PTFE Liner

1. These liners are used for a wide variety of medical procedures, including joint replacement surgery and cardiovascular intervention.

2. PTFE liners are highly durable and can withstand extreme temperatures, making them perfect for use in minimally invasive medical procedures.

3. PTFE liners can be easily molded into any shape, allowing them to be used in complex medical procedures.

4. These liners are made from Teflon, which is renowned for its strength and non-stick qualities, making them ideal for applications in sensitive medical environments.

5. PTFE liners are also resistant to most chemicals, making them a safer choice for the medical device or component production.

6. They are extremely lightweight, making them easy to install in confined areas with limited access and allowing them to be used in many different types of medical equipment.

7. They provide superior protection against severe wear and tear during frequent use. This makes them useful for medical devices such as catheters, stents, and guidewires, as these tools require reliable protection against abrasion and damage.

An answer to situations where the performance envelope cannot be covered by metal-to-metal bearings is to consider PTFE lined bearings. Here, the lubricant configuration is such that it functions as the load carrying element of the bearing. PTFE bearings may be specified under all or some of the following situations:

• Where lubrication is undesirable, difficult to perform, or impossible.
• Where loads are high and angular movement is low.
• Where space is limited.
• Where vibration is present.
• Where temperature of the environment renders greasing infeasible.
• Where a joint must remain static for an extended period of time before movement is initiated.
• Where friction in a greased bearing would be so high as to render the joint area useless after a limited number of cycles or impose an unacceptable fatigue situation.
• Where, in static joints, fretting is a problem.

While PTFE lined bearings can do an excellent job in many areas, there have been areas of misapplication. Also, there exist some misunderstandings regarding life and failure as applied to hardware of this type. Following are important clarifications concerning these products:

• The PTFE lined bearing starts life with a finite rotational pre-load torque or clearance.
• This rotational pre-load torque always decreases with bearing usage and clearance always increases with usage.
• A bearing may be said to have failed if the rotational pre-load torque drops below some specified value. This is always a systems application characteristic.
• A bearing may be said to have failed when the clearance generated by wear exceeds some specified value. This, again, is always some specified systems characteristic.
• A bearing may be said to have failed if the liner wears through enough to permit the ball to contact the race.
• No bearing, including PTFE lined bearings, will last forever. The “lifetime” lubrication concept applies to the bearing alone, not to the end usage item.
• The presence of liner debris on a bearing is not a definitive indication of failure.
• PTFE lined bearings tend to telegraph their impending failure by increased radial and axial play.

When evaluating the probable service life of a PTFE lined bearing application, there are some factors that do not appear in the PV = K relationship, (seePVFactor). Some considerations for a given application might include:

• Surface sliding speed
• Maximum ambient temperature
• Size of the heat sink
• Acceptable friction levels
• Load per unit of area, or liner stress level
• Mode of load application; i.e., the duty cycle
• Service alignment accuracy, particularly with respect to sleeve and flanged bearings
• Surrounding atmosphere
• Tolerable wear rate
• Surface finish of the bearing mating shaft and the shaft material