Heavy-Duty Industrial Chain: How It’s Made
Since Leonardo da Vinci famously made sketches of what appeared to be the first steel chains in the 16th century, people have been innovating new ways to make industrial chain safer, stronger, and more wear and weather resistant. At Laclede Chain, we’re constantly refining our processes to achieve this same thing.
Why does high quality industrial chain matter?
Why strive for continuous improvement? Isn’t chain, simply, well…chain? We don’t think so. Whether you buy chain for use in agricultural equipment, marine applications, traction, cargo control, construction, playground equipment, amusement parks, or any of the other thousands of applications we create products for, the quality of your chain matters. It keeps industrial workers, military personnel, and the general public safe because it’s strong enough to withstand the forces of its environment. And when chain is engineered to last, it prevents premature replacement, which saves valuable natural resources as well as cost for the user.
But how do you know whether your chain is good quality? It all comes down to how it’s made and how it’s tested to keep you and people everywhere safe.
Raw materials are critical
Great chain starts with great steel rod. It’s important that your chain supplier is using high quality rod from a recognized steel manufacturer or distribution channel. All steel should have a quality certification paper trail to ensure your steel won’t fail when it’s in an extreme environment. At Laclede, all of our rod is certified directly from the mills. Our preference, whenever possible, is to use locally sourced products, because we’re a proud US manufacturer and want to support near-sourcing whenever we can.
The chain-making process
- Rod is received and processed. We receive our rod in large metal spools. It is then pickled to remove impurities, rust, and scale from the surface. Then, our steel rod is drawn to the exact required wire diameter. At this point in the process, the steel rod is transformed into wire.
- Making each pin. Then, wire is fed into a forming machine where it is first straightened, then stamped. Once the chain has been stamped, it is notched on either side of the wire. The notches mark where the wire will be sliced into pieces, which we call cutting to “pin length.” A pin is one link of formed chain.
- Forming the pin. The pin enters another forming machine, and roller arms bend it around a steel head into an open-ended link. The newly formed link is then pushed into the previous link and fully closed. After that, it begins the slow crawl towards the welder.
- Preparing for welding. As it approaches the welding position, the chain is automatically rotated to ensure that the weld is applied directly to the notched area of the chain—critical for maximum weld strength.
- Welding. The coppers close on the link and apply electricity, heating the link, forcing it fully closed at the last instant. This is when the weld is formed and a new chain link has been made. Before it leaves the saddle, the burrs from welding are trimmed smooth. After being smoothed, the link crawls slowly back down off the welder and heads to the calibrator.
- Calibration & tolerance check. On the calibrator, the chain is pulled to the final precise length. It is pulled to a force at 2.2x the desired strength for each specified grade of chain.
- Heat treating (if required). Then, depending on the end product grade, the chain is fed into a box and passed on to heat treating. It is passed through an induction coil (heating the chain to between 1600–1700℉, into a water quench, and tempered. The induction heat treating process gives consistent and reliable heat treatment of every chain link.
We conduct two different types of testing regularly after chain has been manufactured and undergone heat treatment: proof testing and ultimate pull testing.
Ultimate (Destructive) Pull Testing
At regular intervals during each shift and any time a machine adjustment is made, our team takes a sample for visual inspection which is then pulled to destruction. We call this process ultimate testing.
How It Works
Sample links are cut from the continuous length of chain, heat treated (if required), and placed in a hydraulic unit that pulls the chain until it breaks. The break is inspected as well as the weld. If the weld breaks or if a break occurs below the designated minimum break strength, then the chain sample is rejected. In this way, we ensure that the weld will be the strongest component of the chain.
Proof Testing – For Heat treated Chain only
How It Works
Heat treated chain is loaded into an automated proof testing machine which applies a straight tension load to a small section of chain. The tension load applied for testing is 2.2x the working load limit (WLL) based on the size and grade of the chain.
Why Proof Testing?
Proof testing is done on every single link of heat-treated Laclede chain, so you can be certain it will perform up to (and beyond) standards in the field. This ensures that the chain is both the proper dimensions as well as has the proper strength. Because we cannot destruct every link of chain, this test ensures every link has already held up to a value well above WLL and so will do so in the field.
If your chain does not have grade identification, then your chain is considered to be the lowest grade—Grade 30 for purposes of working load limit (WLL) and usage. Make sure that you can properly identify and read your grade marking. Our heat treated chain also has a heat treat code that can be used by our quality team to identify the complete process that chain went through all the way back to the steel rod production. A well-hallmarked chain is a sign of proper quality procedures.
Need quality industrial chain? We can help!
Laclede Chain has been committed to innovation and safety in chain manufacturing since 1854, when our company started making chains that hitched the Conestoga wagons of the pioneers as they headed west. Things have changed since then, but our dedication has remained the same to making the highest quality products backed by the best service in domestic chain today. For help with your chain needs, please use our online tool at the top right corner of this page to find your Laclede rep, or call us directly at 800-325-2699.