label machine problem

Hello all,
I've a problem with a labeller machine, its with the label step length!
when i adjust the label to a correct position and run the machine, the label step length begin to decrease making the label edge close to the metal blade edge ( where the product take the label) and after 4 or 5 labels , the label edge disappear from the blade edge making the machine stop!
the label step length is setted up correctly in the control panel !
please, if any one have expert in this types of machines, advice me to the cause of such a problem and how to avoide it, also, i'm asking if the fork photo stop sensor which sense the gap between labels might cause such a problem?
waiting for kind help if possible..

johneedw said:

waiting for kind help if possible..

Click to expand...

Not possible. We have no information about the control system. Who makes the machine? What type of controls?

Just a wild stab in the dark with my eyes closed -

If there is an encoder to tell the length, I would check the coupling first (sounds like it could be slipping) or even just replace it.

But as OkiePC states, the information you provided is inadequate to give a good guess.

In addition to checking the encoder, check the setup of the fork sensor. This can cause problems if it is not finding the gap between the labels.

there is usually a procedure to "teach" the sensor to find the gap.

My thoughts are mechanical reason which is causing the reel to drag or label lenght setting too short. Try increasing the label length to see if the labels feed more.

On labellers I worked on, the fork sensor told the drive to stop.

Silly question: Is the reel threadded correctly?

Many thanks for kind replies friend..
I'll try your suggestions, but i'm asking (specially Mr.3.Phase), how can i teach this type of sensor to read the labels and gap correctly since it has no (teach ) button?!
The sensor is shown in the two photos attached..

the photos of my sensor

hello,
the attached photos are shown the sensor used in my machine. its flash ON when no label(gap) and become OFF when there is a label in inside.
please help me how to teach or set it correctly..
Thank you

chances are..
a) the fork sensor is weak....there generally some procedure to check sensor....it can also be the sensor is not cleaned...
b) the card for movement of winding motor is faulty..(capacitor problem .can be) for which winding stopped before /continue to run..even after sensor signal change...

johneedw said:

hello,
the attached photos are shown the sensor used in my machine. its flash ON when no label(gap) and become OFF when there is a label in inside.
please help me how to teach or set it correctly..
Thank you

Click to expand...

Your sensor is working. If there is no teach - you cannot teach it.

Do not forget the obvious - have you started buying label reels from a new supplier?

I worked with labelers for many years...my first bit of advise is ...CLEAN, CLEAN, CLEAN...any speck of smeared glue anywhere in the film path will cause major, sporadic, label movement.

Next dig out the books...Every labeler that I have worked on came with at least a couple of DETAILED setup and trouble-shooting manuals...learn your machine, learn the sequence of operations, in other words, what has to happen first, what conditions need to be set before the next part of the sequence can happen.

Check the vacuum pump suction filter...too little vacuum will allow the label to slide too much on the applicator pad, which in turn will let glue get on the pad, forcing you to clean, clean, clean again.

Make sure that the spindle that the wheel of labels sits on is free and not sticky or binding, and that the tension brake is set properly...Oil is a BAD thing in this area!!!

I am guessing that you have a vacuum problem...:site:

David

Thanks for all,
Thank you Mr.David,
I'd like to declare my problem with more details,
When i set the label to a suitable length from the matal blade edge and run the machine, its give 3 labels with exact and fine step length, but at the 4th label ,the step length begin to decrease making the gap of the film (the space between a two labels)to be close to the fork sensor, and at end of the 5th label step, the gap of film become settled inside the fork sensor making it stay flash on and the machine stop !
The question is that why the machine gave a first 3 labels corrctly while the step length become wrong at the 4th and 5th step?!..
Hope to get suffecient reply( specially from Mr.David) if possible plz..
Note, The fork sensor has no teach button.. it only has a sensitivity adjustable screw..
Thank you

Note, The fork sensor has no teach button.. it only has a sensitivity adjustable screw..

Click to expand...

You may want to change the sensitivity on the fork sensor to see if this corrects your problem.

On our label applicators, we had problems with erratic label placement. We found that the metal pressure roller that pressed the label backing paper against the rubber coated drive roller would let the backing paper slip on the drive roller. We found that by putting a knurl on the metal pressure roller, it helped the rubber drive roller grip the backing paper for a more accurate pull of the labels.
Also, when we converted our label applicators from a clutch/brake design to a stepper motor design, we had to increase the distance from the gap sensor to the applicator plate edge (the gap sensor is upstream from the edge) by 3/16” from the original design. We had to account for the time and distance it took for the stepper motor to accelerate to speed and decelerate to a stop. I hope this helps.

johneedw said:

Thanks for all,
Thank you Mr.David,
I'd like to declare my problem with more details,
When i set the label to a suitable length from the matal blade edge and run the machine, its give 3 labels with exact and fine step length, but at the 4th label ,the step length begin to decrease making the gap of the film (the space between a two labels)to be close to the fork sensor, and at end of the 5th label step, the gap of film become settled inside the fork sensor making it stay flash on and the machine stop !
The question is that why the machine gave a first 3 labels corrctly while the step length become wrong at the 4th and 5th step?!..
Hope to get suffecient reply( specially from Mr.David) if possible plz..
Note, The fork sensor has no teach button.. it only has a sensitivity adjustable screw..
Thank you

Click to expand...

I will bet you are off on the first three as well but it doesn't cause a problem yet. It almost sounds like you are trying to generate a label to large for the stock you are using. What ever you define your label length to be trumps the sensor.

A silly thing that got me once was the label length units. It was set to metric when the label stock we were using was measured in inches so we got drift that way.