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: 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) Sides – Reuse 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) Plates – Replace. 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 Support – Reuse. 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 Door – Replace. 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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