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How to Solve Issues With Calender Gauge Control? (Part 2)

Continued from Part 1, this post is on force induced variations in calendered gauge (or thickness).

Force Induced Variations

Force induced variations result from the way your calender is operated. This is also an outcome from previous process steps such as your feed mill operation and compound consistency from rubber mixing.

The separating forces generated during calendering are quite high! For example, if you have a 66 inch calender roll and producing 60 inch wide rubber sheet, the separating forces are in the range of 72,575 Kg (approx. 160,000 lbs) to 136,000 Kgs (approx. 300,000 lbs) at each actuator.

Such high forces literally stretch your calender frame. Variations in these forces will therefore vary the amount of frame stretch and thus vary roll position and calendered gauge of your rubber sheet.

Calender-From-Comerio

Here are FIVE tips on how you could solve issues of calender gauge control from force induced variations.

  1. Keep the rubber calender running
  2. Increase the temperature by 5 degrees Celsius when you stop the rolls.
  3. Limit the temperature rate of change at all times to a maximum of 3 degrees per minute.
  4. Minimize speed changes.
  5. Mill management

Let’s examine each one.

1. Keep the rubber calender running.

Because stoppages cause your calender rolls to become egg-shaped, that in turn introduce significant gauge thickness variation.

When you stop the rubber calender, the heat loss from the rolls is not uniform around their surface. Heat loss along the face of the rolls near adjacent rolls is minimal, while heat loss in other areas that are open is higher. This differential heat transfer leads to different temperatures on your calender rolls. And therefore different degrees of calender roll expansion.

If you have a calender with rolls that is 24 -30 inches in diameter, even a few degrees of expansion will result in “out-of-roundness” of each roll that you can measure. This is true when the calender is empty but even more so when there is a hot bank of rubber between the rolls. If you stop the calender for longer period, this condition worsens further.

Your calender rolls run at different speeds. This means that periodically the high and low spots on the rolls match up. When high spots of adjacent rolls match up, you get thin gauge spots on your calendered sheet. When the low spots match up a thick spot is observed. So calender stops induced variation results in an effective doubling of any roll “out-of-round” or run-out error.

Typical short-term thermal out-of-round gauge variations are (+/-) 0.0005 to .002 inches. Though thermal run-out is gradually reduced as the calender runs, it takes 15 to 25 minutes for variations to be eliminated.

Experts recommend you to adopt the following steps to minimize “thermal run-out” of rubber calender,

  • Keep the calender running during warm up. If not done, severe thermal run-out can be introduced. You need to remember that the calender nip gap between adjacent rolls will be reduced as the rolls enlarge with their temperature increases. So, a good practice is to open your rubber calender at least 0.10 inches (2.54 mm) before starting to increase the roll temperature above ambient. Keeping the calender rolls turning during warm-up and cool-down also eliminates the possibility of warping the rolls.
  • Minimize calender stops.
  • When you stop the calender for longer time, remove the rubber from the banks. This is a good operating practice for the rubber compound as well.
  • When leader is going thru the calender, dropping off tension and allowing the uncoated fabric or leader to go slack will permit running the calender during delays and personnel breaks. This will dramatically reduce thermal run-out.
Calendar line

A Calendar Line at Bharaj Machines

2. Increase the temperature by 5 degrees Celsius when you stop the rolls.

Because this helps to maintain a more uniform roll surface temperature.

You need to realize that the TCU (Temperature Control Unit) of your rubber calender controls the temperature of the water exiting the rolls and not the ‘roll surface temperature’. This is an important distinction.

Visualize these two scenarios –

Scenario 1 – When the calender is not processing rubber (i.e. during warm-up and when the calender is stopped), the roll surface is losing heat to the atmosphere. Here, the TCU is actively heating the water loop. In this condition the roll surface temperature is below the water temperature.

Scenario 2 – When the calender is running and processing rubber, heat is being generated. Here, the TCU is cooling the water loop. In this condition the roll surface temperature is above the water temperature.

From the above, you will realize that for a constant water circuit temperature, the roll surface temperature swings (above & below the water temperature) between the calender normal running condition and when the calender is stopped. This difference in roll surface temperature means that your rubber compound is being processed under varying conditions. Shrinkage and other properties of your processed compound will therefore vary.

To minimize the differences from such processing condition variations, the roll temperatures should be increased whenever the calender stops. The temperature increase should be gradual. Your specific value should be experimentally determined by comparing roll surface temperatures in normal operation and after the calender has been stopped for 20 minutes.

In the concluding Part 3, you will see more on the other tips

  • Limit the temperature rate of change at all times to a maximum of 3 degrees per minute.
  • Minimize speed changes.
  • Mill management

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How to Solve Issues With Calender Gauge Control? – Part 1

Calender Gauge Control related variations was first in the list of of my earlier post 8 Common Defects In Rubber Calendering. Calender control issues directly affect your ability to properly control the rubber gauge or to produce a rubber sheet of consistent thickness. Rubber Calendering is the mechanical process by which rubber is pressed into textiles (cloth, fabric, tire cord) forming composite sheets.

While these sources are closely related, for quicker understanding, you may visualize and attribute the two main sources of variations in calendered gauge (or thickness) as,

  1. Mechanical Induced  – variations when your calender is not operating under any load and is at ambient conditions.
  2. Force Induced – variations when your calender is in operation or is programmed to follow a set-process for your product under manufacturing.
Tyre Cord Calender Line From Bharaj

India’s First Fully Automatic Tyre Cord Calender Line From Bharaj Machineries.

In this post, I will touch on Mechanically Induced Variations

Mechanically induced Calender Gauge variations relate directly to your rubber calender’s mechanical condition. Thus it’s basically a maintenance issue. While there are many maintenance issues that could affect your calender performance, the following FIVE directly effect your rubber sheet’s calendered gauge

  1. Grind Profile of Calender Roll (Roll Crowning)
  2. Eccentricity of Calender Roll or Run-out at Ambient Temperature
  3. Condition of Calender Roll’s Bearings
  4. Condition of Calender Roll’s Water Passage
  5. Condition of Calender Roll’s End Actuator

Let’s briefly examine each one.

  1. Grind Profile of Calender Roll (Roll Crowning)

You must periodically grind the calender rolls to establish the proper profile. Your selected crown profile is based on
the range of your rubber compound hardness, type of center compensation such as cross-axis or roll bending, and roll width.

The forces that separate the rubber calender rolls to bend apart in the center are partially compensated for, by grinding the center to a larger diameter. When the grind profile is incorrect it will be difficult or even impossible for you to achieve a consistently flat-calendered rubber sheet.

2. Eccentricity of Calender Roll or Run-out at Ambient Temperature

Your calender rolls must be round and free of run-out at ambient temperature. Any run-out of the individual calender rolls will be amplified as the high spots and low spots periodically match up between the roll pairs. You can easily check this with dial indicators when the calender is running without rubber and with a small nip gap between the pairing rolls.

3. Condition of Calender Roll’s Bearings

You must ensure that your Rubber Calender roll bearings does not have excessive run-out. Excessive bearing clearance will result in the roll shifting during operation because the roll separating forces vary. This could appear as calender roll surface run-out and will adversely affect your ability to control calendered gauge.

4. Condition of Calender Roll’s Water Passage 

Most modern calenders have drilled rolls. A drilled roll has water passages across the roll face beneath their surface. These water passages effectively forms a radiator-like heat exchanger around the periphery of your calender rolls.

In an event when these passages become plugged, then non-uniform heat transfer will occur. And this results in a thermal ‘out-of-round’ condition for your calender roll which subsequently has has the same effect as if the rolls were machined ‘out-of-round’.

You may avoid this situation by using only treated water and ensuring that the rolls are periodically flushed. You could also can check this condition by comparing the roll run-out or eccentricty at ambient temperature with that at normal operating temperatures of your Calender.

5. Condition of Calender Roll’s End Actuator

Of the different variants – manual, motor-driven and hydraulic nip gap adjustments – electric screw actuators are the most common type of calender roll end-positioning-system. The screw and nut operate under very high loads and thus, you will observe, that they experience significant wear even with proper lubrication. As these actuators wear, backlash develops.

When the backlash increases, the response to small changes or corrections deteriorate. Further with increased backlash the number of corrections required would increase, which in turn causes additional wear.

Rubber calenders that have fixed speed electric motors with mechanical brakes require periodic maintenance, particularly the brakes. Because sticky brakes will adversely affect your gauge control results.

Summarizing, proper maintenance of all the above systems is crucial to your rubber calender performance and solve issues with calender gauge control that are mechanically induced.

Mechanically Induced Variations in Calender Gauge

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Do you agree?

(In Part 2, we will cover the force induced variations)


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Slitter: It’s Not as Simple as You Think

Slitter is a simple cutting machinery used in tyre industry to slit the wider ply to narrow strips. Yet, its not as simple as the name sounds.

The contents of this post has been adopted from a newsletter shared with us by L&T Rubber Processing Machinery.

Slitter

Each slitter consists of

  1. Let-off Assembly
  2. Cutter Assembly
  3. Winder Assembly and
  4. Conveyor Assembly

Let-off Assembly:  You feed the material and the insulating liner into the slitter cutter area using a mobile cart known as let-off cart.

Cutter Assembly: As the name suggests, your ply is cut or slit through two to eleven cutters, that are arranged in a single-line assembly. Key features of this part of the assembly are

  • You can adjust the width of the output web using the manual slide option.
  • You can adjust the Ply tension using a pneumatic system.
  • The knife assembly is also adjustable.
  • Depending on your preference, you could also opt for Pneumatic knife cutter.

Slitter Knife Arrangement

Conveyor Assembly: After the web or ply has been slit, they are guided through a belt conveyor to maintain them wrinkle-free. Key features of this part of the assembly are

  • There is a yard meter for display so you could see the running cut length.
  • The assembly maintains constant line speed and web tension.
  • An equal spread of web is maintained.
  • Hand wheel is provided for you to adjust the conveyor belt tension.

Winder Assembly: The web or ply that has been cut by the knife assembly is wound using the winding mechanism on the mobile rewind carts.

These Slitters can also be identified as Stage 1 and Stage 2 Slitters.

Stage 1 Slitter – Here, you can slit the ply into two strips (each of 730 mm)  to a max of 12 strips (each of 120 mm). The wound ply obtained from 1st stage slitter on the winder cart can be used as an input in 2nd stage for further slicing.

Stage 2 Slitter – If you require the width of the ply strips to be narrowed further from 120 mm, then you could use a stage 2 slitter machine. Here’s how you do the second stage slitting.

  • The rewind cart from 1st stage slitter machine (output) is easily towed and moved into the 2nd stage machine as its Let-off Unit (input).
  • The cart is aligned on the fixed guide rails.
  • The web is gradually unwound individually from each drum at a time interval of 40-50 minutes.
  • The web is fed into the 2nd stage slitter and slit through a knife assembly into smaller widths.
  • The ply is rewound across “n” numbers of winders depending on your requirement.

A sample Slitter Machinery specification offered by L&T is as below:

  • Width of Supply Material:                        1460 mm (Maximum)
  • Diameter of Supply Material:                  1250 mm (Maximum)
  • Thickness of Supply Material:                 1.2 mm (Maximum)
  • Diameter of Supply Material Shell:        360 mm
  • Max chord angle for supply material:    0°
  • Supply Material:                                         Rubber / Nylon
  • Diameter of liner material:                       800 mm (Maximum)
  • Diameter of liner material shell:             360 mm
  • Trimming:                                                    Knife type
  • No of Knives:                                               02 to 11
  • Line speed:                                                   20 m/min
  • Width of output Layer:                             (730 mm x 2) to (120 mm x 12)
  • No of winders (Rewind carts)                  Two
  • Let-off material loading /unloading:      Manual
  • Cutter adjustment:                                     Manual
  • Setting liner-roller:                                    Semi-Automatic
  • Winding cart loading / unloading:         Manual

Summarizing a slitter is not as simple a rubber machinery as you think and suppliers offer you designs with various levels of automation to meet your requirement of slitting the ply or rubber sheet for your product applications.

Do you agree?

(L&T’s Rubber Processing Machinery business manufactures and markets machinery for the global tyre and rubber industry. The machines are produced at its facility in Kancheepuram, Tamil Nadu. You could reach out to them for customized solutions on rpmsales.ltmbu@larsentoubro.com.)


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Here’s How Siemens Technology Drives The Tyre Industry

Tyre manufacturing is a highly competitive field and faces volatile changes. The ecosystem of tyre manufacturers, raw material suppliers, and machinery manufacturers are affected by industry consolidation, innovations in technology, labeling and safety requirements, increasing government regulations, shifting customer demands, and the pressure for lower customer prices.

Tyre manufacturing is also a complex process. A fault or improper procedure at any of the manufacturing stages threatens the structural integrity of the tire. And, tyre manufacturers demand the highest productivity from every stage of their manufacturing process.

This means every tyre machinery manufacturer must produce machines that offer high production output, manufacturing accuracy, reliability and product quality with low processing and maintenance costs and lowest possible manpower.

It is here Siemens, the automation and drive solutions leader, brings in technology that drives the tyre industry. Using cutting-edge technology such as Totally Integrated Automation from Siemens, local tyre manufacturers are able to fulfill demand for new and retrofit solutions, in the process sustaining their profitable business.

TIA for the Tyre Industry

The tyre industry in India stands to gain massively by integrating automation right at the onset of the tyre production life-cycle. The typical value chain for manufacturing tyres start from R&D, moving to production planning, production of tyres, quality assurance, warehousing and supply.

Under the motto “Get your tire production rolling”, Siemens successfully participated in the leading international Tyre Technology Expo 2016 in Hannover on February 16 to 18, 2016. At the so far largest show – which was 20 % bigger than in 2015Siemens held highly interesting customer discussions both with various tyre manufacturers and machine OEMs.

Siemens at TTE2016

Siemens Stall at TTE2016

Their discussions were supported by the highlights and demonstrations shown by the booth personnel as well as the Siemens presentations held at the conference. This exhibition provided a perfect platform for Siemens to showcase its latest technologies for the tyre manufacturing industries from across the world.

Through the Totally Integrated Automation and Siemens PLM software (which has a significant presence in India), Indian tyre manufacturers have ready access to technology for data integration between the various points of the value chain.

The innovative engineering framework TIA Portal integrates HMI, controllers, distributed IO, motion control and drives seamlessly into one engineering environment.

In addition, by implementing the SIMATIC range of solutions, machine builders for the tyre industry can increase productivity and cost efficiency through the latest technology.

Siemens S7 1500 PLC

SIMATIC PLCs support tyre manufacturers right from factory layouts and factory designs that are highly automated according to their requirements.

Explains Siemens official, “SIMATIC S7-1500 has proven to have the highest efficiency and maximum usability for complex automation tasks, having set new standards in system performance, usability, quality of control and response times. The SIMATIC S7-1200 Basic Controllers are the ideal choice for simple and autonomous tasks in the low to mid performance ranges.

What do you think?


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Practical Modern Solutions For Tyre And Rubber Industry

Change is inevitable. Changes in the business environment happen all the time. The economy fluctuates up or down on a daily basis, frequently causing businesses to alter the way they operate. New competitors enter the marketplace while others leave. Advancements in technologies, products and innovation lead to change in a business environment.

Sustaining and innovating amidst changes is the hallmark of exemplary leadership. Pelmar Group has been displaying dynamic leadership for the last 50 years! Hence, in this special edition of Know Your Supplier’s cover story, we showcase for you Pelmar Engineering Ltd., the Practical Modern Solution Providers For Tyre And Rubber Industry.

We understand from our conversation with Jacob Peled, Founder and Executive Chairman, that Pelmar had three consecutive record years. And is now planning expansion of both its commercial and technical activities in Israel and worldwide.

It’s not easy to achieve three record years consecutively handling a range of activities that include pre-owned machinery, new equipment, complete engineering services, raw materials, military technical rubber production, technology transfer, M&A activity and more. Because, this requires efficiency and focus.

Don’t miss our main interview to know how Pelmar has been consistently outperforming customer expectations year-on-year.

Know-Your-Supplier-Pelmar-May-2016

Click on the image to read

(You may read this digital edition either on Youblisher and/or Yumpu platform.)

An anecdote shared by Peled in his own words that I choose to mention here.

“I was asked a question yesterday evening by one of the persons I admire most in the industry, Michael Labbe the Managing Director of Rema TipTop, how could I and Pelmar cope with handling so many various subjects efficiently at the same time. He referred mainly to Pelmar handling pre-owned machinery, new equipment, complete engineering services, raw materials, military technical rubber production, technology transfer, M&A activity and more. I did not have a proper answer.

This morning I had breakfast with the technical director of one of the major Tier 1 tyre companies, who asked me how could I with the size of our Group, with the international spread, with the diversity of functions handle only one industry, the tire and rubber industry. I tried to explain that tire and the technical rubber industry are separate, but found myself mumbling.

The worst thing about the above is that both questions are absolutely correct and in place. The only answer that I can think of is that because we are handling “just one industry” we can and should be involved in as many aspects of this industry as possible.”

Pelmar Engineering Ltd.

Identifying and capitalizing on the opportunities swiftly along with thirst for growth has helped Pelmar diversify their expertise, spread reach globally and offer single-stop shop total solutions for rubber and tyre industry.

Additionally, on this digital edition, we have two knowledge-enriching topics from our portal aptly titled ‘Insight’ and ‘Tips’ sections.

Download PDF of this special edition here

I hope you find the contents informative to learn more about this leader in rubber and tyre industry.


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Know Your Supplier is an advertorial initiative of Rubber & Tyre Machinery World. 

If you would like your organization to be promoted on Rubber Machinery World, please see the opportunities on Partner Me or Contact Me at engage@rubbermachineryworld.com for your customized offering.


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Will Post Cure Inflator Machinery Ever Die?

Few weeks back, I shared Jacob Peled’s presentation ‘The Future of Tire Plants’ and more recently, ‘Visions of the Future’ on our LinkedIn Page. On reading, an industry friend asked me this question – ‘Will Post Cure Inflator Machinery Ever Die?

While Jacob’s presentation envisions the shortening of curing time by use of higher temperatures and pressure, automation, development of bladder, materials etc, there have been no specific mention of Post Cure Inflators.

So where did this question rise from, I was curious.

Historically, the process of Post Curing Inflation has seen its popularity rise and fall at different time intervals. Tyre technology has been evolving to embrace increased efficiency at all stages of manufacturing. And Post Curing Inflation is not really an energy efficient process, reasoned my friend clarifying the basis for his question.

So, what is Post Cure Inflator Machinery?

Post Cure Inflator (PCI) machinery cools the tyre under pressure immediately after it has been cured.

post-cure-inflator-tire-machinery

Image: L&T Make Post Cure Inflator

For the tyre, this stage involves mounting them on the flanges, inflating it and cooling it according to a selected procedure. You may do this for one or two cycles (Note: one cycle is equal to the time taken for one curing cycle) depending on the specification arrived at for the time your cured tyre takes to cool down to room temperature.

Types of Post Cure Inflator Machinery

There are two types of Post Cure Inflator machinery, viz. Automatic and Semi-Automatic, in the market for use with tyres of passenger cars, light trucks, trucks and off-the-road equipment.

  1. Automatic Post Cure Inflator units are installed at the rear of tyre curing presses, to receive the cured tyres from the curing presses. The tyres are cooled to ambient temperature under controlled air pressure to avoid distortion of plies. After cooling, tyres are discharged onto the takeaway conveyor rollers. Post Cure Inflators are available in 2-position and 4-position designs, which allow for inflation time equivalent to curing time and double the curing time respectively.
  2. Semi Automatic Post Cure Inflator units are located in the curing area and cured tyres are loaded into these units. Tyres are cooled to the ambient temperature under controlled air pressure and are manually discharged from these units.

Machinery suppliers offer design features like adjustable inflation, auto/manual rotation, and adjustable bead width. These features enable Post Cure Inflator machinery to also function as a testing stand for secondary, manual inspection of sidewall or runout rejects.

To examine the importance of this tyre machinery further, let’s understand the process deeper.

Post Curing Inflation Process & its Significance

Post Curing Inflation is recommended especially for tyres of nylon carcass construction. This is because nylon has a unique property of shrinking while it is heated.  When you have nylon in your tyre carcass (i.e. the skeleton of the tyre), there is a tendency for it to shrink as you heat the tyre to vulcanize.

Since vulcanizing of the tyre happens inside a curing press, it is not possible for these nylon cords to shrink. This is because there is high pressure inside the tyre which keeps these nylon cords in the stretched condition. But when the curing is completed and you release the pressure inside the bladder, the nylon cords tend to shrink since your tyre is still hot.

To avoid this hot or thermal shrinkage, the tyre is to be cooled under pressure. If you skip this process, the tyres may lose shape or get distorted or have changes in dimensions.

Post Cure Inflator machinery stabilizes the shape of your tyre in production. When you delay Post Curing Inflation, the damage caused would be irreversible and highly undesirable – both for your company’s reputation and customers safety.

If your customer is given a tyre which was affected by Post Curing Inflation delay, its dimensions will be different from normal tyres. This leads to uneven wear, problems to the axle and bearings of their vehicle. The distortion in shape further leads to tyre uniformity problems that adversely impacts the level of comfort and performance of tyres in the highly advanced vehicles. Last but not the least, a distorted tyre is not safe and lead to accidents.  Needless to say, all of the above creates a negative impact on the company’s image and lead to economic and legal implications for your company.

When the design of your tyre construction changes, Post Curing Inflation process allow your tyres to maintain their designed profile and performance characteristics as they reach road temperatures.

Summarizing, while the popularity of Post Curing Inflation process (and hence Post Cure Inflator Machinery) may shift back and forth, this tyre machinery will not die soon.

What do you think?


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Why We Love Gear Coupling (And You Should, Too!)

First things first! You choose a coupling to connect two shafts together at their ends to transmit power. The primary purpose of coupling is to join two pieces of rotating equipment while permitting some degree of misalignment or end movement or both.

Normally, couplings do not allow shafts to disconnect during operation, however there are torque limiting couplings which can slip or disconnect when some torque limit is exceeded. Hence, you should carefully select, install and maintain couplings; as this could give you substantial savings in the form of reduced maintenance costs and downtime.

Gear Coupling

A gear coupling is a mechanical device to join two rotating shafts (that are not collinear) for efficient transmission of mechanical power. These are crucial because although you may align the shafts (for example, between the gearbox and the mixing mill roll) at the time of installation, it is likely that during the operation there may be disruption to this alignment.

Disruptions could occur due to setting of foundation, thermal expansion, shaft deflection, wearing out of other parts, improper maintenance and many more reasons. At these times, where the misalignment occurring during the operation is unavoidable, a gear coupling compensate or minimize the effect of misalignment thus providing a good solution to prevent your rubber machinery, bearings, seals and shafts from being subjected to the additional forces.

Gear couplings are power intensive and considered as the king of the coupling types. You would see the gear couplings being adopted for wide range of application in drive technologies. Hence, we love love gear coupling (and I think, you would too!).

Gear Couplings and Universal Joints

Gear couplings and universal joints are used in similar applications. Gear couplings have higher torque densities than universal joints designed to fit a given space, while universal joints induce lower vibrations. The limit on torque density in universal joints is due to the limited cross sections of the cross and yoke.

The gear teeth in a gear coupling have high backlash to allow for angular misalignment. The excess backlash can contribute to vibration.

Structure of a Gear Coupling

Gear couplings are torsionally rigid and consist of hubs with multi crowned teeth at flank, tip and chamfering on teeth, gaskets, sleeve and O-rings. The hubs attach to the machinery shafts, and sleeves span the gap from one hub to the next. They are available in two designs – completely flexible and flexible/rigid.

The hub is the heart of any gear coupling. Hence manufacturers take great care to impart a superior design and mostly manufacture the hub on CNC machine for precision. Together with the tooth profile of the hub, these aspects enable the gear coupling to function well under all operating conditions with increased reliability and long life.

The tooth flanks and outer diameter of the external gear are crowned to allow for angular displacement between the two gears. The multi crowned teeth reduce the alignment adjustment and improve the load carrying capacity of the teeth. The backlash between the teeth is minimal due to multi-crown tooth design.

A completely flexible coupling comprises two hubs with an external gear and two outer sleeves with an internal gear. It’s a universal coupling for all sorts of applications and accommodates all possible misalignment (angular, radial and combined) as well as large axial moments.

Structure of a Gear Coupling

A flexible/rigid coupling comprises one flexible geared half and one rigid half. It does not accommodate parallel displacement of shafts but does accommodate angular misalignment.

Information to order Gear Coupling

When you are buying rubber machinery, your machinery supplier or OEM would take care of this. However, you need to understand that there is a check list of information that needs to be provided to a gear coupling supplier that includes,

  1. Specify quantity required and delivery expectations.
  2. Specify shaft or bore sizes and key-way dimensions. You need to give exact dimensions with tolerances.
  3. Specify load – HP and/or torque at a specific RPM. State the normal and maximum conditions of use.
  4. Specify Speed of operation – Minimum, Normal and Maximum.
  5. Specify Application. Most Rubber & Tyre Machinery (Mixers, Kneaders, Mills, Calenders, Extruders, etc) conforms to a service factor classification where heavy shock conditions or frequent reversing peak loads that do not exceed 150 per cent average horse power is observed. Uneven load is usually present during operation. Service factor ranges from 1.25 to 1.50.
  6. Specify Coupling Series, Type and Size.
  7. Specify Space limitations – envelope dimensions, shaft extensions and shaft spacing.
  8. Specify unusual misalignment conditions if any.
  9. Specify Modifications – tapered bores, special keys, hub cut off, counter bores or others
  10. Specify unusual operating conditions ambient temperatures and atmospheres, if any.

Maintenance of Gear Coupling

Gear Coupling maintenance is mostly simple – requiring a regularly scheduled inspection of each coupling. Your schedule should consist of:

  • Performing visual inspections – checking for signs of wear or fatigue, and cleaning couplings regularly.
  • Checking and changing lubricant Each coupling half is provided with grease nipple/plug on the housing from where grease can be filled directly. The coupling is supplied with some quality of grease to facilitate assembly. It is recommended to fill the required quality and quantity of grease before putting the coupling in operation. This maintenance is required annually for most couplings and more frequently for couplings in adverse environments or in demanding operating conditions.
  • Documenting the maintenance performed on each coupling, along with the date.

Here’s a 1:17 min video of dismantling of a gear coupling so you could appreciate the components that make-up this coupling much better.

Video of Dismantling of A Gear Coupling

Video

Failure of Gear Coupling

Caution! Even with proper maintenance, your gear couplings can fail. The other causes of failure include:

  • Improper installation
  • Poor coupling selection
  • Operation beyond design capabilities

The only way to improve your coupling life is to understand what caused the failure and to correct it prior to installing a new coupling. You could check for some external signs that indicate potential coupling failure like,

  • Abnormal noise, such as screeching, squealing or chattering
  • Excessive vibration or wobble
  • Failed seals indicated by lubricant leakage or contamination

Summarizing, gear coupling is a mechanical device to join two rotating shafts for efficient transmission of mechanical power, are power intensive and is the king amongst the coupling types. They offer the highest load capacity and stiffness, yet easy to maintain. These are some of our reasons to love this gear coupling on the rubber machinery. 

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