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VMI iCOM – A New Alternative to Final Rubber Mixing I Learnt At RUBBERCON 2015 Chennai

The rescheduled edition of RUBBERCON 2015, held on March 1-3, 2016 at Chennai was well-organized by IRI (Indian Rubber Institute) and IRCO (International Rubber Conference Organization).

Personally, this has been one of the best attended, well-organized and amongst biggest conferences I have been to recently. And to most delegates, this has been a different experience altogether.

Kudos to the complete team of organizing committee and supporting members for their massive efforts and time invested to make this conference a success. Because of them, I think RUBBERCON 2015 Chennai would easily occupy its unique place of prominence amongst biggest international conferences.

Over 75 speakers from 19 countries presented papers.

I was fortunate to successfully attend all my shortlisted speakers.

In an earlier post on mixing, I had mentioned that Single-stage mixing is not always cheaper and two-stage mixing is not always better. So, when my good friend, Dirk G.H. Reurslag, Sales Director (Industrial Solutions) of VMI Group (innovative leaders in rubber and tyre machinery) presented a new alternative on Continuous Final Mixing, it caught my attention quickly.

If you are looking to operate the complete mixing line by a single person, then you will find this JIT (Just in Time) approach to continuous mixing and blending of final rubber compounds interesting.

Before you get excited and review it’s long list of advantages, let me brief you the basic concept.

Basic Concept:

At its heart, this “mixing approach” has a cold-feed extruder along with the gear pump and they are controlled by software. VMI calls it iCOM®.

Sound’s simple (Right?)…. Wait. There’s more to it.

VMI Continuous final mixing

VMI Continuous Final Mixing Line

Operating Principle:

If you are seeking continuous proportional blending, you will know that proper distribution-mixing should take in the screw extruder.  And for final mixing, you require the screw extruder to properly incorporate the chemicals into the compound mix. Hence, the mixing screw design from VMI is advanced and unique.

The software used is equally sophisticated to control the speeds of the screw, the pump (and input pressure) and the volumetrically operated loss-in-weight feeding system.  The mixing and proportional blending uses

  1. the volumetric operating principle of the gear pump (Read our earlier post on the concept of gear pump working) and
  2. the abilities of homogeneous plasticizing of the rubber by the screw type extruder.

The special screw extruders are the VMI SHARK® extruder gear pump combinations. Different screw types are available. VMI recommends that they select a screw for you depending on your specific application.

The chemicals to be mixed are usually polymer bound, pre-dispersed, in the form of granules and are fed to the mixing extruder by an accurate volumetrically operated loss-in-weight feeding system.

Image - VMI

Proportional Blending (L) & Continuous Final Mixing (R)

For Proportional Blending, you require another side-feeding extruder gear-pump. The function of the screw of this side feeding extruder is not to mix. Rather, it only needs to properly plasticize the rubber and feed it (free of entrapped air) to the gear pump. The gear pump, in its turn, pumps the rubber compound into main mixing extruder in a volumetrically controlled fashion.

Continuous Final Mixing:  You can adopt this volumetric controlled mixing-extrusion in combination with accurate dosing of granules (that contains vulcanizing agent and accelerators) by a loss-in-weight feeder, to do continuous mixing.

Controlled Back and Forward Blending:  This is the third type of blending you could achieve in the extruder screw and barrel combination. This ‘compensates’ for little irregularities, if they might occur, in the loss in weight feeding of your polymer bound chemicals

VMI develops new concepts and innovative uses of technology with the end-user. VMI seeks to work with clients that will become launch users and close collaborators. In this way, VMI only ever takes to market concepts that have been tested under real-world conditions and proven to deliver competitive advantage.

Emphasizes Dirk Reurslag, “iCOM® solution is the more economical alternative to mixing in an internal mixer”

VMI worked out the iCOM® final mixing process, which includes the VMI SHARK continuous mixing solution in combination with Rhein Chemie’s  Rhenogran polymer bound chemicals and Rhein Chemie’s Rhenowave in-line analytics.


Your advantages of VMI iCOM® for final mixing are

  1. Lower investment on a final mix line delivering faster ROI and time to profit.
  2. Compact, integrated solution occupying modest footprint.
  3. Lower energy consumption as compared to the use of an internal mixer based final mixing line.
  4. No electricity consumption peaks like in the case of an internal mixer. Hence, a sustainable solution that reduces energy use and improves profit potential.
  5. Decentralized final mixing: This means Just in Time production as it reduces costly transport requirements for final batches. This reduces your stock of compounds and simplifies your logistics.
  6. Just in time (decentralized) final mixing allows more ‘rapid’ vulcanizers, resulting in shorter vulcanizing time.
  7. The proportional blending capabilities gives you various kinds of possibilities – Cross Blending (Most of you in mixing would know it well. This is referred to as just blending from two stage mixing), Controlled back and forward blending or Proportional Blending (both mentioned earlier.)
  8. No ‘fading’ in the produced strip: no difference in heat treatment: With batch production the first part of the (long) strip was shorter on the mill than the last part.
  9. Consistent quality of final mix compound with no scrap or rejects.
  10. One Energy Cycle (Heat-up, Cool-down cycle) can be avoided by combining final mixing with first extrusion step.
  11. Straining in the iCOM® line is possible
  12. Degassing in the iCOM® line is possible
  13. Affordable for even smaller companies

And just in case you thought this is an entirely new concept, you are in for a surprise. A Belgian compound manufacturer has the VMI iCOM® production line installed and successfully working since 2012.

VMI Group’s leadership in Extruder-Gear Pump solutions is renowned. They specialize in designing and engineering superior customized machinery for the rubber and tyre industry.

When I visited their stall at RUBBERCON 2015, I also learnt something new in their souvenir they were gifting to their customers. Known as Klomp, (more interesting facts here – Clogs), they are a type of footwear made in part or completely from wood. Pair of these is known as Klompen.

If you had been to their stall, did you pick up Klomp or Klompen (Single or Pair)?


Summarizing, if you are looking for an innovative, automatic, decentralized, Just-In-Time, final rubber mixing line without internal mixers, this new alternative in VMI iCOM® I learnt at RUBBERCON 2015 Chennai is worth your evaluation. I am also informed, it further enables production of customized, creative and precisely targeted compounds.             

What do you think?

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Rubber Extruders And Extrusion – Special Supplement

Rubber industry only had Hot Feed Extruders until 1950’s. Then came the Cold Feed Extruders and other variations as we see them today.

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.

Life today is mostly spent trying to catch up with latest developments. However, in the process the basics and fundamentals are sometimes overlooked. So, in this Knowledge On-The-Go Special Supplement, we bring to you a ‘collector’s edition’ on Extruders and Extrusion incorporating the fundamentals.

(Our digital editions are available on two platforms – Youblisher or Yumpu)

Extruders_Special Supplement

Click on the Image to Flip Through The Digital Book

Download PDF Here

I hope you find this special supplement informative.

(Disclaimer: All the pictures and statements in this special supplement are sourced from web or shared by respective companies. All copyrights belong to actual owner. Rubber Machinery World does not independently verify them nor will vouch for their genuineness, hence will not be liable for any misrepresented data. The images are used here for representation purpose only.)

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A Productive Rant About Fine Mesh Straining Of Rubber Compound In The Millroom

Hi. This article was sent to me by Dan McAuley*, a regular reader of Rubber Machinery World and avid follower of developments in Rubber Technology.

If you are a producer of technical rubber goods un-dispersed materials or foreign particle contamination can be a significant source of rejects especially in products demanding high show surface quality. Given increasing requirements and the risk of grit, packaging materials etc entering the production process an effective means of ensuring defect free compound for your customers is required.

Extrusion processes have relied on the use of screen packs to provide some measure of protection from such defects and develop back pressure to stabilize output. This stated the extruder screw to barrel interface generates shear heat as it conveys rubber compound to the die in turn reducing its viscosity to promote flow. The use of finer mesh screens will result in greater material resonance time and higher back pressures increasing heat input which can create pre-cure and reduce run duration. Molding processes via injection, compression or transfer are at greater risk as screen use is not possible.

Enter the rubber gear pump or straining device.

Gear pumps are not new technology as they have been used for a multitude of applications ranging from automotive oil pumps to plastic melt pumps and with consideration for its unique and temperature sensitive characteristics are an ideal means of “filtering” your rubber compound.

Unlike extruders, gear pumps offer positive displacement and use two counter rotating gears in place of a screw as a means of conveying material. Shear heat (minimal) in a gear pump is introduced as material enters and is conveyed between the gears and the surrounding housing, both of which are typically temperature controlled.  Similar to an extruder the material then passes through the screen pack and supporting breaker plate en-route to the die. As flow is directional and the shear area is much smaller than an extruder the gear pump is capable of gently processing temperature sensitive materials at pressures in excess of 500 bar with screen packs finer than 100 mesh.


Representative Image From Web

Although extruders are self feeding devices, gear pumps rely on being fed with a consistent supply of compound and this may be accomplished in several ways. Selecting the appropriate design depends on your install application however supply via strip fed extruder or two roll cram feeders are typical methods employed.

Regardless of feed design choice, the gear pump entrance is typically pressurized to less than 50 bar and is maintained by varying the feed device speed relative to gear pump speed.

Gear pumps used for rubber straining are unique in the sense that conventional bearing support of the gear shafts and lubrication with oil or grease can present a contamination risk given the high working pressures. Designs vary, however a common solution permits rubber leakage flow between the rotor  shaft and the housing effectively making the compound the lubricant highlighting the need to ensure consistent gear fill. The tailings generated due to the rubber leakage may in many cases be recycled back into your process to minimize waste.

Gear pump technology in the mill room – in line

Straining technology has advanced to the point where machines capable of outputs in excess of 10000 kg /hr are possible. The use of a gear pump at the source of compound production can reduce capital and operating cost at end use processes, permit the use of lesser grade raw materials and produce continuous and consistent strip feed for your extrusion or downstream mixing operations.

Mill room operation can also benefit as the straining process generates a steady/stable output which establishes a process ”heartbeat” or pull to which other systems must be optimized.

Key considerations in the selection of an appropriate machine include the design of the pump feeding method, touched on earlier. Options such as a mill fed continuous strip to an extruder or a two roll feed mechanism are available as is a conical twin screw feed which presents an alternative to the roller die at mixer discharge.

Taking advantage of the warm feed output from the mixing process to the strainer permits inline fine mesh straining of a wide variety of compound types and viscosity. To accommodate throughput rates, machines make use of large breaker plate -screen pack configurations and may be equipped with dual heads etc to facilitate quick screen change.

Given the nature of the device, the low impact on material temperature vs working pressure and the ability to achieve extremely fine filtration the technology is suited to both master batch and final compound production.

Your peers in the industry are taking advantage of inline straining to provide end users with clean compound improving their operations by reducing defects at the source.  This coupled with added flexibility in raw material selection and the continuous flow output to your mill room’s downstream operations can offer a significant improvement in operating efficiency. A win-win result.

Image of UTH Strainer Extruder

Image of UTH Strainer Extruder

*Dan McAuley is a Mechanical Engineering Technologist with extensive rubber industry experience primarily as a project engineer. He has participated in equipment installations in green field start-up ventures in Brazil and Mexico as well as implementing new processes and supporting programs within existing production facilities. He has worked as project engineer, plant engineer, project engineering manager having worked in the UK, USA, Brazil, Mexico and Canada for various extended assignments. He can be reached at

Contact me if you seek more details. Or if  you are looking for New or Used Rubber Machinery?

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