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Split composite sliding bearing

Wrapped composite sliding bearing, tin-plated steel/PTFE, DIN 1494/ISO 3547, Maintenance-free

PTFE composite bushings are suitable for applications where a sliding material with self lubricating properties is a prerequisite. Application area examples for these bushings are:
automotive
material handling equipment
home appliances and consumer goods
textile machinery

Description

Split bushing sleeve Cylindrical Bushes,china Factory Direct Price

Note: Because of the lead content, PTFE Composite lead free type used in contact with food, beverage or products. Try to use PTFE composite type Stainless Backed Composite bushings.

Lubrication The PTFE-based sliding surface permits smooth, low-friction operation without lubrication or maintenance. During the running-in phase part of the covering layer of PTFE Composite dry sliding bearings is transferred to the mating surface and forms a physically bonded lubricant film.

Bushing Selection

Cross section of  PTFE Composite
PTFE tin bronze copper layer sheet steel backing copper layer tin layer PTFE Composite

Long maintenance-free operating life due to low friction

Overview of Technical Data

PTFE Composite bearings offer many features and advantages

such as:

  • maintenance-free operation
  • very good frictional properties
  • high load capacity
  • operating temperatures up to 250 °C
  • sliding velocity up to 2 m/s
  • small operating clearance

Material Structure

These materiais consist of metal backing bonded to a porous bronze sintered layer with PTFE based polymer bearing layer.The metal backing provides mechanical strength, while the bronze sinter layer provides a strong mechanical bonding between the backing and the bearing lining,the PTFE based polymer offers exceptional low friction even under dry condition.

Lubrication Bushings

The PTFE-based sliding surface permits smooth, low-friction operation without lubrication or maintenance. During the running-in phase part of the covering layer of VIIPLUS PTFE Composite dry sliding bearings is transferred to the mating surface and forms a physically bonded lubricant film. The presence or continuous supply of oil or other non corrosive fluids may be advantageous and improve the perfomance of these bearings.

Advantages

Improved energy efficiency with the low friction performance of PTFE-enriched overlay;
Extended service life with a high wear-resistant bronze layer;
Zero maintenance as self-lubricating bearings can operate dry without grease;
Greater reliability than bimetallic bearings by avoiding potential shaft/bearing seizure under boundary lubricated conditions and frequent stop/start operation;
Compact, lightweight designs with thin-wall bearing construction;
Reduced noise with no metal-to-metal contact between the bearing and the shaft;
Quick, simple assembly without expensive mounting tools.

PTFE composite

PTFE composite bearings consist of a sheet steel backing on which a 0,2 to 0,4 mm thick
porous layer of tin/bronze is sintered . By a rolling process, the pores of the sintered layer are filled with a mixture of PTFE (polytetrafluoroethylene) and molybdenum disulphide (designation suffix E). An additional 5 to 30 μm thick running-in layer of the mixture is then applied to the sintered tin/bronze. This additional layer provides an optimum combination of the mechanical properties of the sintered tin/bronze and the good sliding and lubricating properties of the PTFE mixture. PTFE composite bearings have
good dimensional stability and thermal conductivity

Machining the bore of PTFE composite bushings

PTFE composite bushings conform to ISO 3547:2006 and are ready for installation.
Any re-sizing of the bore, i.e. the sliding surface, will reduce the service life of the bushings and should only be done in exceptional cases. If re-sizing is necessary, the bore should be calibrated, using a mandrel/resizing tool . Because various criteria, like material and wall thickness of the housing as well as the deviation of cylindrical form, have to be taken into consideration,Viiplus recommends using a calibrated mandrel to re-size the bore. After resizing, bushing bore expansion tests and application field tests should be undertaken prior to the release of a final product. 

Guideline values for the requisite interference of the calibrating mandrel as a function of the desired widening of the bushing bore for various bushing bore diameters can be obtained from diagram 1. The diagram is based on tests with bushings of different sizes and valid for bushings mounted in a housing with an outside diameter DG = 2 * bushing outside diameter D . If mandrel expansion tests show that the bore is too wide, the calibrating mandrel should be reground and the tests repeated on new bushings.

Friction

Load, sliding velocity and operating temperature are primary factors in determining the friction in composite plain bearings. Friction is also influenced by the roughness of the surface on which the bearing runs, the degree of contamination and the lubrication conditions. For PTFE composite bearings, the coefficient of friction m lies between 0,03 and 0,25 depending on the operating conditions. Similar values are found for the POM composite material, but the presence or constant supply of lubricating fluids serves to decrease friction. The lowest values are normally obtained where there are high specific loads and low sliding velocities . Under particularly unfavourable operating conditions, like light loads, high velocities or inadequate surfaces, the maximum guideline values may be exceeded.
The coefficient of friction for PTFE composite bearings increases at temperatures above +100 °C. Stick-slip effects are negligible for PTFE and POM bearings.

Characteristics

  • Maintenance free
  • Low friction coefficient
  • Multiple areas of use
  • Long lifetime

Type of applications

  • Person lifts
  • Packaging machines
  • Pneumatic cylinders
  • Pumps

Design

  • Cylindrical bearings
  • Flanged bearings
  • Thrust washers
  • Slide plates
  • Drawing details

Application of PTFE in agricultural machinery

With high strength and high temperature glass fiber reinforced epoxy resin as base, with special fibre and PTFE as the sliding layer, base material layer provides a good bearing performance, and grind resistant layer is provided under the condition of dry friction has very low friction due to the number of features, makes the bearing under the condition of low speed high load condition has excellent wear resistance and shock attack resistance ability, suitable for low speed high load conditions and have special request for corrosion field, such as lifting machinery, logistics, machinery, agricultural machinery and port machinery, etc.

Technical Data

Specific load capacity (static) ≤ 250 [ N/mm² ]
Specific load capacity (dynamic) ≤ 140 N/mm² at low speeds
Specific load capacity(rotating oscillating) ≤60N/m㎡
Friction value 0.03 to 0.25 µ
Temperature -200 to +280 [ °C ]
Max. dry running Pv (Short-term operation) 3.6N/m㎡﹡m/s
Max. dry running Pv (Continuous operation) 1.8N/m㎡﹡m/s
Max. speed (dry running) 2m/s
Max. speed (Hydrodynamic operation) >2m/s

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