Mixing Mill - A Story of Woes To Wows!!

 

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Two-Roll Mixing Mills have been in existence since the time mixing of rubber started for various applications. It is still a sacred machinery for the rubber processors. This feature is a true reflection of what this popular rubber machinery has morphed

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Rubber & Tyre Knowledge On-The-Go Special Supplement Machinery http://rubbermachineryworld.com World File Picture From Wiki MIXING MILL A New Generation Mill A Story Of Woes To Wows!! Ins ide Updated Criterion Checklist To Select Your Two-Roll Mill

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| Editor’s Note | Most Popular Rubber Machinery Two-Roll Mixing Mills have been in existence since the time mixing of rubber started for various applications. It is still a sacred machinery for the rubber processors. Hence, we had to think thrice or even more before we decided to write a feature on this machinery. The theme ‘The Story of Woes To Wows!!’, I think, is a true reflection of what this popular rubber machinery has morphed into. Modern mixing mills are rich in features, safe and automated as compared to ancestors. (This edition’s cover page sums up this contrast well!). Our first attempt at a concise Knowledge On-The-Go special supplement was a success. Thanks to each of you - esteemed readers and supportive advertisers, for reposing faith in our abilities. It’s fascinating to us, when you take your valuable time to pen us your comments and shower generous words of appreciation. The immediate result is what you see here - our team is emboldened. We redesigned the cover of our special supplement to differentiate our look, articulate our approach better and more importantly, reinforce our commitment to you. At Rubber Machinery World, we understand your information requirements and hence our efforts to share authentic information on this portal to help you source your machinery wisely is serious, I reassure you. In this edition, we have also included from our portal, an updated checklist to help you select the right mill. As always, I welcome your feedback on rubbermachineryworld@gmail.com. BestRegards Prasanth Warrier Special Supplement - Rubber Machinery World | SEP 2015 We redesigned the cover of our special supplement to differentiate our look, articulate our approach better and reinforce our commitment to you. 3 rubbermachineri rubbermachineryworld +Rubbermachineryworld1 grp/home?gid=8252803 rubbermachineri

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| MIXING MILL | 4 File Image: A Mill Working Inside A Factory (Source: Wiki). Special Supplement - Rubber Machinery World | SEP 2015

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| MIXING MILL | MIXING MILL A Story Of Woes To Wows!! Prasanth Warrier Mixing Mills have been in existence since the time mixing of rubber started for various applications. Interestingly, the world's first rubber factory was established near Paris in 1803. A Two-Roll Mill is the oldest and simplest type of rubber mixing machinery. You could use these machines for different processes such as mixing, sheeting, plasticizing and warming of the rubber. Some applications include using as Dump mills below an internal mixer for compounding and sheeting-out; Warm-up and feed mills for calendars and extruders; Re-mixing Plain compounding and Mixing. Despite its versatility, they were extremely painful to work with. Because a basic mixing mill operation is dirty and provides a poor working environment that is equally polluted. Lengthy mixing cycle 5 Special Supplement - Rubber Machinery World | SEP 2015

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| MIXING MILL | 6 File Image Of An Operator working on a Mixing Mill at Dunlop Factory leads to higher time consumed. As a supervisor, your productivity from this equipment is dependent on your operator skill. Cutting down hot rubber many times, rolling the sheets and feeding them back into the nip gap of the mill rolls is a physically demanding task for the operator. And from a quality perspective, you could have batch-to-batch variations creating undesired headache. Veteran compounders who have worked on mixing mill will closely relate their painful experiences to the above statements. Nothing could be farther than the truth as the file picture on this page clearly articulates the woes of a mixing mill operator inside a plant. Special Supplement - Rubber Machinery World | SEP 2015

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| MIXING MILL | Mixing & Compounding Operation: When mixing on a mill, you place the polymer between the rolls. It is processed until the polymer forms an even belt around one of the rolls with a certain amount of excess compound on the top crevice where the rolls meet. You then add fillers, plasticizers and other chemicals gradually to the “mixing zone” between the rolls. Some chemicals fall down into the tray below the mill rolls and your operator must then collect it and feed back into the mixing mill again. Finally, when you have incorporated all the non-curative ingredients, curing agents and accelerators are added. The total mixing time often is upto at least 30 minutes for a batch size of approx 100 kg. Opinion varies even today. While everyone agrees that good compounding requires good dispersion, some argue that good dispersion come only with internal mixers. While other users claim that for a particular recipe, there’s A Mixing Operation On A Mill no better equipment than mixing mill. Says, Amardeep Singh Bharaj, Director (Sales) of leading rubber machinery manufacturer, Bharaj Machineries Pvt Ltd, “A rubber mixing mill is no more just a mere machine with two rolls moving and rubber going in, coming out with flaws like running on high torque and consuming high units of electricity and majorly breakdowns due to Bushes and Gears.” It is in this context that we track the modernization or technology improvisations in mixing mills. Modernization And Technology Changes With evolving times, the manufacturers have devised ways to address the shortfalls of working with mixing mills. Says, Eldad Eilam, Co-CEO of Pelmar Engineering Limited, leading worldwide suppliers of rubber and tyre machinery, “The industrial mixing mill may have not significantly changed over time from design point of view. Yet, it has introduced many mechanical improvements and electrical upgrades to meet the on-going demand coming from customer for enhanced processing, safety and automation.” It is said familiarity breeds contempt. And, hence this could be a reason why we consider two-roll mills as a low technology product and automatically assume that anybody can manufacture them. Is this true? 8 Special Supplement - Rubber Machinery World | SEP 2015

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| MIXING MILL | Explains Amardeep Singh Bharaj, “Rubber Mixing mills today are very smart and energy-efficient machines providing highest levels of quality as required. The whole perception has changed. Rubber mixing mills, being the heart of rubber factory in terms of providing rubber to ancillary equipments like calendars/extruders /moulding presses, is taken very seriously in terms of Rubber Mixing mills today are very smart and energy-efficient machines providing highest levels of quality as required. The whole perception has changed. Amardeep Singh Bharaj Director (Sales) Bharaj Machineries Pvt. Ltd. 9 Image: A 60" Mixing Mill With Advanced Features, Controls, and Automation from Bharaj Machineries. Special Supplement - Rubber Machinery World | SEP 2015

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| MIXING MILL | of roll ratios for better mixing quality, Rolls temperature controlling systems for high level quality controlling of compounds, improved safety features like emergency brakes /auto reversing systems for operator safety, precise button operated nip gap adjustment systems for perfect sheet thickness, variable speed drives for hard to process compounds and fully automated mixing cycles through PLC and energy graphs to analyse the power consumption which makes the user smart and competitive to know where one stands.” Adds Philip Thomas, Managing Director of Kelachandra Machines, “Modern mills now have peripherally drilled rolls for better cooling and temperature control, bearings with minimal friction, compact operator friendly design which also saves space, simple base frame for easy installation, and hydraulic nip adjustment for safety of machine parts in the event of overload”. Kelachandra Machines manufactures rubber industrial machinery. There are instances today in the industry where two-roll mills are not meeting the expectations of the customers. The fault lies on either side – end users failed to draft the technical specifications properly and manufacturers failed to understand the expectations properly. After all a two-roll mill is only a two-roll mill, isn't it? How complicated can it be? The fact that each component going into the mill needs to maintain the physical and dimensional integrity is taken 10 Modern mills now have peripherally drilled rolls for better cooling and temperature control, bearings with minimal friction, compact operator friendly design which also saves space, simple base frame for easy installation, and hydraulic nip adjustment for safety of machine parts in the event of overload Philip Thomas Managing Director Kelachandra Machines Special Supplement - Rubber Machinery World | SEP 2015

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| MIXING MILL | for granted. Any mismatch can lead to recurring problems resulting in downtime and causing loss of production. Informs Eldad Eilam, “In terms of processing, new drive technologies, coupled with peripherally drilled rolls are used to enable processing of a broader range of elastomeric compounds by better control of the temperature and ability to make different compound characteristic by easily changing the friction.” Let's examine a few developments these leaders are speaking of. Drives The new mills that are manufactured today adopt compact direct drive where the gearbox output shaft is coupled directly to the roll. Bull gear-pinion that consumed more power, made noise and vibration has become obsolete. There are also uni-drives where two output shafts from the same gear-box drive the two rolls. The external connecting gears 12 Image: Different Configurations of Independent Drive are absent here making the mills appear more aesthetic and compact. Then, there are independently driven rolls where each roll is connected to an individual gearbox taking power from individual motors. The advantage is that variable friction ratio can be obtained for different recipes. A hydraulic drive is another upgrade that saves power though comes with higher initial capital investment. Special Supplement - Rubber Machinery World | SEP 2015

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| MIXING MILL | Stock Blender: In a discussion and exchange of thoughts on this subject recently on LinkedIn platform, veteran compounders have vouched on the “immense value” a stock blender provides to a mixing mill. Not surprising, as Eldad Eilam adds “Use of a stock blender reduces dependence on operator skills; provide better and consistent productivity to achieve the desired batch-tobatch uniformity”. A main disadvantage in mixing on a two-roll mill is that the process is dependent on your operator skill. A Stock blender enhances efficiency and productivity through reduced operator fatigue because this accessory eliminates the demanding task of cutting down hot rubber many times, rolling the sheets and feeding them back into the nip gap of the mill rolls. The operator also benefits from a safe work environment. The Stock Blender is an addon accessory mounted on top of an open two-roll mill. Image: CE Certified 6"x13" Lab Mill with Variable Friction Ratio, VSD, Digital Nip-Gap display and Temperature Controlling Mechanism (By Bharaj Machineries) Special Supplement - Rubber Machinery World | SEP 2015 Image: 84" Mixing Mill With Stock Blender from Kelachandra Machines. It aids in rubber blending by pulling the mix compound from the front roll of the mill and guiding it to the nip gap between the two mill rolls. A stock blender helps in homogeneous mixing and repeatability of the mixing operations. They are also used on pre-warming mills before feeding the rubber sheet to a Calender. Nip-gap Adjustment: A motorized / hydraulically actuated nip-gap adjustment 13

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| MIXING MILL | improves precision and facilitate faster nip setting for multiple recipes. This can further be automated to have 'preset nip gaps 'obtained at the press of a button on the operator panel. Nip Gap can be controlled / measured in electronic devices. Informs Sugundhan Nagendhran, Solutions Head of Base Automation Technologies Private Ltd, “We can monitor the nip gap with suitable sensor installed in the machine.” Stock Guides We can monitor the nip gap with sensor installed in the machine. Sugundhan Nagendhran Solutions Head Base Automation Technologies Pvt Ltd for the quality of many high-tech products manufactured by the rubber industry. Generally, these rolls are made of Chilled Cast Iron (CI) through a process of vertical casting. Chilled CI has greater resistance to deflection and uniform heat transfer characteristics. Depending on the presence or absence of alloy, the hardness of the outer working (chill) zone could be in the range of 460-650 HV with a thickness 12-20 mm. As these rolls operate at high speeds, precise concentricity with proper balancing of rolls is a prerequisite for efficient utilization of material and energy. The surface quality of the rolls is crucial for the products to be produced. The smoother and more precise the rolls, better the product. Viscous deformation of the rubber compounds occurs between the rolls of mills during mixing and mastication. This generates heat that needs to be removed through effective cooling. Hence, water circulation passages for cooling are an essential feature of the roll design in rubber mills. 14 The movement of stock guides can be made pneumatically or hydraulically actuated for faster movement and precision. The shape of the stock guides in such uses may be modified to make the rubber flow always to the centre of the rolls so that the compound does not seep sideways prolonging the mixing process further. Rolls Roll selection for a mixing mill is of decisive importance A Lab Mill From Pelmar Special Supplement - Rubber Machinery World | SEP 2015

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AMCL MACHINERY LIMITED SERVICE TO THE NATION FOR FOUR DECADES Product Range • 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 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: shmehta@amcl.in Website: www.amcl.in

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