Rubber & Tyre Machinery World - Collectors Edition - Dec 2015

 

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In this concluding issue of 2015, we chose to reciprocate your appreciation and feedback in the most apt manner. So, we compiled the 3 most-read topics on our portal into a single ‘collector’s edition’ for your quick reference always.

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Rubber & Tyre Knowledge On-The-Go Special Supplement Machinery http://rubbermachineryworld.com World 14 Single-Stage or Two-Stage Mixing? COLLECTOR’S EDITION: 3 Most-Read Topics of 2015 4 Internal Mixer Batch Weight Calculation 20 Tandem Mixing Technology o Als ide s In Pg. 24 | Recruit For These Top 15 Skills In Your Mixer (or Kneader) Operator

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| Editor’s Note | Happy New Year 2016 As 2015 draws to a close, reflecting on your progress is a sure way to move ahead. Because, though you cannot change your past, by learning from the ‘misses’ and building confidence from your ‘hits’, you can ‘plan’ for greater success in 2016. 2015 has been an exciting year for RUBBER MACHINERY WORLD. A passion that started out on Valentine’s Day is now a well regarded Knowledge Portal on Rubber & Tyre Machinery touching 40k hits with a fast growing base of readers across 5 continents. My sincere thanks to you for your encouragement and feedback on our efforts to broaden the reach of information through various themes including ‘Know A Leader - In 10 Questions’ and forging unique partnerships in expos and shows. This in turn helps us reach out to a larger brotherhood of equipment buyers in Rubber & Tyre Industry and help them make informed-purchase decisions. In this issue, we reciprocate your love, appreciation and time. We compiled the 3 most-read topics on our portal into a single ‘collector’s edition’ that I hope will find space in your digital library - either as favorite bookmarks or valuable PDF downloads. As always, I welcome your feedback on rubbermachineryworld@gmail.com. Happy Holidays, Merry Christmas and A Prosperous New Year. May all your dreams turn into reality and all your efforts into great achievements in 2016. Best Regards Prasanth Warrier In this issue, we reciprocate your love, affection and time by creating a single ‘collector’s edition’ of the top sought topics in ‘15. 3 rubbermachineri rubbermachineryworld +Rubbermachineryworld1 grp/home?gid=8252803 rubbermachineri Cover Page Wooden Sign Image Source: Gallery Yopriceville Rubber & Tyre Machinery World | DEC 2015

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| BEST OF 2015 | 7 Quick Tips About Batch Weight Calculation For An Internal Mixer Internal mixer is standard rubber machinery for volume mixing in both tire industry and non-tire rubber industry. When you use one, your most elementary requirement is to calculate the batch weight for your respective mixer model. Because when mixing rubber compounds, you should under-stand that different compounds based on the same polymer might require different batch weights. And different polymers will almost certainly require different batch weights. Here's 7 quick tips for you to fix the batch weight for your rubber mixing. Image: Internal Mixer With Hydraulic Ram (Bainite) Rubber & Tyre Machinery World | DEC 2015 4

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| BEST OF 2015 | 1) Theoretical Equation The thumb rule is the theoretical equation W= NV x SG x FF, where W - Batch Wt [kg]; NV - Net Mixer Volume [dm³]; SG - Specific Gravity (density) of the mixed batch [kg/dm³]; and FF= Fill Factor. For example, NR-rich compounds in an intermeshing mixer has a fill factor of around 0.65 while for the same compound in a two-wing tangential mixer, it is about 0.75. 6 rebuilt or reconditioned (Read our posts on Generally, most mixer manufacturers share mixer rebuilding – Top 25 Things You Should Know to Discuss with Mixer Rebuilder and 17 this calculation with you. But remember, Essential Questions to Select the Right what they give you is only a theoretical number. This is only a starting or reference Rebuilder for your Internal Mixer) point and you need to arrive at your own 3) Guesstimate the Fill Factor (FF) mixing batch weight for your compound If you have a Tangential Mixer (aka Banbury) recipes, following some of the other tips then your FF can range between 0.70 - 0.85. stated below. And for a Intermeshing Mixer (aka Intermix), your FF can range between 0.62 and 0.70. 2) Net Mixer Volume (NV) Since Internal mixer has a fixed volume Knowledge of the fill factor is necessary mixing chamber, knowledge of the net because an under-filled mixing chamber volume (in liters) is required. This can be results in the ram bottoming out too soon. obtained from the manufacturer directly This reduces the pressure on the rubber stock or in some cases from their literature for and increases the mixing time. An over-filled their various models. chamber leads to unmixed ingredients When the mixer is used regularly (or if you staying in the mixer throat. This creates a mess under the mixer when the batch is have procured a used-mixer) the effective volume increases due to wear on the rotors dumped. and mixing chamber. If not compensated For example, NR-rich compounds in an for this inside wear, your batch volume intermeshing mixer has a fill factor of around will be effectively too small leading to 0.65 while for the same compound in a insufficient ram on the compound, poor two-wing tangential mixer, it is about 0.75. dispersion and longer mixing times. This compound will have an increased FF of Annual measurements of chamber are about 0.78 for a tangential mixer with recommended to update your batch our-wing rotors. Each polymer also has its weight correctly. ideal fill factor and that varies again with Excessively worn out mixers will have to be Mooney viscosity and filler system. Rubber & Tyre Machinery World | DEC 2015

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| BEST OF 2015 | Fill factor of a mixer depends on the age of the machine, wear and tear of the rotors and chamber, the rotor type, rotor speed, rotor friction ratio, nature of elastomer, ratio of elastomers/ fillers, mixing sequence, kind of polymers, fillers and individual SG of the ingredients in your recipe, viscosity of ingredients, etc. Generally, the lower the compound viscosity, the fill factor is higher. Hence, we initially guesstimate the FF before stabilizing on the figure later on through actual trials. 4) Estimate the Specific Gravity (SG) of your Compound You can estimate the density of your compound by multiplying the quantity of each ingredient with its individual density (you can get this figure in any Image: Kobelco Make Internal Mixers compounding handbook or ingredient supplier literature). Sum up your individual results and then divide this number by the total sum (usually phr). The result will give you the estimated density of the compound. (Mathematically, this is the weighted average calculation). For example, lets consider a sample recipe as shown below (I got this recipe from a web search). Calculating, the SG of this Compound mix is arrived at 1.16 (=179.3/155). 8 Mathematically, this is the weighted average calculation. Rubber & Tyre Machinery World | DEC 2015

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| BEST OF 2015 | 5) Know your Internal Mixer Knowing your internal mixer – its capabilities, design features like rotor (tangential or intermeshing), ram (pneumatic with dedicated air supply at the plant or hydraulic), variable speed capabilities of the motor, SCADA, PLC, automation and control features, etc. Rotor speeds are critical because you can use higher speeds at the initial mix and then reduce the rotor speed to allow the batch to “knead” well. This will allow you to get both your dispersion and distribution tasks of mixing right. Hence, when selecting a mixer explore variable speed drives since it give you advantage in your mixing process. The key to successful mixing is optimizing your mix batch size, and not maximizing. And good mixing is a form of art. can be assured that the chamber is properly filled and mixed compounds will be of high quality. You need to observe the position of the ram by watching the tell-tail rod attached to the top of the ram. Hence, this requires more of practice and experience than theoretical knowledge. If you have a good mixing system with controls and feedback features, you can correlate the position of the ram with the current and rise in temperature – these are important to get an optimized batch size and high quality of mix. 7) Optimize Your Mix Batch Size (...Do Not Maximize) The key to successful mixing is optimizing your mix batch size, and not maximizing. And good mixing is a form of art. Most mixer users want to get the most out of their internal mixer (quite natural!) and they test its capabilities to the full. Finally, when they get poor mixing, they wonder if they have done the right investment! If you try to take your batch size to the upper limits of the mixer's “capacity” as specified in Rubber & Tyre Machinery World | DEC 2015 10 Similarly, think of ram pressure. If your ram pressure is too high you will cause excessive heat build up and poor flow of ingredients across the rotor tips. In intermeshing mixers, this will also cause internal pressure within the mixing chamber and might cause mixer failure. If ram pressure is too low, then you will not get the ingredients down into the rotors and this will result in poor mixing. 6) Watch the Ram Action After the above reference calculations are done and mixing initiated; watch the ram action during the mix. The ram should start high, move up and down about an inch or two and bottom out when mixing is complete. Good mixing practice dictates that when the ram bottoms out about 30-45 seconds before the batch is dumped, you

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| BEST OF 2015 | the manufacturer's manual (that is usually a peak magical figure) and you have raw material variations such as particle size or bulk density changes in your fillers, this can lead to poor mixing (dispersion and distribution of ingredients). The right batch size will be smaller, but your internal mixer throughput is increased by shorter mixing time and thus more batches in the same period. Thus, optimizing your batch weight will allow you to get consistent batch quality and repeatability that are of paramount importance to your (or your customers') downstream processes. The key factors that will influence your mixing optimization are compound formulation, ram pressure, mix procedure, mixing speed and rotor design. The key factors that will influence your mixing optimization are compound formulation, ram pressure, mix procedure, mixing speed and rotor design. Each mixer is different and it would be very difficult to determine the optimized fill factor without actually conducting several mixing trials. Experience is a key to good mixing. Summarizing, when mixing rubber compounds, different compounds require different batch weights. These 7 tips will help you calculate the optimized batch weight for your compounding recipes on an internal mixer quicker. RMW 12 Attn: Buyers of New, Used Or Rebuild Rubber Mixers. Here’s a singular directory that lists out 99 companies over 6 continents and saves you over 100 hours of painful search on your computer. Because when you are buying a rubber mixer, you want to evaluate your suppliers wisely. Here’s what you get in this directory. Rubber Machinery World MM E RUBB R Rubber y er Machin World R RUBBE ER MIX rs upplie Global S 2015 ublicat A Rubbe nery r Machi eP World ion Direc  toryof - You will be introduced to the types of rubber mixers with pictures. - List of additional resources for your finer understanding of rubber mixers. - Email, Telephone, Fax and Postal Address so you get multiple choices to contact them faster. - Verified website addresses to help you do the online research of specific companies that you shortlist. - New Mixer, Rebuilding Services, Used Mixer, and Sales Offices in Asia, Europe, North America, South America, Australia and Africa so that you can contact them quickly . Price: $15 + Taxes Extra at Actual To preview table of contents or purchase this directory, please email us on rubbermachineryworld@gmail.com. Rubber & Tyre Machinery World | DEC 2015

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| BEST OF 2015 | Image: Bosch Rexroth 14 Should You Do Single-Stage Mixing or Two-Stage Mixing? Have you encountered this often dilemma, “Should I do single-stage or two-stage mixing for my compound; which machinery to use?” – do not be surprised! You are not alone. Single-stage mixing is considered for productivity reasons (and costeffectiveness). While Two-stage mixing gives a better dispersion of the finer size blacks. And interestingly, for some compounds with high levels of blacks, even three or more mixing-passes may be necessary. Rubber mixing as a subject would have been quite simpler, if we could answer this Rubber & Tyre Machinery World | DEC 2015 topic effortlessly. Unfortunately, it is not! Single-stage mixing in an internal mixer is a cost-effective solution but difficult for all compounds. If the compounds have high filler loadings, you may be forced to mix in two-stages due to the high amount of shear and heat generated in the mixing cycle. If you use peroxide cures or are mixing expensive FKM, then you must be even more worried of the batch temperature. Most experts feel two-stage mixing, with short time spans for each of the mixing stages, is helpful.

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