Hello, I am working to build a machine to count brass at high speed for my business. We process thousands of cartridges per week and currently have to weigh or hand count them all.

My machine will feed the brass one at a a time down a tube where they will fall past some type of sensor. I wish to use a light-based (infrared) sensor to operate the counter. The brass we sort will actually be made of brass, nickel plated brass or steel.

What I need is a simple but accurate sensor system that can count up to 30 counts per second (the limit of the timer) and that I can build from readily available parts. The sensor system of course needs to be able to trigger the counter (DH48J) directly.

I am a computer guy and I have a basic understanding of electronics (I can read circuit diagrams) but not very advanced past that.

 

A thru-beam sensor should be an off the shelf solution. Local electric supply or Ebay.

I like prox sensors for reliable counting. If parts can be funneled close enough.

 

Hello Walterwoj,
First off, where are you located? Unless we have an idea were you are, it can be difficult to recommend things that you could obtain either at all, or in a relatively short period of time. I suggest that you edit your profile (under User CP) and at least enter your country & state, preferably your closest city or town.

At the point where you wish to count the brass, is the brass clean/bright and of a single size/caliber?

Are the cartridges fed singly, or could they be in a stack (as in a serial FIFO queue)?

Do you have a datasheet for this counter? It's not readily apparent what the trigger signal is, aside from connecting terminals 3 and 1; for example is their 220VAC present on those terminals? If so, you'd either need some kind of fast relay or an SCR/TRIAC to make the connection.

 

Sgt Wookie: The will be running through a ~1/2" pipe and can practically touch the sensor if need be. Is a prox sensor easier to implement?

inwo: I'm in olean, NY (near buffalo or jamestown Ny) Radioshack is what I have nearby, but amazon\ebay are good too.

The brass may or may not be clean and bright as we count it coming in (dirty) and going out (clean/shiny) and some may be steel/aluminum casings so they wont be uniform in reflectivity. They will also be of all different sizes/calibers

The cases will be fed singly so they should have gaps between them as they fall. They won't be allowed to stack when passing the sensor.

As for the specs, I'm not totally sure as I have had trouble googling them. I'll look some more in a but and post if I find more data for you.

Thank you both for your responses.

 

I find prox sensors easier to implement and maintain. No problem sensing brass @ 10mm.

Get an inductive sensor rated at at least twice the sensing distance you need. They are rated for ferrous material.

You would need a non-metalic section of tube. Or use optics.

One thing that leads to miscounting is tumble, but if parts are in a tube, there should not be an issue.

You may not even need de-bouncing with the slow counter.

 

You may have to confirm what the content is of the brass object is as some prox sensors are ferrous only and if ferrous and non-ferrous, the range can differ for non-ferrous materials.
You can also get specifically non-ferrous types.
Manuf such as Turk offer Capacitive type sensor as well as inductive.
Open collector input between 1 & 3 of the counter.
Max.

 

Thru-beam sensors seem expensive (relatively) and these prox sensors sound good if they will work. I have some questions though:

Most of my 'brass' is actual brass, which is non-ferrous, but some of it is steel which is ferrous, so will a prox sensor for non-ferrous work for ferrous?

Are capacitive prox sensors for for non-ferrous only?

 

another way to count brass is to use a magnet and a coil the brass falls through. the magnetic field will induce current in the brass,which will induce a pulse in the coil every time a moving piece of brass goes through.

 

Thru-beam sensors seem expensive (relatively) and these prox sensors sound good if they will work. I have some questions though:

Most of my 'brass' is actual brass, which is non-ferrous, but some of it is steel which is ferrous, so will a prox sensor for non-ferrous work for ferrous?

Are capacitive prox sensors for for non-ferrous only?

When looking at proximity sw you need to confirm whether both ferrous only, ferrous and non-ferrous.
If sensing close, the decreased range on brass, if any should not be a problem.
You pay a little extra for a popular make, but get data sheets which you don't often get with ebay sources.
Plug the counter in and measure the open circuit DC voltage between 1 & 3 this will give you the voltage range required by the prox, usually 24vdc.
It looks like you need a 3 wire NPN open collector type.
Max.

 

IF you can guarantee a gap between parts,
AND IF the metallurgy can vary randomly,
THEN I vote for optical with a narrow beam width, such as a low power laser diode.

Basically, a laser pointer plus a detector. With a small hole on each side of the pipe section it no longer needs to be clear (although that too helps in troubleshooting. Plus, there is no diffusion or scattering that might confuse the detector. Shooting a beam of anything through plastic walls will spread out not matter how clear and clean the plastic is.

I also prefer visible beams for something like this. Makes alignment way easier, and eliminates Question #1 (Is this thing on?).

ak

 

I found voltage data for the counter:
1. Operating voltage: AC12~380V, 50Hz, DC12-48V
2. Delay time range: Count range 1~9999(x1/x10/x100)
3. Counting speed:30times/s
4. Working model: According to input signal of contact count
5. Mounting style: Moungting panel style
6. Outline dimensions: 48 x 48 x 122mm
7. Mounting dimensions: 46 x 46mm
8.Contact capacity:AC220V 3A,DC28V 3A
9.Huminity:35%~85%
10.Life:Mech:10000000;Elec:10000
11.Weight:100g
12.Counting method:Accumulator

I believe that this means it can run on AC 12-380V or DC12-48V. I found this sensor on amazon: SMAKN LJC18A3-H-Z/BX DC 3 Wire Capacitive Proximity Switch Sensor the specs say: Supply Voltage: DC 6-36V; Current Output: 300mA; Response Frequency: 100Hz and Output Type:: NPN NO(Normal Open).

So the sensor will work with that counter using a 36V power source, right?

 

I also prefer visible beams for something like this. Makes alignment way easier, and eliminates Question #1 (Is this thing on?).

ak

Most Prox sensor have a status LED.
Max.

 

I found voltage data for the counter:

8.Contact capacity:AC220V 3A,DC28V 3A

I believe that this means it can run on AC 12-380V or DC12-48V. I found this sensor on amazon: SMAKN LJC18A3-H-Z/BX DC 3 Wire Capacitive Proximity Switch Sensor the specs say: Supply Voltage: DC 6-36V; Current Output: 300mA; Response Frequency: 100Hz and Output Type:: NPN NO(Normal Open).

So the sensor will work with that counter using a 36V power source, right?

I believe you are confusing the contact closure output rating with the counter input?
I suspect that the voltage between 1 & 3 is 24v, if so you don't need any other supply just the prox common and output to 1 & 3.
Apart from a supply for the prox power itself.
Remember if using a capacitive type, it can have nothing else in front of the sensor head.
Otherwise it looks like it may work.
Max.

 

Thru-beam sensors seem expensive (relatively) and these prox sensors sound good if they will work. I have some questions though:

Most of my 'brass' is actual brass, which is non-ferrous, but some of it is steel which is ferrous, so will a prox sensor for non-ferrous work for ferrous?

Are capacitive prox sensors for for non-ferrous only?

A capacitive sensor will sense metals.

I just checked a standard prox sensor. An 18mm from the flea market.

It detects brass thru an 18mm hole. That will be different with a 12mm pipe.

I also have some optic sensors in the flea market.

If you give me pipe dimensions I could try a 12mm prox. with brass.

 

If you give me pipe dimensions I could try a 12mm prox. with brass.

Using that method would require a flush head type.
Just for the OP info.
Max.

 

Is the pipe vertical? Or could it be positioned so that parts slide against one side of the pipe.

Small standard prox switches only sense a couple mm. distance.

 

Inwo: As long as the electrical parts work together I will make the mechanical work. I have not bought any of the parts yet (plan to today) as I wanted to make sure I had it all worked out before wasting money on the wrong parts.

The sensor I picked has a 10mm range so in a pipe that's .5" (12.7mm)wide it will detect any brass larger than 2mm (22cal is 5.5mm) so it should be good!

 

Do you have link to the sensor?

I think you should be good to go.

Don't forget Max's advice. Flush head. So it won't react to it's surroundings.

If you find that it double counts sometimes you will have to add a timer.
That will allow it to count only once every .XXX seconds.

All I could find was a 30mm cap. prox.

It does sense brass or aluminum at rated range.
A standard inductive prox will be <1/2 rated range with brass.

Notice the yellow/green led indicator.

 

inwo: One I'm looking at right now is: SMAKN LJC18A3-H-Z/BX DC 3 Wire Capacitive Proximity Switch Sensor
Acording to the listed specs its capasitive and non-ferrous detecting with a 10mm range.
http://www.amazon.com/SMAKN-LJC18A3...4&sr=8-1&keywords=capacitive+proximity+sensor

 

If fitting that flush with the inside dia of a pipe or tube, you need a flush head type (Threaded to the end).
That one is not.
Max.