Surface quality in industrial manufacturing is one of the most critical stages determining both the aesthetic value and functional performance of a product. However, manual sanding and polishing processes applied to metal, stainless steel, aluminum and composite surfaces have now reached their limits in terms of efficiency and consistency.
In industrial production, surface quality is one of the most critical stages determining both the aesthetic value and functional performance of a product. However, today; manual sanding and polishing operations applied to metal, stainless steel, aluminum and composite surfaces have reached their limits in terms of efficiency and consistency.
As Podim Robotics, backed by Podim Zımpara's deep experience in abrasive technologies, we are developing robotic sanding solutions to overcome this bottleneck and transform surface finishing into a "measurable methodology."
Why Robotic Surface Finishing?
Robotic systems are not merely an automation pursuit, but also tools for quality standardization and efficiency. Operator fatigue in manual processes and individual skill differences cause variability in the final product, while a well-designed automation system can turn this into an advantage;
• Sustainable Quality: Consistent and continuous application of the same surface finishing parameters to each part ensures sustainable quality.
• Occupational Health and Safety (OHS): By having robots assume dusty, noisy processes that are quite harmful to operator ergonomics, significant improvements in worker health and safety are achieved.
• Efficiency: Performing repetitive, exhausting and safety-threatening processes through operators is quite costly. Automating such demanding and difficult-to-control processes yields high efficiency gains.
• Traceability: Controlling and monitoring a process that has been reduced to a methodology becomes easier. Digital process monitoring becomes possible, and consequently error rates decrease.
Application Areas and Scenarios
To better understand robotic sanding cells, we can fundamentally divide them into two categories:
Scenario Where the Robot Brings the Abrasive to the Workpiece: This is generally preferred for weld cleaning, pre-paint surface preparation or polishing of large-bodied parts. With active/passive pressure compensation systems and high-torque spindle motors integrated into the robot's 6th axis, perfect conformity to the surface form is achieved.
Scenario Where the Robot Brings the Workpiece to the Abrasive: This is ideal for processing small and medium-sized parts at fixed belt sanding or mop sanding stations. In this scenario, the pressure applied to the part and parameters such as sanding speed are controlled by the sanding machine.
Current Trends and Automation Technologies in Robotic Surface Finishing
Let us address the fundamental technologies that make robotic surface finishing "smart," along with their advantages and possible challenges:
1. Active and Passive Pressure Compensation Units
These are systems that adjust in real time the force that the robot applies to the surface.
• Benefits: By compensating for surface form irregularities and dimensional discrepancies due to manufacturing tolerances, it ensures the desired surface is obtained. By keeping thermal load on the part under control, it minimizes burn risk. It prevents problems that will arise from abrasive media wear over time. It also compensates for imperfections in the robot program, making it the fundamental factor that ensures healthy operation of the systems.
• Possible disadvantages: When a pressure compensation unit with the correct specifications is not selected, the problems it creates, combined with relatively high initial investment costs, can result in a sanding cell with a high payback period that creates inefficiency for the user.
2. Image Processing (Vision) and 3D Scanning
Can be used for different purposes; workpiece identification-recipe selection, automatic path generation for the robot, quality control and so on…
• Benefits: Eliminates part positioning errors and makes quality control processes autonomous within the robotic cell. Allows processing of parts with different variations on the same line. Prevents costly "accidents" resulting from incorrect operator panel entries.
• Challenges: Due to the nature of surface finishing, dust and sparks generated can reduce the performance of optical sensors. If proper integration is not provided, it does not work efficiently. These are systems sensitive to dust in the environment or changing lighting conditions. They must be designed with hardware protections and customized software by an expert team tailored to the process requirements.
3. Offline Programming (OLP) Software
Enables path generation through simulation based on CAD/CAM data without stopping production.
• Benefits: Reduces programming time by up to 80% and minimizes robot downtime. Provides the ability to test collision risks that could occur in the real world on a digital twin.
• Challenges: Millimetric deviations between the digital model and the physical part require fine-tuning in the field. Having high technical competence among the personnel who will use the software is a critical requirement.
4. Modular and Interchangeable Tool Holders
These are automatic abrasive or tool changing systems.
• Benefits: Enables all stages from coarse sanding to precision polishing to be performed on a single robot cell without manual intervention. Reduces operator intervention and improves cycle time.
• Challenges: Wear in mechanical change systems can cause loss of precision over time. Complex tool changers make cell layout design more complex.
5. Collaborative Robots (Cobots)
These are systems that can work safely alongside humans.
• Benefits: Reduces the need for safety barriers, saving floor space, and offers ease of programming. Offers quick setup advantage for flexible production lines.
• Challenges: The high forces and speeds required in industrial sanding and grinding can push cobot safety limits. Lower load capacities compared to standard industrial robots in heavy industrial conditions can be a constraint.
Furthermore, although cobots are suitable for working alongside humans, the abrasive motor speeds used in surface finishing vary between 3,000 RPM and 30,000 RPM. Consequently, most robotic sanding-polishing processes are not collaborative applications. In some applications, use with area scanner work safety sensors can be provided.
Engineering Details That Determine Success: Critical Questions Before Design
Establishing a robotic surface finishing cell is not merely programming the robot, but solving a multi-variable equation. Before moving to the design phase, we clarify process requirements under four main headings:
• Part Requirements: What is the material alloy and type? Are target surface roughness values (Ra-Rz) or gloss/surface quality values defined? If there is no measurable target value, how is the "OK" part defined? These definitions must be stated clearly. Also, the roughest part samples expected to undergo surface finishing in the cell and the most common part samples must be identified.
• Abrasive Product Selection: Will the operation be grinding, sanding, deburring or polishing? What mineral type, grit size, abrasive form and backing structure should be used for this operation? These questions need to be answered before design. Each alloy to be machined has different process parameters and different abrasive product requirements. When determining abrasive products, these requirements must also be taken into account.
• Abrasive Machine and Parameters: Will the operation be performed on a fixed belt/mop sanding machine? What should be the path the robot follows, movement speed and pressure force? Should active or passive pressure control be preferred and what should the damping rate value be?
• Robot and Equipment and Process Compatibility: Is the robot's load capacity (payload) suitable? Will the robot hold the part or the abrasive? Most importantly, how rigid can the robot remain against the high forces during grinding?
Determining these and similar requirements before design and ensuring the configuration advances based on this structure is the path to producing a healthy sanding cell. Otherwise, inefficient sanding cells result. It should not be forgotten that the cost of meeting requirements overlooked during the design phase after cell setup is far higher.
Podim Robotics Roadmap:
To ensure successful process implementation, as Podim Robotics we follow a four-stage roadmap:
1. Identify Opportunities: We analyze problem areas, efficiency potential and the breakeven point of the investment.
2. Current Process: We determine process requirements and clarify part specifications.
3. Proof of Concept (PoC): We perform demo work on your actual work parts in our test laboratory to prove process feasibility and estimated cycle times.
4. Robot Cell: We build the final cell in compliance with work safety standards with a user-friendly interface.
We aim to transform surface finishing from being the weakest link in your production line into the most powerful stage that increases your competitive advantage. Correct integration of these technologies in surface finishing processes can fundamentally change a company's production capacity and quality standards. As Podim Robotics, with our four-stage roadmap from opportunity identification (PoC) to post-installation support, we aim to help our industrial partners complete this technological transformation with minimum risk and maximum efficiency.
References
1) Siciliano, B., & Villani, L. (2012). Robot Force Control . Springer Science & Business Media.
2) Zeng, X., Zhu, G., Gao, Z., et al. (2023). "Surface polishing by industrial robots: a review." The International Journal of Advanced Manufacturing Technology
3) 3M Abrasive Systems Division "Robotic Grinding and Finishing Resource Guide."
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