Tips on How to Select an Automatic Labeling System

Exactly what is an automatic labeling system?

An automatic labeling system consists of three key components: a labeling head (or label applicator), a conveyor (or other product transport device), and an integrated control system each of which, in turn, have their own sub-components. Optionally, other operations can be added to the system, such as Hot Stamp coders, bar code printers (thus: print and apply), power unwinds (for extra large web capacity or feeding a barcode printer), verifiers (to make sure label is on and/or the code is readable), etc. When all of these components are fully integrated meaning they all work together without the need for human intervention, except for replenishing label stock, printer ribbons and physical changeover to a different product, and the system works through the entire speed range without need for readjustment of controls, you have an "automatic labeling system". (You should not assume that a manufacturer who claims to have an "automatic labeling system" really does! All to some degree have the basic components, but many, if not most, are independent components that are not fully integrated!)

Labeling Head (Label Applicator)labelhead.JPG (74574 bytes)

Web Unwind Reel

Pretty Simple - This is where you load your label roll (typically about 12" - 13" diameter. Larger rolls require a power unwind option.

Dancer Arm

Allows for smooth label starts, keeps web tension, and acts as a brake to stop the web unwind roll from overfeeding

Label Sensor

Detects the 1/8" gap between labels to alert the control system to initiate a label stop sequence. This is accomplished with an electro-mechanical switch (still standard on some brands), photoelectric sensor, or capacitive sensor (usually an option for clear labels).
Electro-mechanical switches are for the most part passe (outdated), except for small semi-automatic labelers.
Photoelectric sensors are common on most machines, but the sensitivity must be adjusted whenever changing label stock.

Peel Plate

The peel plate actually separates the label from the backing paper.  As the web breaks sharply over the peel plate, the label continues on in a straight line.

Drive Roller

The Drive roller is actually the workhorse of the labeling head.  In conjunction with a pinch roller, the drive roller pulls the web backing, starting and stopping with each labeling sequence. These are very similar on all machines. The difference in quality in labelers is not so much by the drive roller itself by the means by which the roller is driven and stopped. It is worth taking some time to go over the types of drive systems available and their advantages or disadvantages.

Stepper Motors

This is another confusing area for the purchaser of a labeling machine. There are A.C. (alternating current) and D.C. (direct current) stepping motors. D.C. stepping motors are further categorized as 2-phase and 5-phase.

A.C. Stepping Motors

A.C. Stepper motors are used on a few labeling systems, but not many. The advantage is they are relatively inexpensive. But the disadvantage is that they have a large step angle (about 12 degrees) creating inaccuracy and have limited speed capability.

D.C. Stepping Motors

What is a Stepping Motor?steppic.JPG (40705 bytes)

A stepping motor is an electromechanical device that converts electrical power to torque. But what makes a stepper motor different is that the shaft rotates in fixed angular units (steps) when its phases are energized in a predetermined order. 2-phase motors typically have 200 steps per revolution, whereas 5-phase motors typically have 500 steps per revolution.

stepconst.JPG (94316 bytes)

Stepper Motors are connected to a special driver which is actually a very high speed switching device that accepts input pulses from an encoder or PLC. For each input pulse it receives the motor advances one step. A 5-phase motor therefore requires 500 pulses to advance one full revolution.  However, to smooth out the operation of the motor and get greater accuracy, most drivers can be operated in what is called "half step mode". Half step mode allows the motor to advance with double the resolution or 1000 steps per revolution. So now the input pulses must also be doubled to 1000 pulses per revolution. Further divisions can be made by micro stepping.  However. micro stepping results in considerable loss of torque at each division and is not widely used in labeling applications.

step5ph.JPG (109630 bytes)

Conveyor or "Product Transport"

For a product to accept a label some means must be provided to transport it through the labeling station. In the overwhelming majority of cases this will be a conveyor for transporting boxes, bottles, candles, or any of the myriad of products you can imagine. In very special circumstances where the product is unwieldy, or labeling must be done on a special production line due to some unique circumstance we can build a custom product transport or systems integration.

The most important feature that should concern you is not the type of conveyor you buy (although it must obviously be able to physically handle your product dimensions and loads) but how it is driven and its controls.

Your Labeling Team!


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