400-800kg Capacity | Elliptical Resistance Crucible Furnace | Aluminum Alloy Melting & Holding Casting System

1. Product Overview

This elliptical resistance crucible furnace uses resistance heating and graphite crucible conduction, specifically designed for melting and holding aluminum and aluminum alloys. Equipped with programmable logic controller (PLC) and touchscreen control system, it features three operating modes: cast curing, preheating, and working mode. Cascade PID temperature control achieves precise aluminum liquid temperature control. Typical applications include aluminum alloy melting and liquid supply stations for die-casting, gravity casting, and sand casting.

2. Industry Challenges & Root Cause Analysis

Crucible cracking during preheating and first use:New crucibles used without proper preheating crack due to thermal stress or residual moisture. Root cause: lack of standardized cast curing and preheating procedures.

Insufficient aluminum liquid temperature control accuracy:Large temperature fluctuations affect casting quality consistency. Root cause: slow response of single-loop control, difficult coupled control of chamber atmosphere and aluminum liquid temperature.

Improper crucible installation shortens service life:Wrong crucible base selection, eccentric installation, or improper insulation cotton sealing cause localized overheating or restricted thermal expansion. Root cause: lack of installation specifications and illustrated guidance.

Charging and slag removal operations damage crucible:Horizontal ingot placement, throwing materials, and scraping crucible walls with slag removal tools cause mechanical damage. Root cause: inadequate execution of operating procedures.

Lack of energy consumption measurement:Melting energy consumption cannot be counted – difficult cost accounting. Root cause: lack of electricity metering and data recording functions.

3. Solution

3.1 Three Operating Mode Program Control:Equipment presets "Cast Curing", "Preheat Mode" and "Working Mode" – switchable via touchscreen dropdown menu. Cast curing mode is a dedicated program for first heating of new crucibles; preheat mode is secondary preheating after first cast curing; working mode is normal melting and holding state. Programs include heating rate, holding time, power limit and other parameter settings.

3.2 Cascade PID Temperature Control:Cascade PID control – inner loop (atmosphere temperature) setpoint dynamically generated by outer loop (aluminum liquid temperature) PID output – balancing fast response and overshoot suppression. Aluminum liquid temperature control accuracy ±5℃ (holding stage), measurement range K type 0~1300℃. Two measurement channels: ceramic thermocouple (φ22×350mm) for atmosphere temperature, aluminum liquid thermocouple (φ16×500mm/φ50×500mm) for aluminum liquid temperature.

3.3 Crucible Installation & Usage Specifications:Provides illustrated guidance for crucible base selection (shape matching crucible bottom, about 2cm larger), crucible installation and fixing (reserving thermal expansion space), crucible preheating procedure (200℃ holding 30min → drying 4h → rapid rise to 800-900℃ holding 1h → adjust to working temperature), charging specifications (vertical ingot placement, expansion gap, ≤80% capacity), slag removal specifications (daily, dedicated tools, avoid scraping crucible walls).

3.4 Safety Protection & Alarms:Leakage protection, over-temperature protection. Control cabinet with three-color indicator lights (Red: Level 1 fault alarm; Yellow: Level 2 warning; Green: automatic operation indicator). Touchscreen with alarm event recording – buzzer sounds on fault, can be muted, new faults automatically unmute. I/O monitoring interface displays PLC input/output point status in real-time.

3.5 Energy Statistics & Data Management:Equipped with electricity meter – touchscreen energy statistics interface displays cumulative power consumption and daily consumption for the last two weeks – facilitating cost accounting and energy management. System parameters interface displays equipment model, rated load, heating power, heating current, manufacturing date and system clock calibration.

4. Technical Specifications

5. Selection Guide

5.1 Recommended Scenarios

• Centralized melting and holding for aluminum die-casting workshops

• Aluminum liquid supply for gravity casting and sand casting lines

• Small-to-medium batch aluminum alloy melting stations

5.2 Key Selection Considerations

1. Capacity requirements: Select 400kg/600kg/800kg based on single-batch aluminum demand

2. Melting efficiency: Full load melting time ≤4h – verify meets production cycle

3. Power supply: 380VAC/50Hz 3-phase 5-wire, 66/90/105kW capacity per model

4. Crucible selection: Matching graphite crucible and base required – cast curing program must be executed for first use

5. Site conditions: Verify control cabinet size 650×600×400mm and furnace installation space

6. FAQ

Q1: How to operate a new crucible for the first time?

A: Must execute "Cast Curing" mode. First hold at 200℃ for 30 minutes (no material), dry for 4 hours to evaporate surface moisture; then rise quickly to 800-900℃ and hold for 1 hour, rapidly passing through the graphite oxidation-prone temperature range; then adjust to working temperature. No re-preheating needed after first preheating unless crucible becomes damp.

Q2: How is aluminum liquid temperature control accuracy ensured?

A: Cascade PID control – outer loop is aluminum liquid temperature, inner loop is atmosphere temperature. Inner loop setpoint dynamically generated by outer loop PID output – fast response with overshoot suppression. Aluminum liquid control accuracy ±5℃ (holding stage). Temperature measurement values can be calibrated per formula in system parameters interface.

Q3: How to install the crucible correctly?

A: Crucible base should match crucible bottom shape, about 2cm larger. Place crucible in furnace center, bottom higher than lowest heating element row, seal between top and furnace rim with insulation cotton. Resistance furnace crucible must avoid contact with heating elements to prevent localized overheating.

Q4: What are the charging precautions?

A: Metal material must be dried before adding. Ingots should be placed vertically with expansion gap from crucible wall – never horizontally (thermal expansion damages crucible). Place gently, do not throw or pour. Crucible capacity not exceeding 80%. Small pieces can be added first as base for large ingots.

Q5: What are the slag removal frequency and tool requirements?

A: Additives and impurities form slag adhering to crucible wall during melting – additive components corrode crucible wall – remove slag once daily. Use dedicated tools before slag solidifies, avoid scratching crucible wall. Multiple solidified slag layers affect heat conduction and cause crucible cracking during heating expansion.

7. Why Choose Wuxi Wondery

• Three operating mode program control: Cast curing/preheating/working modes – dedicated program for new crucible first heating

• Cascade PID precise temperature control: Outer aluminum liquid + inner atmosphere dynamic setting – accuracy ±5℃

• Comprehensive crucible usage specifications: Base selection, installation, preheating, charging, slag removal – fully illustrated guidance

• Safety protection and alarms: Leakage/over-temperature protection + three-color indicator + alarm recording + buzzer mute

• Energy statistics function: Electricity meter – cumulative and bi-weekly daily consumption query

• Full range coverage: 400/600/800kg capacities – heating power 66/90/105kW

• Full support: Product manual, installation instructions, operation training, and technical support