By: Sushmita Das
The persistent need for deburring gears machined from solid stock remains as long as gears are cut or hobbed in this manner. A traditional approach to gear deburring involves using a pneumatic grinder, which offers high RPMs, various grits, and tool styles, making it a widely adopted manual deburring method. Despite its popularity, the outcome of manual deburring, like that with a manual mill, heavily relies on the skill of the operator. The edge finish of each gear tooth is directly influenced by the operator’s grinding proficiency, introducing a potential for human error. Even with skilled labour, the unavoidable direct labour expense associated with manual deburring makes it less viable in the global competitive landscape, particularly for high-production gear.
Automated deburring methods, albeit simpler, have existed for years. Some machines employ a pneumatic die grinder with a cutting wheel or an abrasive brush to traverse each tooth while the pinion or gear rotates. Although these methods are suitable and effective for certain gears, they follow a universal approach, treating each gear model and style similarly. This uniform process may not yield optimal results for every gear model, making it a less nuanced and adaptable solution.
CNC machines were once considered a luxury for small businesses, but today they are commonplace. Just as multi-axis CNC machining centres have become standard, the manufacturing landscape is evolving with the rise of six- and seven-axis robots, especially in gear production.
Opting the robotic gear manufacturing involves deciding between a dedicated module for specific needs or a comprehensive system covering all processes. For example, a specialized robotic deburring cell can automate the process but still requires non-value-added labour for loading and unloading machines. A manufacturing system takes a holistic approach, optimizing every aspect of gear-making. The robot handles tasks like retrieving gear blanks, loading and unloading machines, deburring gears, and even packaging. This system allows autonomous operation, reducing the need for direct labour. One operator can oversee multiple systems, making the process more efficient. Once the system’s scope is defined, attention turns to specific processes and equipment needed for execution.
Every automation project must be initiated only after addressing key questions such as: where are the parts sourced, what processes are required, and where do the parts proceed afterwards? Although seemingly simple, these answers profoundly shape the final cell or system, dictating content and cost.
If aiming for largely unattended operation, the way parts are received, influences cell cost and complexity. The challenges differ significantly for bulk metal containers of forged, uncut pinions compared to neatly arranged flat gear blanks or round stock on a conveyor. The pivotal factor is whether we know where the parts are. If yes, the robot is programmed to go to specific locations, pick up the gear, and present it. If not, options include introducing a feeding device to orient parts or providing the robot with added functionality and vision capabilities. Vision-guided robotic applications range from basic 2D systems for part positioning to advanced 3D systems mimicking human hand-eye coordination.
Vision-guided picking offers flexibility compared to hard automation, ideal for high-SKU, low-volume scenarios with frequent changeovers. Once the parts are secured, the cutting or hobbing process becomes a critical, time-consuming aspect. To ensure the cutting machine’s priority, robots use multiple sets of tooling to minimize downtime. This quick part exchange and resumption of cutting prevent violating the manufacturing rule of not starving a bottleneck.
After obtaining the cut gear, the robot proceeds to the deburring process, which begins by establishing specifications and requirements. Factors such as gear material, hardness, dimensional chamfer, burr removal, radiused blending, surface finish, and the availability of a CAD model determine the finishing methods.
In terms of cutting vs. grinding, the material type and hardness guide the choice between using a carbide cutter for shaping or employing abrasive discs, belts, or wheels for grinding. The gear’s geometry influences the deburring method, with some tools unsuitable for tight spaces. Abrasive brushes, available in various sizes and materials, are effective for removing burrs, but their impact on parent material depends on the gear’s composition.
Part marking, crucial for gear identification, involves impact pin writers or laser markers. Impact markers use a carbide stylus to create indention dots, while laser markers etch marks on the substrate, suitable for various materials. The choice between them depends on the application’s requirements and environmental conditions.
For gears requiring part numbers or bar codes, the robotic cell easily incorporates part marking methods. Part numbers, batch information, and serial numbers can be applied using impact pin writers or laser markers, depending on material and depth requirements.
Rinsing becomes necessary if the gear undergoes heat treatment, ensuring clean parts for improved process control and furnace life. The robot, holding the gear in its tooling, can dip it into a washing fluid tank or be loaded into a washing machine, streamlining the cleaning process.
Once cut, deburred, marked, and rinsed, the part is ready for the next step, which could be heat treated, additional machine work, or final packaging. The integrator tailors the cell based on the intended destination, such as loading parts into heat treat racks, placing them in dunnage for further automation, or preparing them for direct packaging. Advanced planning is crucial to maintain efficiency and prevent erosion of gains achieved in earlier steps, especially considering the gear-cutting machine takes time.
Throughout history, the alchemist’s fabled quest to turn lead into gold finds a modern parallel in the robot programmer’s aspiration to convert CAD data into a robot path. Unlike the alchemist’s elusive dream, significant advancements have brought the CAD-to-path conversion into reality today. Many major robot manufacturers now provide their versions of offline programming software, empowering users to transform CAD data into robot paths. While these programs are powerful tools, proficiency in robotic programming is still required, though the learning curve is often manageable for those skilled in CNC programming.
CNC programmers, accustomed to using CAD/CAM programs for generating tool paths and multi-axis G-code programs for CNC machines, are witnessing a crossover into robotic programming. A prominent CAD/CAM programming entity has developed an add-on package that essentially transforms a six-axis robot into a six-axis machine tool. Resembling its parent CAD/CAM program, this package seamlessly integrates with the workflow of CNC programmers, allowing manufacturers to leverage their existing expertise in a broader and valuable capacity. The essential steps involve opening the CAD file in the parent program, defining surfaces for processing, setting process parameters, specifying robot parameters, conducting process simulation, post-processing simulation, and finally exporting the program to the robot controller.
To sum up, the evolution of automation and robotics in the gear industry represents a transformative journey, driven by the persistent need for efficiency, precision, and competitiveness. The shift from traditional manual deburring methods to automated processes, such as those involving six- and seven-axis robots, reflects the industry’s commitment to embracing advanced technologies.
The integration of CNC machines, robotic gear manufacturing, and vision-guided picking demonstrates a dynamic landscape where traditional barriers are dismantled. The emphasis on understanding the foundational elements of an automation project, from part sourcing to destination, underscores the importance of thoughtful planning in achieving optimal efficiency and cost-effectiveness.
The intricate processes involved in deburring, cutting, marking, and rinsing gears showcase the intricate dance between technology and craftsmanship. Automated solutions not only address the challenges posed by manual labour but also open new possibilities for flexibility and adaptability in handling diverse gear models.
The article also highlights the critical role of robot programming in realizing the dream of seamlessly converting CAD data into robot paths. The integration of offline programming software streamlines this process, making it more accessible for those with CNC programming expertise. This signifies a significant leap in efficiency, bridging the gap between traditional and modern manufacturing methods.
As the gear industry navigates global competition, the incorporation of robotic systems and automated cells emerges as a strategic response to staying competitive. The emphasis on minimizing non-value-added labour, optimizing processes, and leveraging existing expertise positions manufacturers to not only survive but thrive in the dynamic landscape of contemporary gear production.
In a broader context, the article recognizes the economic shifts and manufacturing challenges faced by the United States in the last two decades. The role of robotic system integrators in developing automated solutions for gear producers becomes crucial in levelling the playing field and reclaiming a competitive edge. Ultimately, the overarching theme underscores the importance of embracing technological advancements and strategic planning to remain at the forefront of the evolving gear industry.