Greater efficiency and precision in aluminium machining
Whilst lightweight construction using suitable materials and structures has always been a key focus in the aerospace sector, the use of aluminium to reduce weight has also steadily increased in the automotive industry and has received a further boost with the rise of electromobility. With decades of experience in the design, production and use of tools for aluminium machining, MAPAL is the leading technology partner for the machining of aluminium components.
Material expertise as the key to optimal machining processes
Aluminium and aluminium alloys are, in themselves, easy to machine. As the cutting forces are low, users can achieve high cutting rates and, in particular, long tool life with appropriate process design. However, aluminium alloys also have specific properties that need to be managed. Furthermore, the geometries of the components and the ever-increasing demands on tolerances and process capability contribute to the challenges involved in machining aluminium.
Aluminium alloys can generally be classified into the main categories of cast alloys, wrought alloys and powder metallurgical alloys, although it is primarily the first two that are relevant for machining. In the case of cast alloys, the desired properties of the components are achieved through various alloying elements and by taking the relevant casting process into account. During casting, the aim is to get as close as possible to the final shape of the component in order to simplify mechanical machining. This ‘near-net-shape’ technology has become particularly well established in mass production.
When it comes to machining cast parts, the silicon content is the key factor amongst the alloying elements, as it has a significant influence on wear and tool life. In the case of wrought alloys, too, the desired properties are influenced by the alloying elements; however, the silicon content is very low here to ensure non-machining formability. To achieve good strength, stability and fatigue strength here as well, other alloying elements are used. This results in cold- or heat-treatable alloys, which are processed into semi-finished products and subsequently machined.
Solutions for parts manufacturing and assembly in the aerospace industry
The aerospace industry uses MAPAL tools both for part machining – that is, the manufacture of components that are assembled into sections of the fuselage or a wing – and for final assembly, in which the individual sections are assembled into the complete aircraft.
In the part machining of aluminium components, the part is very often machined from solid material. Material removal rates of more than 90 per cent require efficient volume machining in order to remove as much raw material as possible in the shortest possible time. High-performance tools are a key factor here. During final assembly, the tools must cope with widely varying requirements. Here, it is often not only aluminium that is machined, but also other lightweight materials such as titanium or fibre-reinforced plastics in the same machining sequence. These so-called ‘stacks’ – combinations of materials – present a particular challenge, as the machining properties of the combined materials vary greatly and the tool must meet these mixed requirements.
To save weight, the aviation industry has always used aluminium for its components. In addition to its favourable strength-to-weight ratio, the material also meets other requirements such as corrosion resistance, fatigue strength and low embrittlement. As such, there is a high demand for machining solutions for aluminium in parts manufacturing, but also, in particular, in the final assembly of aircraft.
Greater range with every kilogram saved
Weight reduction is also a key focus in the development of electric vehicles: After all, every kilogram less means greater range and lower CO₂ emissions2. Among the mechanical machining processes for components in electric vehicles, there are some that can be managed very effectively using familiar processes and tools. However, new systems and components are inevitably finding their way into electric vehicles, which, due to their function, must be newly developed in terms of geometry, precision and/or material properties. In particular, given the scale of production volumes within the automotive industry and the associated familiar demands for process stability, consistent component quality and low costs, the tooling industry must provide solutions.
One example of such specific requirements is electric motor housings. The large stator bore, with diameter tolerances in the range of IT6 to IT7 and roundness and cylindricity of 20 to 30 µm or less, combined with other functional surfaces designed to accommodate the rotor and gearbox components, demands the highest levels of accuracy in terms of form and positional tolerances.
Another example is large battery trays, the main structure of which consists of extruded profiles made from low-silicon aluminium. Here, the challenge lies in controlling chip formation and burrs, as well as machining the very large components at productive cutting parameters without causing vibration. This also applies to the trend towards mega- or gigacasting, where large-area structural components are no longer made up of individual parts but are cast in a single piece. The size and tendency of the components to vibrate require special tool geometries for low-vibration machining with high precision. Another challenge in this context is posed by new aluminium alloys that produce long chips, the machining properties of which need to be mastered.
Aluminium is also used in many other industries due to its properties. Depending on production volumes and the variety of variants, users are increasingly turning to standardised machining solutions for components involving a high proportion of machining. However, even here, aluminium components are produced in large quantities that place high demands on bespoke solutions. For example, in fluid technology, components such as pneumatic valve housings or pneumatic cylinders are manufactured in high volumes. For sectors with high product variation and low production volumes, standardised tooling solutions are advisable.
Extensive product and application portfolio for aluminium
MAPAL has developed an extensive product and application portfolio based on its many years of experience and the countless solutions devised for machining aluminium. For bore machining, the classic applications of fine boring, reaming and boring are comprehensively covered. With its guide rail technology for fine boring, MAPAL achieves the highest levels of accuracy in terms of diameter, roundness and cylindricity in components. For solid-edge tools used in reaming and boring, MAPAL offers a unique range of PCD tools, spanning from simple tools for diameters with a chamfer to highly complex tools for multi-stage bore geometries. A wide selection of solid carbide drills and drills with indexable inserts is also available for drilling into solid material. Particular challenges in this area include deep drilling and dry drilling, each of which requires highly specialised geometries and expertise.
For milling aluminium, MAPAL offers a wide-ranging range of face mills, volume mills, end mills and special designs. For face milling, for example, series are available with cassettes or indexable inserts, as well as in fixed designs. The cutting materials used include PCD and various grades of cemented carbide, which cover a range of cutting depths in combination with the required surface finishes and profiles. One example of this is the creation of a special cross-cut pattern for sealing surfaces. In addition to its universally applicable range of end mills made from solid carbide or with PCD cutting edges, MAPAL offers products that meet specific requirements, such as increased accuracy, vibration-prone components or high-volume machining.
Engineering for perfect aluminium machining
The product range and extensive manufacturing expertise form the basis for the optimal machining process for aluminium components. However, tools alone are not enough. It is the art of engineering that transforms a broad product and application portfolio into the perfect solution. This is where MAPAL’s true strength lies. Its long-standing experience and the continuous development of new solutions for the production of aluminium components make the tool manufacturer a leading solution provider in this field. The focus is always on the user.
According to MAPAL’s philosophy, the perfect solution is only one that is precisely tailored to the customer’s needs and requirements. What is expected here is not over-engineering, but the requirement-oriented design of machining processes. MAPAL sees itself as a solution provider and technology partner and, unlike a mere tool supplier, does not merely consider the technical aspects but puts itself in the customer’s shoes. This customer-centric approach underpins the ‘Basic-Performance-Expert’ solution concept and enables MAPAL to ‘tailor’ tools to the customer’s specific needs.