To Grind or Not to Grind Your Pins? When making field connections on your chain DO NOT grind your pins because this will only cause you more headaches in the upcoming months. When discussing chain, the old saying “Your chain is only as strong as your weakest link.” has never been so true and by grinding a pin you have just created a weak link.
As machining and hole punching processes get more precise we can use these processes to our advantage and add more value into the chain for our customers. Websters current processes allow us to reproduce a consistent and repeatable interference fit between the pins and the sidebar holes. With this repeatability, we solely rely on our press fit to keep the pins stationary in the sidebar. There are always a few exceptions to the rule based upon the geometry of the parts, but for the most part you will notice our pins with a full round end.
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Measuring Chain Elongation
Chain elongation is an easy way for the customer to determine the wear on the internal components of the chain just by taking a few measurements while the chain is on the conveyor. The measurement can then be compared to the chain’s original length and used to determine how much life is remaining in the chain.
To measure chain elongation, you will first need to follow any and all safety guidelines to lockout the conveyor and remove any guards needed to gain access to the chain. Usually, a 10 pitch section of chain is preferred, but more or less can be used depending on access to the chain. When taking the measurement on the chain there are several locations you can measure from and to, but the measurement needs to be taken from a consistent place. In other words, if the measurement starts from the centerline of the pin it will need to end on the centerline of the pin approximately 10 pitches away, or however many pitches are being measured. Other common places to measure to and from would be the front edge of the pin head or the front edge of a sidebar. Once this measurement is taken it can be used in the formula below to determine the chain’s elongation. Once the chain elongation is determined the rules of thumb are as follows:
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RWL vs. AUS – An Engineering Perspective
What are Rated Working Load (RWL) and the Average Ultimate Strength (AUS) of an engineered class chain and what do they mean?
First let’s tackle the AUS and a general overview of how it is calculated. The AUS is a calculated value from the chain manufacturer of the average breaking strength of the chain. The published AUS rating is generally the lowest calculated value between the following: the sidebar’s tensile strength, the sidebar’s shear strength and the pin’s shear strength (see Figure 1). Generally speaking this number should not be used when sizing a chain for a particular application because this is the breaking limit of the chain; the chain should never equal or exceed this value as it will result in total chain failure. It should be considered into your chain choice when a higher fatigue strength is required for the more demanding applications.
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Direction of Chain Travel – It Goes That-A-Way
What is the proper direction of travel for welded steel chains? If run in the proper direction, you can actually reduce wear on the chain and sprockets by 80-90% when compared with chain operated in the wrong direction. Running your chain in the right direction will improve chain life, extend the life of the sprockets, decrease maintenance costs, and increase the “uptime” of your operation.
Welded steel chains are normally produced with offset style sidebars. In addition, welded steel chains have a “fixed” barrel. However, before we get into the particulars of the sprocket interaction with these chains, the first decision is to determine whether the chain is used as a conveyor chain or as a drive chain. Most welded steel chains in the forest products industry are used as conveyor chains. For this discussion, we will concentrate on the use of welded steel chains on conveying applications. For general purposes, remember these two rules:
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Metallurgy – The Key to Good Performance
Metallurgy is a very important part of good chain design. Some would argue, and I tend to agree, that the proper selection and treatment of the materials is the most important function is getting the most chain life. Using the right materials, treated in the proper manner can achieve very important benefits especially in the rapidly changing conditions we all face in today’s applications.
In order to understand metallurgy you only need a working knowledge of some of the basic terms. In order to get the benefits of proper metallurgy you must have a full understanding of your particular application to see if there is some peculiarity about it. For example, if your application is highly corrosive, or you have conditions of extreme cold or heat, or you may have a changing environment such as running the chain in salt or fresh water and then exposing the chain to the outside air. The proper selection of materials can help overcome some of these or other damaging effects of any known condition. The key is good communication with your supplier. The chain engineer will select the best material for your application provided he knows the facts, but until you communicate with him, he will base his decisions on his past experiences with what he thinks is a similar application. This may not be true in your case.
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