Reasoning your way through the FSAE design process

[moose]

Originally posted by Jersey Tom:
Disagree slightly on the minimal parts bit, though it depends on where you're looking at it.

While it's nice to have lots of features integrated together in one unit (ex: tripod housing integrated into hub), in my experience it tends to add complexity to the manufacturing process.

In a pro shop, doing larger quantities, taking advantage of castings or tooling that's already set up, I'd suspect the minimal part approach works well. May even take less total time on a per part basis if you can take advantage of custom tooling. In a one-off amateur level series like this, especially with very limited fabrication equipment and time, in a lot of places I'd rather use two simple easy-to-make parts in place of one complicated one. There's certainly the opportunity for losing some rigidity, but the manufacturing timeline is critical.

I think this being what is is, a one-off situation, "part count" can really be liberalized a little bit to consider a sub-assembly essentially one part. If your tripod housing consists of one or two parts, it doesn't really matter in the final scheme of things, its still one piece of the car that needs to be there. Its getting designed as one, and made as two. Where part count matters more in my opinion is when there are separate interacting designs to be placed on the car.

One example of this that I dealt with, was making what at the time was, a back-up pedal tray out of aluminum for one of our cars (we had broken one on an older car - so wanted to have a super strong spare - but ended up using it for real). I could have made it out of about a 3" thick plate, or ~1" thick piece (still mostly hollowed out) that had a few tabs bolted on. Doing it in 1 would have reduced the overall piece by piece part count, but certainly would have taken a lot longer to make, as I would have had to remove about 250% more material in total - and used ridiculously long tools for some features.
This is where the higher-level and lower level design needs to come together some.
If the management goals disseminated to the level 1 guys is to "minimize part count whenever possible" then I could have spent $300 on matl, and hours and hours making it. Instead, it was quicker to make, cheaper, and ultimately simpler.

[murpia]

The kind of thought process I'm trying to encourage is this:

Following the systems engineering approach we have some nice design targets for the rear hubs, and for the rear tripod outer. The 'Level 1 guys' get their assignments, design their parts, do a good job and the 'Level 2 guys' make sure they bolt together properly. The car runs fine.

But, where in the process is the guy who says 'don't make a separate rear hub and tripod outer, just machine the tripod detail into the hub and throw away those bolts etc.'?

Take that approach on the whole car and I think you'll get somewhere.

Also, BTW I don't think sub-parts of fabrications etc. really come into this. Imagine a catalogue of spares, and reduce that list to the minimum. Assemblies like brake calipers are just one item, I'm not advocating counting every o-ring like the OEMs do!

Regards, Ian

[Brad Tollefson]

Thank you very much for this Geoff, I am definitely going to send this around to my teammates. As a first year team we will definitely need this. Also, I am definitely looking forward to any updates that you have on this topic

Brad

[Big Bird]

Thanks Brad,

I never really got back to this. The thread dropped off the front page rather quickly and it seemed like very few were reading it. But I'll think of what else I can add and post it in due course (i.e. when it fits around my postgrad stuff!).

Cheers

[Big Bird]

Moose & Murpia,

A belated response, but agreed to the intent of both your posts. It might be the "minimal process count" racecar that is the common ground here. I don't think anyone would reasonably suggest overly complicating individual parts just for the sake of reducing a total parts count.

Cheers,

[Tom W]

Originally posted by Big Bird:
Thanks Brad,

I never really got back to this. The thread dropped off the front page rather quickly and it seemed like very few were reading it. But I'll think of what else I can add and post it in due course (i.e. when it fits around my postgrad stuff!).

Cheers

Geoff I can guarantee you that a lot of people at UNSW have read this thread. We may not have had much to contribute to it but I know that it has provoked a lot of thought in the UNSW team.

[Nick Renold]

As a level 2 guy in the NU team working on our team's second car, I can tell you that many of us have read this and are definitely thinking about it, because it is what we have tried to do this year with restructuring our team.

One member from the 2008 team has come back to be our level 3/4 project manager and we have worked hard to grow from the 4-5 seniors who finished a car for 2008 but did not transfer knowledge well to any new members. Thanks for giving us some insight into what we are doing with our team now and how to make it sustainable for future years.

[Scott Wordley]

Nice work Geoff, cant wait to hear more.

All sounds very sensible and rational.
I've seen some good teams and exceptional team members through the years who, after much experience, loosely follow this process informally and instinctively. You see this in teams that have have a good year or two.

The challenge is formalising it so that it becomes ingrained, top to bottom in the team culture, and one that even new team members can work effectively within it. You only see this in the teams which have left a legacy of top performances over many many years. Cornell and UWA spring to mind.

Im very interesting in hearing your thoughts on developing those kind of LEVEL 4 management systems and processes, which can endure through the years even long after the initial managers have departed.

[ed_pratt]

Mods, can you please sticky this!!!

[Adambomb]

Originally posted by ed_pratt:
Mods, can you please sticky this!!!

+1