Design for assembly

Explore important considerations when deigning for assembly for mechanical design engineers

Design for assembly - A methodology aimed at designing products in such a way that they are easy to assemble, reducing production costs and improving efficiency

Generic rules of thumb

Minimize Part count

Provide space for insertion of tools or fingers

Design parts so that there is no possibility of them tangling within each other

Provide aids for alignment like chamfers

Use gravity to advantage and tryo to keep insertion of parts from top

Make the assembly process obvious through design

Reducing part count and standardization

Here is an assembly with one fastener being fixed and another floating. In the Bill of materials 2 separate fasteners are required.

What if we modify the design to accommodate Fixed fastener on the other side as well?

Reduces the number of parts:

Integrating parts which perform two or more separate or similar functions into one

A block is being supported by three separate brackets .

What if we integrate all the three into one We will reduce the number of parts and make assembly easier faster.

Floating fastener insertion:

Inserting a fastener blindly in an assembly requires time , effort and skills. IF the fastener end is designed to be easy to insert in holes then it makes a lot easier.

Tool access:

A nut has to be Fastened from below a part . If there is no access for the tool , the assembly will not take place. Sufficient space is to be provided for tool access

Avoiding fasteners using snap fits

One common way of reducing fasteners especially in plastics design is using snap fits

Designing assemblies to minimize Distortion in welding

Here is an example of two plates being welded using a butt weld. There will be distortion in the material which will cause change in shape of end product. To minimize this effect the geometry should be stiff enough.

Error proofing:

Mistake proofing, or its Japanese equivalent poka-yoke (pronounced PO-ka yo-KAY), is the use of any automatic device or method that either makes it impossible for an error to occur or makes the error immediately obvious once it has occurred

Categories: : DFM