While not exactly the best analogy, a misaligned web-converting machine—be it a printing, press, coater, laminator or slitter/rewinder—is somewhat like a misaligned spine. Not having all your vertebrae in their proper place can be the cause of a host of other problems elsewhere in the body, as any chiropractor will tell you.

So it can also be with misaligned stations or subsystems on a converting line. From a skewed web path come problems ranging from poor registration to improper curing and drying—or simply having to run the machinery slower than its optimum productivity.

Over time, there are many variables that can affect the alignment of a converting line. The foundation or concrete slab it is resting on may settle. Bearings and rollers are replaced without alignment. Mishaps from setups or roll changeovers can go unreported and undetected.

Whether performing an optical alignment to correct web problems on an existing converting line or to retrofit/upgrade a line by installing or adding new rollers or additional stations, a baseline and centerline are essential to the success of the task.

What are the steps to re-align an existing converting machine or make a modification such as adding a station where a centerline and/or baseline cannot be found? To properly align or “tram” the many rollers, drums and stations requires an accurate centerline and baseline be established. This will be the basis of all optical alignment measurements, corrections or modifications, and it's the only true reference that can be used.

Unfortunately, not all converting machinery is installed using accurate center and baselines with brass or stainless-steel floor monuments. By not having an accurate centerline, the converting stations may or may not be following the same axis throughout the length of the machine, causing the web to be skewed and experience sheer stresses. To establish an accurate centerline and baseline, an optical survey of the entire machine should be conducted by qualified alignment technicians.

With the results from that survey, the following steps can be followed to re-align or make additions to a converting machine.

1. The true center of each station should be determined. Then a careful measurement from that station's center can made to a temporary reference line. Usually the center of two major stations, such as the unwinder and rewinder near the opposite ends of the machine can be used to establish the temporary reference.
2. Next, using this temporary reference line, an alignment scope can determine if each station in the converting line is aligned perpendicular to the centerline. After comparing each station's measurements with the temporary reference line, a permanent “best fit” baseline is established.
3. Following the establishment of the true center and baseline, an accurate alignment survey can begin. Once complete, a report is generated and a plan of corrective action made.
4. Minor alignment corrections typically begin as part of the survey. This usually involves shimming and adjusting bearings and brackets until an object is aligned. Sometimes the corrections require more planning and preparation. For example, worn rollers or damaged bearings may be discovered during the survey. Replacements may need to be ordered, if not already on hand.
5. At other times the corrections needed are major. For example, an entire station may need to be moved far enough so that the anchors securing the station to the floor will have to be cut. The station will then, obviously, have to be re-anchored.
   In another example, to correct a misaligned tunnel dryer the attaching bolt holes or attaching plates would need to have the holes slotted. This could involve field machining.
   In either instance, a planned downtime or operation “outage” may need to be scheduled to cut the loss in production time.
6. Making modifications to an existing converting line many times require relocating or replacing an entire unit such as a print station, diecutter, stamper or rewinder. Sometimes the modification may simply be adding a corona treater or a profile scanner. Again an accurate center and baseline are necessary to make any of these kinds of upgrades.
   While it's inevitable that a converting line will go out of alignment sooner or later, it's not difficult to bring that machinery back into line—along with resulting productivity and profitability.