| Furnace Type | Available configurations may include gas-fired, electric resistance, induction, reverberatory, crucible, or rotary furnaces. | Select the furnace according to melt volume, alloy type, fuel availability, metal-loss tolerance, and required melt cleanliness. | Review the process-flow diagram, furnace layout, loading method, and a reference installation with a similar alloy and production capacity. | 8% |
| Rated Melting Capacity | Compare both hourly melting rate and usable holding capacity; do not rely only on the furnace nameplate capacity. | The quoted melting rate should be supported by a documented test condition, including charge temperature, alloy, ambient temperature, and furnace loading pattern. | Request a guaranteed performance test using the intended aluminum alloy and a clearly defined charge-to-tap cycle. | 8% |
| Operating Temperature | Aluminum melts at approximately 660.3°C. Industrial melting and holding temperatures are normally set above the liquidus temperature according to alloy and process requirements. | The control system should provide stable temperature control without unnecessary overheating, which can increase oxidation, hydrogen pickup, and energy use. | Check temperature uniformity at multiple points and compare the controller reading with a calibrated independent instrument. | 9% |
| Specific Energy Consumption | Measure energy used per tonne of aluminum melted, including fuel or electricity and clearly stated auxiliary equipment. | A practical project target is commonly about 500–900 kWh per tonne for a well-operated melting system, but the actual value varies by furnace type, charge condition, alloy, and recovery rate. | Require a site or factory acceptance test with calibrated gas meters, electricity meters, weighing equipment, and a defined production cycle. | 15% |
| Thermal Efficiency | Evaluate heat transfer to the charge, exhaust heat loss, wall loss, door loss, and standby consumption. | The supplier should provide a heat-balance calculation and identify the conditions used for the stated efficiency. Compare suppliers using the same test boundary. | Review combustion data, flue-gas temperature, insulation specification, burner turndown ratio, and measured energy consumption at partial load. | 10% |
| Temperature Uniformity | Check temperature differences between the bath surface, bottom, corners, and discharge area during stable operation. | For a controlled aluminum process, a practical acceptance target is often within approximately ±5–10°C at defined measurement points. | Use a calibrated thermocouple or data logger and perform a temperature-mapping test at empty, partial-load, and normal-load conditions. | 8% |
| Metal Recovery and Dross Control | Assess oxidation, dross generation, metal retained in dross, skimming method, and charging disturbance. | Lower metal loss is generally associated with controlled temperature, reduced turbulence, shorter holding time, and appropriate flux or inert-gas practice where applicable. | Compare charge weight, tapped metal weight, dross weight, and recovered metal over several repeatable production cycles. | 10% |
| Combustion and Emissions | For fuel-fired systems, review burner control, air-to-fuel ratio, flue-gas temperature, CO, NOx, and particulate control. | The design should comply with applicable local emission limits and recognized industrial-furnace safety requirements, such as EN 746-2 or equivalent local standards. | Request combustion commissioning records, emission-test reports, burner certificates, and details of interlocks for flame failure and excess temperature. | 9% |
| Refractory and Insulation Quality | Evaluate refractory type, working temperature, thermal conductivity, abrasion resistance, chemical compatibility, and repair method. | The refractory system should be selected for molten aluminum service and protected against wet charging, thermal shock, corrosion, and mechanical damage. | Review material datasheets, installation procedures, curing records, refractory thickness, and the expected service-life conditions. | 8% |
| Control and Automation | Check PLC control, recipe management, temperature recording, alarm history, remote diagnostics, and energy monitoring. | A suitable system should record temperature and energy data by batch or production cycle and include password-controlled set-point access. | Request a live demonstration of the HMI, alarm logic, data export, recipe permissions, backup procedure, and failure recovery sequence. | 7% |
| Safety Systems | Inspect emergency stop, over-temperature protection, flame-failure protection, fuel shutoff, door interlocks, molten-metal spill protection, and guarding. | Safety functions should be risk-assessed, documented, tested, and aligned with applicable machinery, electrical, gas, and industrial-furnace regulations. | Review the risk assessment, safety circuit drawings, interlock test records, operator instructions, and emergency-response procedures. | 8% |
| Maintenance and Serviceability | Consider access to burners, heating elements, thermocouples, filters, refractory areas, drain points, and electrical cabinets. | Critical wear parts should have defined replacement intervals, clear maintenance procedures, and locally available alternatives where possible. | Inspect the maintenance schedule, spare-parts list, response-time commitment, training plan, and troubleshooting documentation. | 5% |
| Total Cost of Ownership | Include purchase price, installation, utilities, refractory replacement, consumables, labor, downtime, emissions equipment, and disposal costs. | Select the solution using a multi-year cost model rather than initial price alone. Energy and metal-loss costs should be calculated from measured or contractually guaranteed data. | Request a five-year total-cost-of-ownership model with assumptions, sensitivity analysis, warranty terms, and exclusions clearly stated. | 5% |
| Factory and Site Acceptance | Define measurable acceptance criteria for capacity, energy use, temperature stability, safety functions, emissions, and automation. | Use the same test method and production conditions for all shortlisted suppliers to make the technical comparison meaningful. | Include acceptance thresholds, measurement instruments, test duration, responsibilities, corrective-action rules, and final documentation requirements in the purchase contract. | 10% |
