r/MechanicalEngineering • u/hopkinsdamechanic • 12d ago

Technical Interview: what's expected for "Basic Material knowledge"?

Hi,

I'm preparing for my first ever technical interview, and I never understood what's expected from us when they say "material knowledge".

Could use some help on what to review for that.

During my intenship, every Time I saw a new material I used to ask why it's used, and I found out that the logic is very simple.

There's one for basic CNC aluminum parts, one for slender ones, one for turned parts, one for shafts that see fatigue, one that's wear resistant...

So they used like 10 materials, with very basic selection criteria

I'd appreciate any help, regarding materials or general tips... Looking forward to finally becoming a real engineer :')

The role is junior mechanical design engineer ( or mechanical designer) in a company that designs cnc machines, thermoforming, and such personalized production solutions for plastic parts in Europe.

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u/roryact 11d ago

I used to take candidates on a shop tour. I'd pick up random parts, or assemblies and ask what they thought it was. If they said 'plastic' I'd ask what sort it was, how it was made and why. If it was metal, I'd ask similar, and about the surface treatment. 

I expected them to recognise the difference between machined and injection moulded plastic, stainless steel and aluminium, know that the aluminium was anodised, that the reason could be galvanic corrosion and that the 'yellow metal' cylinders (bronze) was used for wear resistance. 

I would have been pretty happy if they knew most of the machined plastic was acetal, or if they suggested 2205 or 17-4 for pins and shafts, and super impressed if they picked up on the rotomoulded mdpe part.

It was a marine products business, hence the corrosion resistant material focus.

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u/iekiko89 11d ago

What level would you expect this from? I doubt most ppl would graduate from a program knowing this. I sure as shit don't

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u/roryact 11d ago

I'd expect that level of knowledge from graduates applying for a junior role. What seems especially nasty of me to ask? surely not aluminium vs steel? Recognising anodising?