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Top 25 Things You Should Know to Discuss with Mixer Rebuilder

The first step to rebuilding your internal mixer is to select the right rebuilder. (Check out 17 essential questions to select the right rebuilder for your internal mixer). After, the mixer is disassembled and cleaned, a joint inspection (between the rebuilder and you/your company representative) should be conducted at work site.

During this joint inspection, you will need to take or approve decisions on different critical components of the mixer. Some of these could be rebuilt, few repaired, very few reused as it is and some will have to be replaced fully. If you choose your options wisely here, you avoid being shortchanged on the final scope of work and get the best Return on your Investment (ROI)….after all you would not want to pay for something that you can reuse!

Internal Mixer

Internal Mixer: An image from the web

So what are the 25 key things you should prepare for discussions on rebuilding your internal mixer? Lets list them.

  1. Chamber (Drilled) SidesReuse or Replace. If the bore is out of tolerance and/or surface worn out, this component cannot be reused.
  2. Rotors – Reuse or Replace. Some rotors can be reused by rebuilding the profile if they are not too old or not excessively worn out of shape.
  3. Rotor End (RE) PlatesReplace. Rarely can this component be rebuilt.
  4. End Frames – Reuse. In most of the mixers, this component can be reused unless the end frame casting has cracked.
  5. Bearings – Reuse or Replace. Rebuilders will recommend replacement on a cautionary note, however exceptions are possible if the bearings are new or not damaged during disassembly.
  6. Dust Stop Assemblies – Replace. Always
  7. Oil injector – Replace. Always
  8. Couplings – Reuse. Because these are long-life components.
  9. Door SupportReuse. In most of the mixers, this component can be reused unless there is a crack.
  10. Drop Door Shaft –  Reuse. In most of the mixers, this component can be reused unless excessively worn out.
  11. Drop Door (Door Top) – Replace. This component usually exhibits higher wear and tear. Hence, unless it is new, usually recommended for replacement.
  12. Latch Assembly – Reuse. In most of the mixers, this component can be reused as it is.
  13. Linear Actuators – Reuse. Rebuild and service them after dismantling.
  14. Throat Plates – Replace. This component wears out due to constant contact with floating weight.
  15. Floating Weight (Ram) – Reuse or Replace. Depending on the condition.
  16. Hopper – Reuse or Replace. Rebuilders will recommend replacement together with mixer body. Depending on the condition, this can be examined for reuse.
  17. Hopper Front, Rear & Side Plates – Reuse.
  18. Hopper DoorReplace. Always.
  19. Piston Rod, Plates & Cup Seals – Replace. Always.
  20. Grease & Oil Lube Assemblies – Replace. Always.
  21. Hydraulic Cylinders – Reuse. Change the seals.
  22. Hardeners & Fasteners – Replace. Always.
  23. Seals & Bushes – Replace. Always.
  24. Thermocouples – Replace. Always
  25. Rotary Joints – Replace. Always

Initial budget estimates notwithstanding, these decisions on “Reuse or Repair” that you take on the components (after disassembly and joint inspection) impact the final cost of mixer rebuilding. The cost could either increase or decrease depending on the trade-offs you are willing to take. If you have chosen a good rebuilder, he will guide you towards an informed decision – finely balancing the cost and the optimum restoration of your mixer.

Have you rebuilt your internal mixer? If so let us know your experience.

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17 Essential Questions to Select the Right Rebuilder for your Internal Mixer

Rebuilding an internal mixer can be less expensive than purchasing a new machinery. Your production downtime can also be reduced by proper planning because of faster turnaround times on rebuilds.

Depending on the condition of the internal mixer; they could be rebuilt, remanufactured or upgraded.

Internal Mixer

An Internal Mixer: Image from the Web

Rebuilding a mixer requires expertise in mechanical aspects and knowledge of its functioning. Rebuilders’ knowledge of hydraulic, lubrication, pneumatic, electrical, control, and cooling systems are equally important if you plan to upgrade.The rebuilding process will require your mixer (and its components) to be disassembled, cleaned, inspected, and repaired (or replaced as is required).

Hence, an expert rebuilder follows these steps.

  • Disassembly, cleaning, and inspection.
  • Estimation on the scope of rebuild and guidance to upgrade the mixer components (in case of old designs and brands) to improve performance.
  • Rebuilding or remanufacturing mixer components to original dimensions, clearances and tolerances.
  • Ordering of the required electrical, control, hydraulic, lubrication, pneumatic, and cooling system parts.
  • Reassembly of the mixer and painting.
  • Documentation and manuals for installation, spares, maintenance (and operations in case of upgrading the mixer)
  • Inspection, testing and mechanical recertification.
  • Installation and Startup support at site.
  • After-market service and spares support.

There are a significant number of details within each of the steps outlined above, that needs extensive expertise. Hence, I suggest that you ask yourself the following 17 questions (that needs a “yes” answer) to decide on your choice of a mixer rebuilder (reputed companies recognize the importance of these questions and will provide you full details. Most would even display documentary evidence during your discussions).

  1. Is the company well-established in the industry?
  2. Does the company have drawings to rebuild and remanufacture your mixer to specifications?
  3. Does the company have design capabilities to upgrade, modify or custom-design your mixer components to new/improved specifications?
  4. Can the company service your mixer?
  5. Does the company have competent personnel for field service?
  6. Can the company provide installation support?
  7. Does the company have the required engineering infrastructure to remanufacture your mixer components? What are its manufacturing capabilities?
  8. Can the company extend service and spares support throughout the life of your mixer?
  9. Does the company have the required testing (like pressure, steam, hydrostatic, ultrasonic, etc) facilities for your mixer and its components?
  10. Does the company supply installation and parts manuals?
  11. Can the company ensure final mixer dimensions match the existing dimensions available at your site?
  12. Does the company provide you verification of inspection reports, test certifications of critical components?
  13. Are they confident of their internal quality processes and systems?
  14. Do they agree for a third-party inspector for final inspection and validation?
  15. How does the company go about determining the scope of rebuild?
  16. Does the company display transparency when sharing – which components are rebuilt? Which are remanufactured? which are upgraded designs?, etc.
  17. Does the company have the expertise or resourcefulness to guide you on electrical, control, hydraulic, lubrication, pneumatic, and cooling systems?

Plan a visit to research and evaluate your prospective companies well. Because a mixer rebuild can cost your pocket at least 50% or more of a new machinery price depending on its condition. Select the right rebuilder to restore your internal mixer to its original capacity, maintain them well (Recommended Maintenance Schedule For Internal Mixer) for longer life and thus maximise your ROI.

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Internal Mixers Maintenance Chart

Internal Mixer is a favourite equipment for volume and quality rubber mixing world-wide. These could be Tangential Type Mixer (referred as Banbury) or Intermeshing Type Mixer (referred as Intermix).

HF Mixer

Image from HF Mixing Group

Users buy brand new internal mixers from the manufacturers. Or they get used-machinery from the secondary market. The used-machinery could be either from a trader or from another user. Reputed internal mixer manufacturers include HF Mixing Group, Kobelco, Bainite Machines, Carter, Yiyang etc.

Brand new mixers (and some times old ones too!) come with an Operation and Maintenance (O&M) manual. In such cases, the owner gets comprehensive information on the recommended maintenance practices of the mixer from this manual. Well maintained mixers have longer life, shorter break-down times and gives highest ROI.

In case you do not have the O&M Manual of your internal mixer, here is a template chart of recommended maintenance schedule. You may want to adopt this chart with some customization. Please download the pdf here – Recommended Maintenance Schedule For Internal Mixer

Let us know if you found this chart useful for your internal mixer maintenance.

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