ndzied1
Lifetime Supporting Member
Hello:
This started as a private message with Eric Nelson but I figured more people might be interested in the topic.
Recently, Eric had discussed his spice cap inspection problem on this forum. He posted a video showing the rejected parts being blown off the conveyor with an air blast. I now have a possible job where we would need to blow reject parts off a conveyor and wanted to know what kind of air valve he used which wasn't discussed in the previous topic.
Some other questions I have would be
For my application, the part length will be about 12mm with approx 24mm between parts (thus, 36mm from the leading edge of one part tot he leading edge of the next). My target is 4 parts per sec. so the part will pass by a stationary point in 83 msec.
Will probably have a micrologix 1500 processor on the machine.
Any answers or other suggestions greatly appreciated.
Thanks
This started as a private message with Eric Nelson but I figured more people might be interested in the topic.
Recently, Eric had discussed his spice cap inspection problem on this forum. He posted a video showing the rejected parts being blown off the conveyor with an air blast. I now have a possible job where we would need to blow reject parts off a conveyor and wanted to know what kind of air valve he used which wasn't discussed in the previous topic.
... from Eric Nelson ...
Hi Norm,
I usually use SMC valves on all our machines, but on this particular machine the customer requested Mac valves. I have never been a fan of Mac as they used to be quite unreliable. They have improved since them, so I can recommend them. They actually have one of the fastest response times in the industry, so in your application they just might be ideal (not bad prices either!).
The valve I used for the reject was a simple Mac 35 series 3-way. The reject system had no trouble keeping up with a throughput of 400/min. Scan time becomes an issue as you start getting fast, so consider interrupts to trigger the blowoff at the correct position. At 100 ft/min, a conveyor travels farther than you'd think in only a few milliseconds! Also be sure to use a higher resolution timer to control the blowoff time. A timer with a 0.1 second time base just won't be repeatable...
Good luck with the project!...
Some other questions I have would be
- how do you come up with the on time for the air blast
- should I use any specific type of nozzle... (I'm thinking a small oriface to avoid spreading the air stream and affecting other parts)
- what pressure do things like this usually run at?
For my application, the part length will be about 12mm with approx 24mm between parts (thus, 36mm from the leading edge of one part tot he leading edge of the next). My target is 4 parts per sec. so the part will pass by a stationary point in 83 msec.
Will probably have a micrologix 1500 processor on the machine.
Any answers or other suggestions greatly appreciated.
Thanks