about CAD management as part of product design process. I gathered some working methods, guidelines, and tips for working with CAD. It is not a specific CAD “how to” manual, but a general CAD working methods and ideas to help you when working with your CAD.
The conceptual design stage is, of course, crucial to any product design. Some prefer hand sketching, and others use CAD for the product’s concept design. If you use CAD, don’t be tempted to move from concept design to the product design stage while maintaining the same CAD files. It might seem like the natural thing to do, but it can actually harm both your conceptual design work and your product design CAD files.
Parts’ names and numbers
Giving names and numbers (P/N) to your parts might seem like a silly task; yet, you might experience it as very annoying and time consuming. Finding short and meaningful names and unique P/N for hundreds of parts can be very frustrating. Here are four simple tips for naming and numbering parts:
- Don’t underestimate the importance of naming and numbering your parts.
- Give a short and descriptive name to all your parts.
- Build a P/N generating method and keep all the company’s P/N in one big list.
- Use the same names and P/Ns everywhere – CAD, drawings, BOMs, quotes, etc.
The leading dimensions and references of a CAD’s 3D design should be the ones that matter to the design. For instance: if a hole location should be 100mm from the centerline, make sure to place it based on this reference (in most cases, these would also be the dimensions you want to have on the drawing).
It is much faster, safer, and easier to create and edit three simple features than one complicated feature. Build your design by taking small bites—avoid complicated features that try to achieve two (or more) steps in one bite.
CAD systems are very complicated; sometimes they do not act as expected, especially when you reach complicated geometry and small details. On one hand, you don’t want to let the CAD’s abilities affect your design, but, on the other hand, you want to avoid spending too much time in forcing the CAD software to do things it can’t do. Simply find a walk-around solution.
Back in the early days of Pro-E, you could not create a sketch that was under- or over-defined. You had to reach a “fully defined” sketch in order to move forward. The idea behind this strict method was to force users to control all dimensions. Today, the CAD systems are much more flexible—you can use any definition level. An under-defined sketch means that some of the geometry is not in your control. Try to avoid random parameters in your design.
Some features could cause you a lot of after work if you do not consider them properly. Draft, mirror, pattern, shall, and part’s gaps (in an assembly) are all simple features with wide effects on the geometry. Make sure to properly use and consider them during your design work.
Any part has three types of properties: administrative, engineering, and production properties. Here is a detailed view of the three:
1. Administrative properties (name, number, rev.).
Name and number all your parts based on your naming and numbering system.
2. Engineering properties (BOM level, quantity, volume, material, mass).
The only engineering property you have to type in manually is the material. The CAD automatically calculates all other engineering properties. Adding the material property to the parts facilitates the other engineering properties, as well as enables CAD analysis (strength, moldflow, center of gravity, etc.).
3. Production properties (UOM, supplier, cost, finishing, notes, etc.).
These are the kinds of properties you do not want to manage within your CAD system. Production properties are often changed (even after the design work has ended) and can be managed by different people (some with no access to CAD). CAD is simply not the right tool to manage these properties. These properties should be part of the BOM and managed with BOM management software.
CAD files management
Managing many parts, assemblies, and their versions is not a simple task—especially if you have the same parts used in different assemblies. PDM and PLM are the industry solutions for CAD files management. Unfortunately, these tools are overkill for many businesses in terms of money and time investment, and they also have many downsides. If you don’t use PDM or PLM, here are some useful techniques to manage your CAD files:
- All project’s CAD files should be saved under the project’s folder. This folder should be the only “source of truth,” with read/write access given only to those who need it.
- Standard parts (cross-project parts) should be saved in a special standard parts folder. This folder should be under the R&D manager’s responsibility, as its parts might affect different projects (including history ones), with “read-only” status as the default.
- These two folders should have only the up-to-date files. All other versions and history files should be kept under the “history” folder.
- Communication with external suppliers and subcontractors should be in sent as closed file formats (IJES, STEP, XT, etc.). These files should have a meaningful name—including the date—and be saved under the “sent” folder.
Drawings have two main purposes: reviewing and communicating the design. The sooner you make 2D drawings, the sooner you’ll be able to find design problems. Make sure you include in your drawings:
- Title, including assembly and part’s name, number, designer, approval, material, revision, and date.
- Section and detailed views for all sensitive spots.
- Assembly view with related parts.
- All the dimensions needed for manual manufacturing.
- All the dimensions needed for reviewing.
- All important tolerances.
- Important notes.
I didn’t plan to mention any specific CAD software in this article, but I cannot ignore the last week’s beta launch of Onshape – the first cloud-based CAD. After a few days of playing with this awesome CAD system, I’ll take a risk by predicting that they are going to lead the CAD market in just a few years’ time, mainly in the SMB market. The new capabilities of no-installation, non-expensive graphic cards, working on any device (including mobile), built-in sharing, easy versioning, and no-PDM, is simply too good to ignore.
My next post title is “10 Questions a Product Design Manager Should Ask.” I’ll describe the main question you have to answer before and during the design process. Be notified about this upcoming post.