During a medical procedure, the quality of the wire being used can mean the difference between a successful outcome and a product failure. One of the biggest distinguishing factors of an exceptional wire is tolerance—and that is achieved through superior micro-grinding capabilities. Over the years, micro-grinding has been growing as an aspect of advanced manufacturing technology. As machines have become more sophisticated with the development of rigid machining tools, so too has the art of micro-grinding. Companies that specialize in this type of machining have emerged as important players in many different industries.
Micro-grinding is a tool-based machining process that creates micro-features on hard, brittle materials. It uses a large tool to create minute details, which makes it an extremely important process when a product requires precise specifications, such as in the medical industry. Doctors need equipment—such as catheters, pins and wires for angioplasty and other procedures—that enable them to navigate or insert tools in the exact right place. Micro-grinding can be used on many different types of materials, including glass and plastic, but the primary focus for companies that work with the medical industry is on metallic materials such as steel and titanium.
Precision wire grinding requires a combination of meticulous attention to detail and an efficient process that produces components at a rapid rate. Custom Wire Technologies’ capabilities range from a minimum starting size of 0.005” (0.13 mm) OD to a maximum starting size of .188” (4.77 mm) OD, with lengths of 10 feet and beyond. CWT specializes in core wire centerless grinding, which results in an exceptional finished product of top quality.
Advantages of Centerless Grinding
Centerless grinding is different from profile grinding in that it does not use a spindle or fixture to secure the material that is undergoing grinding. Instead, the user secures the piece between two rotary grinding wheels and adjusts the speed at which they are rotating relative to each other to change how the material is shaped. Centerless grinders are particularly useful because they have amazing production capability that doesn’t decrease the quality of the product. Other advantages include:
- Fast loading – This means the user can run grinders without stopping.
- Long life – The grinding wheels last a long time because the user doesn’t need to externally feed components.
- Equipment doesn’t need resetting – The user can complete the full production run without resetting, which saves on time and labor.
- No deflection – Manufacturers can use heavier passes than they would with profile grinding.
Customized medical devices can necessitate customized mandrels, which are used for catheter development such as reflow efforts often have unique designs. Specialized manufacturers can accommodate specialty wire mandrels and wire stylets at their customers’ request. In many cases, mandrels address very specific needs, such as tapers or steps, and they can grind them with multiple taper levels and very tight tolerances.
Orthopedic wires can be quite complicated and require very individualized manufacturing processes. Kirschner wires (k-wires), Steinmann pins and olive wires all are types of wires used in orthopedic surgeries as components or fasteners for hand and foot surgery. They are literally holding patients’ bones together, so they need to be precise—both in design and tolerance. Micro-grinding is the only way to obtain the type of precision required. Manufacturers use the highest quality of equipment to produce custom designed orthopedic wires that stand the test of time.
When a component has a very complex geometry, it may not lend itself to the centerless grinding process. Profile grinding involves precision grinding the outside diameter (OD) of cylindrical parts. It can be particularly helpful for parts with features such as grooves, radii and tapers. In some cases, manufacturers can use form grinding, in which the component’s profile is formed into the grinding wheel. This type of grinding work well for threads, points and specialized profiles in a wire. Companies grind flat wires for medical components using profile grinding. They also use the process for grooves, notches, steps, bumps and flats.
Nitinol is a metal alloy that can change shape depending on temperature. Very few manufacturers work with this type of material because it is quite abrasive and causes a large amount of heat during the grinding process, which requires specialized wheels and coolant. However, because it has such an incredible elasticity, it can be used in applications that have extremely tight space requirements, which makes it invaluable for the medical industry in particular.
Micro-grinding is complex and varied, which is why some manufacturers prefer to outsource it. When it’s performed well, however, it can turn a good component into an excellent component that performs beyond expectations.