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Why You Should Spend More Time Thinking About Gearbox for Rubber Extruders?

As a rubber machinery salesman, I have sold several single screw extruders in both extrusion categories – hot feed and cold feed.  In each of my sale, the buyers had strong views and apprehensions on screw and barrel life, throughput and strained production capabilities, extrudate temperature, extrudate appearance, die head design and performance, etc (all of which I acknowledge are really important).

Strangely, the topic of gearbox usually concluded in few questions – “Which brands of gearbox do you offer and what is the SF?” or “If I select XYZ over ABC, will the delivery lead time of my extruder change?” or “Should I call you or the gearbox vendor for service during warranty period of gearbox?”

I do not recall a single discussion where the buyer asked me about gearbox technical details. Nor do I remember the buyer asking me to arrange for a separate technical discussion with extruder gearbox manufacturer to clarify their requirements.

Why do I think this aspect of joint discussion (if any) was relevant for me as a extruder supplier? Because the assembly of a rubber extruder “practically commences” only after the gearbox is ready at the extruder builder’s shop-floor. Unlike an internal mixer or a mixing mill or calender, buyers would not opt for buying the gearbox and main machinery separately. To any reputed machinery manufacturer, there is no bigger pet peeve than a customer buying different components from different vendors trying to save pennies. (But I digress here… do read Prof. Andreas Limper interview).

Extruder Gearbox

Image from Web

And yes, a gearbox is also the single-most-expensive-component on this popular rubber machinery.

I safely presume that this single argument reinforces the relevance of this post here – Why You Should Spend More Time Thinking about Gearbox for Rubber Extruders?

First things first – Why do your single screw extruders need gearboxes?

Extruder manufacturers prefer 1800/1500 RPM or 1200/1000 RPM motors (depending on your country of use) because they are economical, readily available and compact in size to mount on your extruder base. However, most rubber extruder screws during production run in the speed range of 4 rpm to 40 rpm.

Hence, the role of a gearbox or gear reducer here is to reduce the drive motor’s speed and, in turn, multiply the available torque from the motor in order to produce sufficient power to mix and push out your rubber compound.

Plain Cold Feed Extruder

A Representative Image

As an individual and independent component, the key specification that defines the capacity and durability of your extruder gearbox is the power (HP/kW) rating along with its service factor (SF). Single screw extruder gearboxes are normally rated for power (HP/kW) or torque at a specific rpm based on common calculations and standards. This uniform standard allows you to compare gearboxes from different manufacturers.

Your extruder manufacturers follow these guidelines and select a model for different service factors and applications. A key question you should ask is whether, the SF considered by your manufacturer is optimal for your extrusion application or not.

Knowledge of AGMA (American Gear Manufacturers Association) recommendation will certainly help you to discuss better with extruder manufacturers, but experienced gearbox manufacturers can guide you even better. I have witnessed buyers in Asia been taken for a ride for their ignorance and offered lower specification gearboxes on their extruders to compete on cost.

When you compare gearboxes, always evaluate on calculated power. The formula for calculated power of a gearbox is:

                        Calculated Power = Quoted Power X Service Factor.

Typically, single screw rubber extruder gearbox has service factors of 1.5 or 1.75 for optimal operating capacity. For example, a 6 inch pin type cold feed extruder gearbox with a calculated rating of 367.5 kW would have a quoted rating of 210 kW with a 1.75 service factor.

The overall rating of a gearbox is based on the ratings of all its individual components. This includes the gear teeth design, gear hardness, shaft dimensions, bearing selection and sizes, housing design (thickness & rigidity), and thermal considerations. All these considerations are to ensure that your gearbox has sufficient support and capacity to effectively transmit the motor torque to the screw without significant distortion or failure.

Gearbox Internals

Image from Web

Within the gearbox, the most important component (and most expensive) is it’s thrust bearing. You evaluate a thrust bearing based on its type and life (B-10 or L-10 rating).

The B-10 Life (sometimes called L-10 Life) of the thrust bearing is based on an engineering calculation that estimates the number of hours of operation at which 10% of the bearings are likely to fail. Additional rating adjustment factors are to be applied to the basic B-10 life based on application factors including how the bearing is mounted.

For example, a thrust bearing that is mounted between two radial bearings is more likely to have precise thrust bearing alignment, and will therefore have a higher rating adjustment factor.


Here are 6 other key criteria of a gearbox evaluation, which you should know

  1. Gear Design, Hardness & its Construction – Each of the individual gears that go into your gearbox assembly are rated for power or torque based on their strength and durability ratings. The calculations would be according to industry standard AGMA rating systems. Factors include the gear tooth pitch, center distance, material and hardness.
  2. Gear Shafts – The shafts must be designed to transmit the full power and torque capacity of the gears. The length and diameter of these shafts is decisive and must match the ability to transmit this torque without excessive deflection, fatigue and failure. The diameter of the input shaft must be adequate to properly support sheaves (in the case of belt driven models) or a coupling. The output shafts must be properly designed to handle the correct range of screw shanks that will be inserted. Adequate access to the drive keys is beneficial when they become worn or damaged and need to be replaced.
  3. Radial Bearings and Seals – The radial bearings support the rotational forces of the gear shafts and must be designed to handle the load forces and speeds effectively. The dynamic load capacity of these radial bearings must also be considered when evaluating the design and durability of the gearbox. Radial bearings must also be properly lubricated and sealed.
  4. Gearbox Housing Design and Construction – Cast Iron is the cost-effective material of choice for most manufacturers. Traditionally, CI gearboxes are made in two pieces, split either horizontally or vertically. Newer designs have the gearbox housing cast as one piece to reduce any potential leakages.
  5. Thrust Bearing – Thrust bearing isolates the backward forces from the screw. The larger the screw and/or the higher the back pressure, the greater the backward thrust forces. There are three basic types of thrust bearings – cylindrical, spherical and tapered.
  6. Serviceability – When you select a gearbox, you should give prime importance to the availability to affordable parts and service. It is best to select rubber extruder suppliers who purchase their gearboxes from proven and reputable manufacturers that specialize only in gearboxes for better serviceability.

Pin Type CFE

A Note of Caution:

If you plan to replace your old gearbox or comparing one, take note of below developments.

An old gearbox manufactured around through-hardened process and shaved gears technology has shafts, bearings and housings designed accordingly. Replacing new hardened gears with a higher HP capacity, does not automatically guarantee the gearbox rating to increase, if you do not replace the assembly with stronger shafts, bearings and housing.

Gear manufacturing technology today has changed and consists of carburized and ground gears. These gears are capable of delivering much more power in its smaller size. When old gear designs are constructed using the new materials and process, the power calculations yield much higher gear tooth ratings. But if the rest of the design is unchanged, and the same bearings, shafts, and housings are used, the total gearbox rating cannot simply be based on the new higher gear rating alone.

The higher torque could never be applied to the original sized input shaft without causing bending or twisting. The bearings and/or shafts would be overloaded with the higher forces, and the housing would probably not have sufficient strength to resist significant distortion. Reputed gearbox rebuilders will guide you well.

Summarizing, as an extruder buyer, you need to pay extra attention to the design and manufacture of the gearbox when evaluating and selecting a single screw extruder. 

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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 –

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.


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.


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 for your customized offering.


The Ultimate Guide to Asset Management

If you had read my earlier post “A New Hope: Top 6 Things I Learnt At NRC 2015 Mumbai“, then you would have also read my learning from Naushad Shikalgar of J.N.Engineering – ‘Proactive Machinery Maintenance is not an expense and is an investment that has long-term benefits’.

Maintenance is important in any organization. Without proper maintenance, assets deteriorate over time reducing the quality of your output produced. It can also impact the safety of your asset or your people who operate it.

Traditionally, maintenance has been viewed as a cost center in an organization because it costs you money to hire maintenance technicians and purchase the spare parts to keep your systems running smoothly. Too often, senior executives ignore the value-add that maintenance can bring to your organization. These include:

  • A reduction in reactive maintenance costs
  • Reducing costs to restart production after a breakdown
  • Limiting production scrap
  • Costs of downtime such as missed orders and lost revenue
  • Customer perception/satisfaction
  • Improved quality of products
  • Reduced environmental impact


By definition, Asset management is a systematic process of deploying, operating, maintaining, upgrading, and disposing of assets cost-effectively.

During his talk, Naushad spoke extensively on Asset Management Strategy-Plan-Execution including the various approaches to maintenance that I found interesting and hope you too would like it when you read. Hence, I have reproduced the 34 slides (click on the picture below) here that effectively forms a comprehensive guide on asset management.

Asset Management

Click on Image

Summarizing, asset management focuses on assuring your people, parts and processes are optimized to improve asset performance. Reducing inventory, maintenance costs and the number of downtime events raises your productivity, while simultaneously driving financial performance and predictability. It also helps your employees with the right tools to make good decisions about driving your plant performance.

Do you agree? How do you look at Asset Management?

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Adopt Higher Levels of Mechanization To Improve Quality And Reduce Cost – T.K.Mukherjee

The Indian entrepreneurs must accept that only by adopting a higher degree of mechanization they would be able to improve the quality and reduce cost, says T.K.Mukherjee, CEO Mentor & Strategist and Past President of AIRIA in an exclusive interview with Rubber Machinery World. He further adds that Indian Rubber industry could grow at 7 per cent CAGR during the next 5 years to touch USD 19 billion with maximum demand from automotive sector.

Mukherjee, a post-graduate in science and an MDP alumnus of IIM Calcutta, served for over 18 years as the CEO/MD of Phoenix Yule (erstwhile Andrew Yule and now Phoenix Conveyor Belts India Pvt Ltd). A motivational leader who strongly believes in hard work, smart networking and team development, Mukherjee taught me two things 1) there is no end to enrich one’s job knowledge 2) Always recognize that ‘Customer is the Master’.

Currently a mentor to CEOs and strategist, he has been rooted to his belief that Knowledge is Power and Power is Leadership.

His interview here in this edition of “Know A Rubber Leader” series brings in a leadership perspective of a experienced manager who has, worked with rubber machinery early in his career and, used his knowledge to transform a sick PSU (Public Sector Unit) into a dynamic and vibrant MNC.

Know A Rubber Leader

Here’s is Mukherjee’s complete interview reproduced for you.

  1. Hello Mr. Mukherjee. First of all thank you for accepting an interview with Rubber Machinery World and sharing your thoughts. For over 4 years, that we have been interacting, I have seen you transitioning within different leadership and mentoring roles with inspiration and ease. I have been in awe of your energy level and dynamism. So let me start with a personal question – what drives you?

 The various driving forces which act on me are generally situational. However, the biggest forces are:

  • I still believe that my best is yet to come
  • I always feel that as an Indian why can’t we be the best
  • There must be a continuous transaction with the society under which I operate

However, strong driving forces do not always bring success. I grew up predominantly during pre-91 era. We had limited resources and hence ability to take up challenges was less. With the opening up of the economy, various opportunities started knocking at our doors and thus we progressed faster. Failures still remained as a great teacher in my life. One point is very relevant – the definition of success changes from generation to generation. We must appreciate that.

  1. Tell me about a leadership position that you enjoyed the most? Why?

I had the good luck to work as a CEO/MD for over 18 long years. During this period the most enjoyable and rewarding experience was to transform a sick PSU to a vibrant and profitable MNC. This process provided me a great learning – how to change the mind-set of the people. One very challenging issue was to convince the leftist trade unionists about the fruits of privatization! There were cultural issues, communication issues – all providing challenges.

  1. Indian rubber industry has a turnover of around USD 14 Bn with exports touching USD 2.67 Bn. Where do you see this in next 5 years and which sub-sector will have the most significant growth?

I believe that Indian Rubber industry could grow @7% CAGR during the next 5 years, thereby USD 14 Bn may touch 19 Bn. Similarly as far as Indian exports of rubber products are concerned it may touch 4 Bn, thanks to some recent govt. initiatives. The demand growth could be maximum in automotive sector – tyre and non-tyre rubber products. However, due to shift of energy sources from conventional to non-conventional, the rubber products sector depending on usage of fossil fuel may not grow at the same rate.

  1. Apart from serving the interests of Indian Rubber Industry, you have also been a successful business leader of a leading MNC business brand in conveyor belt industry. Since you started, what have been the major changes in your business ecosystem? And how have you repositioned yourself against the challenges to sustain your company’s leadership position in the conveyor belt industry?

My 18 years’ experience in conveyor belt industry (till Sept.’13) is a mixed one. The growth was achieved primarily in correctly understanding the intrinsic needs of the customers early. Once that was mapped, then we could mobilise all the available resources at a fast pace in meeting them. The manufacturing process was re-designed to make it customer centric. And finally improving the core competence of the team members through series of HR initiatives in order to continuously accept and win challenges. The company’s leadership position was achieved by networking with all the stakeholders as per the business need.

Know A Rubber Leader - T.K.Mukherjee

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  1. What kind of technological improvisations had you bought in to your business? Was this sufficient?

By being part of a MNC, we always had the opportunity to obtain continuous exposure of a world-class technology, whereby the customers always found the winning products from the company. Be it application issues or environmental issues or capex issues – we could always provide a workable solution. We always believed that improvement was a continuous process; hence the question of ‘sufficiency’ did not arise.

  1. Today you also consult clients in rubber industry. Is the machinery industry in India currently meeting your client’s technology requirement? Do they import machinery? If yes, how do you feel this gap in technology be bridged over next 5 years?

The Indian Rubber Machine manufacturing industry need to grow in terms of scale, cost competitiveness and quality. Chinese machines with comparable quality are still cheaper. The ultimate customers have more reliance on American/European/Japanese machines, equipment and process, though these are expensive. We definitely need to bridge this gap. Perhaps many companies are trying to manufacture all the major machines as a package deal. Instead of that, we need to focus on mixing, calendaring/extruding, curing press etc. Technology tie-up/equity partnership with American/Japanese companies may help Indian companies to achieve world class standard during the next 5 years’ time. In this direction the ‘Make in India’ initiative, Mumbai-Delhi Economic corridor could provide an excellent opportunity.

  1. I know you have traveled widely and visited many rubber goods manufacturing plants. What is the level of awareness about developments in Rubber Machinery and production technology today in India? Is it different globally?

Now a days the Indian entrepreneurs are travelling outside India quite a bit. They have a fair amount of knowledge of what is globally available. But they are not equally informative of what is possible within the country. It could be a good idea that Indian Rubber Machinery companies may jointly undertake to showcase to Indian entrepreneurs their capabilities by organizing pan India roadshows. This would also help them to understand their customers need.

  1. Rubber sector in India has grown to over 6000 units and is today a highly labour and energy intensive sector. Employing over half a million skilled manpower and many unskilled, what difference do you see the National Rubber Policy making to the stakeholders including the rubber machinery sector?

National Policy on Rubber (NPoR) is an excellent initiative in addressing various issues of the stakeholders- though sometimes these are diametrically opposite. Definitely issues related to Rubber Machinery industry must also be highlighted as they are also a stakeholder.

Handling skill level of a labor intensive industry like Rubber is a challenge. However, under the NSDC umbrella we are quite active in sectoral skill development initiatives under RSDC. This would help sustaining the growth momentum as mentioned earlier.

  1. Currently, you play a very key role as a strategic mentor to CEO’s and also involved in financial sector. SME’s today starve due to lack of “timely” funds and this has been the case in the past too. No change. Is this situation improving? Is there something that SME entrepreneurs can proactively work on to attract funding?

I agree that finding fund for growth of SME sector continues to be a problem. Banks have their issues like – mounting NPAs, high cost of operation etc. Similarly SME sector has their own problem of organizing collaterals and proportionate equity contribution. Various schemes of govt. are also not known sufficiently to the entrepreneurs. In this regard Industry associations may take a leading role in facilitating the process. The financial conditions of many state governments are weak and uncertain- as a result they are able to meet their own commitments. Actually a sustained work is necessary during the next 5 years in order to improve the lot.

The Indian rubber industry is dominated by SME sector, hence such improvements can only ensure growth of this sector.

  1. Great! And one last question, what would be your advice on machinery to your clients and entrepreneurial business leaders in rubber industry?

The Indian entrepreneurs must accept that only by adopting a higher degree of mechanization they would be able to improve the quality and reduce cost. However, they are somewhat uncertain about the skill level of their own people- Blue and white collar. There has to be an engagement program involving all the work force. There has to be a low cost mechanization program. If one looks at some of the successful SME rubber companies, this point would be well established


Download the full PDF of this interview here

Let me know your thoughts.

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Skills Required For An Rubber Extruder Operator: What No One Is Talking About

To a layman and HR Department of most organizations, an extruder operator is a person who operates and maintains this rubber machinery. Period!

Is that it?


An Image From Web

Depending upon your final product, rubber extrusion could be either a very important or the most critical manufacturing aspect of your operations. Thus the skills required for your extruder operator are paramount.

Extruded rubber products differ from those produced through moulding. In extrusion, parts are forced through a die of the required cross section under pressure of an rubber extruder. The extrusion process begins when you feed the unvulcanized rubber compound into the extruder. The rubber travels over the flutes of the revolving screw into the die, with the pressure and temperature increasing as the compound gets closer to the die. And when it reaches the die, the built up pressure forces the material through the die-opening, where it will consequently swell in various degrees based on your compound and hardness.

Most extruded products are unvulcanized before extrusion. This leaves the the rubber in a soft and pliable state post-extrusion. Hence they need to be vulcanized before they are they are rendered usable. During the vulcanization, the extruded rubber will swell or shrink in both its cross section and its length (again based on the type of rubber compound used).

Hence, the cost of errors or omissions could turn out to be very high when extruding rubber. You need a skilled operator.

Rubicon-Halle Extruder

Image of Rubicon-Halle Extruder

Here are the skills required for an rubber extruder operator.

Monitoring and Control Of Operations – The most important skill of your extruder operator should be to have a keen eye for watching gauges, dials, or other indicators in the control panel to make sure the extruder is working properly. Your extruder operator should be able to adjust screw speed, set water flow to the required rate, operate temperature control unit (TCU) or the metal detector in cold feed extruders, observe the extrusion parameters and ensure adherence to SOP (temperature or die swell). He has to ensure that the extruder, dies and its allied downstream equipment are kept clean, safety features are functional, and all accessories are ready.

Quality Control Analysis – Conducting tests and inspections of products, services, or processes to evaluate quality or performance is a desirable basic skill that your operator should have. This could be as critical as preventing wastage (from scorch of your rubber extrudate) to as trivial as sending the sample to lab for testing.

Critical Thinking, Judgement and Decision Making – Operating a rubber extruder requires critical thinking skills because your operator should use logic and reasoning to identify alternative solutions, conclusions or approaches to problems he faces while extruder is in operation. There could be many problems while extruding rubber like die-swell, melt fracture, or poor appearance amongst others. While all of them may not be extrusion related, your operator should be able to judge the gravity of the error and also decide what to do about it – whether to fine tune the extruder operating parameters, or escalate to supervisor or raise a service visit request of the manufacturer’s engineer.

Troubleshooting, Repairing & Maintenance – Your operator is the first point of contact with your extruder in operation. Hence, he should have the experience or knowledge on extruders to determine the causes of any operating errors when they occur. Performing routine maintenance and determining when and what kind of maintenance is needed is an important skill that your operator should posses. He should be able to use the required tools to both repair and assist repair of your extruders when needed in the most urgent manner.

Complex Problem Solving – As a addendum to the above skill, your operator should develop skills to identify and solve complex problems when they occur at site and support maintenance department effectively over a period of time. This will reduce the downtime of your extruder and ensure maximum availability at site.

Speaking – Your operator should be able to talk to you (or his supervisor) to convey information effectively be it to report data/problems/incidents as applicable in a timely manner.

Reading Comprehension – Extruders have an operating and maintenance manual supplied by the manufacturer. This is a crucial document that requires a reading by your operator for his safety, training as well as equipment safety. Again your extrusion process would have specific work related instructions or SOP. Your operator should be able to understand written sentences and paragraphs in these documents. Hence, reading skills is very important for a successful operator. It is not necessary (while it is preferred) that they read English, because you could translate these documents to your operator’s local language for ease of reading.

Active Learning – Your operator should display active learning skills.  This is because, the sophistication of the rubber extrusion machinery has risen over the years. Automation and new controls might get introduced or new parameters of extrusion could be introduced further too –  all of which he might have to learn or get trained in.

Summarizing, your rubber extruder operator needs high level of skills to give you maximum output. Hence, its wise that either you hire a skilled operator or train your operator to upgrade his skills. Your extruder operator must stay up-to-date on current and developing technologies and techniques. He must also have a solid understanding of safety techniques and practices.

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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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A New Hope: Top 6 Things I Learnt At NRC 2015 Mumbai

NRC Mumbai 2015

The Mumbai edition of National Rubber Conference (NRC) 2015, held on Jun 19 & 20, 2015, was well-organized by Western Region team of AIRIA (All India Rubber Industries Association).

I have been attending this conference since its first edition and have seen it evolve successfully over the last 4 years, scaling up each year.

This NRC outperformed its previous versions and was different.

The sessions were designed around the theme, ‘Path to The Future – Stride With NRC’, in a thoughtful manner to impart cutting-edge knowledge to the delegates. Technology was embraced by shifting to electronic format of souvenir and giving tabs to the delegates.

Heavy rains bought Mumbai to a standstill on Friday, June 19 and its previous night. Despite the traffic being thrown out of gear, the presence of over 170 delegates at the venue (The Westin Mumbai Garden City) clearly demonstrated the relevance of this conference for the attendees.

Prasanth Warrier speaking at NRC 2015 Mumbai

Speaker at NRC 2015 Mumbai

Extrusion And Screw Design

Extrusion And Screw Design – Full PDF

While I spoke on “Extrusion And Screw Design….What You Should Know“, here are the top 6 things I learnt at NRC 2015 Mumbai.

  1. Future of India – The Winning Leapthe keynote address by Shashank Tripathi of PwC, gives renewed hope that an aggressive GDP increase of 9% per year to reach a $10.4 trillion economy by 2034 is possible. If India can create capabilities for growth and new solutions, the opportunities, both at home and abroad, are limitless. His report is driven by the belief that India can build shared prosperity for its 1.25 billion citizens by transforming the way the economy creates value. A concerted effort from Corporate India, supported by a vibrant entrepreneurial ecosystem and a constructive partnership with the government will play a critical role to achieve this milestone, we are informed. The report analyses that up to 40% of India’s US$10 trillion economy of 2034 could be derived from new solutions. This new hope when India stands on the cusp of a major change is refreshing and motivational.
  2. The discussion “Distilling India’s Competitive Advantage” had renowned business leaders in the panel. I learnt from Mirisch Damani of Zylog Plastalloys Pvt Ltd that the entrepreneurial skills together with frugal engineering mindset is unique to Indians and we should capitalize on them while we learn to innovate. When Mazhar Vohra of Zenith Industrial Rubber Products spoke of his entrepreneurial experience, he drove home the importance of anticipating changes and focusing on a niche to compete globally in business. I absorbed from stories shared by Anil Sampat of Elastochemie Impex Pvt Ltd that brand building is extremely important for you to gain premium in your market. Health and Safety along with investment on R&D has to be an important strategy for growth, I understood from thoughts shared by Vilas Dhavale on the practices at his company Lord India Pvt Ltd.
  3. Cryogenic Deflashing is a cost-effective technology that is fast gaining popularity, I learnt with interest from Musahudeen of Nissanki GB APAC Sales Pte Ltd. Cryogenic deflashing is a deflashing process that uses cryogenic temperatures to aid in the removal of flash on your cast or molded work-pieces. These temperatures cause the flash to become stiff or brittle and to break away cleanly. Cryogenic deflashing is the preferred process when removing excess material from oddly shaped, custom molded products. By adopting cryogenic deflashing, you can aspire to meet stringent quality expectations of your OEM’s effortlessly.
  4. I learnt from Sugundhan of Base Automation Technologies Pvt Ltd that Rubber Mixing Plant Automation is a necessity, if you aspire to gear up and meet the traceability demands of your customers. Because automotive leaders are forcing sub vendors to Implement Process Improvement systems like Traceability, Product Integration, and Genealogy. While they in turn are preparing themselves for the “voluntary recall code” of Road and Safety Bill 2014 that enforces stringent penalty, legal action, that leads to erosion of market image, high cost of recall, damages brand value, etc. Automation also increases your productivity and efficiency of rubber mixing plant.
  5. Proactive Machinery Maintenance is not an expense and is an investment that has long-term benefits, I absorbed from Naushad Shikalgar of J N Engineering. He spoke extensively on Asset Management Strategy-Plan-Execution including the various approaches to maintenance.
  6. Thermoplastic Elastomer (TPE) is not a threat rather an opportunity for the Rubber Industry, I learnt from a well articulated presentation of Mirisch Damani from Zylog Plastalloys Pvt Ltd.


I missed some sessions. However all presentations and panel discussions, I understand from other delegates, were of high quality. The organizers of this conference has done an extremely good job. (Congratulations to all of you and here’s wishing you greater success in future too.)

Here is the link to e-souvenir if you missed this conference or desire to know more of the papers presented and the key team members of the organizing committee.

NRC Mumbai eSouvenir

Read PDF

Like me, I am sure each one of the delegates took back an idea or thought they could work on immediately in their area of work – overall a new hope, direction and an excitement of potential $10.4 Trillion Indian economy by 2034.

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