Segmented PTFE Composite Bearing for Machining Precision
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Solution Overview
Problem
Composite bearings with high content of continuous PTFE fibers have poor machinability, leading to fiber breakage and undesirable surface roughness and voids, making it difficult to achieve tight dimensional tolerances.
Innovation Solution
A self-lubricating composite material comprising discontinuous polymer fiber segments, semi-continuous thermoplastic fibers, and a thermosetting resin, with additional lubricants like PTFE, boron nitride, and graphite, which are dispersed throughout a woven matrix and embedded in the resin, allowing for improved machining and wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous PTFE fibers are used in high content for self-lubrication, then wear resistance and low friction are improved, but machinability deteriorates causing fiber breakage and surface roughness
Solution Approach 1:
The patent divides continuous PTFE fibers into discontinuous fiber segments with lengths of 0.5 to 3.0 mm. This segmentation allows the PTFE to maintain self-lubricating properties while eliminating the fiber breakage and surface fuzz problems associated with machining continuous fibers. The segmented fibers are distributed throughout the thermoplastic matrix, providing lubrication without compromising machinability.
Solution Approach 2:
The patent creates a composite material system consisting of discontinuous PTFE fiber segments embedded in a thermoplastic polymer matrix. This composite structure combines the low friction and wear resistance of PTFE with the machinability and structural integrity of the thermoplastic matrix, resolving the contradiction between wear performance and ease of manufacture.
2Reliability
If continuous PTFE fibers are used in high content, then low wear rates are achieved, but dimensional precision deteriorates due to surface voids and roughness
Solution Approach 1:
By segmenting continuous PTFE fibers into discrete fibers of controlled length (0.5 to 3.0 mm), the patent eliminates the formation of surface voids and fuzz during machining. The segmented fibers distribute more uniformly in the matrix and do not protrude or break during machining operations, enabling achievement of tight dimensional tolerances while maintaining low wear rates.
Solution Approach 2:
The patent changes the physical state of PTFE from continuous fibers to discontinuous segments with specific length parameters. This parameter change transforms the material behavior during machining, allowing the bearing surface to be machined to tight tolerances without the fiber breakage and void formation that occur with continuous fibers.
3Reliability
If continuous PTFE fibers are used for self-lubrication, then friction reduction is improved, but surface quality deteriorates with fuzz and voids
Solution Approach 1:
The patent segments continuous PTFE fibers into discontinuous fibers that are fully embedded in the thermoplastic matrix. This segmentation prevents fiber protrusion and fuzz formation on the surface during machining. The discontinuous fibers maintain their self-lubricating function while eliminating the harmful surface fuzz that results from machining continuous fibers.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composite material exhibits favorable machining properties and wear resistance, reducing surface roughness and voids, while maintaining low friction and wear rates across a broad range of application conditions.
Implementation Method 1
A self-lubricating composite material which includes discontinuous polymer fiber segments, semi-continuous thermoplastic fiber, and thermosetting resin
Implementation Method 2
The thermosetting resin used in the composite material described herein also may include one or more additional self-lubricants. The additional self-lubricants can include from 1-10 wt % boron nitride (BN) particulates, from 5 to 15 wt % polytetrafluoroethylene (PTFE) particulates,—and from 5-20 wt % graphite particulates
Data Source
AI summary
A self-lubricating composite material is disclosed. The self-lubricating composite material can include discontinuous polymer fiber segments dispersed within a woven matrix of semi-continuous thermoplastic fiber. The woven matrix can be embedded within a thermosetting resin. Also disclosed are methods of manufacturing the self-lubricating composite material.