ASTM F543 | Medical Devices and Equipment | Mechanical Properties
ASTM F543 is used to measure four different mechanical properties of bone screws, including the vertical torsion (A1), the insertion/removal torque(A2), the pullout strength (A3), and the axial compression load force of self-tapping bone screws (A4). An axial-torsion testing machine is capable of performing the ASTM F543 specification. Before performing the test, it is important to read the entire F543 specification as values below have been removed to protect the integrity of the standard.
ASTM F543 | Medical Devices and Equipment | Mechanical Properties
Test Procedure for A1
- Secure the specimen so that the specimen is exposed according to the standard. A collet is a common fixture used for securing the screw that prevents the specimen from rotating.
- While maintaining contact between the drill bit and the screw, drive the specimen at the specified rate found in the standard.
Calculations:
- Torsional Yield Strength
- Maximum Torque
- Breaking Angle
Test Procedure for A2
- Place the test block in the block clamp device. Load the bone screw specimen onto the driver. The specimen and driver are then lowered by the spindle into the pilot hole.
- Drive the specimen into the test block by applying torsional force at the specified rate found in the standard. Record the maximum torque durring those revolutions.
- Once inserted the specified number of revolutions, reverse direction of rotation record the maximum toque during those revolutions.
Calculations:
- Insertion Torque
- Axial Load
- Insertion Depth
- Removal Torque
Test Procedure for A3
- The bone screw should be inserted into the test block as specified in the standard.
- While the test block is secured to the base of the frame, the screw head shall be gripped and a tensile load shall be applied at a rate of 5 mm/min until the screw fails or releases from the test block.
Calculations:
- Insertion Depth
- Axial Pullout Strength
Test Procedure for A4
- Place the test block in the block clamp device. Load the bone screw specimen onto the driver. The specimen and driver are then lowered by the spindle into the pilot hole.
- Conduct the test by driving the specimen using a rotational rate found in the standard.
- Axial compression force will continue to be increased until the self-taping features of the screw engage the test block as indicated by a marked increase in torque. At this point increasing axial-force shall conclude and the system should maintain the axial compressive force at which the self-tap was first noted.
- Continue the rotation while maintaining axial load until the specified number of complete rotations have been achieved, thereby concluding that the specimen encompasses valid self-tap properties.
Calculations:
- Axial Load
- Maximum Self-Tap Force
- Maximum Torque
- Axial Displacement
ASTM F543 | Medical Devices and Equipment | Mechanical Properties
ASTM F543 | Medical Devices and Equipment | Mechanical Properties
ASTM F543 | Recommended Equipment |
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Testing System | |
Fixturing |
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