Lubrication of Chains

The Chain is one of the eldest traction and drive components, consisting of individual links gripping movable into each other.

Open link chains – functioning without lubrication normal open-link chain stud-link or anchor chain caterpillar-type drive chain (similar to track chains)

Base of the Chain Lubrication All other Chains need an optimal Lubrication! They never can work in the ideal state of hydrodynamic friction but always in the critical areas of boundary friction and mixed friction (see Stribeck diagram). High loads restricted on linear surface contacts and no rotational motion but angular motion only prevails! Therefore : Speciality lubricants are of especial importance for the use at chains.

Link Chains Makes and Shapes Load chains Drive chains

Load Chains Liner chains Fly-frame chains (without chain sprockets)

Drive Chains Rotary chains Bush chains Roller chains

Construction of roller chains Pin Bushing Roller Side bar or plate

Types of Drive Chains Single-row roller chain Double-row roller chain Triple-row roller chain

Types of Conveyor Chains Single row chainDouble row chainTriple row chain

Failures and their Reasons Dirtiness At heavily soiled chains the oil only can partially and not completely penetrate into the chain joints. Elongation of Chains Even with optimal lubrication, chain stretching will occur after long operation time. However with an adequate lubrication the lifetime is 60 times longer than at dry running Already with a 3% elongation, the sprocket has no more chance to gear in perfectly. Broken Pins and Side Bars The reason is often overloading or corrosion in the chain joint Rust on Surface and Joint Reasons are inadequate lubrication or insufficient corrosion protection. Noise Inadequate lubrication causes metallic friction which effects grating and squeaking. Stiff Joints After leaving the sprocket wheel the chain does not get back to its stretched length. Reasons are cold seizing, corrosion of the joint or residues of unsuitable lubricants, caused by insufficient or wrong lubrication.

Dependence of Wear, Chain Elongation and kind of Lubrication Graph 2: Lubrication only once a time, delay of wear occurrence until lubricant is used up. Graph 3: Irregular lubrication, temporary dry running by hand lubrication if relubrication schedule is not followed. Graph 4: Inadequate lubrication, irregular wear due to inferior, dirty, non-suitable or too small quantity of lubricant. Graph 5: Perfect lubrication, strongly reduced wear, enhanced safety for long service life of the chain. Graph 1: Dry running, excessive wear, destruction of chain in very short time Chain elongation [%] Service time [h]

Ways of Lubrication Depending on the speed of the chain v [m/s] Hand lubrication Drip lubrication Slash lubrication Pump lubrication

Hand Lubrication Lubrication by oil can or brush is a very unsure method. It is not useful for continuous operation and therefore only suitable for driving units of minor importance and slow chain speeds.

Drip-feed Lubrication Lubrication by wick, needle or drip oiler is suitable for driving units with low stress. In order that the lubricant will attain the linkages, the dripping pipes outlets have to be placed above the pin row.

Splash Lubrication in Oil Bath A chain protection case has a soundproofing effect. Its dimension should be such big, that the elongated chain does not beat against the walls. The chain pins should immerse into the bath not more than to the rollers or bushings. At the oil bath there is no loss of the lubricant.

Forced-feed circulatory Lubrication Used for fast running chains and subject to high loads. Oil feeding may be carried out by connecting it to an already installed pressure oil pipe or a pump. The oil spurts from the pipe on the whole width of the chain on the inner side of the pulling strand and in direction of the course.

Requirements on the Lubricant Lubricating performance Wear protection Penetrative and clearance fitting ability Noise suppression Corrosion protection Adhesive ability Temperature stability Resistance to media Food grade property Environmentally safe

Service Temperature range of OKS Products with MoS 2 with Mo x - Active with MoS 2 + Mo x - Active with white solid lubricants + Mo x -Active with graphite

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