david said:
Thanks for the reply
Genuine question this.
We have a small on farm dairy we set up last year.
Just seeking guidance on whether something is available off the self or
we need to aquire components.
We have full poly bottles
1 every 2 seconds
should be possible to fix a microswitch to the conveyor guide rails
DB
Hi, David. Just asking to get an idea of what you needed.
If you can work out a mechanical setup to sense the bottles, your job
has become much easier and less expensive. Some microswitches
(trademarked name, they're made by many suppliers) have rather long
vane actuators at their ends which can be depressed by the bottles
going by. This has the real advantage of greatest simplicity, but you
have to make sure product goes only one way on the conveyor. On some
of the long vane actuators, you can bend the end back to give it a
roller effect. But be sure to get one that's rated for dry contact
switching. You're going to be switching a low voltage at a low
current. If you use a standard microswitch, the contacts will oxidize
over time and become unreliable long before end of life.
As I mentioned before, it's far easier and more efficient just to
purchase a counter module than to make one. There are many of these
available which will work for you.
Unless you want a big display, you can go with one that's self-powered
(e.g. a 3V replaceable lithium battery that should last for years).
You need to specify one that has contact actuation (for your
microswitch normally open contacts), and that has either provision for
an external reset button or one built-in on the front display of the
counter, or both. The contact activation part is critical -- if you
get one that's voltage-actuated, the contact bounce of the microswitch
will lead to multiple counts per bottle, especially as the microswitch
contacts get old.
One provision I hadn't taken into consideration is that your
electronics may need to be rated for washdown, seeing as this is a food
handling environment. This is going to increase your costs by quite a
bit, and may require you to get a switch with the appropriate food
handling rating. Many of these counters come with a mountable silicone
rubber boot you can put over the front of the display, which will give
you the appropriate rating.
But if you don't have to be washdown rated, you can easily get the
whole thing done for less than $40 USD for a new microswitch and a new
counter. You also might want to ask around in your maintenance
department -- they're typically pack rats, and may have the components
waiting in a locker or drawer for you to pick them up.
I'm not familiar with too many distributor sources in the UK, but you
could do worse than getting an Omron H7EC-N at Farnell (3262807) for
£35.02 in stock. A little pricey, but it's got everything you need
for a washdown environment except the microswitch. It's got contact
switching (set the DIP switch for 30Hz max), a reset button on the
front panel as well as provision for external count, and it's also able
to be hosed down if needed. Be sure to use the provided mounting kit,
and use an approved gasket for mounting to a washdown box if you need
it.
Good luck
Chris