Guiding Success from End to End: Coiling and Doming Guidewires

Medical guidewires require both flexibility and rigidity to weave around the body without collapsing. They are typically made of very finely coiled stainless-steel wire with a solid domed tip which helps prevent them from getting caught or snagged along the way. Guidewire manufacturers, therefore, need machines to accomplish both processes – coil winding and tip welding – and success is dependent on precision equipment and operator/process expertise. Amada has both manufacturing technologies in their portfolio: wire coiling from Amada Press System and precision welding from Amada Weld Tech.

Amada Press System’s MEC Spring-Forming Machine Division, originally established as Matsuoka Engineering Co., Ltd. and later joined the AMADA Group in 2018, has been developing and building coil winding and wire-forming machines for more than 50 years. Similarly, Amada Weld Tech has been in the medical device welding business since its founding as Unitek Corporation way back in 1948. Together, they embody the AMADA ONE philosophy which is “Synergy in Action through Diverse Technologies” giving customers a single source with clear points of contact and a partnership to develop applications and quickly address issues if/when they arise.

Expertise at Both Ends

The two key manufacturing processes to make guidewires are the coiling process and the doming process. As the wire diameter – and, therefore, the coil diameter – gets smaller, success requires special knowledge.

Ultrafine coil winding (30 µm-200 µm wire diameter) for medical guidewires demands delicate wire handling and precision motion to produce consistently high-quality coils. Manufacturers face three key challenges: achieving extremely accurate coil outer diameters, boosting production speed to meet growing demand, and simplifying the process through automated setup. Advanced coil winding solutions are essential to maintain tight tolerances while improving efficiency and reducing manual intervention.

Doming or welding the end of the coils requires extreme precision to ensure that the dome is the correct size. Without proper balance of energy, the dome will form on just one side which can prevent closure of the coil or create issues where the ball exceeds the outer diameter of the coil, preventing easy gliding. In addition, the dome needs to be consistent with a clean finish free of soot or oxidation. Due to the fine gauge of the wire, getting the cover gas just right also requires special considerations.

A Look Under the Hood at Technology Solutions

Amada Press System’s new WH-2A is a 13-axis CNC dual-point coiling machine for ultra-fine wire that addresses these unique needs by equalizing the forming force during coiling, delivering excellent outer diameter precision. And by maintaining constant wire tension and load throughout the process, it achieves production speeds up to three times faster than traditional shaft winding machines. Its dual-point servo mechanism eliminates the need for highly skilled operators and allows easy switching between right- and left-handed coiling, facilitating integration into existing production lines. Full automation is possible, including measurement, sorting, and discharge processes. In addition, the WH-2A is capable of coiling specialized materials, offering even greater manufacturing flexibility.

This precision coiling process can be combined with Amada Weld Tech’s advanced welding solutions, such as the TC-W resistance welder or the ML-2150W 25W Nd:YAG laser welder, providing a complete manufacturing solution.

The TC-W100A, is designed specifically for the challenging task of welding delicate wires. Typically used for welding thermocouple wires, it can also be used to dome wires, coiled wires, and tubes. Built in the USA, the TC-W100A welds 70 µ to 600 µ diameter wires to form a uniform bead, consistent in size and quality, without detrimental oxide layers.

Amada Weld Tech’s ML-2150A Nd:YAG laser welder is designed specifically to meet the stringent demands of precision welding applications such as medical devices, electronic components and other macro and micro processing requiring the highest levels of quality, precision, reliability, and uptime with the lowest cost of ownership. With exchangeable fiber delivery and focusing optics, it can manage coil diameters between 200 µ to 600 µ.

Synergistic Success

Medical device manufacturers who currently coil stainless steel guidewires but outsource the doming step—or vice versa—and are facing production delays, inefficiencies, or lost revenue may benefit from a new integrated approach. A joint offering from MEC Spring-Forming Machine Division and Amada Weld Tech has the potential to address both stages of manufacturing, allowing the entire operation to be brought in-house. This collaboration showcases the promise of AMADA ONE—two companies combining expertise to streamline production, improve process control, and lower costs.