Managing Director, Böke-IE GmbH & Co. KG
Simulation with Altair Product Design of Die Cast Structural Components with Simulation
Aluminum die casting is becoming increasingly important due to many new requirements such as electromobility. How can simulation support the structural component product development in a positive way?
The foundry industry is not immune to a constantly changing world. Trends in the automotive and aircraft industries are regarded as key drivers. With the advent of electromobility, ever lighter vehicle components are becoming increasingly relevant. This also includes die cast structural components. This growing market places high demands on foundries.
Nevertheless, in a European comparison, Germany is a pioneer in the use of aluminum casting with more than 1.2 million tonnes (see Figure 1). According to a forecast by McKinsey, global aluminum consumption in the automotive industry will even triple by 2030.
Structural Components on the Rise
Structural parts are produced in a horizontal cold chamber process under vacuum. Large structural parts are already popular today and are successfully used in various model series such as the T-models from Mercedes-Benz, the Audi A8 and the Cadillac ATS (see Figures 2 - 4).
Foundries that want to take advantage of this development must have the proper know-how and suitable facilities. Read now how die casters identify potential for cost reduction and what role cooperation plays in this.
The increasing globalization causes new challenges, e. g. automobile manufacturers expect their suppliers to operate own manufacturing facilities near the car factories. One of the greatest challenges is the number of different engines. Regardless of whether electric or hybrid vehicles are used, lightweight design always plays a key role so that die casters have good market opportunities with the design of structural components.
Advantages of Aluminum Die Casting
The use of cast aluminum structural components by well-known OEMs indicates many advantages. Low density, good castability and machinability are just a few of the many advantages:
- Favourable strength properties
- Good chemical, weather and seawater resistance
- Good suitability for connection work
- Versatile surface treatability
- Spark-free (chips), non-combustibility
- High electrical conductivity
- High thermal conductivity
- Low melting point
- Health harmlessness
- High recycling rate (> 80%)
- Highly productive, economical and automatable
- Near-net-shape component production (function integration)
Disadvantages of Aluminum Die Casting
In addition to a number of advantages, aluminum die casting also has disadvantages:
- Low elongation (without special process)
- Conditionally weldable (without special process)
- Limited corrosion resistance for alloys containing CU
- Steel as tool-material is dissolved by Al-Leg
- Solubility of hydrogen in AL melts
- Process-related mould filling highly turbulent
- Extremely high power consumption during primary production
Product Design with Altair Inspire Cast Simulation
But how can the optimized product design function by means of simulation? The aluminum die cast structural part of the strut dome with the alloy AlSi10MnMg, a weight of 5.9 kg, dimensions of 530 x 520 x 440 mm and a wall thickness of 2.5 mm is shown. This component from Figure 5 is to be produced in a vacuum die casting, CNC machining and T7 heat treatment. Even before the first simulation, the following questions arise:
- Where should the gating system be placed?
- Are overflows required?
- Are cores needed?
- Are squeezers needed?
- Where can cooling be placed?
- Where do I need to heat?
In order to be able to compare the results better, two simulations with two different sprue systems are illuminated laterally and centrally in the following (see Figure 6). The total time required of nine hours consists of the simulation, the evaluation of the results and the subsequent evaluation of the respective sprue system.
Figures 7 to 9 show the result of the simulation with the lateral sprue system. The filling is relatively evenly distributed and there are fewer overflows on the sides. Another advantage is the use of a simpler tool. The resulting porosity in the threaded holes is a fundamental disadvantage which can only be avoided by additional cores or squeezers.
If the structural part is cast centrally, the filling front is slightly more uneven and overflows are necessary on all four sides (see Figures 10 - 12). Production requires a more complex tool that involves higher costs, a slower cycle and more complex production. Porosities in threaded holes and porosities close to the gate are also disadvantages here.