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Paper / Printing / Converting Problems & Solutions

Paper Mill Proves Kopper Kool® Brake

PROBLEM

For years, a mill customer satisfactorily operated several water cooled tension brakes. Over a period of time, their cooling efficiency had dropped off and leaks had become an increasing problem.

SOLUTION

A careful examination revealed that corrosion had opened up the o-ring grooves as well as mechanical wear in the snap ring slot.

Following up on these problems, we came up with repair kits that include new water jackets with bolt on wear plates eliminating the snap rings. Additionally, we came up with components that offer an improved flow pattern which will result in more uniform heat distribution - extending seal life.

If you want to improve your Kopper Kool® brake — give us a call.

Couch Roll Coupling

PROBLEM

A paper mill recently changed over from a belt drive take off to an individual 150 HP DC motor. To complicate matters, space was limited and the mounting resulted in fairly significant misalignment.

As a result, the original gear coupling failed on a regular basis. The mill then went to a grid coupling, but unfortunately it also failed.

SOLUTION

Given the torque and misalignment required in this envelope, there were not a lot of options. We were able to come up with a custom universal shaft assembly which significantly increased the coupling's torque capacity.

Additionally, we made up the assembly with custom flanges that matched the existing gear and grid coupling rigid hubs. This made the replacement a simple drop-in operation.

Let us know if you have a tough application.

Paper Unwind Stand - Drum Brake Wear

PROBLEM

Our paper converting customer found that they were replacing their metal brake drum on an annual basis. Closer examination revealed that the excessive wear pattern matched the spacing of the rivet holes.

It was concluded that in this application and environment, some aggressive particles worked in the path of the rivet holes causing unacceptable, uneven wear.

SOLUTION

We came up with undrilled blocks in the correct arc and thickness. Next, we bonded this lining to our customers brake shoes, eliminating the need for rivets. Our customer cleaned up the worn drum and has been running smoothly since.

If you have a brake wear problem, let us know.

Extended Foil Blade Life

PROBLEM

The wet end of a paper machine presents a number of maintenance challenges. A key part of the system are the foil blades on which the forming fabric rides.

The constant rubbing action results in wear of the blades necessitating resurfacing and eventually replacement.

SOLUTION

Over recent years there has been an explosion of new materials. Some of the ultra high molecular weight (UHMW) polyethylenes have proven to be good foil blades.

There have been some ceramics developed for similar applications which have offered extended life, but their expensive, fragile nature reduces their cost effectiveness.

We can now offer UHMW polyethylenes with ceramic fill. This hybrid material offers extended life with only a modest price increase. The material is much more flexible, hence easier to install and less likely to fracture.

So if your interested in reducing your maintenance cost on the wet end of your machine, give us a call.

Metric To English

PROBLEM

Our customer operates paper converting equipment including a water cooling tension brake. Since the equipment was manufactured off-shore all of the components were metric.

In this operation, the brake was the only regular maintenance item. However; given the high price and limited availability of the parts, keeping up with this brake was an expensive headache.

SOLUTION

We reviewed the application and were able to come up with another brake which would do the job. More importantly, we were able to identify a unit similar to existing in house designs.

This allowed our customer to take advantage of parts he already stocked. Additionally, his maintenance teams were already familiar with the operation of these brakes.

We were able to modify the new brakes to mount directly to his metric side frame.

If you have metric equipment and want to simplify things, give us a call!

Re-machine Wet End Polys

PROBLEM

Over a period of time, the forming board and foil blades on this paper maker's fourdrinier wore down. As a result the drying efficiency of his machine was dropping off significantly.

Given the several thousand dollars cost of replacement, our customer did not look forward to replacing these components.

SOLUTION

We visited and reviewed their table layout and design. We were able to quote re-machining the existing ultra high molecular weight (UHMW) polyethylene blades. Not only did we return these working surfaces to like new, but were also able to offer new blade angles.

This approach cost only a few hundred dollars as opposed to the several thousand involved for new polys.

We can often re-machine an original set two or three times. If you're interested, we would be happy to visit and discuss the specifics with you.

Roll Stand Brake — Water-Cooled To Air-Cooled

PROBLEM

The customer had operated our water-cooled brakes on his unwind stands for eight years with very little maintenance. However, some additional demands on his cooling system resulted in some corrosion and capacity concerns.

SOLUTION

We closely reviewed their tension needs and thermal horsepower requirements. Additionally, close attention had to be paid to size — since the roll arms move, every position and process function had to be checked for clearance.

We were able to come up with a unit that will do the work and fit. The new brakes are air-cooled, eliminating the need for cooling water. These units will operate significantly hotter and friction material life will be shorter. However, the customer eliminated the overload on his cooling system and any potential for corrosion problems.

This is a situation where we were able to come up with an alternative which did have a trade off, but one that our customer found more acceptable. Give us a call if you need additional options.

Printer Upgrades Universal-Joint - Eliminating Weekly Failure

PROBLEM

A printer found that he was replacing a pin and block style universal joint on his embosser weekly. Heavier universal joints only seemed to result in gear box bearing failures.

SOLUTION

A careful review of the installation revealed that the misalignment involved compound angles. Given this situation, the coupling was producing an irregular velocity on the output side. Since the inertia of the driven roll was larger, a significant torsional shock was produced in the coupling twice every revolution. When they went to a heavier joint, this shock load was passed back to the gear box bearing.

At our suggestion, the customer was able to move the drive assembly to minimize the compound angle. We were also able to supply a needle bearing universal joint which could accept more misalignment and absorb higher shock loads.

That was several years ago - so far ... no replacement. Do you have a problem coupling that needs help? Eaton Airflex clutches in stock

Coupling Upgrade

PROBLEM

Our customer manufacturers corrugated boxes. One of their roll drives involved a universal-joint assembly to accommodate a rather severe angle (20°). Unfortunately, the shaft failed on a regular basis. They needed to eliminate this costly maintenance headache.

SOLUTION

We reviewed the application. The angle and envelope were both challenging. The distance between shaft ends limited our options.

After reviewing several approaches, we came up with two options. The first was another cardan style assembly that would drop into the existing connections, yet offer increased capacity. The alternate design would use constant velocity components. This assembly would require end fitting changes and the overall cost would be greater. However, it would insure even longer life.

Considering the costs involved, the best solution was to try and monitor the performance of the cardan design.

Universal-Joint Vibration

PROBLEM

Our customer uses a universal shaft assembly to drive his printing press rolls. The need to move the roll creates some high misalignment angles dictating a universal assembly. They found some objectionable vibration during operation.

SOLUTION

Upon review of their new operating requirements, it was found they were exceeding the angular acceleration capacity of the universal joints. With cardan (cross) style universals, a combination of high angle and high speed can result in unacceptable deflection of the yoke ears. This will result in vibration and extremely short life.

We reviewed the installation and attempted some minor adjustrments to minimize the misalignment and ensure that the driving and driven shafts were parallel. These changes reduced the vibration, but not to an acceptable level.

The final solution was a constant velocity Rzeppa style universal shaft. We were able to come up with a direct replacement. Though more expensive, it did what our customer needed it to do - without vibration.

Paper Machine Vibration

PROBLEM

A large paper mill operates a 500 HP drive running a 15' diameter steam roll at 800 RPM. Due to the layout of the process, a significant shaft offset existed necessitating the use of a universal shaft.

During operation, they noticed a vibration. Over the years, it became more and more severe. The vibration grew to the point where it shook the entire dryer platform.

SOLUTION

We reviewed the application. One of the first things we looked at was the frequency of the vibration. It turned out to be twice the RPM. This indicated that the vibration might be initiating at the universal shaft.

The next step was to see if the shaft was properly phased - it was. We then reviewed the alignment and found compound angles. This was the source of the vibration. A Cardan design universal-joint produces an irregular velocity in its center section. If you have uneven angles, the second joint will not cancel the velocity change. The result is a vibration, which in this case resonated throughout the entire dryer.

The process didn't allow any alignment changes. We proposed a constant velocity universal shaft. This design is more expensive than the traditional Cardan design, but allows for greater angles while maintaining speed - problem solved.

If you have a vibration problem, let us see if we can help you.

Upgrading Corrugator Roll Stand

PROBLEM

After 25 years of operation, the hydraulic drum brakes on the roll stands had become a high maintenance item. Additionally, it had become increasingly difficult to maintain consistent tension control.

SOLUTION

A careful review of the application was necessary to determine the required thermal capacity and detail the envelope restrictions. It was determined that a new air actuated brake with an integral cover could be mounted with minimal changes. The upgrade also included adding and automatic danger control system, which has resulted in a significant quality improvement.