Lightening parts
 

I'll start simple:

I know nothing about CAD and received a lecture the other day about CAM when I asked about how many billable hours it might cost to run a piece through the waterjet at work.

That said- Is there an automatic method to 'lighten' parts in CAD? Or does someone draw little triangles and squares and holes - which is then taken care of at the shop?

I don't even know the right questions to ask the questions.

Thanks kindly-

Jason

Re: Lightening parts
 

Do you have an existing part that needs to be lightened?

There is no "automatic" lightening feature in CAD software, as the lightening all depends upon what features and tolerances are critical in the part, what manufacturing processes are used to fabricate the part, and any other critical operating characteristics of the part.

To lighten the parts, you'll have to draw all the lightening triangles or holes yourself. While waterjetting can produce sharp corners, you should use a radius in all inside corners to prevent stress risers in the part. You should also note that waterjetting produces a draft angle in all parts that may affect critical (such as press fit) tolerances.

Traditionally, most machine shops have little to no knowledge of how the parts they are contracted to make are used or assembled. You send them drawings (or CAD models) of dimensions and tolerances, and they make the parts. Some machine shops offer engineering services to help refine parts to increase manufacturability/reduce costs by reducing the complexity/number of fixtures or setups/etc. But this costs additional setup money, so it's cheaper and faster if you know the limits of the manufacturing processes ahead of time and design around them.

Re: Lightening parts
 

If you are running Inventor, SolidWorks or Pro/E you could set up a parametric FEA study to reduce weight without compromising required strength - but this is an advanced use of the software.

Re: Lightening parts
 

A wise structures engineer once said, "Putting holes in parts doesn't add too much weight."

Of course removing material does reduce weight, but it means there are generally much better ways to go about it. If you're starting blank slate, consider other methods like reducing overall gauge or the configuration of the entire part.