Zimmer Biomet, a provider of orthopedic implants, operates a production site with around 1,000 employees in Winterthur, Switzerland. Almost all CNC machining methods are used in its manufacturing processes. With the help of Janus Engineering, the company now programs the robots of its INSYS grinding center independently – directly from the CAM system.
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Process reliability and stability are essential pillars in medical technology. Ensuring them is a major challenge. The more of these processes a company can handle in-house, the more flexible and efficient it becomes. Antonio Bressi is Senior Production Team Leader at Zimmer Biomet in Winterthur. He has achieved exactly that.
He is responsible for two INSYS grinding centers that fine-grind titanium prosthetic parts in several steps. These parts are held and guided to different grinding stations by a Stäubli robot. The process works well – until new products are introduced or the grinding process needs adjustment. “In such cases, we used to rely on INSYS service to reprogram the robot,” Bressi explains. “That was time-consuming and costly, so we looked for an alternative.”
NX CAM as the Manufacturing Foundation
Three CAM workstations based on Siemens NX CAM are used in hip prosthesis preparation alone. Many more NX licenses are in use across the site. Siemens NX has proven to be the ideal foundation for digital manufacturing. 3D models from the U.S. can be imported as STEP files and then prepared in NX CAM for CNC machining. The error-free simulation provides a reliable basis for programming milling, turning, and grinding operations. The corresponding postprocessor generates a detailed program for exact execution at the machine. All programs, processes, and machining operations in traditional manufacturing can be created, managed, and reproduced in NX CAM – without requiring external expertise.
Grinding from Coarse to Fine
Titanium hip prostheses are milled and turned in upstream processes. In the grinding cell, they receive their final touch. Small transitions, edges, or burrs are removed, and radii are refined. Grinding progresses from coarse to fine, ending with a rubber wheel that creates nearly polished surfaces. The parts are then blasted, laser-marked, and finished.
INSYS Grinding Cell with Robot
The grinding and machining stations are arranged around the robot. A swivelling loading and unloading system for dual-sided handling surrounds the unit. The robot picks up the raw part from the loading area and checks the current clamping situation using a probe. Small deviations in clamping can be compensated. The prosthetic blank can then be processed at three stations: two grinding belts with different grits and a rubber disc. Depending on the program and part requirements, blanks pass through one or more stations and are machined at different points.
No In-House Modifications Possible
Previously, robot programming changes required a specialist from INSYS. Immediate implementation was not possible due to limited availability, and programming occurred directly at the grinding cell, which could mean a week of downtime – an unsatisfactory situation for Antonio Bressi.
Striving for Independence
Since Janus Engineering has been managing the NX CAM infrastructure at Zimmer Biomet for years, Bressi wanted to bring robot programming into Siemens NX – just as easily as with other machines. A request to Janus gave the green light. As a versatile system, NX CAM offers the necessary functionality to integrate robotic systems, run simulations, and generate the corresponding robot code.
Reducing Downtime
Uwe Roosz, Project Manager at Janus Engineering Switzerland, organized a kickoff meeting in February 2021 to define the requirements for the robot-guided grinding cell. The investment was reasonable, and return on investment achievable in the short term. Janus defined a transparent budget and clear timeline. The analysis showed that most robot movements could be simulated and translated into code. While the grinding process itself is complex and still requires manual fine-tuning, overall downtimes were significantly reduced and will continue to decrease with growing experience.
A First: Reprogramming the Control System
The control system of the entire grinding cell – including the robot – is based on a proprietary INSYS program, where all parameters are integrated. Janus faced the challenge of replicating the entire program, as individual commands to the robot couldn‘t be changed within the existing INSYS software. They initiated a reverse engineering process to understand all operations – every grinding wheel, belt, and robot motion. The result was a custom XML-based control program for the full cell, now available in NX CAM for Zimmer Biomet. Its look and feel match the original INSYS system – something never achieved before.
For highly specific values such as “grinding pressure,” Janus created input templates in NX CAM where values can be entered manually. Since there were two different INSYS cells in use, a separate control program had to be created for each. This detailed onboarding process took up the majority of the project timeline.
Unified Foundation Brings Flexibility and Efficiency
In addition to increased productivity, the greatest benefit is achieving the original goal: independent programming. Robot programs can now be created without delays. The entire manufacturing setup now operates in a unified NX CAM environment. Janus easily trained Zimmer Biomet’s internal programmers on the robotic functions, as they were already familiar with NX CAM. Simple adjustments, like modifying a grinding path, can now be made quickly in-house. Programs are just as manageable as CNC programs and can serve as templates for similar tasks.
The savings potential is enormous: Antonio Bressi estimates a 15% time reduction – conservatively. Moreover, the team can now explore the limits of the grinding system through simulations and make corrections efficiently, without additional manual rework. This new flexibility is a major value-add.
Successful Project Execution
In the middle of the project, in December 2022, unexpected news arrived: INSYS Industrial Systems had filed for bankruptcy and entered liquidation. This shocking development confirmed how right Zimmer Biomet was in pursuing independence. Antonio Bressi concludes: “We are extremely satisfied with the implementation – everything ran brilliantly in my view. The collaboration with Janus Engineering was excellent. We supported each other pragmatically and completed the project successfully. Time, budget, and project plans were all met. Communication was exemplary, and the approach was well-structured.” He adds: “Together, we successfully defined a standard in NX CAM for Zimmer Biomet to program the two existing INSYS grinding cells. We now aim to further optimize this standard. In the future, we want to continue our strategy of automation and expanding our in-house capabilities.”