| 1 | Mixer Configuration | High-speed hot mixer combined with a separate cooling mixer; commonly available working volumes range from approximately 50 to 1,000 L. | PVC dry blends require rapid heating, homogeneous dispersion, and controlled cooling before extrusion. | Request the equipment layout, effective working volume, batch diagram, and a witnessed trial using the intended formulation. |
| 2 | Batch Capacity and Throughput | A practical batch size is often about 50–70% of the nominal vessel volume, depending on bulk density and formulation. Confirm output in kg/h rather than relying only on vessel size. | Overfilling can reduce mixing quality, while underfilling lowers productivity and increases energy consumption per kilogram. | Compare tested batch records, cycle time, discharge time, and actual kilograms per hour with PVC stabilizer and filler included. |
| 3 | Temperature Control | Independent temperature measurement and PLC-based control, with a typical hot-mixing discharge range of approximately 110–130°C and cooling discharge commonly below 45–50°C. | Stable temperature control helps prevent premature fusion, thermal degradation, uneven lubrication, and inconsistent extrusion behavior. | Check sensor locations, calibration records, alarm limits, temperature uniformity, and repeatability across at least three test batches. |
| 4 | Rotor and Paddle Design | Rotor geometry should provide axial and radial circulation, with variable-speed operation typically available within a manufacturer-defined range suited to the formulation. | Efficient circulation improves dispersion of calcium carbonate, titanium dioxide, pigments, stabilizers, and lubricants. | Review rotor drawings, mixing dead-zone analysis, speed control range, wear-clearance data, and sample blend uniformity. |
| 5 | Drive System and Energy Efficiency | The drive should provide adequate torque during loading and stable speed under changing material resistance; inverter control and overload protection are preferred. | PVC formulations can produce significant torque fluctuations, especially when fillers and dry additives are introduced. | Compare motor rating, starting method, peak current, energy consumption per batch, overload settings, and service access to the drive system. |
| 6 | Contact Materials and Wear Resistance | Product-contact surfaces should use suitable stainless steel or wear-resistant alloy components; high-filler applications require replaceable wear parts. | Abrasive mineral fillers can accelerate paddle, liner, discharge-gate, and vessel wear, affecting clearance and blend consistency. | Ask for material certificates, hardness or treatment specifications, expected wear life, spare-part pricing, and replacement procedures. |
| 7 | Automation and Process Traceability | PLC and HMI control should record recipe, speed, temperature, mixing time, alarms, and batch results; remote diagnostics are an additional advantage. | Recorded process data supports repeatable color, density, fusion behavior, and extrusion stability. | Inspect the control screens, recipe permissions, data-export functions, backup method, language options, and fault-history records. |
| 8 | Safety and Compliance | The machine should include guarded moving parts, emergency stops, lid interlocks, overload protection, grounding, pressure or discharge safeguards, and electrical documentation appropriate to the destination market. | Hot surfaces, rotating equipment, stored energy, and automatic discharge operations create significant operator risks. | Review risk assessment, wiring diagrams, factory acceptance test records, safety-device testing, and applicable conformity documentation. |
| 9 | Quality Assurance and Testing | A reliable manufacturer should maintain documented inspections for fabrication, welding, machining, assembly, electrical testing, empty-load operation, and full-load trials. | Documented quality checks reduce the risk of vibration, leakage, temperature deviation, premature wear, and commissioning delays. | Request inspection plans, dimensional reports, motor and electrical test records, factory acceptance criteria, and corrective-action procedures. |
| 10 | After-Sales Support and Total Cost | Evaluate installation guidance, operator training, spare-parts availability, response time, warranty terms, maintenance requirements, shipping cost, and lifecycle energy use. | The lowest purchase price may lead to higher downtime, difficult maintenance, and greater long-term operating costs. | Use a five-year total-cost comparison covering purchase, installation, consumables, planned maintenance, critical spares, energy, and downtime risk. |