Understanding Roller Chain Wear & Elongation

Roller chains are an essential component in many types of machinery, from agricultural equipment to industrial equipment and heavy machinery. They are designed to transmit power efficiently from one shaft to another while maintaining accurate speed ratios. However, over time, roller chains are subject to wear and elongation, which can result in reduced efficiency, increased maintenance costs, and even failure of the system. In this article, we will explore the common causes of roller chain wear and elongation, as well as possible solutions.

What is Roller Chain Wear?

Roller chain wear is a natural phenomenon that occurs when two metal surfaces rub against each other during operation, causing material removal from the contacting surfaces. The wear process is influenced by various factors, including load, speed, lubrication, alignment, and environmental conditions. The most common spots for chain wear is on the bushings and pins with is the main "bearing" point where the chain articulates.

What is Roller Chain Elongation?

As pictured above, roller chain elongation is the gradual lengthening of the chain due to wear on the pins and bushings. As the chain material wears away, there becomes more space between the pin & bushing that causes the chain become longer due to excess space between the parts. This causes the chain to ride higher on the sprocket teeth, reducing the effectiveness of the chain and increasing the likelihood of skipping teeth or jumping off the sprockets. This is commonly referred to as chain stretch even though the chain does not technically stretch. All chains should normally be replaced once it has elongated 3% from it's original length.

Common Causes of Roller Chain Wear and Elongation

Several factors can contribute to roller chain wear and elongation. Some of the most common include:

• Inadequate Lubrication: Roller chains require proper lubrication to reduce friction and wear between the chain components. Inadequate or improper lubrication can cause the chain to wear quickly and lead to premature elongation.
• Chain Construction Quality: A huge factor is the quality of the components used within the chain. The bushing, which is one of the most important parts of chain comes in two styles, a solid and a split. The solid bushings are superior to spilt bushing for wear resistance. All Nitro Chains are being built with solid bushings.
• Pre-Loading: Pre-loading also known as pre-stretching is process applying a load to a newly manufactured chain, which seats all the components within a chain that eliminates initial elongation. All Nitro chains are pre-stretch to at least the minimum required by the ANSI & British Standards.
• Overloading: Excessive loads beyond the design capacity of the chain can cause the chain to stretch and elongate over time due to excessive stress. This is particularly common in industrial applications, where heavy loads and high-speed operations can cause rapid wear and elongation. Loads should normally never exceed the max working loads listed for any given chain size.
• Contamination: Dirt, dust, and other abrasive debris can build up in the chain, causing increased friction and wear. In some cases, contaminants can even cause corrosion of the metal components, further accelerating wear and elongation.
• Corrosion: Roller chains operating in corrosive environments can experience accelerated wear due to the corrosive action of chemicals or moisture on the metal surfaces.
• Misalignment: When the sprockets are not properly aligned, the chain will be subject to increased stress, which can cause accelerated wear and elongation. Misalignment can be caused by improper installation, worn sprockets, or excessive axial or radial loading.
• High Operating Temperatures: If the operating temperature of the chain exceeds the recommended range, the metal parts can expand and contract, leading to accelerated wear and elongation.

What are the possible solutions?

Fortunately, there are several solutions available to address roller chain wear and elongation. Some of the most effective solutions include:

• Proper lubrication: Applying a high quality lubricant and ensuring that it is applied regularly can help reduce friction and extend the life of the chain.
• High quality solid bushing chains: Upgrade to higher quality chains such as Nitro Chains new enhanced N2 Series for superior wear resistance. The solid bushing comes standard in all Nitro ANSI roller chains.
• Cleaning: Regular cleaning of the chain can help remove contaminants that can contribute to wear and elongation.
• Proper alignment: Ensuring that the sprockets are properly aligned can reduce stress on the chain and extend its life.
• Load management: Avoiding overloading the chain and operating it within the recommended load range can prevent accelerated wear and elongation.
• Temperature management: Monitoring the operating temperature of the chain and ensuring that it remains within the recommended range can prevent thermal expansion and contraction, which can lead to wear and elongation. Adding a special formulated lubricant for high temperature can help with wear.
• Regular inspection: Regularly inspecting the chain for signs of wear and elongation can help identify problems early and prevent more significant issues from occurring.

Problem Solving Chains

Nitro Chain offers various specialty roller chains as well as corrosive & high temperature resistant roller chains. These are perfect for applications needing features that extended beyond the standard series ANSI & British standard roller chains. Some examples include:

Stainless Steel

The stainless steel roller chains are perfect for both high corrosive and high temperature applications.

Coated Chain

When an application requires higher-strength than what stainless can offer, then our ShieldX® product line is another great option for higher corrosive environments.

Sealed O-Ring Roller Chain

Our o-ring roller chain is great solution for chain drives where re-lubrication is difficult. We do recommend periodically lubricating the chain to prevent the o-ring from drying out and cracking.

Self Lube Roller Chain

The self lube roller chain is another option for clean environments where no lubrication is required.

Custom Chain Solutions

In addition to these options, we offer custom options for unique situations where any standard stock item will not get the job done. Chains can be manufactured with chrome plated pins or Nitride heat treated pin that create extremely hard surfaces on the pins for increased wear protection.

Conclusion

Roller chain wear and elongation are common problems that can significantly impact the performance of machinery and equipment. However, by taking steps to address the underlying causes of these issues, including proper lubrication, cleaning, alignment, load management, temperature management, and regular inspection, it is possible to extend the life of the chain and maintain optimal system performance. By implementing these solutions, equipment owners can reduce maintenance costs, increase efficiency, and avoid downtime due to roller chain failure.