Vintage idea modernizes emerging processes

April 6, 1998 Design News

FAST TRACK: MOTION CONTROL

Vintage idea modernizes emerging processes

Intelligent air-bearing design delivers repeatable precision

by John Lewis, Northeast Technical Editor

Westborough, MA--In its simplest form, an air bearing consists of nothing more than two accurately machined surfaces separated by a film of pressurized air. As surprising as it may seem in this era of rapidly advancing technology, however, design engineers are turning toward this rather "old" technology to solve a variety of problems such as improved precision, accuracy, cleanliness, and longer life. It also has helped put a small Massachusetts company, Dover Instrument Corp., on the map.

Although use of air as a bearing lubricant is an idea that dates back to the 1800s, it took air-bearing pioneers nearly a century to successfully implement the concept. Papers and patents written throughout the 1900s define modern air-bearing principles, but the lack of modern manufacturing and computational techniques limited early work in the field. In fact, practical applications for the technology didn't appear until the early space program needed to manufacture and measure components to accuracies of a millionth of an inch (25 nm).

The cornerstone of Dover Instrument, founded in 1964, was the work of a small team of engineers from MIT Instrumentation and Draper laboratories. The team solved the metrology problem with an air bearing design that ran true to a millionth of an inch. "The early years were lean," says Dover's President and CEO Stephen Hero, son of Dover's founder, John Hero. "Back then, not many applications required the kind of micro-inch motion that air bearings deliver."

Dover's early air bearings were fabricated and assembled in a 100-sq-ft cubical in a Westborough basement. Most were used in one-of-a-kind R&D, government, or aerospace projects. "We've grown from a company that supplied maybe a hundred components per year, to a present-day facility that fills 75,000 sq ft. Today we design, manufacture, and assemble thousands of components and systems annually."

"Driving this growth," says VP of Sales Mike Townsend, "is micro-electronic and optical product miniaturization, plus our shift from supplying components to integrating systems."

Miniaturization drives component features to tighter tolerances. This increases the number of products requiring air-bearing accuracy. Flat panel displays, diskdrives, diamond-turned optics, and semiconductors--emerging technologies 20 years ago--are now vital to the economy. Dover's recent 30,000-sq-ft expansion enables manufacture of hundreds of units to satisfy modern, high-volume production requirements.

Air-bearing integration. Dover's growth, spurred on by miniaturization, has also changed the way Dover implements its air bearings. Previously, customers specified air bearings with only mechanical accuracy in mind. They typically mounted a motor, then integrated it into their machine. Today customers specify not only mechanical accuracy, but often ask for specific throughputs, accelerations, and step and settle times.

To address these needs, Dover combines motor, amplifier, and control technologies into its air-bearing systems. "That's where most of our technical growth has come from," says Townsend. To support these technologies, the company employs close to 200 people, with 40 designers and engineers, 60 machinists, 60 assemblers, and other administrative, sales, and marketing staff.

A "long" project may last only six months. "From a technology standpoint, it's a fast-paced, exciting place to work," says VP of Engineering Phil Greene. Employees are exposed to a variety of industries and technologies. They frequently work on custom projects that have never been tried before. There's roughly a 40/60 split between standard product sales and custom design work, where engineers work closely with customers to implement catalog products into custom machines.

Technological advances and the drive toward miniaturization in semiconductors, microelectronics, and optics have propelled Dover?s average annual sales by 30% over the last six years.

Once an order comes in, a project engineer opens dialogue to cultivate the relationship, Townsend explains. After solving customer problems for one product, many customers return at the end of its life cycle to work on the next one.

Dover's engineers juggle many projects simultaneously. "As engineers are shipping one project, they're supporting products that have already shipped, and designing new ones," says Greene.

"A core management group meets regularly to make 'big-picture' decisions as to where the company is headed," Greene explains. "Once decisions are made, however, management empowers individual employees to take whatever steps are necessary to make a better product or satisfy the customer further," Townsend adds.

Hiring prospects are good for engineers at Dover. The company hired 65 people last year, 12 were engineers. Greene looks for engineers with a "can do" attitude and the ability to think quickly, adapt, and execute practical solutions. "A company such as ours depends on team players," Greene says. Engineers need good interpersonal skills and business sense. "The hardest part of the job is doing custom design work with limited time, and understanding that the opportunity to satisfy a customer may evaporate."

"The schedule can be hectic, and our people put in a lot of hours. Still there's virtually zero turnover among employees here," Townsend says. "We have many employees that have worked here for 10, 15, or even 20 years."

Despite its rapid growth, Dover strives to maintain a small-company atmosphere. "We try to keep the entrepreneurial spirit alive within the company," Hero says. The comprehensive benefits and rewards system, tied to individual and team effort, includes bonuses and profit sharing.