ZW3D Top-Down Design

by Steve Cunningham

Top-Down Assembly Design: In short, in the Top-Down approach you create a blank assembly first and then you go on creating the sub-assemblies and individual parts in it. So, if the main assembly is at the top-most level and the components are at the bottom-most level, then you are designing from the top to the bottom and it's a Top-Down Assembly.

This is a highly efficient practice for Product and Mold Design. It's not just a method for managing big assemblies but is also an efficient way to fulfill your design intentions and to make a clear and concise organizational structure. What's more, it enables your team to smoothly communicate and freely share information.

Let's take the design of a Flash disk assembly as an example as how the top-down design process works in ZW3D.

While working on the overall design, potential future needs should be considered, including possible changes of each component's parameters. This means you should fully understand the design intent. Furthermore, the overall parameters can adjust automatically to update the components, and the assembly control structure can be properly defined. If you change the parameters of the overall structure, ZW3D updates all the sub-components immediately. Now, let's see how it works step by step:

1. First, create the basic shape of the Flash disk which includes the key structure parameters. Give it a name "Structure control":

2. Add Electronics part. For our purposes here this will be an individual part.

3. Create the assembly structure of the Flash disk, and copy the shape and keep the associative relation: 3.1 Open the Structure control to make it the active part. This part contains the geometry that will become the BASE and the CAP. Construction of these parts will occur in the same object but once complete, they need to be separated into their own part objects. 3.2 Use the Copy Geometry to part command, copy the main shape and split face to Cap and Base.

Note: In order for future regenerations of the destination part to always re-import geometry, select the NO BACKUP - History option. This makes an associated copy. The destination part will regen and re-import any updated geometry.

4. Activate the Cap and finish the detailed design as shown below:

5. As shown above the Base is made up of the Top, Bottom and Electronics

Note: In this step, Open the Base and use the Copy Geometry to part command again to control the associative relation between the Electronics and other sub component, Top and Bottom, so it can meet the structural design.

6. Use the Link Manager command, to do an automatic regen of the sub components every time the Structure Control and the Base are regenerated.

7. The final result:

The design of the Flash disk is complete. The main product form and fit is defined by the Structure Control. Product dimension modifications will directly affect its sub-components. Meanwhile, the established relationship between Top & Bottom components and PCB board ensure that changes in the Structure Control are passed along to all sub-components.

This example shows how Top-Down Assembly Design works to maintain the design intent in a simple way and produce designs more clearly.

About ZW3D ZW3D, The All-in-one CAD/CAM, was included into ZWSOFT's product portfolio in 2010. As the successor of VX CAD/CAM, ZW3D provides ease-of-use, performance, and all-in-one capability. The brand new software can extend enterprise-level mechanical design and engineering capabilities to the desktop at a fraction of the cost of other comparable systems. Experience ZW3D 2010, where the only limit is your imagination. Please go to http://zw3d.zwcad.org/ to download a free 30-day trial today.

About the Author

A Product Design Engineer

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