Tech Briefs

Fifty Years of Small Diameter High Quality Precision Tube Technology

Technology, applications, and materials evolve from analog meters to cutting edge medical devices.

Over the past fifty years, thin wall small diameter precision metal tubing has undergone quite a transformation. From its use in the mid-1960s as pointers for analog meters, tubes have become essential components in the most cutting edge medical devices. To make that transition, precision tube companies have had to adapt to changing technology, applications, and materials.

altTo be successful, some companies have evolved from being single drawing mills into one-stop tube fabrication shops, where the tube is customized to a customer’s specifications. With fabrication, tube companies cut random tube lengths to size and perform numerous operations, including bending, expanding, laser cutting or welding, or swaging.

From the 1960s through the early 1980s, one of the most common tube applications was pointer tubing for what were then considered innovative analog meters. Single drawing mill companies sold tubing in lengths cut to particular meter specifications. For example, Judson Smith Company, which was started in the mid-1960s, estimates that it sold to that industry since its inception. This part of the business has been declining for years because of the digital age.

By the early 1980s many tube companies had begun the long evolution toward value-added tube fabrication operations, primarily for OEMs in aerospace and automotive industries, but also for the early stages of the growing medical device industry. Custom tubing for OEMs in these areas has evolved into tighter dimensional tolerances as well as the use of more sophisticated equipment, such as laser cutting. With medical devices, this evolution has continued and accelerated, as today’s designers’ seek additional tube features and capabilities to improve performance.

Evolving Tube Technology Driven Primarily by Cost Pressures

Increasing cost pressures year after year led tube companies to seek out technologies to reduce costs. Process efficiency in response to OEM requirements for year over year savings is a key reason for adopting new technology.

For example, laser cutting technology allows tube companies to do in one step what used to take three or four steps with punch press equipment. Laser cutting is also faster, significantly improving throughput.

Providing vertical integration is another change, in which tube companies offer in-house capabilities. Minimizing outsourcing steps helps maintain traceability and reduces lead-time for overall customer satisfaction.

Many tube companies are also adopting newer fiber laser technology, which offers finer cutting and better tolerance control on complicated geometries. While a relatively expensive technology, fiber lasers provide a cleaner cut, which, in turn, eliminates cleaning steps downstream. For many recent medical device redesigns, customers are looking to improve instrument performance by tightening tolerances on the tube’s distal and proximal end. Along with new laser technology, tube companies are also beginning to adopt automated robotics system for loading tubes into laser cutting machines.

Changing Applications Require Tube Improvements

A great deal of precision tube business was traditionally in aerospace, particularly for engine ventilation and cooling chambers. By the late 1980s, the medical device industry began to take off, and is now a major market for the precision tube fabrication business. Initially, tubes were used as trocars, which allowed the surgeon to pass instruments, lighting sources, or a camera into the body. Now, some tube fabricators have evolved into providing tube components used in device instrumentation, rather than just the delivery system.

Materials Include More Flexible Alloys

Materials have stayed relatively constant, with stainless steel remaining the primary choice, especially for medical tubes. Titanium has evolved in response to the need for lightweight, strong, and corrosion resistant tubes for aerospace, automotive, and medical applications. More flexible alloys, for example nickel titanium (nitinol), have become more and more popular for their shape memory and superelasticity. (See Figure 1)

To survive in this era, precision tube fabricators need to adapt to new technology, stable processes that offers tighter tolerances, and faster throughput at reduced costs.

This article was written by John Shields, Director of Sales & Marketing at Judson A. Smith, Boyertown, PA. For more information, visit http://info.hotims.com/45604-162. See Judson A. Smith at MD&M East, Booth 3434.