Frequent failures in Donghua chains and how to prevent them

Donghua roller chains are power transmission elements used in a wide variety of industrial and agricultural equipment. They consist of interconnected links with rollers that rotate on bushings, allowing motion transmission between shafts with high efficiency. We stock these chains in standard ASA sizes, such as ASA 60, ASA 80, and ASA 50, which adapt to different loads and speeds.

In Argentine industry, Donghua chains are found in conveyors, elevators, agricultural machinery, packaging equipment, and transmission systems in general. Choosing the correct pitch, such as that of ASA 60 or ASA 80, is essential to ensure smooth and durable operation. An inadequate pitch can cause vibrations, noise, and premature wear.

To identify a Donghua chain, you can observe the marking on the links, which usually includes the series code and pitch. For example, an ASA 50 chain has a pitch of 5/8 inch, while ASA 60 has 3/4 inch and ASA 80 has 1 inch. Additionally, you can measure the distance between centers of consecutive pins to confirm the pitch. If you have doubts about which chain you need, you can send us a photo of the part or the engraved code and we will help you identify it.

Wear is the most common failure in roller chains, and it mainly manifests as elongation or stretching of the chain. This occurs when pins and bushings lose material due to friction, which increases the effective pitch and causes the chain to no longer seat correctly on the sprockets. A clear sign is that the chain looks loose or jumps on the teeth, and it can be measured by comparing the length of several links with a new chain. If elongation exceeds a critical value, the chain must be replaced to avoid major damage.

Another frequent failure is roller wear, which can be external or internal. External wear appears as flattening or scoring on the roller surface, while internal wear affects the fit between roller and bushing. This can be due to lack of lubrication, contamination with abrasive particles, or excessive load. To recognize it, visually inspect the chain and rotate each roller by hand: if it feels rough or has play, it is a sign of wear.

Wear of the side plates is also common, especially in the holes where the pins are housed. This wear can cause pins to loosen and the chain to come apart. It is detected by observing if there are cracks or deformations in the plates, or if the pins move laterally. In all cases, it is important to act in time: a worn chain can damage sprockets and other system components. If you notice any of these symptoms, we recommend getting a quote for a new chain, for example an ASA 60 or ASA 80 depending on your application.

Fatigue is a failure that occurs due to repeated cyclic loads, even if the maximum load is below the tensile strength of the chain. It manifests as cracks in the plates or pins, which can propagate to sudden breakage. If the load limit is exceeded or impact loads are present, service life is drastically reduced. It is important to respect the load capacity indicated for each pitch, such as ASA 50, ASA 60, or ASA 80.

Overload can be due to sudden starts, system blockages, or incorrect chain selection. A sign of overload is plastic deformation of the plates or breakage of pins. Permanent stretching of the chain without significant wear can also be observed. To prevent it, the working load must be calculated correctly and a chain with an adequate safety factor must be chosen. If you have doubts, you can consult us and we will help you select the correct Donghua chain.

Another cause of fatigue is excessive vibration or resonance in the system. This can generate alternating stresses that accelerate the appearance of cracks. It is recommended to check the alignment of the sprockets, the chain tension, and the condition of the supports. Correct assembly reduces vibrations and extends chain life. If you notice abnormal vibrations, check the system and the chain.

Incorrect assembly is one of the main causes of premature failures in roller chains. Misalignment of sprockets generates lateral loads that wear links and teeth unevenly. It can be checked with a ruler or laser level: shafts must be parallel and sprockets in the same plane. If the chain tends to come off or looks twisted, it is a sign of misalignment.

Inadequate tension also causes failures. A chain that is too tight increases the load on pins and bushings, accelerating wear and fatigue. A loose chain can jump teeth, hit the casing, or come off the sprocket. Correct tension is adjusted by leaving a small sag in the center of the slack span, according to the manufacturer's recommendations. For an ASA 60 chain, for example, sag should be measured and adjusted according to specifications.

Using inappropriate tools to join the chain can damage the links. When installing a connecting link, ensure that the pins are well seated and that the clip is placed in the correct direction. Never hammer directly on rollers or plates. If you do not have the right tool, it is better to consult a specialist. At MR we can advise you on the correct assembly of your Donghua chain.

Lubrication is essential to reduce friction between pins and bushings and to protect against corrosion. A poorly lubricated chain wears quickly and can generate excessive heat. The type of lubricant and application method depend on speed and working conditions. For low-speed applications, grease or oil can be applied manually; for high speeds, drip or oil bath lubrication is recommended.

Preventive maintenance includes periodic inspections to detect wear, elongation, cracks, or lack of lubrication. Chain elongation should be measured with a caliper or by comparing with a new chain. The condition of sprockets should also be checked: if teeth are worn or hook-shaped, they must be replaced along with the chain. A well-implemented maintenance program can avoid unplanned downtime and reduce costs.

Chain cleaning is also important to remove contaminants that accelerate wear. A suitable solvent can be used and then re-lubricated. Avoid using aggressive solvents that may damage seals or material. If the chain operates in dusty or humid environments, lubrication and cleaning frequency should be increased. For Donghua chains, follow the manufacturer's recommendations regarding lubricants and frequencies.

To order a replacement chain, it is essential to identify the pitch and type. Pitch is measured in inches and corresponds to the distance between centers of consecutive pins. Standard ASA chains are designated with numbers: ASA 50 for 5/8", ASA 60 for 3/4", and ASA 80 for 1". The number of strands should also be considered: single, double, or triple. If the original chain has an engraved code, you can use it to find the equivalent.

If you do not have the code, you can measure the pitch with a caliper and count the number of links. It is also useful to measure the inner width between plates and the roller diameter. With that data, we can help you identify the appropriate Donghua chain. At MR we stock Donghua roller chains in standard sizes, and we quote the one you need.

It is important not to confuse pitch with chain width. Using a chain with the wrong pitch will damage sprockets and cause premature failures. If you have doubts, send us a photo of the chain and sprocket, and we will advise you.

It is recommended to replace the chain when elongation exceeds the critical value indicated by the manufacturer, or when cracks, breakage, or excessive wear are observed on rollers and plates. It should also be replaced if the chain has come off several times or if the sprockets are very worn. It is preferable to change the chain and sprockets at the same time to ensure optimal operation.

To get a quote for a Donghua chain at MR, you can send us the chain code, for example ASA 60 or ASA 80, along with the number of links or total length. If you do not have the code, send us a photo of the chain and sprocket, and we will help you identify it. You can also indicate the application and working conditions so we can recommend the best option.

At MR we market and distribute Donghua roller chains in Buenos Aires, Argentina. We work with standard ASA sizes. Write to us via WhatsApp or email with your chain data and we will respond promptly with a quote.