Get your surface finishing under control!

Get your surface finishing under control!

Buffing mop polishing using the ROBOTsander

Mike Richardson hears how Suhner Automation has harnessed robotic technology to save time, improve repeatability and remove the grind from what can be an extremely manual and repetitive surface finishing process.

Suhner Automation says it has applied all its expertise and experience in the field of grinding and process automation to develop a new robotic technology for the purposes of surface machining to perform comprehensive grinding tasks for high-quality assemblies.

The ROBOTsander has been developed for aircraft assemblies, such as control surfaces, fuselage segments, leading edges, engine inlets and engine components, setting new standards for automated surface machining in the aircraft industry.

Suhner Automation initially decided to test its experience and knowledge in abrasive workmanship and process automation by developing a unique surface treatment technology to automate surface abrasive tasks of complex, high-value assemblies.

The result is the Suhner ROBOTsander, a highly-adaptive and capable surface treatment solution serving various industries and designed to offer significant reduction of cycle time and usage of abrasive material. The ROBOTsander meets surface treatment needs and requirements in a cost-effective manner within minimum deployment time.

The eccentric sander is powered by a 2.1kW servomotor and can rotate up to 10,000rpm

Seeing is believing

The company says proof of concept and process validation has been fully demonstrated and the requirements achieved for different customers. In the case of polishing aircraft wing leading edges, Suhner can offer turnkey solutions to its customers. Due to the 3m long, D-nose shape size of the wing slat and following the simulation evaluation, it was decided to place one 6-axis industrial robot on a linear (7th) axis. The challenge here was to deliver at least the same quality as the manual process, but within a much shorter cycle time.

In this example, the objective was to offer a stable process invulnerable to variation in the work environment. Key to a controlled process is a defined and accurately controlled rotation speed of the abrasive tool, tool angle to the surface, tool horizontal feed and surface contact pressure. This is why Suhner chose to use only electrical end-effectors, servo-motor driven in order to monitor and control the process parameters and deliver a repetitive process.

The process is typically divided into two steps: first sanding with an eccentric sander, then polishing with a buffing mop. The eccentric sander is powered by a 2.1kW servomotor and can rotate up to 10,000rpm. The buffing mop is more focused on providing high torque up to 15Nm, to take the maximum benefit from the polish paste. The two end-effectors integrate an active contact flange able to deliver a constant, off-line programmed force on the surface. The amount of material removed remains under control.

For each customer, Suhner ran an intensive programme to develop an optimised process, i.e. sanding paper, path, speed, to reach the required quality in a minimal duration. In addition, a solution was developed during this project to automatically exchange the sanding discs of the end-effector. The newly developed and Suhner patented ESW150 Abrasive Changer system enables the renewal of sanding discs in less than 10s, which is said to outperform any other available system on the market. The ESW150 offers a fast abrasive change time and reduces non-productive time to an absolute minimum during the sanding process.

By applying such an optimised process, Suhner was able to divide the consumable usage by five, whilst reducing process duration by a factor of three compared to a manual process. An evolution of the ROBOTsander is under study to combine two robots working on the part, thus reducing the process time by a factor of six.

Alongside digital factory software partner CENIT, Suhner has developed a label surface treatment technology packet for the ROBOTsander

Input equals output

By the time the part has reached the surface treatment stage, it usually means that it is at the end of the production process. This means that the part includes all its added value and is close to final delivery. A process failure, part damage or delay impacts the manufacturer’s margin on their parts and its on-time delivery performance as subcontractor. Therefore, it is critical to ensure process stability, for proper prediction and reliability.

The benefits include a fully-controllable and stable process; a fail-safe controller set up to safeguard high-value parts as well as operators; fewer consumables means less waste and an optimal use of resources; stable, repeatable working process safeguarding the high-value parts; minimal deployment time for new applications and overall cycle times reductions from digital process simulation.

Meanwhile, Suhner has installed a new robot R&D cell in its Lupfig, Switzerland facility to further develop the ROBOTsander system to include 3D surface scanning and parts recognition, optimise process development to further reduce cycle time, improved process steps, and process parameters definition (speed, force, paper type) for new customers.

During process developments, Suhner uses its expertise to evaluate the proper abrasive materials, corresponding resistance and efficiency to define the correct process parameters and save process time. Developments in offline programming are said to make it possible to run robots in a virtual process, i.e. a digital factory, before committing it to the actual shopfloor to help reduce pre-production niggles. Thanks to Suhner’s approach, each process, as well as the complete robot cell functionality can be properly analysed. This allows optimisation, performed well in advance, to the initial delivery, further reducing process risks and overall deployment time.

In close collaboration with digital factory software partner CENIT, Suhner has developed a specific label surface treatment technology packet dedicated to the ROBOTsander. Based on the CAD surface model, working parameters can be determined, digitally tested and with the use of an interpreter directly downloaded into the robot controller. Follow-on verification and validation of critical qualification, parameters can either be performed at the Suhner Robot Test Cell in Switzerland, or at any customer location worldwide.

In addition, Suhner can evaluate the proper robot and cell dimensions, thus confirming reach on the complete part, checking and correcting potential collisions or forbidden moves of the robot at the very beginning of the study.

Sanding paper exchanger compatible with eccentric and concentric pads

Factories of the future

How well can Suhner’s robotic automation align itself to the growing influence of the industrial Internet, also known as Industry 4.0 and the smart factory/smart tools philosophy?

Thomas Combemale, head of the aerospace team says the company is already onboard with the Smart Factory solution, and thanks to its extensive use of offline programming (OLP) is at the stage where this philosophy can be fully implemented. Based on Industry 4.0 objectives and the usage of the Suhner Digital Factory Monitoring System, the customer can monitor – onsite or remotely – the ROBOTsander’s performance, including online data recording, process diagnostic and optimisation, predictive maintenance and remote product support, as well as spare parts and usable management.

Recent statistics claim skills shortages and the need to recruit young talent and demonstrate what an exciting, diverse and rewarding career engineering can offer young people entering the industry. But, just how many jobs will be available when the increase in automated manufacturing processes will clearly reduce the amount of human involvement? What new jobs can be created?

Combemale says, the industry is suffering from a manpower shortage for surface finishing. It can be physically exhausting and repetitive, and because of the dust, unhealthy too. Many companies are having difficulties finding people with the correct competences for this type of work, so automation is solving this issue. Also, some of Suhner’s customers have commented that the younger generation “only wants to play with computers” and doesn’t want to integrate with dirty jobs, so this is what its robot cell proposes: simply a bigger and much more efficient tool.

Such a cell requires an automation engineer to maintain the robot, i.e. maintenance, possible new programming, plus a manual operator with process knowledge to perform local repairs, corrections or any specific jobs that do not fall into the robot’s scope is also required. Ultimately, such a robot system does not only provide cycle time and cost reduction values, but also a new work environment for skilled and talented workers.

In summary, robotic automation technology and abrasive expert knowledge, as combined in Suhner’s ROBOTsander, offers the benefits of removing manual labour from hazardous operations, improved consistency, process repeatability and quality, obviating human issues like sickness, lunch breaks and variable skills levels, and coping with production fluctuations. Meanwhile, Suhner continues the development of its automatic system to change sanding paper and ongoing research into the integration of optical technology for part calibration and tool calibration.


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