Pricing pressures, intense competition, and strict regulatory demands are challenging scientists and researchers in the fast-growing, highly-regulated pharmaceutical, life science, biochemical, industrial, and environmental industries to make important breakthroughs faster and more efficiently.

Heightened productivity in scientific labs has become paramount for companies to succeed. Waters Corporation, a manufacturer of high-performance liquid chromatography instruments, mass spectrometers, and thermal analyzers and rheology instruments, understands this pressure first-hand. As a major supplier to analytical laboratories around the world, Waters is known for its constant commitment to providing innovative solutions that help customers better understand the secrets of chemistry and of life itself.

A New Category in Separation Science

Typical Kerk® spline shaft and bushing assemblies.
The company’s reputation as a creator of pioneering technology was recently illustrated with the release of ACQUITY Ultra Performance Liquid Chromatography® (UPLC), a new category of separation science. UPLC represents a revolutionary improvement over High Performance Liquid Chromatography (HPLC), the widely accepted chemical separation technique. By offering increased resolution, sensitivity, and speed, UPLC greatly improves productivity and provides scientists with considerably more information in a single run.

Waters ACQUITY UPLC® System incorporating the Kerk® lead screw assemblies, and spline shaft and bushing assemblies for three axes of motion control.
The new system uses the power of 1.7 micron particles to give laboratories as much as nine times higher throughput, three times higher routine sensitivity, and two times greater resolution or peak capacity than today’s HPLC instruments can achieve with larger particles.

Additionally, the UPLC process reduces time and cost per sample from the analytical process: rather than one minute to analyze each sample, Waters’ UPLC system cuts the minimum analysis time down to a scant 15 seconds. This 75% reduction per sample, multiplied by the millions of samples that the typical laboratory analyzes, results in dramatic time savings and process improvement.

High Performance with a Small Footprint

While the performance of the ACQUITY system was certainly at the forefront for the Waters engineers who developed the product, it was not their sole design criterion. Management envisioned a system that would sport a much smaller footprint than traditional HPLC systems, ensuring that it would consume less of a laboratory’s valuable bench space. This compact footprint would also guarantee that users could more easily stack and arrange the various modules. The design engineers hoped that the completed basic system would consist of a sample manager, one of several UPLC detectors, and a high-pressure pump. Several upgrades would also be available, including a high-capacity sample organizer.

Accomplishing this goal would require the use of smaller internal components in both the main unit and the optional module, which holds an additional 21 sample plates. Initial efforts to create the required parts did not yield the desired results, according to Ken Plant, a principal engineer on the Waters ULPC project.

“We initially attempted to devise a homemade solution, an adaptation of a mechanism we had developed about eight years ago,” he explained. “That mechanism created an XYZ movement to replace our traditional Z/Rotational movement and had served us quite well in our older models. However, this system of off-the-shelf pulleys and belts simply could not be squeezed into the smaller footprint we were looking for. If it was going to happen, we knew it would require some truly ‘out-of-thebox’ thinking. More to the point, it became clear that in our effort to produce this compact mechanism, we could benefit from the use of specialized outside resources.”

Customized Motion Control

Examples of Kerk® customized nuts.
One of Plant’s colleagues had worked with Kerk Motion Products (now part of Haydon Kerk Motion Solutions) when he was involved in the automation industry, and he felt that Kerk might be able to offer the optimal combination of reliability and miniaturization for this mechanism. After consulting with Waters’ engineers, Kerk presented Waters with components that would allow the engineers to produce a sample manager — the heart of the UPLC system — that would meet the company’s reduced size requirements and produce the increased speed and performance that was so vital to the UPLC concept.

Within the sample manager, the Kerk components are being utilized to drive the robotic XYZ mechanism holding the needle that draws liquid samples from each sample plate. To achieve the “X” and “Y” movements, the ACQUITY arm incorporates one Kerk 1⁄4" lead screw and two specially adapted Kerk nuts, and the “Z” motion is accomplished through two Kerk spline shafts and splined bushings.

In the optional sample organizer, a 1⁄2" lead screw and antibacklash nut are employed to produce the Z-axis motion, allowing the robotic machine to shuttle as many as 21 sample plates back and forth to the sample manager. The spline shafts, which run parallel to each other and feature custom splined bushings, provide a drive mechanism for two axes of motion. They are excellent alternatives for applications where hex shafts or square shafts are used (Waters’ original mechanism utilized square shafts). The assembly utilizes lightweight alloy steel spline shafts treated with Kerk's proprietary low-friction Kerkote® TFE coating mated with Kerkite® composite polymer bushings.

“It wasn’t simply performance or size that made the Kerk components so desirable. Kerk’s products offer extremely long wear-life,” Plant said. “This was a critical consideration, as our chromatography systems need to operate at a very high level of reliability. Continuous uptime is very important to most of our customers.”

The launch of the UPLC has been a tremendous success, with praise from countless customers, including some of the world’s most prestigious pharmaceutical companies. “The ACQUITY UPLC (System) will soon become the choice for the development of fast LC methods in the pharmaceutical industry,” said Dr. Anton D. Jerkovich of Novartis Pharmaceuticals Corp., a Waters customer.

This article was contributed by Haydon Kerk Motion Solutions, Waterbury, CT. For more information, Click Here 


Motion Control Technology Magazine

This article first appeared in the December, 2010 issue of Motion Control Technology Magazine.

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