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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?

Operator

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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Top 15 Skills Required For An Internal Mixer (or Kneader) Operator

Rubber Mixing is a capital and energy intensive operation. And mixing machinery are the mother equipment. This could be an Internal Mixer (Banbury or Intermix) or Rubber Dispersion Kneader depending on the size of your organization and/or products manufactured.

Hence, the cost of errors or omissions are very high when compounding a batch in a mixer. You need a skilled operator. Ever pondered on the skills that make a mixer operator successful?

Internal Mixer Operator

Here is the list of top 15 skills for an successful batch mixer (or kneader) operator. (Updated on 23rd Dec 2015: Flip through this post in our digital edition and download here)

  1. Control of Operations – Your mixer operator should be able to adjust ram pressure, control the mixing process, set parameters and ensure its completion as per SOP (temperature or time or energy as programmed/specified).
  2. Monitoring Operations – The most important skill of your operator should be to have a keen eye for watching gauges, dials, or other indicators in the control panel or HMI to make sure the mixer is working properly. He has to ensure that the mixer is kept clean, safety features are functional,  upstream and downstream equipment along with all accessories (like cooling water, hydraulic/pneumatic system, temperature control unit (TCU), lubrication system, etc) are ready
  3. Active Listening – Your operator should be a skilled listener. He should actively listen to the sounds of the mixer and its motor during a mixing cycle; pay full attention to what his supervisor (or you) or his colleagues on the mixing room safety are saying, take time to understand the points being made, and ask relevant questions.
  4. 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
  5. Reading Comprehension – An operating and maintenance manual is normally supplied together with the rubber mixer. This is a crucial document. Again your compounding process may involve specific work related instructions or SOP. Or there could be a training manual in some instances. 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.
  6. Troubleshooting, Judgment and Decision Making – Your operator is the first point of contact with your mixer in operation. Hence, he should have the experience or knowledge on mixers to determine/read the causes of any operating errors when they occur, judge the gravity of the error and also decide what to do about it – whether to reset the mixer, or escalate to supervisor or raise a service visit request of the manufacturer’s engineer.
  7. Critical Thinking – Operating a rubber mixer requires critical thinking skills because your operator should use logic and reasoning to identify alternative solutions, conclusions or approaches to problems he faces while mixer is in operation.
  8. Quality Control Analysis – Your operator should have basic skills on quality control with an outlook to meet your set mix quality parameters in every batch. This may involve need for appropriate fine tuning like helping you fix the batch weight, or sending the sample of specified compound/ batch in specified form to lab for testing.
  9. Social Perceptiveness – Emotions could run high in the rubber mixing room. Your operator should display “awareness” of others’ reactions and understanding of why they react as they do in a particular circumstance.
  10. Repairing – Your mixer operator should be able to use the required tools to both repair and assist repair of mixers when needed in the most urgent manner.
  11. Time Management – Your operator should manage his own time and display sensitivity to the time of other co-workers involved in the mixing room.
  12. Mixer Maintenance – Performing routine maintenance on mixer and determining when and what kind of maintenance is needed is an important skill that your operator should posses.
  13. Active Learning – Your operator should display active learning skills. This is because, mixers get upgraded, automation and new controls might get introduced or new methods of mixing could be introduced all of which he might have to learn or get trained in.
  14. Writing – If you could get an operator who could communicate effectively in writing to you (or his supervisor) or to other departments, then I would say you have a great asset.
  15. Complex Problem Solving – 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 reduces the downtime of your mixer.

Do you agree the above listed 15 skills, required for an Internal Mixer or Kneader Operator, are comprehensive? Let us know.

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Should you buy a Stock Blender for your Open Mill?

The Stock Blender is an add-on accessory mounted on top of an open two-roll mill. It aids in rubber blending by pulling the mix compound from the front roll of the mill and guiding it to the nip gap between the two mill rolls.

A Mixing Mill With Stock Blender and Hydraulically Operated Mill Guides

Structurally, this machine assembly consists of a blender roll, a carriage unit with guide rolls, pressure roll and rear roll along with required automation.

The Blender Roll is a hollow roll with water passage for internal cooling. The surface of this roll is hard chrome plated, mounted on antifriction bearings at both ends and operates on a variable speed motor. The VFD allows you to tune for every compound or recipe, thus enabling the speed of the stock blender to follow mill speed. This feature is crucial to ensure that compound does not sack-in or tear-off when taken up and through the stock blender.

On the assembly frame is also a hollow pressure-roll mounted on antifriction bearings and has a swivel operating arrangement. Pneumatic cylinders actuate this movement. The Carriage with screw and guide rollers is equipped with two limit switches at either end of travel. These limit switches signal the carriage traverse motor to reverse at extreme ends during to & fro travel, while guiding flow of rubber to mill nip via blender roll.

A stock blender helps in homogeneous mixing and repeatability of the mixing operations. Many companies use them on the open mill (also known as dump mill) below the internal mixer. After masterbatch mixed in an internal mixer, curatives are added and final homogenization done on these mills. Because the mill helps incorporate undispersed curative or fillers that might have fallen off the ram or drop-door when the batch was dropped. In a different scenario, if you need to drop the mix batch at a higher dump temperature, you could use the stock blender to take some heat out of the batch and then add the curatives on the mill. Reduction in temperature is obtained by allowing the batch from the mill roll airborne to pass over the water-cooled blender roll before it returns back to the nip gap. When these mill rolls (centrally cored or peripherally drilled design) are properly cooled, the stock-blender allows you to reduce the batch’s temperature continuously for lower viscosity compounds.

Stock Blenders are also used on pre-warming mills before feeding the rubber sheet to a Calender.

A Stock blender enhances efficiency and productivity through reduced operator fatigue. Cutting down hot rubber many times, rolling the sheets and feeding them back into the nip gap of the mill rolls is a physically demanding task for the operator. Stock blenders eliminate this completely and improve your batch to batch consistency. The operator also benefits from a safe work-environment.

The operators, though need to be trained well. For an open mixing mill the stock blender can be used only when the batch has achieved a certain stage of homogeneity. When a batch from the internal mixer is dropped on an open mill with stock blender, the operator must pass the complete batch through the nip before diverting the batch to the stock blender. Else, there is a risk that only a part of the batch turns round the stock blender. A big lump,which is neither cooled nor mixed, would continue to ride and turn on top of the nip. This lump does not pass the nip until the operator evacuates the compound to second mill or batch off.

The stock blender designs vary among manufacturers. Hence, not paying attention to the design features can result in owner’s or operator’s nightmare. For example designs with ledges behind the rolls can cause compound to accumulate and these must be cleared out regularly to prevent contamination. Similarly, a ball screw with tube casing for carriage movement is superior to a conventional screw design and eliminates contamination from lubrication of the screw. Compact designs and increased level of automation with programmable carriage traverse movements make the stock blenders a joy to work with a high level of safety.

Summarizing, buying a good robust stock blender increases the mixing capacity of an open mill, improves the batch cooling, reduce mixing time and improves dispersion. With a trained operator, you can extract the best returns out of your investment in this rubber mixing machinery accessory.

 

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