A manufacturer of medical implant devices sought a better method of crimping a very fine cable, consisting of even finer woven strands, to a crimp ring used in the medical device’s power supply. Summit Engineered Automation was able to work with the manufacturer and turn around their total efficiency with a new crimping manufacturing cell.
The Challenge: Upgrade Archaic and Outdated Cable Crimping Processes with Advanced Automation Technology to Boost Efficiency and Throughput
A manufacturer of medical implant devices had a manufacturing cell that crimped a .010″ fine cable to a ring used in the device’s power supply.
The operation had been using mechanical equipment that was indexed into multiple process steps. It had 17 stations in the process. Over time, many of the stations had become dysfunctional and the process was down to only three functional stations. The outdated equipment did not have a sustained grasp of the fine cable wires, plus the equipment used to crimp the wire to the ring began to wear out.
There were quality problems as well. The cable wiring had been mechanically stripped of its insulation. This left filars, or threads of removed insulation, which did not meet quality assurance standards. In addition, the crimp was often misaligned to the ring it was designed to join. Subsequently, these issues resulted in defects, rework, material wastage, downtime, and overall reduced efficiency.
The company sought an improved manufacturing cell that would provide a continuous hold on the wire, better control, and dynamic adjustment capability to eliminate inefficiencies.
The manufacturer had sought solutions from several sources, but mostly received proposals that were similar to what they had been previously using in indexing the parts. What they sought was an approach that incorporated a more continuous grasp of the wire until it crimped into the ring, and a process less prone to production problems.
The Solution: A Redesigned Cable Prep and Crimp Cell with Updated Equipment and Technology
Summit Engineered Automation was tasked with redesigning and developing a new manufacturing cell that would improve the crimping process.
Summit proposed a cell that would utilize two Fanuc robots. One of the robots was used to handle the wire through fusion, ablation, wire inspection, and positioning the wire into the ring. The other robot transports the ring from the tray to the crimp station, then from the crimp station to final inspection. If not rejected, it then transports it into the finished product tray.
The fusing robot used an IPG 200-watt rack mount multi-mode ytterbium fiber laser to fuse or “ball tip” the end of the .010” wire, and a Synrad CO2 laser to ablate the insulation from the wire. Summit also introduced a Keyence TMX telecentric measurement device to help align the process. This cell would ensure that the wire crimping was continuous with no breaks in the flow of the crimping process.
There were some problems initially in the implementation of the new cell.
One of the joints of the Fanuc gripping robot produced some thermal expansion at one of its joints. This caused it to drift about .005” as it warmed up. The motion of one of the FANUC robots that moves the wire was almost 180 degrees in movement over a mere 300 milliseconds of time. This put too much force on one of the robot’s joint (joint two) causing thermal expansion. Over the course of five minutes, it would drift .005”. When you’re dealing with a .0010” diameter wire, such movement is substantial.
Thermal expansion of the robot could degrade its useful life. If the robot is designed with a useful life of seven years, the thermal expansion upon a robot that is operating twenty-four hours a day, seven days per week, could shorten its life to three and a half years.
Summit discovered the problem early and is working to ease the grip, or if necessary, attain feedback from the Keyence TMX device when it inspects the wire prior to the crimp to dynamically compensate for this variable and correct its movement in real time.
With the new crimp cell, the operation is enabled to run one shift, unattended. They load four rings of trays, or about one thousand parts to produce one lot in one eight-hour shift.
The Result: Enhancing Manufacturing Efficiency on Several Measures Expected to Produce 98% Yield
The previous operation’s cycle time was about 45 seconds and had worsened as the intended stations became non-operational. Their yield had dropped to below 50%, and were, in essence, throwing away every other part.
The new cell, designed by Summit Engineered Automation, changed everything. It eliminated the quality problems from the previous filars generated by stripping the insulation. It had a continuous hold on the cable, less rework, much less wastage, and much less downtime. The new design is targeted to produce a yield of about 98%. Overall, the new crimping cell enabled a much more efficient process.
Such solutions can improve cable crimping for any cabling material with such a fine and small diameter. Their selection of robotic crimping technologies provides added value as an advanced manufacturing solution, much needed by a manufacturer. The same approach can be applied to any manufacturer seeking a better manufacturing cell.
Summit Engineered Automation’s solution could be used in many similar crimping operations and demonstrates their ability to add value in such precise scenarios of cable preparation, automation, and quality control.