Technical specifications for PTFE slide bearings from Poly Fluoro Ltd.

Description:

The Poly Fluoro slide bearing is composed of an upper unit, a thin, stainless steel plate bonded to a sole plate and a lower unit composed of PTFE bonded to a durable, resilient fibre-free pad. Sliding or translation occurs between the stainless steel and the PTFE while deflection, rotation and load distribution are accommodated by the resilient pad.

Upper Unit:

Sole Plate: The sole plate shall conform to ASTM A-36, and the dimensions will comply with the details as shown on the structural drawings. All exposed surfaces must be given a prime coat of FX-708 two-component, zinc rich primer.

Stainless Steel: The stainless sheet shall be no less than 20 gauge, meeting ANSI, AISI, type 304 (ASTM A-240) specifications and have a mirror finish of less than 10 micro-inches R.M.S. (Root-Mean-Square) on the side in contact with the PTFE.

The stainless steel shall be a minimum of 1/4" smaller than the sole plate all around, and these shall be bonded together with a high temperature-resistant epoxy adhesive, or welded.

Epoxy: The epoxy adhesive shall meet the following requirements:

REQUIREMENT TEST METHOD VALUE

Requirement	Test method	Value
Flexural modulus	ASTM D 790	2 x 10^4
Safe operating temp.		-60° to 145°C
Linear Expansion co-efficient	ASTM D 696	4.8 X 10^5
Bond Strength tensile shear at 77°F	ASTM D 1002	70kgf/cm^2

LOWER UNIT:

PTFE: The PTFE, self-lubricating bearing element shall be 3/32" thick and composed of either 100% virgin (unfilled) PTFE or PTFE with a 15%-25% glass filling. The PTFE shall meet the following requirements:

Requirement	Test method	Value
Hardness (Shore D)	ASTM D 2240	60
Tensile Strength (kgf/cm^2)	ASTM D 1457	195 (min. avg.)
Elongation (%)	ASTM D 1457	200 (min. avg.)
Deformation Under Load %, 78°F, 140kgf/cm^2 (1/2" X 1/2" X 1/32")	ASTM D 621	4 (max.)
Specific Gravity	ASTM D 792	2.14 to 2.21

Bearing Pad: The resilient fibre-free pad shall meet the following requirements:

ELECTRICAL PROPERTIES:

Resistivity	Volume Resistivity 23°C 50% RH, Ohm-CM	8.3 x 10^10
Surface Resistivity	23°C 50% RH, Ohm	4.0 x 10^12
Resistivity	Impressed Voltage - 500
Dielectric Constant	23°C 50% RH
	Frequency
	60	cps	8.55
	103	cps	7.82
	106	cps	6.0
Dissipation Factor	23° 50% RH
	Frequency
	60	cps	0.089
	103	cps	0.060
	106	cps	0.087
Dielectric Strength	Electrodes 25mm apart 28°C oil temperature 500 vps rate of rise volts/mil 330

Tolerances: The expansion bearing total thickness will be +10%. The PTFE thickness shall be -0 + 1/64"

Co-Efficient of Friction: The co-efficient of friction between the self-lubricating bearing element (PTFE) and the stainless steel shall not be more than 0.06 at 55 kgf/cm² compressive loading.

POLY FLUORO LTD.

260A. Bommasandra Industrial Area, Hosur Road, Bangalore – 560 099

(: 91-80-27832627. Fax: 91-80-27832549. Mail: sales@polyfluoroltd.com

Note: This Information is based on our experience to date and believed to be reliable. It is intended only as a guide for use at your discretion. We cannot guarantee favourable results and assume no liability for use of this product. A local test programme is always recommended.