Case Study – How a Chinese Expert Improved Casting Line Output in the Philippines

How a Chinese expert improved aluminium ingot casting line output in the Philippines by 47%. Temperature, speed, cooling, moulds, and scheduling.

In early 2024, I received a call from a recycling plant manager in Batangas, Philippines. His plant produces ADC12 aluminium ingots for export to Japan, South Korea, and Taiwan. The casting line was designed to produce 30 tonnes per day. It was producing 18 tonnes per day. The plant had orders it could not fill. The manager told me: “We are losing customers because we cannot deliver. We need to increase output without buying a new line.”

I spent five days on site. We did not replace the furnace. We did not buy a new casting line. We optimised the existing system. By the end of the following month, casting line output had reached 26.5 tonnes per day — a 47% increase. Surface rejection dropped from 9% to 2.1%. Metal recovery improved from 85% to 92%.

This is how we did it.

The Starting Point: 18 Tonnes per Day from a 30-Tonne Line

The plant operates a 5-tonne tilting rotary furnace feeding a 2-tonne holding furnace and a continuous ingot casting line. They produce 6 kg ADC12 ingots. The line runs two shifts per day, six days per week.

The problems were visible from the first day:

The plant manager admitted they had no formal measurement system. They relied on the furnace controller display. They had never used a hydrogen analyser. The operators had never been trained on the relationship between casting parameters and output.

I told him: “Your furnace is not the problem. The casting line is not the problem. The system is the problem. We need to measure everything before we change anything.”

Step 1: Diagnosing the Root Cause

I started with a full process audit. The findings were revealing.

Temperature. The metal temperature at the tundish was 682°C. For 6 kg ADC12 ingots, the target is 710–720°C. The metal was 30°C too cold. That explained the cold shuts and poor surface. The transfer distance was 9 metres. The launder was unheated.

Casting speed. The line was running at 2.4 metres per minute. For 6 kg ingots, the recommended speed is 3.2–3.5 m/min. The slower speed meant lower output and longer exposure to air.

Cooling. The cooling water temperature was 43°C. The target is 30–35°C. The spray nozzles were partially blocked. Cooling was uneven, causing thermal stresses and cracks.

Moulds. The moulds were worn. The inner surfaces had scratches and deposits. The mould release agent was applied unevenly. That caused sticking and surface defects.

Hydrogen. The hydrogen content was 0.24 ml/100g Al. The target for surface-critical ingots is below 0.15 ml/100g. The high hydrogen caused surface pinholes.

Synchronisation. The melting furnace and casting line were not synchronised. The line waited an average of 35 minutes between batches. That was lost production time.

Skimming. Operators were skimming every 20 minutes with a solid rake. The dross metal content was 43%. They were losing metal with every skim.

Scrap storage. Scrap was stored outdoors, uncovered. After rain, it was charged wet. Moisture caused steam explosions, thermal shock, and hydrogen pickup.

The root cause was clear: the casting line was not optimised for the ingot size and alloy. Temperature, speed, cooling, moulds, hydrogen, and scheduling were all out of specification.

Step 2: Fix the Temperature

The first fix was temperature. We needed the metal to arrive at the tundish at 710–720°C, not 682°C.

We made three changes:

Increased holding furnace setpoint from 735°C to 750°C. This compensated for transfer losses.

Insulated and heated the launder. We installed a ceramic fibre insulation blanket and a simple electrical heating element. Cost: $1,200.

Reduced transfer distance from 9 metres to 3 metres. We repositioned the holding furnace closer to the casting line.

We also added a second thermocouple in the holding furnace near the door. The controller now averages two readings. Temperature stability improved from ±16°C to ±5°C.

Cost: $3,100 for insulation, heating, thermocouple, and relocation.

The result: tundish temperature rose to 715°C. Cold shuts dropped by 70% in the first week.

Step 3: Increase Casting Speed and Fix Cooling

The line was running at 2.4 m/min. We increased it to 3.4 m/min. The faster speed reduced the time the metal spent in the mould, which reduced surface oxidation and improved surface finish.

We also fixed the cooling system:

• Cleaned all spray nozzles.
• Balanced the water flow across the moulds.
• Installed a simple water chiller to maintain temperature at 33°C.

Cost: $4,800 for the chiller and nozzle cleaning.

The result: casting speed increased by 42%. Cooling became uniform. Cracks dropped by 80%.

Step 4: Restore Mould Condition

The moulds were worn and poorly maintained. We implemented a daily mould cleaning routine:

• After each shift, remove moulds and clean with a wire brush.
• Inspect for wear, cracks, and deposits.
• Replace worn moulds immediately.
• Apply mould release agent evenly and thinly.
• Preheat moulds before the first pour.

We also replaced the worst moulds. Cost: $3,200 for a new set.

The result: sticking and surface defects dropped by 60%.

Step 5: Synchronise Melting and Casting

The line waited an average of 35 minutes between batches. That was lost production time.

We made four changes:

Reduced batch size from 4.5 tonnes to 3.8 tonnes. Smaller batches melted faster and reduced waiting time.

Increased holding furnace buffer capacity. The holding furnace could now hold two batches instead of one. The line never waited for metal.

Scheduled melting and casting together. The furnace operator and line operator now work from the same schedule.

Reduced skimming frequency from every 20 minutes to every 45 minutes. This reduced temperature loss and metal loss.

Cost: $0. Just procedure changes.

The result: waiting time dropped from 35 minutes to 5 minutes. Line uptime improved by 18%.

Step 6: Reduce Hydrogen Content

Hydrogen was the cause of surface pinholes. The reading was 0.24 ml/100g. The target was below 0.15 ml/100g.

We installed a rotary degasser with argon. The parameters:

We also installed a portable hydrogen analyser. The operator measures hydrogen before every pour. If the reading is above 0.15 ml/100g, the melt goes back for additional degassing.

Cost: $9,500 for the degasser and analyser.

The result: hydrogen dropped to 0.11 ml/100g within two weeks. Surface pinholes dropped by 85%.

Step 7: Improve Skimming and Metal Recovery

Operators were skimming every 20 minutes with a solid rake. That stirred the melt and created more oxide. The dross metal content was 43%.

We changed the skimming frequency to every 45 minutes. We switched to a perforated skimming tool that drains metal back into the furnace. We installed a dross press to recover residual metal from the dross. We also added a cover flux during holding.

Cost: $12,000 for the dross press and tools.

The result: dross metal content dropped from 43% to 25%. Metal recovery improved from 85% to 92%.

Step 8: Pre-Dry Scrap

Scrap was stored outdoors. After rain, it was charged wet. Moisture caused steam explosions, thermal shock, and hydrogen pickup.

We built a covered drying rack next to the furnace. Scrap is now stored under cover and pre-dried before charging. We also installed a simple scrap preheater using waste heat from the furnace exhaust. The preheater raises scrap temperature to 200–250°C, driving off moisture.

Cost: $2,000 for the drying rack and preheater.

The result: no more wet charging. Hydrogen pickup reduced. Surface quality improved.

Step 9: Train Operators and Measure Everything

We trained all operators on the new procedures:

Target tundish temperature: 710–720°C

Casting speed: 3.4 m/min

Hydrogen target: below 0.15 ml/100g

Skimming frequency: every 45 minutes

Mould cleaning: every shift

Cooling water temperature: 33°C

Scrap must be dry before charging

We also started measuring output every shift. We track rejection type and cause. The operators now see the results of their work.

Cost: $2,500 for training and measurement system.

The Results After One Month

The plant manager was stunned. He had been ready to buy a new casting line. He didn’t need one. He needed to fix the process.

What Made the Difference

Three things drove the improvement:

1. Temperature and speed. Increasing tundish temperature to 715°C and casting speed to 3.4 m/min eliminated cold shuts and increased output. This was the single biggest win.

2. Synchronisation. Reducing waiting time between batches from 35 minutes to 5 minutes recovered lost production time. The line now runs continuously.

3. Hydrogen and skimming. Rotary degassing with measurement reduced hydrogen from 0.24 to 0.11 ml/100g. Better skimming practice improved metal recovery from 85% to 92%.

I have written about how to reduce metal loss in secondary aluminium melting for ingot production and how to improve heat transfer efficiency in a rotary furnace. Both are directly relevant to this case.

What You Can Apply

If you operate an aluminium ingot casting line, ask yourself these questions:

What is your metal temperature at the tundish? If it is below 710°C, you will have cold shuts.

What is your casting speed? If it is below 3.0 m/min for 6 kg ingots, you are losing output.

What is your cooling water temperature? If it is above 35°C, you will have uneven cooling and cracks.

Are your moulds clean and in good condition? If not, you will have surface defects.

What is your hydrogen content? If you do not measure it, you cannot control it.

How often do you skim? If it is more than every 30 minutes, you are losing metal.

Is your scrap dry? If it is stored outdoors, it is wet.

Is your melting schedule synchronised with casting? If not, you are losing uptime.

These are not theoretical. They are the minimum requirements for efficient ingot casting. I have seen plants in the Philippines, Thailand, Malaysia, Vietnam, and India fail because they ignored one of these.

When to Call an Expert

You can measure these things yourself. A pyrometer, a hydrogen analyser, and a stopwatch will tell you most of what you need to know. But sometimes an experienced eye sees the system, not just the components.

The Philippine plant had a competent maintenance team. They had kept the casting line running for years. But they had never been trained on hydrogen measurement, cooling system optimisation, or furnace-line synchronisation. They did not know what they did not know.

My fee for the five-day audit and commissioning support was $13,000. The annual benefit was $510,000. That is a 39x return.

If your casting line output is below design capacity, call someone. Or use the checklists on this blog. Either way, do not wait.

Final Thoughts

Improving casting line output is not about buying a new casting line. It is about controlling temperature, speed, cooling, moulds, hydrogen, skimming, and scheduling.

In my 25 years, I have seen plants increase output by 30–50% by fixing the process, not the equipment. The furnace did not change. The people did.

If you run a recycling plant, start by measuring your tundish temperature and casting speed. If either is out of specification, fix it. You will see the difference in your output.

Internal links: How to Reduce Metal Loss in Secondary Aluminium Melting for Ingot Production, How to Improve Heat Transfer Efficiency in a Rotary Furnace, Case Study – How a Chinese Expert Optimized an Aluminium Ingot Casting Line in Malaysia, Case Study – How a Chinese Expert Solved Ingot Surface Quality Issues in Thailand, How to Choose a Secondary Aluminium Melting Furnace for Ingot Production.