In my CV I mention that my firt ‘real job’ was working as a cost engineer.
To cite Wikipedia
The engineering practice devoted to the management of project cost, involving such activities as estimating, cost control, cost forecasting, investment appraisal and risk analysis
In my case it was less project costs but the rest seems fine :D
So what did I do?
The company I started with (ECS - which was later aquired by A2MAC1) focused on costing automotive parts. My former bosses were ex-BMW cost engineers with an enormous knowledge on how everything in a modern car is built. This ranges from lenses of lane assist cameras to full EV batteries. The worklow here was quite amusing! We ordered a component or got one from an automotive manufacturer/supplier and tore it down to the tiniest pieces. A very good example are lenses, which are tiny and you have to measure to get their focal length and everything. You will spend your day in a small chamber meticulously dis-assembling tiny parts, weighing them, measuring them all while figuring out how the heck something like this is produced by the millions to a reasonable price.
After your excurse to your office ‘lab’ with all the dis-assembly tools (the good ol’ Dremel and heat gun!) you sit down with the list of parts you noted down.
Then you have some maintenance tasks, building your ‘Bill of Materials’ (BOM) and preparing for the hard work.
Now we have to figure out how things are produced! For many parts this is relatively simple. Cars are mostly steel, aluminum and plastic and various forms. Consequently, the main production techniques are some form of die-casting (pressure die casting, sand-casting, …), stamping, aluminum extrusion and injection molding for plastic parts. The interesting bit is to figure out if any additional processes were used! Was there heat-treatment, can I figure out what hard requirements are on that part, e.g. roughness contraints. Does it need to be waterproof? Do any of the cars passengers ‘see’ the part?
Here research begins, you read through books, watch youtube videos of automotive production lines (yes they are like ASMR videos for production of cars) and ask your collegues what they would think about the part.
You do your best to consider everything here before you go to the next step.
Figuring out the supply chain and overhead structure!
Was the part produced in one factory or does it contain parts from sub-suppliers which would affect overhead cost! Where were the materials sourced? All these things need to be considered while doing costing.
And the lesson here is, it is not an exact science. You can often only apply best practices, like leakage testing certain parts, but you will never know for sure. Especially material prices, from simple plastics to electronic components, are strongly volume dependent. A company like Volkswagen will pay a very different price for their Resistor than Rimac.
In summary, its a fun little sherlock holmes activity you do!