Rubber & Tyre Machinery World

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7 Must-Ask Questions When Buying Used Rubber Internal Mixer

An Internal Mixer, whether it is a Banbury mixer or Intermix mixer, is the heart of your rubber processing plant. The market for used rubber internal mixer is wide with sellers spread across. You can find an excellent quality pre-owned rubber mixer that can produce high-quality compound mix, without spending excessively.

Rebuild Farrel F270 Mixer From Pelmar Engineering Ltd

Rebuild Farrel Make F270 Mixer – Pelmar Engineering Ltd

Your purchase decision on used or pre-owned machinery has to be thoughtfully made. Because you will see that even in the secondary market for internal mixers, the costs are relatively high considering there could be additional rebuild costs (if not already refurbished by the rebuilder). In any case, you are making a significant investment from your affordability standards and hence you need to consider a variety of factors to help assess the mixer’s value to your rubber compounding requirements and, ultimately, to your bottom line.

Here are 7 Must-Ask Questions when buying used rubber internal mixer that will help you appraise the second-hand or rebuilt mixer value and usefulness to your rubber compounding operations.

  1. What are my mixer requirements?

You need to have a clear idea of what you wish to buy. This entails knowing capacity, the mixing process for your rubber compounding requirements, matching upstream and downstream machinery availability in your rubber mixing room and the remaining useful life of the equipment you are willing to live with.

(Read my post on the Internal Mixer Selection Questionnaire where you can also download a template. You can modify this template to clarify your needs and refine your decision process).

  1. What is my budget?

Your budget will be a crucial purchase factor including the brand, exact model and vintage of the mixer that you can buy. You should have clarity of breakup of costs associated with your batch mixer purchase.

This includes the cost of additional space required (in case you are expanding operations), cost of dismantling (if mixer is running at a particular location) and transporting the mixer to your factory, actual cost of mixer, its controls and accessories to be paid to the seller; plus various duties applicable, to name a few.

  1. Should I partner the right people – the pre-owned equipment sellers?

Given the global nature of rubber compounding business, there are internal mixers available across the key global markets. Hence, it is not possible for you to be informed about the best deals out there in terms of overall cost and mixer quality. This is where pre-owned equipment sellers or dealers come in to help you.

I think, a good dealer will be able to present you with multiple options and help you select the best used mixer for your requirement.

  1. Is the mixer I am considering to buy in Good Working Condition?

Whether buying used or rebuild mixer, you must always test them whenever feasible or you should ask for a start-up guarantee assurance. This is a precaution to be sure that the mixer is in good running order before your final purchase decision.

If you are buying a running mixer, you can easily test them on-site before dismantling. Or if you are buying from a warehouse, many of the reputed used rubber machinery dealers provide arrangements to allow you to test the mixer at least on a test-bed (if not on-site) to help you make a quick purchase decision.

Else, the last resort is a start-up guarantee assurance from the seller. Reputed used machinery dealers  will be transparent on the condition of the mixers they sell, but it is always smart that you check.

When buying with motor and controls, you should verify the operations and safety of electrical components and software licences along with its adaptability to your country of installation. (If not working properly of found unsuitable, you need to factor in the cost of its replacement into your purchase cost)

Another key aspect to check is whether the pre-owned mixer that you propose to buy comes with complete set of manuals, schematics and diagrams. (You may read my earlier post on mixer maintenance here.)

  1. Should I do Visual inspection?

Absolutely. Though the internet has made your communication easy and you can conduct a lot of your business communication online. You can even demand pictures and videos of your mixer in consideration through email. However, there is no alternative to physically inspecting the machinery you are going to purchase.

Used mixers are usually not warranted. This means you need to know the extent of rebuild or refurbishment, and get an idea of the actual state of the internal mixer.

You should insist on a test run of the mixer in your presence and keep your eyes and ears open for tell-tale signs of machine ill-health such as unusual vibrations or noise. Question the maintenance practices of the previous owner and keep your eyes open for worn out parts and leakages.

Additionally, your visual observation of the machinery empowers you to negotiate better with the seller.

  1. Should I Buy a Standard Model of a Brand Name?

When it comes to buying pre-owned mixers, brand plays an important role. Buying standard models of branded and reputed manufacturers of used mixers can assure you about its quality. In addition to this, you will find it very easy to get spares and servicing for a standard internal mixer models in case of future repairs.

On the other hand, if you go for non-branded or non-standard rubber internal mixer, buying and maintaining the spares can prove a difficult task.

Kobelco Make Mixers

Kobelco Make Mixers – Image From Web

  1. Should I get everything on paper?

I think this is a very important step whether you are buying new or used rubber machinery.

You should get everything on record, from the first formal quotation, the details of the rubber machinery, the accompanying accessories, delivery terms, mode of payment, extent of buyer liability, seller liability, etc. It could be an exhaustive document or a simple set of key clauses basis your comfort – either way they are critical to your purchase. (You may wish to explore the rubber machinery purchase and sale agreement here. Preview – Rubber Machinery Purchase and Sale Agreement Template  To buy the full agreement kindly email me directly.)

Once you have answered these questions satisfactorily and determined which factors are most important in your current purchase decision, you can confidently negotiate and purchase a pre-owned mixer that will meet your rubber compounding requirements.

Summarizing, when buying used rubber internal mixer, you need to conduct a proactive due-diligence; identify and partner the apt seller for your needs, and have proper documentation in place. When you make an informed used or pre-owned internal mixer purchase, you avoid buyer’s remorse. 

Happy Buying!

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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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