Introduction
Countermeasures against global warming and tightening fuel efficiency regulations in various countries are unavoidable challenges for the manufacturing industry, including the automotive sector. In particular, electric vehicles (EVs) and hybrid vehicles (HVs) require even greater weight reduction than conventional cars due to their increased battery capacity. Vehicle weight reduction is a key strategy for simultaneously improving fuel efficiency and reducing environmental impact, and it has become a critical factor that will determine future competitiveness.
The numerical effects are also clear. According to a report by the Ministry of Land, Infrastructure, Transport and Tourism, reducing vehicle weight by 100 kg improves fuel efficiency by 3-5% and can reduce CO2 emissions by 8-12 g/km [MLIT, Fuel Economy Standards for Motor Vehicles]. Statistics from the International Energy Agency (IEA) also list weight reduction as one of the most effective measures for reducing CO2 in the transportation sector [IEA, Transport Outlook].
This is where aluminum alloys come into focus. They are about one-third the weight of steel, and advancements in high-strength technology have ensured their safety. Furthermore, with a recycling rate of over 90%, the use of recycled aluminum can reduce CO2 emissions by up to 95%, making it a material directly linked to reducing environmental impact.
How Aluminization Achieves Weight Reduction
Replacing Different Materials with Aluminum Castings
Simply changing conventional iron and steel parts to aluminum castings can reduce weight to about one-third. In particular, by integrating parts using “casting-in” technology, it is possible to achieve process reduction and cost reduction simultaneously with weight reduction [Karumo Kohki Co., Ltd.].
Thin-Walling Technology
The latest casting technology has made it possible to achieve thin walls with a minimum thickness of 1 mm. Designs that reduce conventional draft angles to cut unnecessary material are also advancing, leading to weight reductions in the single-digit percentages that directly translate to improved fuel efficiency.
High-Strength Aluminum Forging
The perceived weakness of insufficient strength has been overcome by high-speed isothermal forging. This process achieves a weight reduction to one-third that of iron while retaining 81% of its strength, and has been adopted for mass production of steering components (tie rod ends) for EVs [Tobata Turret Works Co., Ltd.].
Case Studies of Aluminum Weight Reduction in the Automotive Industry
Adoption in EV/HV Parts
Aluminizing engine blocks and cylinder heads can achieve a 20-30% weight reduction. As a result, this simultaneously improves fuel and electric efficiency, and also contributes to reducing exhaust gas emissions.
Innovation in Body Structure
The “Gigapress” introduced by Tesla, Inc. reduced the number of body parts from several hundred to just a few dozen through integrated aluminum casting. This achieved both rigidity and weight reduction, directly leading to an extension of cruising range, i.e., improved fuel efficiency.
Other Application Examples
Progress in “improving fuel efficiency and reducing environmental impact through weight reduction” is being made in a wide range of fields, including electric-assist bicycle frames (using a combination of magnesium and aluminum), achieving over 20% weight reduction with aluminum bodies for railway cars, and the use of aluminum-lithium alloys in aircraft.
Environmental Impact Reduction and Sustainability
Recyclability
The recycling rate for aluminum is over 90%. By using recycled aluminum, CO2 emissions can be reduced by 95%, creating a synergistic effect of improved fuel efficiency and reduced environmental impact.
Energy Saving in the Manufacturing Process
Energy savings are realized through the use of die casting and 3D printed casting molds. At Yamato Keikinzoku Vietnam, they achieve both reduced transportation energy and cost competitiveness through local production.
Future Outlook
The effects of weight reduction, fuel efficiency improvement, and environmental impact reduction are expected to intensify with the expanded application to battery cases and motor housings for EVs, as well as research into carbon fiber reinforced aluminum (CFRA).
Success Stories
- Mass-Produced Aluminum Tie Rod Ends Achieved a weight reduction to 1/3 that of iron while securing 81% of its strength. Its adoption in actual vehicles extended cruising range, directly contributing to improved fuel efficiency.
- Tesla’s Gigapress Reduced the number of parts through large-scale integrated aluminum casting. It simultaneously achieved weight reduction and increased rigidity, also contributing to manufacturing efficiency and reduced environmental impact.
Failure Stories
- Special aluminum parts for luxury cars were difficult to mass-produce because the cost of isothermal forging was more than double that of iron.
- Special molds for thin-walling succeeded in reducing weight but led to increased costs, resulting in limited market adoption.
Conclusion
Aluminization is a sustainable technology that can achieve both improved fuel efficiency and reduced environmental impact. It is expanding, primarily in the automotive industry, and will continue to evolve through fusion with electrification and composite material research.
In terms of procurement strategy, the model of Vietnamese production + Japanese-style quality control is gaining attention as an optimal solution that combines cost competitiveness and reliability.
Overall, aluminization is a foundational technology that realizes the “lightness and environmental performance” essential for the next-generation mobility society, and it will be a decisive factor in strengthening the competitiveness of the manufacturing industry.