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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. 

Do you have more? Let us know your thoughts.


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7 Do’s (And Don’ts) In Calendering

Our earlier post on 8 Common Defects In Rubber Calendering (And How You Can Fix It) received few additional questions from your industry peers asking about the right practices in Rubber Calendering.

So, here are 7 Do’s And Don’ts in Rubber Calendering compiled as an info-sheet for your quick review.

7-Dos-And-Donts-in-Calendering

Download as PDF Here

Summarizing, while choosing the right rubber calender is important, learning to operate it smartly is equally key for your success with this machine.

Do you have more to add to this list of Do’s and Don’ts? Let us know.


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Industrie 4.0 And Why You Should Be Excited About It?

If you are even remotely following the advancements in manufacturing and automation, then you have already heard this term – Industrie 4.0. A German branded initiative, this is a term coined for the next stage of manufacturing that describes the main future development tasks required to achieve a ‘Smart Factory‘.

To quickly understand, you may visualize smart factories as ‘social networks’ where humans, machines and materials communicate and interact in real time.

Considered the 4th industrial revolution in manufacturing (watch a video), Industrie 4.0 is a dynamic process of evolution. It refers to the technological evolution from embedded systems to Cyber-Physical Systems (CPS).

Too much of jargons? Let me make an effort to explain…..

Relevance of CPS

In your manufacturing environment, these Cyber-Physical Systems comprise of smart machines, storage systems and production facilities capable of autonomously exchanging information, triggering actions and controlling each other independently.

This means all your machines, processes, control systems, logistics and even end-products are closely interconnected via internet-based, data-handling technologies and devices.

CPS makes your next level of decentralization realistic. It improves your resource productivity and efficiency, enables more flexible models of your work organization.

Says, Ashutosh Chincholikar, Business Head, Smart Controls India Ltd, “With Industrie 4.0, rubber and tyre machinery will no longer simply ‘processes’ the product, but your product would communicate with the machinery to tell it exactly what to do.”

Industrie-4.0-Rubber-Tyre-Machinery

Benefits of Industrie 4.0

Your benefits include flexibility in specification and volume, fine-tuning to your customer needs, and improving efficiency as a way to reduce your cost.

Your product development-to-market and order-to-shipment lead times become shorter. Expensive downtime for your machinery and plant gets reduced through remote monitoring and predictive maintenance.

Digitization, connected-ness and virtual tool planning opens your door to customized mass-production. This means you can produce very small batch sizes and yet sell at a profit.  Flexible manufacturing may mean that more of your parts and production materials have to be detected, inspected and identified. Transparency and reproducibility of your processes will enhance your product quality.

Experiences shared by Smart Controls India Ltd, include significant benefits like

  • 5% increase in productivity on 20 machines was equal to an extra machine.
  • 25% saving on a plant in Auto industry
  • 11% efficiency improvements in first 3 months at a Tire Company.
  • 68% gain in production by just fine tuning setup processes (up from 410 to 690 parts/week)
  • A large equipment manufacturer’s OEE shot up from 24% to 62% on machines

It is these benefits of speed, flexibility, quality amongst others that should keep you excited and upbeat about the prospects of Industrie 4.0. Further when you use CPS, you will have a clear advantage to attract the best employee talent since you can offer a better work-life balance.

| It is these benefits of speed, flexibility, quality amongst others that should keep you excited and upbeat about the prospects of Industrie 4.0. |

Need for a balanced approach

Interestingly, Industrie 4.0 goes by a variety of names: ‘Advanced Manufacturing’ in the USA and the UK, ‘les usines du futur’ (The Factories of the Future) in France, ‘Made Different – Factories of the Future’ in Belgium, and “Smart Industries” in the Netherlands.

As a manufacturer, you definitely need to procure equipment with right level of futuristic automation. Because Industrie 4.0 is bringing fundamental change to your business competition in today’s ‘VUCA’ (Volatile, Uncertain, Complex and Ambiguous) world.  If you continue using today’s automation systems you will fail due to excess cost in automation.

| If you continue using today’s automation systems you will fail due to excess cost in automation. |

However, it is also necessary to find the balance between full automation and manual work. It doesn’t make sense to automate all your manufacturing processes completely as the cost of that will be too high.

For example, tire production is high-volume customization. The tire industry seeks to consistently improve quality while cutting waste, thus reduce the cost of each tire. Experts and Leaders will tell you that the steps you need to do this in China or India are different than they are in Japan or in Europe or in the U.S.

Every application must be evaluated with regards to the breakeven point. And that is where you will benefit with the assistance of a systems integrator.

balanced-approach

Adopt a Balanced Approach. (Image Source: Web)

| Every application must be evaluated with regards to the break-even point.|

Adds Ashutosh, “In order to implement automation solutions in the tyre industry someone who understands the intricacies of tyre manufacturing processes – from mixing, tyre building, curing to inspection – is needed. This is where Smart Controls plays a big role. With over 15 years of experience in serving the tyre industry, Smart Controls has full knowledge and experience of using the Siemens Technological Platform to implement automation solutions for almost all processes of tyre making.”

(You may wish to hear more on the ‘role of a system integrator in your smart factory’, when Ashutosh Chincholikar speaks at the International Rubber Conference in Chennai on March 1-3, 2016.) 

Summarizing, Industrie 4.0 is more than just a buzzword today and hence important that you take notice. Because it ensures that your resources are used more efficiently while people and machinery work far more productively.

Let us know your thoughts on Smart Factory and and plans for Industrie 4.0.


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8 Common Defects In Rubber Calendering (And How You Can Fix It)

Rubber Calendering, the mechanical process by which rubber is pressed into textiles (cloth, fabric, tire cord) forming composite sheets, is amongst the oldest rubber processing technology.

Today, you have a wide range of new and used calender purchase options (albeit of varying nature of quality, features and durability) for your budget. And this post is not on price or quality.

Rather I draw your attention on a more significant aspect of rubber calendering – operating this rubber machinery itself.

You could have chosen your rubber calender wisely but if you do not operate it smartly, you are likely to have defects in the calendered sheet. And when you know the causes leading to the defect, it becomes easy for you to investigate them deeper,  resolve and continue production.

So, here is a detailed info-sheet of 8 common defects in rubber calendering (and how you can fix it)

8-Common-Calendering-Defects

Summarizing, while choosing the right rubber calender is important, learning to operate it smartly to avoid these 8 common calendering defects is equally key for your success with this machine.

Let me know your views.


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The Biggest Problem with Heat Transfer Efficiency in Rubber Machinery (And How You Can Fix It)

Rubber processing has a bizarre energy pattern, when seen from a layman’s perspective. Because you add heat into your process and then you cool down!

Heat addition and removal is repeated in each of your subsequent stages as well.

When you process rubber, energy is consumed across the value chain – right from transport of raw rubber, to the various processing operations (be it rubber mixing, rubber extrusion, rubber calendering, moulding etc) to convert into your suitable product and then transportation of your product.

Energy Uses in Rubber Processing

Source: Tangram

This implies that you need to cool down your rubber processing machinery regularly, which simultaneously involves heat exchange from a hot medium to a cooler medium.

And the most common medium to cool is water.

But where there’s water, you will face water-related problems caused by its mineral deposits. These deposits could give you varying degrees of water-related problems that affect your operating efficiencies and/or even leading to more costly equipment downtime issues.

This could be in your Rubber Machinery like Mixer, Mixing Mill Rolls, Calender Rolls, Press, Extruder, Heat Exchangers, Moulds, and factory equipment like Boilers, Chillers, Compressors, and TCU‘s or other Ancillary Units, etc.

You would notice that the mineral deposits accumulate quickly regardless of screens or treatment actions adopted. Even a thin coating of water scale will act to insulate the water system’s surface and retard the transfer of heat.

Hence, scaling is the biggest problem affecting the heat transfer efficiency in rubber machinery.

To increase heat transfer efficiency, lower maintenance cost, conserve overall energy consumption and thus enhance the usable life of your machinery, removing scales in all your water-cooled or water-heated rubber and tyre equipment is very important.

In a simple rubber machinery like the mixing mill, the presence of scales on rolls leads to localized hot spots affecting your mixing quality. In the case of boilers, scales can be very damaging leading to even boiler rupture. When water scale, lime and rust deposits accumulate on the water side of chambers, rotors and the drop door of the Mixer, it causes temperature of your rubber stock to rise and gradually lead to a loss in production.

Different machinery has different safe and effective method to remove scales. Recently, I was shown an instruction sheet, from one of the descalers (RYDLYME), on the process to descale a rubber mixer that I found interesting.

Here’s the process reproduced. I hope you too find it informative.

How To Clean Your Rubber Mixer

Image From RYDLYME

  1. Take mixer out of service.
  2. Close water supply valve at header as shown in the sketch above.
  3. Drain all water from all sections of mixer.
  4. Connect Descaling Solution pump discharge hose to water header. Header usually supplies all circuits.
  5. Connect return hoses to drain lines from all circuits and place into the Descaling Solution receiver.
  6. Close water supply valves to gate and jacket circuits.
  7. Start pump and pump the descaling solution into rotors to purge the water from this circuit to sewer. When the descaling solution begins to discharge from this hose, return to the receiver.
  8. Open water supply valve to gate and maintain Descaling Solution circulation through this circuit.
  9. Open water supply valve to jacket and maintain Descaling Solution circulation through this circuit.
  10. If any circuit is NOT flowing properly, restrict Descaling Solution flow in other circuits until flow returns to normal in this circuit.
  11. Circulate a total of 120 Litres of Descaling Solution through all circuits of mixer until clean. This will require approximately four (4) hours pumping time.
  12. It is suggested to periodically rotate the rotors during Descaling Solution cleaning to assure that the Descaling Solution is in contact with all of the lobes of the rotor.
  13. Upon completion of cleaning, flush all Descaling Solution from all circuits with fresh water.
  14. Disconnect the Descaling Solution pump and all hoses. The mixer is now ready to be returned to service.
  15. Periodic descaling will keep the temperatures of the mixer within acceptable limits, assuring you a better product and minimize burnt or improperly mixed stock.
  16. Clean out the Descaling Solution System and store for future use.

Summarizing, scaling is the biggest problem with heat transfer efficiency in your rubber machinery. Descaling or cleaning the scales helps you fix this issue. Hence incorporating descaling solutions into your preventive maintenance program is recommended to keep your equipment running effectively and economically.

Do you agree?


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Rubber Calenders At A Glance

From our earlier post,  you would already know that a Rubber Calender is heavy-duty rubber machinery consisting of two or more rolls that revolve in opposite directions. And that the Classification of Rubber Calenders is based on

  1. The Number of rolls
  2. The Position or Orientation of the rolls

Precisely, the reason why you will see various rubber calender manufacturers offering you,

  • 2-Roll Horizontal Type Calender
  • 2-Roll Vertical Type Calender
  • 2-Roll Inclined or Tilted Type Calender
  • 3-Roll Vertical Type Calender
  • 3-Roll Offset Stack Calender
  • 4-Roll Vertical Type Calender
  • 4-Roll Offset Stack Calender (Inverted ‘L’ Type)
  • 4-Roll Offset Stack Calender (‘S’ Type)
  • 4-Roll Offset Stack Calender (‘Z’ Type)

Your selection of the type of rubber calender depends on the calendering process you require.

Here is a info-sheet to help you grasp the different rubber calenders quickly.

Know Your Different Rubber Calenders At A Glance

Rubber-Calenders-At-A-Glance

Know Your Different Rubber Calenders At A Glance

Download this Info-Sheet in PDF

Let me know if you found this info-sheet informative.


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What I Wish I Knew a Year Ago About The Different Types Of Rubber Calendering

Our readers who read 5 Answers to the Most Frequently Asked Questions about Rubber Calendering, would recall my apprehensions, I had on the topic.

However, to my surprise, I admit that my industry friend was right when he said that for many rubber good manufacturers, a Rubber Calender continues to be amongst the “mysterious” rubber machinery.

And I am glad that I was wrong. Because, if not, I would have not written the post that many readers found useful. Thank you Henry!

Rubber Calendering is classified based on what you are calendering

  1. Fabric calendering and
  2. Steel cord calendering.

Well, that’s the basics. Let’s explore a bit further.

What I Wish I Knew a Year Ago About The Different Types Of Rubber Calendering

Fabric Calendering:

The materials that go into your fabric calendering are your softened rubber compound (from mills) and Nylon or Polyester from the Dip Unit.

Rubber Calender Collage 1

A collage of images from different source in the web.

In this process, the tension, temperature and humidity are critical parameters of your fabric cords before they are calendared with the rubber compound. And hence is the reason you will observe that the fabric cord is kept in a room (where temperature and humidity are controlled well) once this raw material arrives in your shop floor.

This textile is arranged in a flat and parallel manner. Under proper tension they are continually pressed through two rolls. Simultaneously, you add the rubber compound to the opening area or nip between the rolls. As a result, a thin layer of rubber is applied into top of and the bottom layers of the fabric.

Then you make this continuous sheet of fabric and rubber go through many additional rolls to ensure that rubber is penetrated properly between the cords achieving the desired adhesion between rubber and the fabric.

The sheets are cut at required angles so that the cords are set at predetermined angles across the sheet.

Even inner liners for tyre manufacturing are calendered the same way into sheets of required thickness and then cut into appropriate widths for use in tire construction.

Finally, your calendered fabric sheets are wound into rolls with layers of woven fabric liner to prevent the surfaces of sheets from sticking together.

Steel Cord Calendering:

In the tire industry, steel cord calendering is for the radial tires.

Here, the body plies and reinforcing strips incorporate polyester cord that is coated in an adhesive liquid. This cord is passed between large, heated rolls of a rubber calender machine. Woven fabric is similarly prepared and calendered for the anti-chafing strips.

Since your rubber compound will not adhere to bare steel, the steel cord wires for the steel belts are coated with a very thin layer of brass. These high-tensile brass-coated rubber-encased steel cords (multi-strand cables) become the steel belts.

You may note that the steel cords come in various arrangements like cross-section of pairs, triplets and so on.

The brass-coated steel wires used in the manufacture of tire components are also extremely moisture sensitive. Hence, they must be protected in a temperature and humidity controlled environment – right from procurement, to during shipment and at the tire plant location. More importantly, any exposure to moisture can result in corrosion and a breakdown in rubber adhesion when calendered.

At your plant, these wires are stored in an environmentally controlled “Creel Room” until it is processed in your rubber calender. You pass a preset number of steel cords under proper tension from the creel room on rolls through aligning combs into the calender where the wires are coated with a thin sheet of skim stock rubber. For maximum adhesion, the rubber should also penetrate these steel cords. Maximum adhesion also means least rusting.

These steel cords are cut at specified angles and widths for use in tire building process.

Rubber Calender Collage 2

A collage of images from different sources in the web.

In ground reality, the distance between the creel room and your rubber calender (varying between 20 – 60 feet depending on your layout) is usually not environmentally controlled and, hence the wire may be exposed to moisture prior to its being encapsulated in rubber.

This problem is worsened by slowdowns, temporary shutdowns, humidity spikes and failure to adequately control temperature and humidity within the creel room. Once the belt wire becomes contaminated with moisture, it becomes more difficult to obtain proper adhesion of the rubber to the brass-coated wire.

The strongest possible bond between the rubber and the belt wire is critical in the construction of your steel belted radial tires.

Next, how do you judge the quality of a calendered sheet?

Well, you could quantify the quality of your fabric calendered sheet in terms of your pre-desired

  • Thickness of the sheet
  • Spacing between cords
  • Number of cords and
  • Penetration of rubber into the space in between cords.

Summarizing, Rubber Calendering is classified into Fabric Cord Calendering and Steel Cord Calendering based on what you are calendering. Each of these is different yet similar in operations and sensitive to environment influence for your high quality product.

Let me know your views.


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