Seal - Sealings - Radial Oil Seals

Introduction

Rings sealing rotation shafts /other terms used: radial oil seals, rings for radial sealing of shafts/ are one of the most widespread type of sealing.

They have:

an external cylindrical surface made from steel sheet metal or elastomer which seals the ring and makes it possible to properly encase it,
a sealing elastomer lip /movable and resting shaft sealing/. An additional dustproof lip provides protection form dust and other solid impurities.

Due to their very wide application in many branches of industry, rings sealing rotation shafts have required well-developed standardisation with regard to the dimensions, materials, types. This study provides primarily information on this matter, which will enable the user to move in the maze of materials and catalogues of individual manufacturers.

Terminology, construction process

Terminology, construction process

Elements of standardisation - norms

PN - 72/M-86964 - shaft sealing rubber rings with a metal stiffening insert - dimensions
PN - 72/M-86965 - shaft sealing rings with in metal casing - dimensions
PN - 88/M-73067 - rotation shaft sealing rings ISO compliant - nominal dimensions and tolerances
PN - 81/M-86960 - rubber rings for sealing rotation shafts, ISO compliant - shared requirements and tests
ISO 6194/1-1982 - rings for radial sealing of rotation shafts - nominal dimensions and tolerances
ISO 6194/2-1991 - rings for radial sealing of rotation shafts - glossary
ISO 6194/3-1988 - rings for radial sealing of rotation shafts - storage and installation
ISO 6194/4-1988 - rings for radial sealing of rotation shafts - testing procedures
ISO 6194/5-1990 - rings for radial sealing of rotation shafts - flaw identification
DIN 3760 - rings for radial sealing of rotation shafts
DIN 3761 - rings for radial sealing of shafts in cars, parts 1 to 15 - the norm includes all aspects with the glossary, requirements for the material and testing methods.

Structural variations

structure	structure variation	marking according to ISO 6194/1	marking according to DIN 3760	marking according to ERIKS
Type: rubber with a metal stiffening insert
	without a dustproof lip	type 1	A	R
	with a dustproof lip	type 4	AS	Rst
	springless	-	-	RZV
Type: in a metal casing
	without a dustproof lip	type 2	B	M
	reinforced without a dustproof lip	type 3	C	GV
	with a dustproof lip	type 5	BS	Mst
	reinforced with a dustproof lip	type 6	CS	GVst
	springless	-	-	MZV

Materials

symbol	basic type	working temp. range	operating environment
NBR		-40°C +100°C	resistant to: engine, transmission and fuel oils, hydraulic fluids, grease, emulsions, oil-water emulsions and water, not resistant to: synthetic slow-burning liquids and brake fluids.
ACM		-20°C +130°C	resistant to: engine and transmission oils, hydraulic fluids, not resistant to: water, oil-water emulsions, synthetic slow-burning liquids and brake fluids.
MQ MVQ		-50°C +150°C	resistant to: engine and transmission oils, hydraulic fluids, oil-water emulsions.
FPM FKM		-30°C +180°C	resistant to: engine and transmission oils, hydraulic fluids, fuel oils, oil-water emulsions, synthetic slow-burning liquids.

Markings

d - nominal shaft size [mm]
D - nominal socket size [mm]
b /H/ - width /height/ of the ring [mm]

Full marking of the ring:

d x D x b - structural type - class / material symbol

Example: a ring with a dustproof lip in a metal casing from the FPM material d=17mm D=33mm b=8mm

17 x 33 x 8 Mst FPM

Tolerances

Diagnostics

symptoms	cause	prevention
1. Leakage	nicks, notches or rips in the lip scratches or notches on the shaft surface	examine the quality of the rings - pt. 2 ensure proper machining of the shaft protect the surface of the shaft from damage
	spiral machining marks on the shaft surface	grind the shaft concave
	errors of positioning the shaft in relation to the casing	build the casing precisely position the rings closer to the bearings
	too little grip of the lip on the shaft	check the dimensions of the shaft
	excess of grease used during the installation	reduce the amount of grease on the shaft or ring before the installation
	damaged spring	see pt. 7
	damaged sealing body	see pt. 6
	rolling up of the lip	see pt. 8
	shaft corrosion caused by the contact of the lift with the shaft surface	change the material of the sealing ring or the shaft
2. Grooves, scratches or wear of the lip	shaft surface too rough	remove splinters from the working surface of the shaft
	wedges, rabbets or sharp edges	use proper installation tools protecting the rings from damage
	careless handling	during transport and storage, the rings should be packed
3. Excessive wear or hardening of the lip	pressure	deaerate the sealing chamber
	no grease	supply grease to the ring
	improperly selected material for a particular factor	change the ring material
4. Shaft wear	filings and other impurities	clean the elements before the installation. In dusty atmosphere, use a dustproof lip. ensure proper hardness of the shaft surface
5. Scratches on the external diameter of the sealing	too rough surface of the casing opening	make an opening in the casing with the correct roughness
	sharp edge of the casing opening	make a bevel in the opening. Dull sharp edges
	decreased opening diameter	check the dimensions
6. Damaged sealing body	incorrect installation	use proper installation methods
6. Damaged sealing body	careless handling	during transport and storage, the rings should be packed
7. Damaged spring	incorrect installation	use proper installation methods. Avoid unnecessary stretching of the spring during installation
7. Damaged spring	careless handling	protect the rings during transport and storage
8. Rolled up lip	too rough surface of the shaft bevel	ensure proper machining of the bevel, the transition of the bevel to the shaft diameter should be smooth
	too great angle of shaft bevel slope	maximum bevel angle in relation to the shaft axis should be 30°
	careless handling	use appropriate installation tools

The data present in this study are for information only. They may not be used as a basis for civil legal claims. Detailed questions should be directed to the Manufacturer. The Manufacturer reserves the right to introduce changes, according to new technical solutions and progress in the area of technologies and materials.