Welded Steel Chains are your best chain buy. There is no other class of chain that offers a package of high strength, flexibility, ruggedness, precision and durability equal to the properties found in Welded Steel Chains. Although relatively low in cost for the work they do, chains can do an even better job if some simple care, attention, timely inspections and preventative steps are taken which on their own will increase the life and service of the chain.
The chain is under constant stress and each component performs a vital function in carrying a load. In actual operation, the stress on each part is a pulsing type movement which over time causes the chain components to fatigue and eventually lose their ability to perform. Because of their unique design welded steel chains can use extra strong parts, which is precisely why these chains are ideal for some of the most strenuous, heavy duty applications.
Although the stresses are exactly as illustrated, the welded steel design eliminates the need for the roller and uses a welded bushing in its place. This simple change eliminates the need to pierce a larger hole in the sidebar to accommodate a bushing, and thus allows the use of a larger size pin in the same size package. The pin is the real heart of a chain, so this ability to use a larger diameter pin is the key to the value of welded chains and why they are ideally suited for the tough conveying jobs.
Selecting the proper pin for your particular need cannot be over emphasized. It would be impossible to list all the different variations available and to explain the merits of each at this time, so I strongly suggest that you discuss the applications with your chain manufacturer. Although standard chains will handle many applications, it is good advice to check with your supplier.
There are some general rules of thumb that you might want to take into consideration:
- The pins should be heat treated using the thru-hardened process for most Forest Product applications. Thru-hardened parts add strength throughout, from the core to the outer surface. It is a wise idea to ask specific questions about the hardness levels. Pins that are too soft could wear fast, while pins that are too hard could be brittle and break easily under load.
- Consider paying a slight premium to have the pins Induction hardened. Proper Induction hardened pins are first heat treated for strength and then surface induction hardened for increased wear. Because the induction process places compressive stresses on the part, it offers added protection against the small cracks that eventually grow and cause fatigue failures. An added bonus of induction hardened pins is the resistance to damp conditions, effects of water, ice, some chemicals and other corrosion causing conditions. As a general statement, I call induction hardened pins, "the secret to good chain life".
- For more severe corrosion problems consider pins that are heat treated and then plated. There are various plating conditions causing the corrosion. Nickel plated pins seem to work well in salt water or similar conditions, whereas, an electro-nickel process, though expensive, seems to work well in various chemicals.
- Under severe corrosive conditions, you might consider stainless steel pins but this is usually a high cost option. Stainless, although good for corrosion protection, does not harden as well so there is a sacrifice of chain life for the added protection. Unless conditions are extreme, it would seem that stainless pins are not a good option in this industry. You should check with your chain supplier for the best grade of stainless to handle your specific problem.
If there were a limit of choices to make in the selection of chain, I would always opt for the following for most welded steel chain applications:
- Select chain with the largest diameter pin in your basic chain limitations. Choose thru-hardened, then induction hardened process.
- Choose a pin of alloy material rather than plain carbon material. Alloy materials use a better steel making process, have less impurities, and have alloying elements which insure better, more consistent heat treatment.
Please contact Mac Chain co. Ltd. for more details about induction hardening, alloy materials, or other processes discussed in this report.