Driving Strategies
Quick Tightening
The Quick Tightening strategy is a three-step process designed to efficiently tighten fasteners while minimizing cycle time.
Steps:
Locate Hole:
The tool starts spinning at a low RPM, allowing for precise positioning.
Once the tool detects contact with the screw threads, it signifies a successful “locate hole” step.
Rundown:
The tool ramps up to its highest RPM to quickly drive the screw toward its final depth.
This step is optimized for speed while maintaining control.
When close to the final insertion depth it moves to the next step.
Tighten:
This step has two phases:
Speed Mode: The tool lowers its RPM and waits for a slight increase in torque. This ensures the screw is nearly seated.
Torque Mode: Once the slight torque rise is detected, the tool switches to a slower, controlled rotation and applies torque until the pre-programmed torque target is reached.
Benefits:
Fast and Efficient: The locate hole and rundown phases ensure quick positioning and driving of the screw, while the tighten phase efficiently reaches the desired low torque.
Reduced Cycle Time: This strategy minimizes unnecessary time spent on slow, high-precision tightening, making it ideal for applications where speed is a priority.
Applications:
Quick Tightening is suitable for most screwdriving tasks, and can also be used as the first step in a Cross tightening.
Simple Tightening
The Simple Tightening strategy is a two-step process designed for a basic and efficient tightening sequence. It is similar to the Quick Tightening strategy but focuses on a more controlled approach.
Steps:
Locate Hole:
Identical to the Locate Hole phase in Quick Tightening, the tool starts by spinning at a low RPM for precise positioning and screw thread engagement.
Tighten:
Similar to the Tighten phase in Quick Tightening, the tool utilizes a controlled lower RPM and applies torque until the pre-programmed torque target is reached. However, unlike Quick Tightening, it skips the speed mode and directly applies torque.
Benefits:
Controlled Tightening: The slower, controlled approach throughout the tightening phase minimizes potential damage to delicate fasteners or surrounding components.
Efficient for Low Torque Applications: This strategy is suitable for situations requiring a secure fit with a pre-determined low torque value, without the need for the initial speed of the Rundown phase found in Quick Tightening.
Applications:
Simple Tightening is ideal for tasks where a secure fit with a low torque is crucial, particularly for sensitive components or applications where precise control is preferred over speed.
Post Tightening
The Post Tightening strategy is a two-step process designed for precise and secure fastening by ensuring accurate screw seating and applying a final specified torque.
Steps:
Locate Screw:
The tool starts by rotating slowly in reverse while moving downward.
This phase carefully positions the bit onto the screw head.
The tool either detects it’s fully seated or a slight torque increase (indicating the bit catching the edge), signaling a successful “locate screw” step.
Tightening:
Similar to the Quick Tightening strategy, this step begins with a lower RPM in the tightening direction.
The tool monitors for a torque rise, indicating the screw is nearing its final position.
Once detected, the tool switches to torque control and applies torque until the pre-programmed torque target is achieved.
Benefits:
Accuracy and Control: The locate screw step ensures proper bit seating, preventing damage and improving tightening accuracy.
Secure Fastening: By applying the specified torque, this strategy guarantees a strong and secure assembly.
Applications:
Post Tightening is ideal for situations requiring critical joints with precise torque control.
It’s commonly used following a Quick Tightening pre-tightening step to achieve the final, high-precision fastening.
Loosening
The Loosening strategy is a three-step process designed for efficient screw removal with control.
Steps:
Locate Screw:
The tool starts by rotating slowly in the tightening direction (forward). This ensures proper engagement with the screw head and minimizes risk of slipping.
Run Up:
The tool ramps up to its highest RPM in reverse, effectively breaking the initial torque holding the screw in place.
This phase prioritizes speed while maintaining control.
Exit Hole:
Once the tool detects the screw is nearly extracted (through various methods like depth sensing or motor current changes), it switches to a slow reverse rotation.
This final step carefully removes the screw completely and positions the tool for easy withdrawal.
Benefits:
Efficient Removal: The high-speed run up phase breaks the initial torque quickly, while the locate screw and exit hole phases ensure controlled engagement and final removal.
Reduced Cycle Time: This strategy optimizes speed for screw removal, making it ideal for applications where fast disassembly is needed.
Applications:
Loosening is suitable for situations where quick screw removal is a priority, such as during product disassembly or part replacement processes.
Position
This program achieves a specific screw insertion depth with a balance of speed and control.
Steps:
Locate Hole:
Identical to Quick Tightening, the tool starts spinning at a low RPM for precise positioning and screw thread engagement.
Once the tool detects contact with the screw threads, it signifies successful positioning.
Rundown:
Similar to Quick Tightening, the tool ramps up to a moderate RPM to drive the screw efficiently toward its final depth. This provides a balance between speed and control.
Reach Depth:
Once the program reaches a pre-defined depth threshold (slightly before the final target depth), it transitions to a slower, controlled rotation.
The program continuously monitors the screw’s depth of insertion.
Upon reaching the pre-programmed insertion depth, the program stops the tool.
Benefits:
Balanced Speed and Control: The rundown phase allows for faster driving compared to locate and tighten only, while the final slow rotation ensures precise depth control.
Optimized for Precise Depth: This program prioritizes reaching the exact desired depth while maintaining some efficiency.
Applications:
This program is suitable for situations where fully inserting the screw is not the goal, like adjustment screws.
situations where the end of the program is not based on a torque target.
Cross Tightening
Cross tightening is not a strategy you select in a program. It is a technique built from two screw programs, used to ensure even pressure on fasteners by tightening them in an alternating pattern — imagine drawing an “X” over the fasteners you will be tightening. It is achieved in two stages:
Criss-Cross Pattern (Low Torque): first insert each fastener following the criss-cross pattern, tightening to a low torque target. This ensures all fasteners share the initial load and minimizes warping.
Final Tightening: finally, apply the final specified torque to each fastener in the same criss-cross pattern, creating a uniform and secure clamp across the entire assembly.
Programming the Spin Robotics system:
Spin Dashboard: create two screw programs — a Quick Tightening program with the low torque target value as its torque goal, and a Post Tightening program with the final torque target value as its torque goal. See Creating a Program.
Robot programming: program the robot’s movements to follow the criss-cross pattern for each fastener.
Program selection: select the Quick Tightening program for the first round of screwdriving, followed by the Post Tightening program for the second round. This ensures the two-stage tightening process is followed for a secure assembly.
Additional considerations:
Ensure the chosen low torque target value is sufficient to snugly hold the fasteners without warping the assembly.