Utility Menu

Powder/Bulk Solids

The Source for Dry Processing and Bulk Handling Technology

Ultrasonic Deblinding System Provides Ultrafine Titanium Powder for Medical Implants

June 18, 2008
The Vibrasonic screener deblinding system from Russell Finex helped Reading Alloys eliminate powder blinding at the small particle-size distributions and high mesh sizes required by the medical device market.

As an aging population requires more hip, knee, and tooth replacements, suppliers to the growing medical implant industry are noticing increased demand for fine-grade titanium. Whereas powders in the range of 150 µm/100 mesh are suitable for many industries, the medical field requires even finer material, which suppliers such as Reading Alloys are stepping up to produce.

“Medical customers such as plasma spray coaters increasingly require unique particle-size distributions (PSDs) below 75 µm/above 200 mesh because they are looking to produce very fine coatings to help join bone to the implant surface,” explains Colin McCracken, development manager of powder products at Reading Alloys, a leading supplier of high-purity titanium and specialty alloy powders. “This is often the case for fine-grade powders where laser PSD measurement is preferred.”

According to McCracken, some coating process equipment and process routes require unique, exceptionally narrow PSDs for fine powders to correctly bond with the implant surface. Medical coating users often choose five or more PSD specifications, depending on the medical device in question. To choose the appropriate PSD, Reading Alloys sought to ramp up capacity to produce titanium and alloy powders from 300 µm/50 mesh to 45 µm/325 mesh. However, the company noticed that its existing vibratory screeners experienced problems attaining the necessary particle-size distributions, throughput, and material recoverability.

“It was difficult to prevent the screeners from blinding, especially at the finer mesh sizes,” says Charles Motchenbacher, technology manager at Reading Alloys. “We tried using a ball deck to agitate the bottom of the screens, but this contaminated the undersized powder, so it could not be used.” Screening the powder multiple times lengthened the company’s manufacturing process, hindering its rapid 24/7 production operation.

In search of a solution, Reading Alloys turned to a state-of-the-art ultrasonic screening deblinding system from Russell Finex (Pineville, NC). The Vibrasonic 2000 system, which is available as ATEX certified to operate within areas designated as zones 20, 21, 22, 0, 1, and 2, enhances screening efficiency. Capable of being retrofitted onto any new or existing vibrating separator/screener, the system uses a combination of ultrasonics and conventional vibration.

By using an acoustically developed transducer, the system applies an ultrasonic frequency directly to the screener mesh to break down surface tension, effectively rendering the stainless-steel wires friction free. This feature eliminates mesh blinding, enabling accurate separation down to 20 µm on even difficult powders while maintaining product consistency. Because the machine does not have to be stopped for operators to manually clean and handle the mesh, downtime is reduced and screen life is prolonged.

“The Vibrasonic system has helped eliminate blinding at the fine mesh sizes and narrow particle-size distributions required by the medical market, all the way to 45 µm/325 mesh,” says Motchenbacher. “It has enhanced our material throughput to the point where we can meet specified requirements in virtually a single screening pass, while improving material recoverability.”

Motchenbacher appreciates the ultrasonic screener deblinding system’s ease of operation and its ability to provide precise control over the production process. “By attuning the system’s controls to meet the different setups of our material and equipment, this has enabled us to match speed and feeding parameters to our processes,” says Motchenbacher. “As a result, we have optimized production.”

“With the Vibrasonic system, we have been able to work with medical customers to achieve their specifications for fine powders and tight particle-size distributions,” adds McCracken. “Any manufacturing process requiring precise, efficient screening below 150 µm or above 100 mesh should consider such a system.”

Russell Finex has more than 70 years of experience in the area of fine-mesh separation technology. Used in a variety of industries, Vibrasonic technology is used to process metal powders, pharmaceuticals, food, chemical powders, toner powders, electrostatic-powder paints, and ceramics. For more information, call 704-588-9808 or visit www.russellfinexusa.com.