The expansion of the product range to include titanium knee implants at a leading implant manufacturer required the purchase of new surface finishing equipment. With the Multi-Surf Finisher RMSF 4/800, Rösler developed a solution that, compared to the typically utilized drag finishing machines, produces the required results in two separate process stages about four times faster. It allows for the fully automatic finishing of the “box” surface area. Cleaning and recycling of the process water are handled by an automatic Z 1000 centrifuge equipped with the digital process water management software “Advanced”. This ensures maximum process stability and excellent finishing quality.

In addition to knee implants made from cobalt-chrome alloys, a leading implant manufacturer expanded its product range to include artificial knees made from titanium. For the final surface finishing operation prior to implantation, the company utilizes the Rösler Multi-Surf Finisher RMSF 4/800, along with cost-efficient and sustainable process technologies, also supplied by Rösler.

Compared to the drag finishing technology typically employed for such finishing tasks, the required cycle times are four times shorter. Depending on the initial surface roughness readings of the raw components, the grinding operation with plastic processing media—specially developed for medical engineering applications—produces surface roughness readings of less than Ra = 0.1 µm in cycle times of about 20 minutes. Moreover, the critical “box” surface area, which frequently requires manual grinding, can be fully automatically ground and polished.

This was made possible with the innovative Surf-Finishing System, the most intensive mass finishing technology. Surf-finishing was developed for treating high-value workpieces with complex shapes that require the targeted finishing of precisely defined surface areas.

Similar to drag finishing, the knee femurs are mounted on a rotary spindle equipped with a servo motor. The actual treatment of the workpieces takes place in a rotating processing bowl filled with grinding and polishing media. Individually adjustable tilting and rotary motions ensure the highly precise and absolutely repeatable surface treatment of the various implant components on precisely defined surface areas.

The process parameters, such as cycle time, rotary speed, and direction, are stored in the equipment PLC as part of workpiece-specific processing programs. Pneumatic clamping of the workpiece fixtures and a loading window, included in the standard machine version, allow for easy automation of the loading operation with an industrial robot.

A Solution That Saves Space, Resources, and Energy

Besides short cycle times, the intensive treatment in Multi-Surf Finishers offers additional benefits. One key advantage is that the pre-grinding process stage with ceramic grinding media—a necessary step in drag finishing—is no longer required. As a result, the number of machines needed for surface grinding and polishing is reduced to two Multi-Surf Finishers, compared to three drag finishers.

This reduction not only lowers capital expenditures but also decreases energy and resource consumption while requiring less floor space for the surface finishing operation.

An additional benefit is that processing times for costly CNC grinding operations can be shortened by transferring part of this work to the Multi-Surf Finisher.

Maximum Process Stability Through Visualization and Digital Process Water Management

To ensure maximum process safety and stability, Rösler augmented the standard equipment controls with a process visualization module. This allows machine operators to visually monitor each process stage in real time.

The cleaning and recycling of process water from the wet surface smoothing operation is managed by a fully automatic Z 1000 centrifuge. The control panel of the centrifuge is equipped with the digital process water management module “Advanced” from Rösler Smart Solutions.

This innovative, interactive software continuously monitors, records, and evaluates up to 14 process parameters, including compound concentration, pH value, and microbiological load. If one or more parameters deviate from the pre-defined range, discrepancies are displayed, and operators receive clear, actionable recommendations for immediate corrective action.

This feature allows employees with no specialized knowledge or training to quickly adjust process water parameters to their pre-defined values, ensuring consistent product quality.

Furthermore, continuous monitoring over extended periods provides a clear indication of when process water quality has deteriorated to the point where replacement is necessary. This results in substantial water and compound savings while ensuring that product quality remains uncompromised.

Finally, the continuous recording of process water parameters serves as documented proof of process quality and stability, which is valuable for quality audits and documentation purposes.

For Information: 

Rösler Oberflächentechnik GmbH Vorstadt 1, 96190 Untermerzbach 

Germany

Tel. +49.9533.924-802

E-mail: d.hund@rosler.com

www.rosler.com