×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

help with figuring combinations
5

help with figuring combinations

help with figuring combinations

(OP)
Ok, first off, I'm not an engineer, so that may be part of the problem.
What I'm trying to figure out is how many combinations of parts we could have.
We have 4 parts. Those parts are assembled togather, and only one of each part is used in the assembly. The parts are made in an 8 cavity mold. I need to know how to figure out how many combinations there possibly are. example:
part a1 a2 a3 a4 a5 a6 a7 a8
part b1 b2 ...
part c1 c2 ...
part d1 d2 ...

so i could have a1 b4 c7 d1

etc. like i said, only one of each a b c d part. If somebody could explain how to do it on paper or in excel or any which way within reason, I'll be most grateful. Thanks!!

SolidWorks 2007
NX4
Mayline 1947

RE: help with figuring combinations

I believe that it is the number of cavities raised to the power equaling the number of parts, or:

nc^np

RE: help with figuring combinations

Simple!  for an assembly, you have 8 choices for the first part, second part 8 choices, third part 8 choices, and fourth part 8 choices means the total combinations  = 8 x 8 x 8 x 8 = 4096

Timelord

RE: help with figuring combinations

(OP)
thank y'all, 8^4 gives a reasonable answer. and the whole reason is they want us to test every possible combination of parts from all cavities to ensure compatability, and we're trying to use this figure to tell them "no way". each test takes ~1day, with 1 person seeing to it full time. and the test is so insanely mind numbing, nobody would survive it. we've already got a robot doing the most repetitive part. but that's all beside the point.

Thanks again!!

Byron Morgan - Tupelo, Mississippi
SolidWorks 2007
NX4
Mayline 1947

RE: help with figuring combinations

I think it's 1680 units (complete). He said that no two of the same part will be used in any assembly. That makes 8 x 7 x 6 x 5 = 1689.

Steve Wagner

RE: help with figuring combinations

don't ... the robot won't survive either ... it'll go insane and bring havoc unto those who mistreated it so ... get an intern (they are expendable, and tend to wreck less havoc when they run amok).

RE: help with figuring combinations

Wait, I mis-read it is 8 to the 4th power, 4096.

Sorry

Steve

RE: help with figuring combinations

An alternative to testing every combination would be to perform a Monte Carlo, or a designed experiment (Taguchi).

Either should give you the approximate statistical data you are probably after.



Cheers

Greg Locock

Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources