As a company that makes sprockets all day every day, and North America's biggest made-to-order sprocket manufacturer, we get questions all the time around tips and tricks on how to get the most out of your sprockets. We'll be adding to this article as we think of more tips, so be sure to bookmark this page!
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Change Your Sprockets When You Replace Your Chain
Sprockets are engineered to provide effective and efficient power transmission in tough, and repetitive work applications - all while resisting wear. Sprockets come in all shapes, sizes, and materials, each with a specific purpose in mind.
In most applications, our number one recommendation to get optimal working life out of your components is to replace your sprockets when you replace your chain.
Each organization has its own policy regarding this, but check out our article discussing the practical science behind this approach before writing it off.
The Double-Life Tooth (aka The Hunting Tooth)
This one is such a great cost-saving tip we have a whole blog article on how hunting tooth sprockets extend the life of your components [coming soon].
The hunting tooth design is a sprocket profile that acts like two sprockets in one. By utilizing particular sprocket ratios and tooth counts, we can create a drive setup that will double the life of your sprocket and chain.
Sprocket Ratio Best Practices
As a best practice, gearing ratios shouldn’t exceed 8:1. If your drive sprocket is driving a sprocket bigger than an 8:1 ratio, use a double reduction drive. While it is possible to use a bigger gear ratio than this, the resulting power loss and strain on the drive sprocket typically make that an impractical solution.
Instead, a more efficient solution is to implement a double reduction setup, where each reduction is less than 8:1. This places less stress on the drive sprocket, and is much more easily driven. The physical envelope of the sprocket assembly is also reduced since sprockets with a smaller circumference may be used to achieve the same final reduction ratio.
The Right Way to Install Engineered Chain
Welded engineered chain comes in two predominant types: offset sidebar and straight sidebar. As the chain rotates around the drive sprocket the teeth engage with the links and pull the chain. Each link is joined by a bushing and pin, creating an incredibly strong power transmission system.
As the chain rotates around the sprocket and engages with the teeth, most of the pressure is placed on the first link of the chain to meet the sprocket. As the link travels around the sprocket, it articulates around the pin to follow the working circumference of the sprocket (this creates the “Pitch Diameter”).
Offset engineered chain has two ends: the open side, where the legs of the link meet the barrel of the next link, and the closed side, where the link’s own barrel holds the sidebars together.
What Happens When Chain is Installed Wide-End First
If the link is installed with the open end in the direction of chain travel, the system works as anticipated: the link is pulled into the root of the sprocket tooth by the link before it. Because the link in front of it is already partway around the sprocket, by the time a link gets into contact with the sprocket tooth the bushing has already aligned with the working circumference of the sprocket. The working force pulls on the link, but the stress on the bushing and pin is negligible since very little rotational friction is occurring. Furthermore, the barrel of the link does not rotate against the sprocket tooth, which both increases sprocket life and chain life.
What Happens When Chain is Installed Narrow-End First
If the chain is installed the opposite way, the link contacts the sprocket tooth closed end first. In this configuration the barrel articulates after the sprocket tooth has engaged, pulling the link around the working circumference. This requires the barrel to rotate in the tooth and articulate around the pin while under working load, creating substantial additional friction. No amount of lubrication can counteract that level of stress, and components wear out much faster this way. Chain orientation is less relevant with chain that has straight sidebars, but is an important maintenance factor for chain with offset sidebars, especially for engineered chain without rollers.
When Sprockets are More Costly Than Chain
The main benefit to installing chain wide-end first is that it prolongs the life of your chain by reducing wear. Of the consumable components, sprockets are typically less costly than a new chain, and therefore prolonging chain life is generally the goal, however there are some applications where the cost of sprockets is higher than the chain.
When circumstances allow for an easy chain swap but a very strenuous, long, and costly sprocket changeout the downtime and installation costs will result in an expensive changeover, where the chain itself makes up only a small part of the total picture. Another situation where sprockets can be the more expensive component is when a short chain run is required, reducing the total cost of the chain, while the cost of two or more sprockets is constant.
If your application requires chain with added attachments such as flights, contact your chain supplier before ordering – most offer customization options so chains can be used in either orientation.
Mark Your Sprocket Expiry Point
A worn-out sprocket is a liability that can lead to a full production shutdown if hooked sprocket teeth catch on the chain and cause the chain to break. Stopping running machinery regularly to check for wear may not be a viable policy for many operations. Instead, prior to installing new sprockets, mark the maximum wear point for each sprocket using the following method.
Guide To Marking Sprocket Wear
Determine the pitch circle diameter (PCD), and mark it on a tooth (Point Z).
Determine the working width of the tooth (Y) at the PCD.
Calculate 10% of value Y to determine your maximum wear allowance (X).
Measure distance X at a 90-degree angle inwards from the tooth at point Z, and mark this point with a marker.
Using a hammer and punch, mark this point so that it’s clearly visible.
This point will be the maximum wear allowance for the sprocket. Once the wear of the sprocket reaches this point, the sprocket will require replacement. Using it further will result in hooking, accelerate the wear on your chain, and can lead to failure.
Once this wear point has been marked, maintenance personnel can observe sprocket health in real time through use of a strobe light by comparing the marked point with the silhouette of the tooth.
Our final note on measuring tooth wear concerns reversing applications. While this is something we typically try to avoid, there are applications where sprockets are run in reverse. This introduces new operating considerations (extra care has to be put into chain tensioning, for example), but will also begin to wear the sprocket tooth from the opposite side of the tooth. Make sure to factor this into your wear calculations if reversing is required in your workplace.
Can You Flip Sprockets?
Sprockets made to ANSI standards can usually be flipped, as they are typically symmetrical with a working surface on both sides of the tooth. Once a sprocket has worn to its maximum tolerance you can flip the sprocket to use the unworn side of the tooth, as long as the rest of the sprocket is still in good shape. This essentially doubles the working life of the sprocket.
Hub styles need to be carefully considered when flipping a sprocket. A-type sprockets (no hub), or C-type sprockets (hub on both sides) can often be easily flipped if the sprocket has been constructed with this in mind, but B-type sprockets (hub on one side) may cause logistical issues if your system has restrictive mounting options.
If you intend to flip your sprockets after the initial surface has worn down, make sure you change your chain out when you flip the sprocket. A new sprocket may eat through an old chain quickly (and vice versa). Also, note that when a sprocket is flipped, the wear from the previous side is still present, and may impact the strength of the sprocket tooth. This might not be as relevant with engineered sprockets, which often have tooth thickness to spare, but with roller chain sprockets, the teeth are usually smaller. If you flip the sprocket after wearing the tooth all way to the 10% mark on the first side, the risk of tooth breakage will become higher as the second side of the tooth wears down. Flipping the sprocket before it has reached the 10% mark may help to extend the working life of the sprocket here.
Replaceable Teeth Can Be Flipped Too
On a similar note, if flipping the sprocket isn’t an option, consider using a sprocket with replaceable teeth. Replaceable teeth sprockets, commonly referred to as segmental sprockets, minimize cost of maintenance by requiring less storage space and also saving installation time. To learn more about many of the great benefits segmental sprockets offer, read our article here.
Another benefit to the segmental design is the ability to flip the teeth. This will allow you to re-use the tooth segment on the unworn side of the tooth. The hub of the sprocket will outlast many sets of teeth, providing long term savings.
Individuals responsible for purchasing should be mindful of equipment restrictions and hub types when purchasing sprockets or replaceable teeth for use in both directions.
Source High Quality Sprockets
Sprockets are purpose-built for a variety of industries, each requiring a differing level of material hardness, tooth profile, and abrasion resistance.
DROP Sprockets primarily manufactures our sprockets from different grades of steel, with hardening and alloy options available upon request, but we also offer products in polyurethane, nylon, and aluminum and specialty steels. You can read about the manufacturing options we offer in this article series for a deep dive comparison of sprocket materials.
DROP sprockets come standard in a high-quality carbon steel, with hardened teeth to extend life and prevent premature wear.
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