Prepare a design for manufacturing? Engineer necessary?

I am a pretty recent graduate so my experience with materials/manufacturing is limited.

I’ve been doing freelance design work (this particular project is privately funded for now, so the budget is small), and am having some road block on determining the best way to complete the design for ideal manufacturing. Visually the design is done, and mechanically it has been thought out. The client doesn’t want me to bring the CAD models/visuals to a specific manufacturer until we know the best way for it to be built out of fear that they will want to do that work in-house.

As of now, the product will most likely have a injected-molded shell parts, a larger rolling part that needs to be of a softer material, and a structural rod that has a ball bearings so the soft part can rotate/roll. I hope that’s enough details. It needs to be rugged, and have quite a bit of strength (that’s why the rod has been incorporated).

I’m looking for suggestions or just advice in general for this phase of the process. I feel like it would be wise to collaborate with an engineer for material/manufacturing advice. I know and understand the basics, but with so little experience I don’t want to make decisions that may cause the product to break or be much more expensive than it has to be.

Where do industrial designers draw the line when determining materials and how a product gets assemble/built?

The answer for “when you need an engineer” should be “when you have a question/concern you can’t answer yourself”.

If you are confident in your design, or you have room for trial and error via prototypes, then you can go down that road yourself.

If you have a number of questions regarding how the thing will hold up, what wall thicknesses/specifications, etc you need to build into your parts to sustain a certain load and that sort of thing, you would be better off consulting with the engineer now.

Even once you get to manufacturing, you will need to make sure you have a realistic manufacturing and tooling approach.

I would try and track down and engineer to help you, but don’t be afraid to push back on things. Ultimately a good designer needs to have nearly as good of an understanding of those issues as the engineer to ensure the design gets carried through properly.

I agree with Cyberdemon. The key is to know when you need help, and a lot of that has to do with experience. When I first started out, I didn’t know what I didn’t know. Now I do… What I mean is, because you’re smart enough to ask the questions, you should probably get a bit of help. I’d rather you do that then to put the project at risk because you didn’t get help. I worry about all the younger designers who don;t ask for help and try to go it alone for fear that it will reflect poorly on them as a designer… Trust me, it won’t… a failed product will.

In my case, I typically do all of the part engineering myself. But that’s because I have a lot of experience and even now when I start to get into some complicated structural issue (like when people’s safety is at stake), or have some thermal issues–that’s when I still bring in an engineer to run an FEA or something… I know what I am and am not capable of.

Plus, when you do pick an engineer’s brain, it’s a great learning experience…

Good luck,


Or… Find a manufacturer (that you trust) that can provide value-added engineering help. I’ve been working with Chinese manufacturers that use this as a competitive advantage. The challenge is to find a good one that can push a “concept” over the goal line. This is a negotiation that can make or break a product.

Key words: Optimization. Design for manufacturing. Value engineering.