The Impact of Precision Machining in Medical Practice

In the intricate world of medical device manufacturing, where precision is paramount and innovation saves lives, a robust production process is essential. From crafting tiny bone screws to producing complex hip prostheses, the demand for accuracy, reliability, and efficiency is extremely high. In this context, Annika Langéen, vice president of offer management and R&D at Sandvik Coromant, the expert in metal cutting tools and manufacturing solutions, is a reference for this article on how small-part machining supports the accurate and precise production of medical device components.

The medical device industry encompasses a wide range of products designed to diagnose, monitor, and treat medical conditions. From diagnostic equipment to implantable devices, the industry meets the evolving needs of healthcare professionals and patients around the world. Today, it is estimated that there are 2 million different classes of medical devices on the global market, categorized into more than 7,000 device groups, according to the World Health Organization (WHO).

Challenges in Medical Device Manufacturing
The manufacturing of medical device components presents unique challenges that require advanced machining solutions. End users rely on these devices being produced to the highest quality standards, as any product that fails to meet them can cause significant disruption. Operations may be halted, products recalled, organizational reputation damaged, and patient lives put at risk.

Furthermore, regulatory requirements in this field are extremely strict. There are international standards for quality management, such as ISO 13485, and risk management, such as ISO 14971, as well as regional regulations, including 21 CFR and FDA requirements in the United States and the EU MDR in the European Union, that all devices must comply with. The need for such high precision means manufacturers cannot risk even a millimeter of deviation between parts, making a robust machining setup essential.

Machining Challenges
From a machining standpoint, the size and complexity of device components require micrometer-level accuracy, meaning any manufacturing process must deliver highly precise final products.

The materials used for a wide range of medical device components — typically titanium, stainless steel, and special alloys — are selected for their corrosion and wear resistance, hardness, and biocompatibility. However, machining such materials with a high degree of precision poses significant challenges. Manufacturers must address issues related to tool wear, heat generation during machining, and surface finish quality.

Productivity is also a key factor. Across industries, there is generally a gap between rising costs and what the market is willing to pay. To bridge that gap, manufacturers must continuously increase efficiency and productivity. Sandvik Coromant estimates that manufacturers waste between 10% and 30% of material in their machining processes, with typical machine utilization below 50%, including design, planning, and cutting stages.

To overcome these challenges, it is essential to partner with specialists who can deliver the required specifications. Sandvik Coromant’s metal cutting solutions focus on reducing non-cutting time to ensure maximum productivity. Its tools are designed to be highly flexible, modular, and capable of using high-pressure coolant to maximize uptime.

An Example: Bone Screws
To illustrate the success of Sandvik Coromant’s machinery and tools for medical devices, consider the manufacturing of bone screws. Bone screws are a commonly used fixation device and have a wide range of applications. They may be used alone in reconstruction or repair surgeries or together with other physical devices, such as plates, to secure them to the bone. Generally, bone screw shafts have a diameter between 4 and 12 millimeters and are made of titanium or stainless steel.

Given their many applications, bone screws are typically long, slender, and manufactured in various sizes to suit different parts of the body. They are usually produced in quantities ranging from 30 to 1,000 units using a technique known as thread whirling — a machining process used to create precise, high‑quality threads. A rotating spindle holds a cutting tool that is fed into the workpiece while it rotates. The cutting tool typically features several inserts arranged around its circumference.

During thread whirling, the workpiece rotates on its axis and also moves longitudinally along it. Meanwhile, the cutting tool rotates around the workpiece, cutting the thread profile. This simultaneous rotation of the workpiece and the cutting tool creates highly precise threads with excellent surface finish while preventing bending and vibrations. However, manufacturers must avoid challenges such as burr formation at the tip during thread whirling or reduced thread quality when using high feed rates.

Sandvik Coromant’s machining solutions for sliding head machines use the CoroMill® 325 whirling system, a rotary unit, and a dedicated high-pressure coolant pump with filtration. The CoroMill® 325 is a thread whirling cutter specifically designed for medical device manufacturing, producing special thread forms quickly and at tight tolerances. With multiple available whirling inserts and holders, the machine ensures bone screws are produced without risk of bending or burr formation.

Additional benefits of Sandvik Coromant’s cutting tool solution include increased productivity. The machine performs machining in one pass from the material diameter, reducing cycle time by minutes, and it is easily configured to shorten idle time. All Sandvik Coromant whirling inserts are available in GC1105 — its first-choice grade for medical machining — providing extended tool life and reduced operating costs.

This is just one example of Sandvik Coromant’s medical machining solutions. The metal cutting expert offers a wide range of machining solutions and advanced tools for numerous additional devices, including pedicle screws, hip joints, and bone plates.

As the medical device manufacturing landscape continues to evolve and become more competitive, driven by advancements in materials, design, and manufacturing technologies, precision machining is essential. Partnering with industry leaders like Sandvik Coromant and adopting cutting-edge solutions helps manufacturers navigate the complex world of medical machining with confidence, enabling them to advance innovation and improve patient outcomes.