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The Art of Owning & Operating Rubber Calenders

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Choosing the right Rubber Calender is important; learning to operate it smartly is equally key for your success with this machine. This edition covers all these aspects in a descriptive manner.

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The Art of Owning & Operating Rubber Calenders

  1. 1. Machinery World Rubber & Tyre Knowledge On-The-Go Special Supplement http://rubbermachineryworld.com / http://tyremachineryworld.com 7 Proven Strategies To Methodically Grow Your BusinessAlso Inside The Art of Owning and Operating Rubber CALENDERS
  2. 2. Contents KNOWLEDGE-ON-THE-GO Through A Gadget Of Your Choice RUBBERTYREMACHINERYWORLD INFORMATIONONEQUIPMENT,TECHNOLOGY,INNOVATIONSUPPLIERS ........... And MoreINFORMATION PORTAL | E-MAGAZINES | INTERVIEWS | KNOWLEDGE PARTNERS | DOWNLOADS 5 37 7 Proven Strategies To Methodically Grow Your Business INSIGHT July 2016 8 COVER STORY The Art of Owning and Operating Rubber Calenders A cover story that you will like for all the right reasons as it covers the different facets of rubber calenders. Machinery World Rubber Tyre Knowledge On-The-Go Special Supplement http://rubbermachineryworld.com / http://tyremachineryworld.com
  3. 3. Calendering is one of the oldest rubber processing technologies. This is a mechanical process by which rubber is pressed into textiles (cloth, fabric, tire cord) forming composite sheets. Rubber Calendering is classified into two based on what you are calendering. Your guiding principle for calender line operation should be consistency and continuity. The machinery that helps you do rubber calendering is known as a Rubber Calender and it performs various functions. This is a heavy-duty machinery consisting of two or more rolls that revolve in opposite directions. Today, you have a wide range of new and used calender purchase options. Choosing the right Rubber Calender is important; learning to operate it smartly is equally key for your success with this machine. This edition covers all these aspects in a descriptive manner. In addition, we have the ‘Insight’ section that is an infographic on ‘7 Proven Strategies To Methodically Grow Your Business’. I hope you enjoy this issue. As always, I welcome your feedback on rubbermachineryworld@gmail.com. Best Regards Prasanth Warrier | Editor’s Note | The Art of Owning Operating Rubber Calenders Choosing the right Rubber Calender is important; learning to operate it smartly is equally key for your success with this machine. 7 rubbermachineri rubbermachineryworld +Rubbermachineryworld1 grp/home?gid=8252803 rubbermachineri (Disclaimer: The pictures and statements in our special supplements are shared by the respective companies and/or sources mentioned. Rubber Tyre Machinery World does not verify/vouch for their genuineness, hence will not be liable for any misrepresented data) Rubber Tyre Machinery World | JUL 2016
  4. 4. 8 | CALENDERS | Rubber Tyre Machinery World | JUL 2016 The Art of Owning and Operating Rubber Calenders Prasanth Warrier Image: Rodolfo Comerio Calendering is one of the oldest rubber processing technologies. This is a mechanical process by which rubber is pressed into textiles (cloth, fabric, tire cord) forming composite sheets. The machinery that helps you do rubber calendering is known as a Rubber Calender. The word 'calender' itself is a derivation of the word kylindros – the Greek word that is also the source of the word 'cylinder'. Despite its development in 1836, calendering as a process became popular only after the 1930's (almost 200 years later)!
  5. 5. | CALENDERS | Rubber Tyre Machinery World | JUL 2016 Delayed rise to popularity In 1836 Edwin M. Chaffee, of the Roxbury India Rubber Company, patented a four- roll calender to make rubber sheet. He worked with Charles Goodyear with the intention to 'produce a sheet of rubber laminated to a fabric base'. Despite this development, calendering as a process became popular only after the 1930's because it was difficult to adjust the desired gap between rolls. Consequently, it was difficult to get an accurate rubber sheet thickness. Since the calender machines became easier to adjust, features have evolved. Modern calenders' can achieve tolerances around ±0.005mm and their lines are adaptive for most sophisticated precision requirements of your product. Purpose of Rubber Calendering In calendering process, you pass pre-selected fabric and rubber through a series of rolls to flatten, smoothen and sandwich the materials. Depending on your end-use, the calendered sheets could have multiple layers 'sandwiched' together. A Rubber Calender can help you get either 'supported' or 'unsupported' calendered sheets. - Unsupported' sheets contain only layers of rubber that has been joined together. - On the other hand, a 'supported' sheet has textile fabric or steel cord coated with a film of rubber (also known as 'skim stock rubber') on both sides and into the material. Supported rubber sheets give you higher strength or tear resistance. The adhesion of rubber to the fabric or steel cord is critical to final performance. And the rubber compound that you coat the fabric is different from the one used to make the tread or that which coats the cords. Coating of fabrics has been done for almost 200 years. Steel cord and fabric cord topping is a process in your tire manufacturing. Specifications and tolerances for calendered cords are tough. So you will find it difficult to fulfill the thickness variation across the calendered ply and the cord density. For example, you use calendared textiles for casing, cap plies and chafers in tyre industry. And you use calendered steel cord for belts. Calendering process is also well adopted in plastic industry (say, PVC sheeting). Image: JM Machinery 9
  6. 6. 10 | CALENDERS | Rubber Tyre Machinery World | JUL 2016 Types of Rubber Calendering Rubber Calendering is classified based on what you are calendering, (A) Fabric calendering and (B) Steel cord calendering. Each of these is different yet similar in operations and sensitive to environment influence for your high quality product. A. 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. 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 Image: Maxxis Canada
  7. 7. | CALENDERS | Rubber Tyre Machinery World | JUL 2016 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. B. 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 You pass 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. 12
  8. 8. | CALENDERS | Rubber Tyre Machinery World | JUL 2016 and widths for use in tire building process. 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 tyres. Judging Quality So, 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. Recently, an industry friend confided that many rubber good manufacturers look at a Rubber Calender as a 'mysterious rubber machinery'. Is it because of all this nuances, I wonder? Image: Cross-section of Radial Tyre 13
  9. 9. | CALENDERS | Rubber Tyre Machinery World | JUL 2016 Functions of Rubber Calendering 1. Skim Coating or Topping: Here, rubber is coated on both sides of the substrate (i.e your fabric or steel cords). This operation strengthens the adhesion between rubber and the substrate. Your process decides whether you use a 3-Roll Calender or a 4-Roll Calender. 2. Frictioning: Here, you use calendering process to force rubber into the fabric weave. Frictioning imparts good adhesiveness. You deploy 3-Roll Calender, where the top and bottom rolls have a lower speed than the middle roll. 4-Roll Calenders cannot be used for Frictioning, because obtaining a speed difference between fabric and compound is difficult. 3. Rolling: Here, you just allow hot rubber compound to pass through a 2-Roll Calender and get a continuous sheet of rubber of thickness 3-4 mm. 4. Embossing and Profile Calendering: If you produce tread sections of cycle tires or involved in hand building of foot wear, you may choose a Calender with “patterns” on the rolls to produce profiled treads or patterned sheets. A step forward of Rolling, here you press a heavy engraved roll against hot rubber compound. You would consider this if your sheet needs a 'design' look. The engraved design of the rolls is transferred to your rubber sheets. Calendering operations need critical checks to ensure you get high quality products. Image: Rodolfo Comerio 14
  10. 10. | CALENDERS | Types of Rubber Calenders A calendar is heavy-duty rubber machinery consisting of two or more rolls that revolve in opposite directions. The classification of Rubber Calenders is based on 1. The Number of rolls 2. The Position or Orientation of the rolls Various rubber calender manufacturers offer you different types. Today, you have a wide range of new and used calender 4-RollCalender » Also known as the “Modern Calender”. » Different Configurations. » Used for Skim Coating. ʻZʼTypeOffset StackCalender InvertedʻLʼTypeOffsetStackCalender ʻIʼTypeorVertical StackCalender 2-RollCalender VerticalTypeCalender InclinedorTiltedTypeCalender 3-RollCalender VerticalStackor ʻIʼTypeCalender OffsetStackTypeCalender » Also known as the “Universal Calender”. » Highly Flexible in usage. » Used for Frictioning and Skim Coating. » ‘I’ Type is the oldest most common configuration. purchase options (see box below) for your budget albeit of varying nature of quality, features and durability. Images from different sources only for representation purposes. “Pelmar is there to offer a total solution. Calendering lines sold as is or refurbished, along with mixing lines are amongst our largest sales chunk” Jacob Peled Executive Chairman Pelmar Engineering Ltd. “The wide range of quality new machinery made by Bharaj is well- accepted worldwide. We offer complete solutions.. I would say that our Calenders are high in demand.” Amardeep Singh Bharaj Director - Sales Projects Bharaj Machineries Pvt. Ltd. Box: Excerpts from ‘Know Your Supplier’ Editions Rubber Tyre Machinery World | JUL 2016 16
  11. 11. 1.DISPLAYYourProductsRegularlytoBuyers. 2.COMMUNICATEYourCompetenciesDifferently. 3.ATTRACTMoreBuyerstoYourBrandInformatively. Because we publish digitally on our portal and promote on social media differently, Buyers get all information of Your Products Solution anytime and anywhere - on any smart gadgets they use (Phone, Tab, Laptop or Desktop). For more details and your customized advertising, please email us at engage@rubbermachineryworld.com On-The-Go With Your Info ReachMachineryBuyersFast.Anytime.Anywhere. ADVERTISE On RUBBERTYREMACHINERYWORLD INFORMATIONONEQUIPMENT,TECHNOLOGY,INNOVATIONSUPPLIERS OptimizedRoIOfYourEquipmentMarketingForRubberTyreIndustry InfoPortal|DigitalMagazines|SocialMarketing Machinery World Rubber Tyre Know A LEADERIn 10 Questions Rubber Tyre Information On Equipment, Technology, Innovation Suppliers Machinery World Rubber Tyre Technology Innovation Special Edition Supplier Know Your rubbermachineryworld.com / tyremachineryworld.com Rubber Tyre Equipment - Accessories
  12. 12. | CALENDERS | Rubber Tyre Machinery World | JUL 2016 8 Common Defects in Rubber Calendering And Their Causes A more significant aspect of rubber calendering is 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 (refer adjacent box), it becomes easy for you to investigate them deeper, resolve and continue production. » Incorrect crowning of calender rolls » Excessive wearing of bearings » Improper operation of roll bending/zero clearance devices » Roll temperature too high » High feed bank on to the rolls » Compound Stock warmed up for longer duration » Insufficient break-down of your compound » Inadequate temperature control » Insufficient compound feed in the banks » Roll temperature too high » Large nip opening » Stock warm up for long time » High Compound in the nips » Insufficient nip opening between rolls » Excess compound in the nip » Improper roll crown » High compound viscosity » Improper Roll temperature » Improper running speed » Low compound viscosity » Improper warming of the compound » High viscosity compound » Improper warm up, high bank » Non uniformity of warm up » Lower roll temperature » Lower temperature in one of the rolls » High friction ratio » High calendering speed » Use of anisotropic fillers Choose Wisely. Operate Smartly Image of A 3-Roll Vertical Calender from Bharaj Machineries Pvt. Ltd. 18
  13. 13. | CALENDERS | Rubber Tyre Machinery World | JUL 2016 7 Do's (And Don'ts) In Calendering Choosing the right rubber calender is important, learning to operate it smartly is equally key for your success with this machine. (Refer adjacent box) » Use lab approved fabric and compound only. » Clean the mill and calender guides including the equipment surrounding area before starting unit. » Load single strip of compound to both the cracker mills. Then feed these compound to your holding mill. » Always keep minimum compound in calender nips and mills. » Apply correct bleeder yarn. » Put identification tags before storing your calendered fabric in racks. » Close cooling water lines to mills when mills are not running » Do not over load your two-roll mills and calender nips. » Do not use held up compounds and dipped fabric. » Do not stop unit with fabric in the line. » Do not throw sheeted-out compound on the floor. » Do not store calendered fabric on floor. » Do not use damaged liner / baggy liner. » Do not run mills with cooling water lines closed. Image: Reconditioned Calender (JM Machinery) Solving issues with Calender Gauge Control Calender control issues directly affect your ability to properly control the rubber gauge or to produce a rubber sheet of consistent thickness. 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, A. Mechanical Induced – variations when your calender is not operating under any load and are at ambient conditions. B. Force Induced – variations when your calender is in operation or is programmed to follow a set-process for your product under manufacturing. A. Mechanical 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 affect your rubber sheet's calendered gauge 1. Grind Profile of Calender Roll (Roll Crowning) You must periodically grind the calender rolls to establish the proper profile. Your selected crown profiles is based on the range of your rubber compound hardness, type of center compensation such as cross-axis or rolls bending, and roll width. 19
  14. 14. | CALENDERS | Rubber Tyre Machinery World | JUL 2016 a) No Crown - No Load b) No Crown - Uniform Load c) Uniform Load - Correct Crown d) Uniform Load - Correct Crown by bending roll to frame e) Uniform Load - Correct Crown by bending reaction roll pair f) Roll Crossing 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. Source: GEA 20
  15. 15. “Complete your Plant with your desired technology to your complete satisfaction on-time through us.” Your Partner in for Rubber Processing MachineryMALAYSIA For your green-field and brown-field expansion or research projects in raw rubber and other technical rubber goods, we can source for you the right machinery to meet your technology requirements, and be your single-window support for after-sales service communication and training in Malaysia. For crucial projects, we train our personnel on the machinery we supply, to give you quick support. In addition, we are established and licenced contractors in Mechanical,Telecommunications, Electrical and Civil Works. Hence, we offer you on turnkey basis - from equipment supply, material handling at site, equipment relocation, erection and installation, services and utilities to equipment commissioning. to know more on ourContact me today team, the equipment brands we partner with, our esteemed clients and full range of services for your rubber related projects. IKATAN TEKUN SDN. BHD. Ahmad Fezal Bin Zakaria Sales Project Manager IKATAN TEKUN SDN. BHD. 1st, Floor, Bangunan Sapura,Lot 2, Jalan Enggang, Kawasan Perindustrian PKNS, Hulu Kelang, 54200, Kuala Lumpur, Malaysia. Tel: (+6) 03 - 425.6 5.589 | Fax: (+6) 03 - 425.7 5.589 * fezal@ikatantekun.com ) (+6) 017-362.79.71 AUTUSCONSULTING@2016
  16. 16. | CALENDERS | Rubber Tyre Machinery World | JUL 2016 3. Condition of Calender Roll's Bearings You must ensure that your Rubber Calender roll bearings does not have excessive run- out. Modern calenders employ precision anti -friction bearings with very small radial clearances. 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 result 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 check this condition by comparing the roll run-out or eccentricity 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. Image: Three-Roll Calender (Left) and Spare Calender Rolls With Bearings (Right) 23
  17. 17. | CALENDERS | Rubber Tyre Machinery World | JUL 2016 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. Thus, proper maintenance of all the above systems is crucial to your rubber calender performance and solves issues with gauge control that are mechanically induced. B. 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 Kg (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. Proper maintenance of all the above systems is crucial to your rubber calender performance and solves issues with gauge control that are mechanically induced. Image: From Web 24
  18. 18. | CALENDERS | Rubber Tyre Machinery World | JUL 2016 Here are five tips on how you could solve issues of calender gauge control from force induced variations. 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. Image: India’s first fully Automatic Tyre Cord Calender Line from Bharaj Machineries 26
  19. 19. | CALENDERS | Rubber Tyre Machinery World | JUL 2016 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. Image Source: Web 27
  20. 20. | CALENDERS | Rubber Tyre Machinery World | JUL 2016 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. Image Source: Pelmar Engineering Ltd. 28
  21. 21. | CALENDERS | Rubber Tyre Machinery World | JUL 2016 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. 3. Limit the temperature rate of change at all times to a maximum of 3 degrees per minute. Because faster rates can damage or warp the rolls. The control system on the TCU should be designed and operated to limit the rate of temperature change for each calender roll water circuit to 3 degrees per minute. Faster rates of change do not allow for equalization of mechanical expansion throughout the rolls, bearings, and calender frames. Differential expansion can stress various components of your calender. In extreme cases, they can actually crack or warp the rolls, or even damage the bearings. Heating usually is limited by the available heating capacity but the cooling system frequently has the capacity to rapidly cool the rolls and therefore also has the potential to cause damage if not limited to 3 degrees per minute. Again, it is important to keep the calender running during warm-up and during cool down. Stopping the calender and turning off the TCU circulation pumps before the calender reaches ambient is not considered good practice. If the temperature control system has rate of change limits properly set, cooling down is easy, since all the operator must do is to lower the temperature set points to ambient and then 60 to 90 minutes later return back to the operator console to turn off the TCU. 4. Minimize speed changes. Because changes in your calender speed result in gum wall gauge thickness variations that are undesirable. When the calender is running there are forces generated that try to separate the rolls, as explained earlier. And these separating forces are proportional to calender speed (although the relationship is not linear). The hardness of your rubber stock and bank temperature determines the magnitude of separating forces. The thickness of the gum wall being calendered also affects the separating force – thinner gum walls generate higher separating forces. Separating forces of 160,000 to 300,000 lbs at each actuator literally stretches the calender frame. When the forces vary, the amount of stretch varies. This further results in the roll-gap varying that in turn causes the gum wall gauge to vary. Hence, speed changes should be avoided 30
  22. 22. AMCL MACHINERY LIMITED SERVICE TO THE NATION FOR FOUR DECADES For all your enquiries please contact: AMCL MACHINERY LIMITED Works: Plot No.A1/1, MIDC, Butirobi-441122, Nagpur Mumbai office: 202, Ackruti Centre Point, MIDC Central Road, Andheri (East), Mumbai-400 093. Contact person: Mr. S.H. Mehta Mobile No. +91-9004697430. Email: Website: www.amcl.inshmehta@amcl.in • Rubber Mixer – 76 liter and 270 liter. • Mixing Mills – 16, 22, 26 and special sizes • Hot feed extruders – 6 and 8 • Rubber Calenders – 2/3 rolls. • Bias Tyre Building machine – RB1/RB3 • Automatic LCV Tyre Building Machine – RB1619 • Automatic Truck Tyre Building Machine-RB2022 • Mechanical Tyre Curing Presses – Scooter to Truck size • Bladder Curing Presses • Tube Splicers Product Range
  23. 23. | CALENDERS | Rubber Tyre Machinery World | JUL 2016 to the extent practical. A speed reduction from 45 mpm (meters per minute) to 9 mpm can result in a gauge decrease of approx. 0.002 inches. Similarly, the vice-versa holds for a gauge increase with roll speed increase. Calenders are of different types. And different calendars have different degrees of frame stiffness so the quantum of the gauge change for a given speed change will vary accordingly. 5. Mill management Maintain consistency. You can substantially reduce gauge variations by feeding the calender consistently. A consistent, uniform, dwell times on the cracker and feed mills, as well as consistent bank size, will give consistent rubber stock temperatures and work history. The stock temperatures, bank sizes, and work history directly influence calender roll-separating forces. When you minimize variations in these 3 important process parameters, you will minimize variations in roll separating forces, and this in turn will minimize gauge variations of your calendered sheet. Further, good mill and bank control practices also give improved uniformity for other final calendered gum and/or fabric properties. When you feed to the calender, you must also ensure that the rubber bank does not have areas that could stagnate. Because if rubber remains in the bank on the calender for an excessive amount of time, it will partially cure and become much harder. Edge trim process that returns to the bank and stagnates is a common source of this problem. Image Source: Pelmar Engineering Ltd. 32
  24. 24. | CALENDERS | Rubber Tyre Machinery World | JUL 2016 Such cured and hardened compound will introduce gauge variations as well as negatively influence other properties of your calendered material. In extreme cases, burnt lumps will appear in the calendered gum. Presence of hard stock makes it difficult to properly penetrate the cord and may cause cord disturbance and improper cord distribution. In such cases the cushion force causes lateral movement in the nip and this further results in cord displacement that is visible. Paired cords are often the first indicator. You will observe that the calendered thickness will be heavy and there will be cord displacement or irregularities. However, the weight of test samples will not be significantly affected. Localized cord disturbance in cord distribution does not usually affect fabric weight, whereas redistribution of the cord does. Overall cord distribution problems can affect fabric weight in the case of fabric calenders. For example, incorrect cord distribution may reduce the average EPI (Ends Per Inch) in the center of the fabric and increase the EPI (Ends Per Inch) on the outer edges. This will affect fabric weight and thickness – the weight of the center would be light, while the outer edges would be heavy. In steel cord calendering, visible cord A) Uniform Cord Spacing - Uniform Top and Bottom Rubber Coat. B) Cords spread at the edge of the sheet. C) Cords paired. Top or Bottom Rubber Coat is heavy in the center. ImageSource:GEA 33
  25. 25. | CALENDERS | Rubber Tyre Machinery World | JUL 2016 displacement and cord pairing after the cushion nip is to be expected in the areas where the cord EPI count is excessive. Training Your guiding principle for calender line operation should be consistency and continuity. If all the inputs to your calendering process are constant, and your installed machinery is functioning correctly, you can produce quality goods meeting tight specification tolerances. Your operators need to acquire knowledge on how the rubber calender works, how changes in process variables affect outcomes, and how changes in machine and/or process conditions can beat those changes. Training them to run the calender under complete manual control Your guiding principle for calender line operation should be consistency and continuity. will make them know enough to understand the importance of maintaining as close to steady-state operation as possible. Further, this knowledge will also help them to operate the line without the gauge or the automatic set-up, if they ever need to do so. Summarizing, the nuances in the world of rubber calenders is an interesting subject and as you understand its operations deeper, the 'mysteriousness' of this rubber machinery disappears faster. Image: Bharaj Machineries Pvt. Ltd. RMW ........... And More NEW INFORMATION DIFFERENTLY Every Month With Machinery World Rubber Tyre Know A LEADERIn 10 Questions Rubber Tyre RUBBERTYREMACHINERYWORLD INFORMATIONONEQUIPMENT,TECHNOLOGY,INNOVATIONSUPPLIERS Information On Equipment, Technology, Innovation Suppliers Machinery World Rubber Tyre Technology Innovation Special Edition Supplier Know Your rubbermachineryworld.com / tyremachineryworld.com Rubber Tyre Equipment - Accessories 34
  26. 26. InfoPortal|DigitalMagazines|SocialMarketing 1.DISPLAYYourProductsRegularlytoBuyers. 2.COMMUNICATEYourCompetenciesDifferently. 3.ATTRACTMoreBuyerstoYourBrandInformatively. ADVERTISE On Because we publish digitally on our portal and promote globally, Buyers get all information of Your Products Solution anytime and anywhere - on any device (Phone, Tab or Computer). Or email us at engage@rubbermachineryworld.com And SELL MORE For more details and your customized advertising, please visit http://rubbermachineryworld.com A Story Every Has....Machinery Every Has...Technology And As Equipment Supplier, Denitely Have...YOU Let Equipment Buyers Know You, Your Products Your Technology Better. WhatIsYourStoryToday? Equipment Marketing Redefined ReachMachineryBuyersFastIn3Steps MM RUBBER Rubber Machinery World http://rubbermachineryworld.com http://tyremachineryworld.com MM TYRE Tyre Machinery World Machinery World Rubber Tyre Know A LEADERIn 10 Questions Rubber Tyre Information On Equipment, Technology, Innovation Suppliers Machinery World Rubber Tyre Technology Innovation Special Edition Supplier Know Your rubbermachineryworld.com / tyremachineryworld.com Rubber Tyre Equipment - Accessories
  27. 27. KELACHANDRA MACHINES (MFRS. OF RUBBER INDUSTRIAL MACHINERY) Chingavanam - 686 531, Kottayam, Kerala. India. Phone Off: +91- 481-2430325. Fax: +91- 481-2430596 e-mail: km1912@gmail.com
  28. 28. | INSIGHT | 7 PROVEN STRATEGIES TO METHODICALLY GROW YOUR BUSINESS Rubber Tyre Machinery World | JUL 2016 This section is bought to you in association with our brand display partners 37
  29. 29. 38
  30. 30. 39 Source: Web
  31. 31. Rubber And Tyre Machinery Now Has An Online Address MM RUBBER Rubber Machinery World http://rubbermachineryworld.com http://tyremachineryworld.com MM TYRE Tyre Machinery World http://rubbermachineryworld.com http://tyremachineryworld.com FREE Access On All Your Devices - Power Your Business Forward With Authentic Information On - Equipment Allied Machinery - Technology - Equipment Suppliers - Read, Absorb Implement Ideas From - Insightful Interviews Of Leaders - Informative Articles - Special e-Editions e-Books - Short Updates Curated from the World Of Machinery Every Thursday In Your Inbox - Resourceful Downloads For Day-to-Day Use - Plan For Your Conferences Expo from event dates - Book Store with Best Rubber Books For Your Quick Buy - Key Documents/Directories to take Powerful Business Decisions Available For Purchase. - Left-Oriented Clean Layout for your easy reading. - Follow Us on Twitter, Google+, LinkedIn Pinterest. Attention: Equipment Buyers Users JOIN OUR READERS FROM 130+COUNTRIES SUBSCRIBE TODAY FOR FREE BENEFIT
  32. 32. Excellent Capability for Customized Heavy Rollers. Please contact4th Axes Precision CNC Machining ROLLERS, SCREWS, FIXTURES MOULDS FOR ALL YOUR RUBBER AND PROCESSING MACHINERY. GET CUSTOM MACHINED SubAero Precision Machining (An ISO 9001:2008 Certified Company) Corp Office: 8/Trivedi Niwas, New Nagardas Road, Andheri (East), Mumbai - 400 069, India. Ph: +91-22-28256599, +91-22-28378478 (Fax) www.subaero.com | Email: info@subaero.com ■ IN-HOUSE CAD CAM STUDIO ■ 3 AND 4 AXIS MACHINING CAPABILITIES ACCURATE AND RELIABLE INSPECTION■ REPORTS THROUGH IN-HOUSE CNC CMM ■ SKILLED AND TRAINED MANPOWER TIMELY DELIVERY■ 24x7 POWER BACK-UP■ AT OUR STATE-OF-THE-ART CNC MACHINING CENTERS, WE GUARANTEE YOU HURCO DCX 32 Vertical Machining Centre UNFAILING PARTNER AND DEPENDABLE SUPPORT FOR YOUR DESIGN TO MANUFACTURING NEEDS AUTUSCONSULTING@2016
  33. 33. Email: rubbermachineryworld@gmail.com ©2016 – ePublished by Rubber Machinery World in JULY 2016 Content For Free eDistribution Download INFORMATION ON EQUIPMENT, TECHNOLOGY, INNOVATION SUPPLIERS ........... And More Practical Solution www. .comracsol KELACHANDRA MACHINES Know More On EQUIPMENT SUPPLIERS And Their SOLUTIONS For YOU Stay Updated On Rubber Tyre Machinery And Their Suppliers. ........... And MoreINFORMATION PORTAL | E-MAGAZINES | INTERVIEWS | KNOWLEDGE PARTNERS | DOWNLOADS Rubber And Tyre Machinery Now Has An Online Address MM RUBBER Rubber Machinery World http://rubbermachineryworld.com http://tyremachineryworld.com MM TYRE Tyre Machinery World ........... And More

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