Jenny,

Some pick n place machine companies design special nozzles for special applications like your connector, and special parts sometimes weighing several ounces (or several decagrams).
Others machine makers simply have a variety that they assume will cover most every need. 
Vacuam levels and degree of seal effect the final outcome. 
The last two are dependent not only on machine design, but on the degree of wear and tear.

To get the right answer, talk to your assembly vendors about what they can do.
At the same time, decide how he parts are to be packaged for automation!

And have them run tests on sample blocks on the correct material, surface texture, and weight, before its too late.
What they believe to be true, and what is reality, are often far apart.

Good luck,
Steve Mikell


> ----- Original Message -----
> From: "Jenny Drake" <[log in to unmask]>
> To: [log in to unmask]
> Subject: Re: [TN] Vacuum pick up nozzle area for component weight.
> Date:         Tue, 6 Jun 2006 10:02:53 +0100
> 
> 
> Thanks for the replies so far. A little clarification on why I am asking
> the question. We are designing a small surface mount connector, but we
> won't be assembling this component ourselves, so I can't test it with
> the machines that will be building it.  What I am looking for is any
> guidance on the flat surface area that will be needed to ensure that it
> is unlikely to move about on the pick up tip as it is accelerated across
> from the pick to place positions. "As large as possible" isn't very
> large on this thing.
> 
> If I take the largest flat circular area on the part, take off the
> tolerance of the part in the tape, then that gives me a maximum pick up
> tip inside diameter. From a reasonable estimate of the vacuum level I
> can then get the holding force. If I then guess a coefficient of
> friction between nozzle and part I can use the weight of the part to see
> if,  say, a 3G acceleration is going to be too much for the holding
> force. Is this a good approach?
> 
> Jenny
> 


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