Rubber & Tyre Machinery World

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Here’s How Siemens Technology Drives The Tyre Industry

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

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

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

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

TIA for the Tyre Industry

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

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

Siemens at TTE2016

Siemens Stall at TTE2016

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

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

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

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

Siemens S7 1500 PLC

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

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

What do you think?


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Anatomy of a Bale Ply Reel Winder

Have you heard of Bale Ply Reel Winder Machine?

Most likely a YES! if you are in the tyre industry.

For the benefit of other starters, this is an allied equipment. Used as a conveying and winding system in tire industry, a Bale Ply Reel Winder consists of two stations for winding up fabric lined rubber sheets.

The winding system receives fabric sandwiched Rubber Ply from your calendar and is wound in a reel at a wind-up speed of 16-32 rpm. The conveying speed is around 40 meters/minute.

Structurally, this machinery consists of four key components.

  1. Wind-Up Conveyor
  2. Ball Screw Assembly
  3. Frame Slide Assembly
  4. Reel Lift Assembly

Below is the equipment information image card on the Anatomy of a Bale Ply Reel Winder (for your quick preview) with inputs from L&T Rubber Processing Machinery.

Bale Reel Winder Image Card

For additional details, I urge you to also check out L&T’s newsletter which is fairly informative on operational aspects and technical specifications along with pictures of this machinery.

Do you want one for your Plant today? Or do you find a compatible use of Bale Ply Reel Winder (with customization) elsewhere for conveying and winding requirements in your operation.

Let us know your thoughts.


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Practical Solutions On Equipment Simplified – A Know Your Supplier Special

At Rubber Machinery World, we understand your information requirements. Our effort on this portal to share authentic information to help you source your machinery wisely remains incomplete without notes on equipment suppliers from whom you source your rubber and tire equipment.

Hence, ‘Know Your Supplierseries is one of our advertorial initiatives to bring to you information on the machinery supplier ecosystem – Manufacturers, OEM Suppliers, Machine Rebuilders, Used and Pre-Owned Equipment Buyers & Suppliers, and Agents.

In Know Your Supplier editions, we cover an equipment supplier’s Competency, Capacity, Commitment, Culture, Communication, Market Presence, Technology, Solutions, amongst other details that you seek; so you know these organizations better and reach them quicker.

In this post, I introduce you to an equipment supplier based in India but wired globally. Read on to know why.


Pracsol Chemicals & Machinery is into trading of Machinery, Raw Materials and Chemicals since 2007 and is growing in reputation in machinery business. We understand from our conversation with Harish Nene, Chief Executive, that in the last 4 years they have secured landmark orders for Used Machinery from Indian Rubber and Tyre industry.

Pracsol is now fast building on this rising confidence and customer trust to extend practical equipment solutions to the industry in new machinery as well.

Flip through this Special Edition using the link – http://is.gd/UHPT5U

In this conversation, Harish Nene outlines on a wide array of his business aspects right from the genesis of his company name to his experiences in rubber and tyre industry, partnership with JM Machinery USA, recent successes and new products on the anvil. Harish also informs us the unique service proposition Pracsol offers to their customers, their competence and comprehensive range of machinery offered to buyers.

I reproduce for you a few snapshots of our conversation here. (For full story, please do read and download here, this special edition of Know Your Supplier)

  • Pracsol is a strange name. What is the story behind this name?

Pracsol is derived from the words ‘Practical Solutions’. Through my experience of last 20 years in International Business, I would state that solution for a problem is possible if looked at it practically not by just following procedures.

Pracsol Logo

  • Having started in 2007 how has been your experience so far in this industry?

Business Ethics, Honesty, Transparency and Hard work is important. Customers who do business with me recognize that they can expect these from me and have helped me succeed in the rubber and tyre industry. I also have good support from my principal company. This makes things simple and gives me time to focus on delivering value to customers. From my last 7 years experience, I would opine that doing business with Private Companies is easier than doing business with Public Limited Companies.

  • Purchasing machinery is a major investment for most buyers and they would need technical inputs and customization. What level of pre-sales support do you offer?

We provide all the important technical details about the machinery with photographs. Through JM Machinery, we can aid in design and engineering from concept thru completion of the desired machine. If the customer insists on Physical Verification Report then physical verification is carried out by our principals’ engineers and a report is provided. The client has the liberty to visit for physical verification if the machines are available at our warehouse in USA.

  • Are you launching any new products?

We are targeting the rubber industry in Europe & USA to export our range of new machinery from India. We have recently bagged an order to design, manufacture and supply a NEW BATCH OFF for Europe. This is expected to be despatched by end of September 2015.

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For full conversation and other details of Pracsol, access this special edition of Know Your Supplier in PDF here.

Meanwhile, here is a quick overview of industries covered by Pracsol and Harish Nene’s contacts if you would like to reach him quickly.

Pracsol-Small-Ad


Know Your Supplier is an advertorial initiative of Rubber Machinery World and all information are as provided by the supplier. If you desire to know more, kindly reach out on the contact details provided or write to me stating the additional details you seek on this supplier.

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


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Tyre Machinery Industry: What to Expect?

At a recent event organized by a major automation brand, I had the opportunity to sit through a customer presentation (a leading tyre brand). A well articulated presentation, the speaker outlined the challenges that the tyre producers are facing in business today – increased competition on price, quality and delivery, pressure to reduce the tire development life cycle, enforcement of modular processes, perform with fewer employees and frequently changing product demands.

I bet that a tire producer three or five-year back would have presented these same set of challenges as the major concerns for their business. So what’s new and why are these concerns still valid?

It’s the fast pace of change!

Tug-of-War

Image from Web

Competition Galore

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

For example, car manufacturers are focusing on energy-saving technologies. Translated to tyre, machinery experts feel energy-saving tyres will be a major focus area on the tyre equipment sector over next few years. As a machinery manufacturer, you must ensure the tires produced using your machinery has the highest manufacturing accuracy to meet the customers’ specifications in their local markets and overall quality standards.

Tyre manufacturing is a complex process. A fault or improper procedure at any of these stages threatens the structural integrity of the tire. And, tyre manufacturers demand the highest productivity from every stage of their manufacturing process. This means as a machinery manufacturer, you must cater to their demands of machines that offer high production output, manufacturing accuracy, reliability and product quality with low processing and maintenance costs and lowest possible manpower.

Over the next few years in tire machinery sector, you will have just two segments – “Chinese” & “Non-Chinese”. This thought first occurred to me a few years back. But in the recent times, I have heard this statement echoing strongly from peers in the industry. There is a handful of technologically strong tyre machinery manufacturers in China and some others are fast growing. I would not get into the industry perceptions because then I could digress.

However, this means that every tyre machinery manufacturer is continuously challenged to evolve rapidly in technology offered and differentiate globally. Also, the machines that you manufacture should possess the flexibility to adapt to changing trends in tire dimensions and complex designs.

Tyre Building Machines (TBM’s) and Curing Presses will be under intense scrutiny by tyre manufacturers for various reasons.

Tyre Building Machines

In TBM, it would be more to do with design and automation. A TBM assembles all components such as tread, sidewall, inner liner, body ply, bead, and cord body together to build green tyres. Each cycle is programmed to carry out the various operations automatically and concurrently, to give a balanced building cycle.

VMI_TBM

Image: VMI Holland

Automation of TBM especially for quicker synchronization of machine sections, including let-off, feed cutter, splicer, and wind-up; achieve better tension and edge control, ergonomics and operator safety, higher accuracy of cut-to-length independent of machine speed, slip correction between belts and tire building material; and capability to make adjustments in tire dimensions with demands for advancements in fault diagnosis would be more rigorous.

Tyre producers are regularly involved in either green field or brown field projects to meet their growing market demands. They demand from you the lowest set-up time for TBM integration, mechanical and electrical optimization and wiring. Leading TBM manufacturers like VMI have advanced models for cycle times of 36 seconds, full hands-off/eyes-off production, with automatic splice checking systems, a robot for green tire removal, connection to a green tire transport system, apexed bead unstacking and loading.

Tyre Curing Press

Curing is the process of applying pressure to the green tire in a mould in order to give it its final shape.  This is traditionally the bottleneck of every tyre manufacturer. For curing presses, the emphasis would be on enhancing the process efficiency and reducing the energy consumption.

One visible trend among tyre manufacturers is to produce smaller lot sizes. This will require more moulds and more frequent mould changes. Quick mould-change devices will become a unique selling feature for machinery builders to compete on. Leading manufacturers like HF have models that achieve the mould-change-time in less than 30 minutes.

HF_curing press

Image: HF

Hydraulic curing presses are preferred (over its mechanical counterparts) because they have repeatable accuracy over their life time. Secondly, they offer higher output which keeps the tyre manufacturers process cost under control. To improve the process efficiency and reduce curing time, post cure inflators are desired.

Curing presses occupy a large real estate space within a plant. So when the curing press manufacturers offer equipment with high-efficiency, tire manufacturers save substantially – not only by reducing the investment in quantity of machinery required (CAPEX) but also in terms of space utilization. Jacob Peled, Executive Chairman of Pelmar Engineering, foresees that split curing (tread and carcass separately) will eventually dominate the industry.

Summarizing, it’s the rapid pace of change faced by tyre producers that is driving the tyre machinery manufacturers to invest more in R&D, evolve rapidly in technology and offer customized automated solutions for maximum output to their customers. For tyre manufacturers, the consequence of increasing the automation to eliminate human errors will be that stringent testing on 100 per cent of tyre production will be a binding procedure in future.


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A Dummies Guide to Rubber Extruders

Rubber extruders have a varied field of application. So, when you come across a rubber profile, strip, hose, cable, wire, cord coating, tire tread, v-belt, tube, or blank remember that they are only a few handful of products manufactured using extrusion process. 

And your main goal of extrusion is to get the highest output at good quality of product.

Based on the convenience and usage history, you need to know of the two types of rubber extruders viz. Hot Feed Extruders (HFE) and Cold Feed Extruders (CFE).

And further, you have variants within Cold Feed Extruders viz. Plain Type, Pin Barrel Type and Vent Type Extruders. The recent most advanced adoption that you will come across is that of co-extrusion lines.

When you choose a rubber extruder, you should deliberate and discuss extensively upon few key things i.e the design, material technology and manufacturing accuracy of screw, barrel and die-head. While, I would cover more on them in a later post, I would like you to remember that very few manufacturers world-wide can guarantee you a well-designed and precisely manufactured rubber extruder.

Hot Feed Extruder (HFE)

Rubber industry only had Hot Feed Extruders until 1950’s. HFE’s extrude your rubber compounds at reduced temperatures.

Hot Feed Extruder with Dual Head

Bainite Machines Make Hot Feed Extruder

The screw depth of a HFE is relatively larger and you get a consistent output due to its short screw design. L/D ratio is mostly in the range of 4:1 to 6:1 which keeps your rubber compound dwell time and its temperature increase to a minimum.

Each HFE has an hopper and feed roller section with spiral undercut liner that allows your compound to enter the extruder easily. The feed roller on a hot feed extruder allows your compound to pass the scraper knife, directed around the roll and then fed back into the hopper. The feed roll bearings are placed in positions to prevent contamination. You can vary the output by changing the screw speed using variable speed drives.

Despite these advantages, the HFE’s are getting outdated in many applications.  Because the rubber that is fed into a Hot Feed Extruder needs to be pre-heated or warmed using two-roll mills to achieve the required degree of viscosity and temperature that facilitates smooth flow of rubber, its compaction and extrusion through the die.

And that made experts introduce Cold Feed Extruders.

Cold Feed Extruder (CFE)

Cold Feed Extruders are designed and manufactured with specially designed screws best suited for cold feeding of rubber. You can discuss with your manufacturer and avail various options of screws for a wide range of compound and extrusion applications.

While manufacturers offer L/D ratio up to 24:1, the most preferred by end-users is generally in the range 12:1 to 18:1.

Pin Type CFE

Pin Type CFE Image from Web

For feeding the cold rubber, it is recommended that you use a feeding conveyor with metal detector to remove metal particles. This avoids damage to the screw or barrel. In some plants, I find the sensitivity of the metal detector calibrated to a low value that it virtually renders the detector useless.

Every CFE comes with a Temperature Controller Unit (TCU) that controls the barrel temperature so that the shape and size of the extruded products are uniform.

Variants in cold feed extruders along with their uses are

  1. Plain Barrel Type Cold Feed Extruder – These CFE’s as the name suggests have a plan barrel and used in manufacturing of hoses, blanks, fluorocarbon rubber, butyl rubber, etc.
  2. Pin Barrel Type Cold Feed Extruder – These CFE’s have around 80-100 pins protruding out of the barrel towards the screw center. These pins enhance the mixing and dispersion of your rubber as it is kneaded between the barrel and screw. And the result is processed rubber with outstanding homogeneity and extrudate quality. This flexibility in Pin Type Cold Feed Extruders endears to all making it a universal extruder for many rubber compound formulations involving varied applications. Hard rubber compounds also can be processed because of high extruder torque.
  3. Vent Type Cold Feed Extruder – Vent type or vacuum type extruders were developed for production of non-porous profiles and hoses. These CFE’s have a custom-built screw, and a degassing barrel with a vacuum pump attached to vent bubbles out of extruded compounds.
Triplex Extruder

Nakata Make Triplex Extruder

Co-extrusion: Customer-specific customization and usage complexity demands led to the introduction of co-extrusion for manufacturing of various profiles. And so you today have Simplex, Multiplex (Duplex, Triplex, Quadruplex, and Quintuplex) and Roller Head technology. Multiplex lines of piggy-back type of 2,3,4, and 5 layers have a compact construction.

Roller-Head-Extruder

Berstoff Make Roller Head Extruder

Roller Head Technology involves a combination of extruder with preform head and two-roll calender. They offer twin advantages of – high uniformity of the material thickness over the entire sheet width with absence of air traps even at higher thicknesses (~ 20mm thick as against conventional calender lines that give max 3mm thick sheets with or without air traps) and excellent homogeneity of the material produced.

Both these characteristics are important for high-quality rubber products such as tire components, V-belts, conveyor belts, tank linings, cover sheets, blank sheets and roofing sheets, etc. For even thickness across the entire sheet width of the roller head, there are three options that can be used alone or in combination with one another – roll crowning, roll crossing or roll bending, that will compensate for the elastic deflection of rolls. (I will cover more on these in an another post)

In today’s world you will see that usages of these technologies are overlapped. For example, in tire industry, you can notice that
Tread & Sidewall are extruded using Simplex, Duplex, Triplex, Quadruplex Lines
Apex are extruded using through Simple & Duplex
Inner Liner are extruded using Simple, Duplex & Roller Head Technology

Rubber extrusion is in itself a vast subject, however if you know the above terms and types of rubber extruders, you have made a good beginning.


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7 Quick Tips About Batch Weight Calculation For An Internal Mixer

Internal mixer is a 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 understand that different compounds based on the same polymer might require different batch weights. And different polymers will almost certainly require different batch weights.

Bainite Make Intermeshing Mixer

Image Courtesy: Bainite Machines Pvt Ltd

Here’s 7 quick tips for you to fix the batch weight for your rubber mixing. (Updated on 23rd Dec 2015: Flip through this post in our digital edition and download here)

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.

Generally, most mixer manufacturers share this calculation with you. But remember, what they give you is only a theoretical number. This is only a starting or reference point and you need to arrive at your own mixing batch weight for your compound recipes, following some of the other tips stated below.

2) Net Mixer Volume (NV)

Since Internal mixer has a fixed volume mixing chamber, knowledge of the net volume (in liters) is required. This can be obtained from the manufacturer directly or in some cases from their literature for their various models.

When the mixer is used regularly (or if you have procured a used-mixer) the effective volume increases due to wear on the rotors and mixing chamber. If not compensated for this inside wear, your batch volume will be effectively too small leading to insufficient ram pressure on the compound, poor dispersion and longer mixing times. Annual measurements of chamber are recommended to update your batch weight correctly.

Excessively worn out mixers will have to be rebuilt or reconditioned (Read our posts on mixer rebuilding – Top 25 Things You Should Know to Discuss with Mixer Rebuilder and 17 Essential Questions to Select the Right Rebuilder for your Internal Mixer)

3) Guesstimate the Fill Factor (FF)

If you have a Tangential Mixer (aka Banbury) , then your FF can range between 0.70 and 0.85. And for a Intermeshing Mixer (aka Intermix), your FF can range between 0.62 and 0.70.

Knowledge of the fill factor is necessary because an under-filled mixing chamber results in the ram bottoming out too soon. This reduces the pressure on the rubber stock and increases the mixing time. An over-filled chamber leads to unmixed ingredients staying in the mixer throat. This creates a mess under the mixer when the batch is dumped.

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. This compound will have an increased FF of about 0.78 for a tangential mixer with four-wing rotors. Each polymer also has its ideal fill factor and that varies again with Mooney viscosity and filler system.

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 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 (I got this recipe from a web search) as below:

Recipe Ingredients  Volume Density Volume x Density
      (L) kg/L kg (or PHR)
SMR 10 106.4 0.94 100.0
Zinc Oxide 1.8 5.55 10.0
Stearic Acid 2.2 0.92 2.0
N550 Carbon Black 27.8 1.8 50.0
Oil 10.9 0.92 10.0
Antioxidant TMQ 1.9 1.08 2.1
Antiozonant DPPD 1.6 1.22 2.0
Sulphur 0.1 2.07 0.2
TBBS 1.6 1.29 2.1
TMTD 0.7 1.35 0.9
Total 155   179.3
Compound SG  (179.3/155) 1.16

Calculating, the SG of this Compound mix is arrived at 1.16 (=179.3/155).

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.

(If you are planning a new purchase, read and download our Questionnaire for Internal Mixer Selection)

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. (Read more about Hydraulic Ram here)

Banbury Mixer

Image of HF Mixer

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 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 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.

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.


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9 Things About Tandem Technology Your Boss Wants To Know In Rubber Mixing

Dr Julius Peter, then Chief Technical Officer at Continental AG patented his idea of Tandem Mixing Technology in 1989. His colleague, G. Weckerle, manager at Continental Technical Rubber promoted this technology at his factory in Northeim, Germany on K2A, K4, K5 and K7 type of mixers.

Francis Shaw & Co had sole world rights for supply of the intermeshing type tandem mixers. Today, HF Mixing Group (Harburg-Freudenberger Maschinenbau GmbH) are owners of tandem mixing technology by virtue of their acquisitions in the rubber machinery world.

(Updated on 23rd Dec 2015: Flip through this post in our digital edition and download here)

Here are 9 key things about tandem technology in rubber mixing you should know to impress your boss.

  1. Tandem technology separates the two main tasks in your rubber mixing process viz. dispersion and distribution. Dispersion means breaking down of your solid materials such as the fillers. Distribution involves achieving homogeneity within your rubber mix compound with its different chemicals added. The temperature profile which is absolutely essential for inducing chemical reactions during your rubber mixing process can be better controlled when these two stages are separated.
  2. In Tandem technology you interconnect two “mixers” in series, a ram type mixer on top of aramless mixer. Each machinery is optimised to perform one rubber mixing task. Ram type mixer does dispersion well whileramless tandem mixer does the task of distribution.

    HF Tandem Mixer

    HF Tandem Mixer

  3. Your masterbatch produced in the primary ram mixer is transferred without intermediate storage to the ramless tandem mixer below. Here your batch is cooled and finals mixed. At the same time a new masterbatch is prepared in ram mixer above. The upper mixer with ram is preferably (but not necessarily) intermeshing type. As your masterbatch mixing does not involve the addition of curatives or accelerators and is essentially a heating operation, the mixing cycle may be carried out rapidly without any need to cool your mixer before the next mixing cycle.
  4. Between the two mixers is a discharge flap and chute which would be closed at all times except when the lower tandem mixer receives the masterbatch dump from above.
  5. The mixer below must be intermeshing type to enable self-feed without pressure and work without a top ram. The finals rubber mixing function is usually a shorter process than the masterbatch stage. This means that the tandem mixer has an idle time after the discharge and before receiving the next hot masterbatch. This idle period with the discharge door open allows the tandem mixer to cool.
  6. The final mix compound is then dumped into a two-roll mill or a dump extruder and processed in the normal way.
  7. When the two tasks of dispersion and distribution are separated, your compound weight is relatively smaller in the larger lower machine. Hence, you can operate this ramless mixer at a higher speed. This improves the quality of your mix because your compound is moved around the mixing chamber more number of times.
  8. Excellent cooling water circulation to the mixers is a must in tandem mixing technology.
  9. HF Mixing Group expert, Dr Harald Keuter, emphasize that a Tandem mixer improves your throughput rate by up to 25 per cent when compounding with carbon black compounds and can rise up to 100 per cent with silica compounds. Hence you can cut costs and increase output with this technology. Depending on your choice of mixing line, say for a mixing room with five tandem mixing lines and production of approx. 100,000 tonnes of rubber compound annually, he says you save up to one million euros per year. (….And that’s lot of money!!)

The population of tandem mixers is higher in the tire industry while its economy of operations is tempting the non-tire rubber industry as well.

Do you plan to reduce the mixing stages for your rubber compound (Read on Single-Stage or Two-Stage Mixing here) using tandem technology? Let us know.


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