Robotics for Gigacasting

SIR Soluzioni Industriali Robotizzate has carved out a significant niche in the aluminium foundry sector with the introduction of robotic automation in gigacasting. Through bespoke applications, high precision, speed and ease of operation of the robots, the company offers solutions that significantly boost production efficiency and quality. In the manufacture of large aluminium die-castings, SIR carries out removal, degassing (shearing and/or plasma cutting) and fine deburring with precision, speed and reliability. These characteristics position SIR as a key player in automation technology for the foundry and automotive industries.

The removal of components from the Gigapress

The manufacture of components using Gigapresses is a complex and technologically demanding process, in which the interaction between the press and the robot used to remove the components plays a crucial role. Due to the considerable size of the gigapress and the cast component, the robots typically used in this application have a high payload and are mounted on a rail with a transverse travel range capable of reaching the centre of the mould and then moving outside the machine doors: this significantly extends the robot’s already extensive range of motion. The cast part consists of the component itself, the gating system, and the sprues and vacuum channels required to ensure its integrity. As soon as the casting is accessible, the robot enters the machine and grips the casting with a multi-jaw gripper. To facilitate removal and ensure it is carried out effectively, the Gigapresse partially ejects the casting from the mould using integrated ejectors.

To prevent deformation caused by the high temperature (approx. 600°C) and the weight of the component, the robot grips the casting at predefined points, which are generally agreed with the customer. A sensor system integrated into the robot’s gripper detects the presence of the gating system and certain sprues at specific strategic positions, ensuring that the component has been cast correctly. Additional checks can be carried out, depending on the customer’s requirements, using fixed sensors, 3D vision systems or thermal imaging cameras. Once the robot has left the machine’s working area and the various quality and integrity checks have been carried out, the control programme authorises the mould blowing and lubrication system to start its cycle, so that the Gigapresse can proceed with the next casting. The sequence of movements and checks is designed to optimise cycle time and increase production.

Deburring the casting

After removal, the production cycle includes a deburring phase to remove the gating system and flash. This process can be carried out by deburring with a Giga-Trim press: in this case, the casting must be quenched by immersion in a water tank. The alternative method used by SIR for deburring is based on plasma cutting: this solution allows the casting to be machined at temperatures close to those at the time of extraction, thereby avoiding the need for quenching. After deburring, if required for logistical reasons, the casting can be air-cooled; the cooling times are significantly reduced thanks to the prior removal of the gating system, which accounts for a considerable percentage of the casting’s total mass. Air cooling is generally much less stressful than quenching, which means the casting’s geometry is better preserved. After deburring, the component is identified with a Datamatrix code for production data traceability; this is marked onto the component using a laser unit.

The advantages of plasma cutting: flexibility and cut quality

Thanks to a fruitful collaboration with several experienced manufacturers of plasma generators, SIR was able to optimise the cutting process by mounting the plasma torch on the robot. The resulting solution proved to be the most cost-effective and efficient alternative to deburring for removing flash and gate systems in one-piece cast frames, offering convenience, flexibility and ease of use. Thanks to their adaptability, the robots can execute various cutting paths on different components, enabling significant cost savings. Plasma cutters ensure lower consumption and lower costs compared to alternatives and enable clean cuts that require less post-processing in subsequent stages. When changing the component type in production, there is no longer any need to replace expensive and bulky moulds: simply reprogramming the robot paths, combined with any necessary adjustment of the reference tool and the casting support, is sufficient. To account for possible part deformation, the robotic cutting cell is equipped with a 3D vision system capable of detecting three-dimensional differences between the actual casting and the nominal part, and consequently adjusting the robot’s local path.

From extraction to fine deburring: a success story in the automotive industry

An application recently developed by SIR for a major automotive customer demonstrates the effectiveness of this solution. The robotic system in question deburrs aluminium castings, in particular front and rear automotive subframes. The system comprises handling robots that load and unload components into several process cells, where other robots carry out plasma cutting and the subsequent removal of flash and sprues. The robotic system can be followed by additional fine-deburring cells. Fine deburring involves the use of pneumatic spindles with compensation, fitted with rotary files or abrasive belts, to remove the burrs formed on the mould joint profiles.

For the deburring of large components, such as those produced by gigapresses, a TOB (Tool On Board) deburring solution is required, in which the component to be machined is positioned on a fixed tool or mounted on an axis-controlled rotary tool. Pneumatic compensation of the deburring units is generally used in all SIR processes: it enables control over the variability in burr sizes, as the stiffness of the compensation can be adjusted programmatically according to specific requirements.

The robot’s pneumatic spindles are fitted with automatic tool changers: this allows different types of tool to be used during the work cycle, which is often necessary due to the nature and position of the burrs to be removed. Where necessary, an automatic EOAT (End-of-Arm Tooling) changeover system is provided: this is essential when the tools used in the process require rotational speeds and/or power ratings that are incompatible with the technical specifications of a single pneumatic spindle. The automatic EOAT changeover system even allows the use of deburring robots (developed and patented by SIR) that operate with abrasive belts: these are also fitted with a pneumatic balancing system and enable automatic belt changes.

The SIR deburring cells are therefore fitted with an internal magazine designed for the exchange of tools (both multi-edge tools and abrasive belts) and, where necessary, for the exchange of EOATs during the machining process. The tools are also fitted with an automatic re-conditioning mechanism in the event of wear: thanks to a turntable, the operator can load new tools from outside the cell without interrupting the robot’s work cycle. Tool lubrication and presence checks are, of course, scheduled cyclically as required. Machining residues are extracted via a metal mesh belt conveyor, which directs them into a container outside the cell. Once deburring is complete, the component can undergo a 3D vision inspection to verify the successful outcome of the process. The entire process, from removal from the gigapress to the final inspection of the component, is designed to increase productivity and ensure the highest efficiency and quality of the manufactured parts.