Improving Surgical Robot Performance Through Seal Design.pdf
- 1. Improving Surgical Robot Performance Through Seal Design Adriana Borcea Global Category Manager, Seals Bal Seal Engineering
- 2. • Complex devices that assist surgeons in procedures ranging from hip arthroplasty and coronary bypass to kidney transplant • Increase dexterity, compensate for tremor, support hand-eye coordination & improve visualization • Enable doctors to perform surgeries from remote locations SURGICAL ROBOTS B A L S E A L . C O M 2 Photo: United States Army
- 3. • Improved precision Arms/instruments with multiple degrees of freedom • Enhanced functionality Greater visualization Motion scaling/filtering • Smaller footprint Instrument level Platform level ADVANCES IN ROBOTIC SURGERY B A L S E A L . C O M 3
- 4. Goals Challenges Better control & dexterity Equipment with greater degrees of freedom Improve haptic sensing & feedback Reduce system static & dynamic friction in kinematic chain Smaller access sites Reduce instrument footprint Greater functionality Increase instrument capabilities SOME SURGICAL ROBOT CHALLENGES B A L S E A L . C O M 4
- 5. • Functions Protect equipment from bodily fluids, dust, grease, wipe downs/sterilization Maintain media pressure • Goals Minimize static and dynamic friction Maintain consistent dynamic friction Protect equipment from premature wear CRITICAL COMPONENTS: SEALS 5 B A L S E A L . C O M
- 6. SEALING APPLICATION EXAMPLES End Effectors Arms/Joints Actuators Motors B A L S E A L . C O M 6
- 7. • Performance conditions RPM Pressure Media Life expectancy Torque capacity Temperature limits • Hardware conditions Shaft diameter, material, surface finish, surface hardness, tolerances Shaft/bore misalignment • Reprocessing conditions Autoclave Gamma sterilization FACTORS THAT IMPACT SEAL DESIGN B A L S E A L . C O M 7
- 8. • PTFE-based composition materials provide the lowest friction, stiction & wear, and also: Exhibit excellent chemical compatibility, can run dry as well/no lubrication Withstand wide temperature range of - 400°F up to 550°F+ FDA compatible & USP class VI certified 8 B A L S E A L . C O M A CLOSER LOOK: SEAL MATERIALS 0 0.1 0.2 0.3 0.4 0.5 0.6 PTFE PFA FEP PEEK UHMWPE HDPE Delrin PVC Nylon Static Coefficient of Friction
- 9. Dynamic lip engineered to minimize friction, optimize sealing performance, prevent media ingress. • Engineered designs that … Handle rotary, oscillating, reciprocating + angular motion Balance sealing effectiveness + low friction & stiction Promote continuous laminar flow, preventing bioburden buildup Reach compact sizes - IDs to 5mm and below A CLOSER LOOK: CUSTOM GEOMETRY 9 B A L S E A L . C O M Metal locking ring prevents seal rotation in hardware, promotes consistent sealing contact under thermal cycling conditions.
- 10. • Customized loads • Preloads sealing lip to maintain protective barrier during thermal cycling • Chemical compatibility Implantable options • Wide amount of sizes Smallest ID = 0.5mm • Accommodate large tolerances A CLOSER LOOK: CANTED COIL ENERGIZER B A L S E A L . C O M 10
- 11. 391 765 1366 2488 4735 0 1000 2000 3000 4000 5000 2.0 4.0 8.0 16.0 32.0 Frictional Force vs. Surface Finish • High/rough surface finish can increase friction and cause material to wear faster • Minimal friction enables smooth system operation & increased life • Friction can influence haptic sensing, sensor feedback, and motor operation 11 B A L S E A L . C O M HARDWARE INSIGHTS: SURFACE FINISH (1.8) (3.6) (7.2) (14.4) (28.8) Surface finish microinches RMS (microinches Ra) Frictional force (grams)
- 12. • Dependent on seal ring material • If low, can increase adhesion of material and friction, causing premature seal wear • Some materials require elevated hardness to ensure longevity of the dynamic surfaces HARDWARE INSIGHTS: DYNAMIC SURFACE HARDNESS 12 B A L S E A L . C O M
- 13. CASE STUDY: SURGICAL ROBOTIC ARM Features Requirements Size Ø7mm shaft Speed 500 to 1K RPM Service type Rotary & oscillating Media Air & oil (dry/wet) Forces Breakout: 4mN-m Running: 2mN-m Lifecycles 9 million revolutions Size constraints 2.5mm x 2.5mm B A L S E A L . C O M 13
- 14. • Polymer-filled PTFE seal Low CoF Low stiction Low wear rate CASE STUDY: SURGICAL ROBOTIC ARM 14 B A L S E A L . C O M Dynamic lip to minimize friction Canted coil spring applying consistent light force Locking ring to easily press into hardware and enhance stability FDA & RoHS compliant material Thin, flexible hinge point
- 15. BETTER ACCESS & ACCURACY: TAKEAWAYS Challenge Requirement The right seal can provide … Better control & dexterity Equipment with greater degrees of freedom • Multiple degrees of freedom to enable rotation, translation & articulation • Greater tolerance absorption Improve haptic sensing & feedback Reduce system static and dynamic friction in kinematic chain • Low friction for improved kinematics & responsiveness • Flat force curve for controlled and predictable friction • Wear limiting features to maintain consistency Smaller access sites Reduced instrument footprint • Smaller, compact design (axial & radial) Greater equipment functionality Increase instrument capabilities • Dry-running, low wear with locking mechanisms enable additional capabilities in smaller spaces B A L S E A L . C O M 15
- 16. • To eliminate costly mistakes and delays, consider sealing requirements as part of overall robot design • In early design stages, collaborate with Bal Seal Engineering to: Get consultative engineering advice Review robot hardware design Estimate frictional outcome Engage in collaborative seal design discussion Custom design a seal that meets all your system/application requirements ▸Determine recommended test failure criteria Produce high-quality seal prototypes Scale up to full production SUMMARY & RECOMMENDATIONS 16 B A L S E A L . C O M
- 17. • “We make seals, springs and contacts that make your designs great” • Established in 1958 • ~650 employees • Offices in US, EMEA, Asia • Quality-driven and ISO certified • Solutions tailored to your design BAL SEAL ENGINEERING 17 B A L S E A L . C O M
- 18. RESOURCES & CONTACT INFORMATION Start the conversation with a robotics sealing expert: Adriana Borcea Global Category Manager, Seals Bal Seal Engineering P: 949.460.2160 aborcea@balseal.com B A L S E A L . C O M 18 solutions@balseal.com www.balseal.com +1 949.460.2100 Design Request Form