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MAC CHAIN CO LTD US OPERATIONS CANADA OPERATIONS 1855 SCHURMAN WAY 9445 193A STREET WOODLAND, WA 98674 SURREY, BC V4N 4N5 PH: (360) 225-6000 PH: (604) 888-1229 FX: (360) 225-3400 FX: (604) 888-0600 TOLL FREE 1-800-663-0072

A GUIDE ON HOW TO GET BETTER LIFE, REDUCE COSTS AND IMPROVE OPERATING

PERFORMANCE OF YOUR WELDED STEEL CHAINS

COMPILED BY TOM HICKEY

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Mac Chain Co. is a leading manufacturer of quality Welded Steel Conveyor Chains for Forest Products and Industrial applications. Our commitment to quality includes extensive research and development, performance testing, rigid quality control and continuous innovation. Each chain is uniquely engineered for strength and durability, given the specific set of conditions for which it was designed and produced. The Sawmill and Mining industries make up a major portion of our market. Included among our customers are Weyerhaeuser, Boise Cascade, Simpson Timber, Potlatch Corporation and many others. Mac Chain’s products are widely used across the United States and around the world. Established in 1979, Mac Chain is a family owned enterprise. The four owner-operators include: W.J. McFarland (President), J.T. McFarland (Vice President), Victor McFarland (Vice President) and Tom Hickey (Vice President and responsible for U.S. operations). With a combined total of over 80 years’ experience in the chain manufacturing business, the four principals have the skills and knowledge required to make a quality product. Mac Chain Co. has the experience, skills and equipment to provide your company with the very best quality steel chains at a reasonable price.

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TABLE OF CONTENTS

1. CHAIN COMPONENTS AND STRESS .................... PAGE 4 2. WHERE DOES IT BEGIN? ...................................... PAGE 8 3. INITIAL INSTALLATION ........................................... PAGE10 4. PREVENTATIVE MAINTENANCE CHECK LIST ..... PAGE 14 5. PIN CORROSION: EFFECT AND PREVENTION ... PAGE 18 6. INDUCTION HARDENED PINS ............................... PAGE 20 7. ENGINEERING NOTES ........................................... PAGE 23

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CHAIN COMPONENTS AND STRESS

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WELDED STEEL CHAINS 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: 1. 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.

2. 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

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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”.

3. 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.

4. 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: 1. Select chain with the largest diameter pin in your basic chain limitations.

Choose thru-hardened, then induction hardened process. 2. 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.

Note: Contact Mac Chain Co. Ltd. for more details about induction

hardening, alloy materials, or other processes discussed in this report.

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WHERE DOES IT BEGIN?

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BETTER CHAIN LIFE

WHERE DOES IT BEGIN? As we look over various applications we see many ways that chain life could be improved, and the operation perform better if only there wasn’t the many restrictions designed into the unit. If the system designer would take into consideration the day to day operating and maintenance requirements, chain life could be increased many times over just by following a few good principles. Where does it begin? Right at the conception stage, before the first pencil is laid on the drawing paper. A discussion with the maintenance people is quite a step in the right direction, the consideration of several other thoughts. Remember, our goal is to design a system that will not only do the job required, but one that will also operate efficiently, at low cost, with little down time and ease of maintenance and replacement when necessary. Although there are many ideas that need to be thought of, a few come to mind that should be considered: 1. Leave ample room, including headroom, so maintenance people can do

their job efficiently and without unnecessary hazards. 2. Select chain wisely. It is better to over specify a chain than to undersize

the chain. Remember to use a chain with the largest diameter pin in that series to take advantage of the benefits of larger diameter pins in overall job performance.

3. Stay away from drives that cause excess flexing of the chain. Every time

a chain flexes, there is increased wear at the joints. “S” drives, for example, are very hard on chain and actually decrease the life of the chain.

Other drive designs that reduce chain life are “water fall”, often used with drag chains, or any application that causes the chain to run over many sprockets. The fewer flexes that the chain performs in its normal operation, the better.

4. Leave room for a proper catenary or chain sag. A proper sag is necessary

for good chain life. Excess tightening of the take-up places the joints under stress, causes poor sprocket / chain interaction and if carried to an extreme, can actually bind up the system. Remember, a sag is essential.

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5. Leave room for sprockets. As a general rule, for good operation, the more teeth in the sprocket, the better the operation. We try to have an odd number of teeth with the ideal sprocket diameter of 3-4 times the pitch of the chain. Thus a 6” pitch chain would have a sprocket of about 24” in diameter.

6. Use a UHMW wear plate where possible to reduce friction and excessive

wear on the chain as it slides over a surface. If metal to metal contact is necessary, try to balance the wear plate material with the hardness of the chain sidebar.

7. Use split sprockets in hard to reach and hard to replace areas. Sprockets

should be replaced whenever new chain is required. By using split sprockets the task of removing shafts and other obstacles is eliminated making the overall task much simpler and more cost efficient.

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INITIAL INSTALLATION

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BETTER CHAIN LIFE

INITIAL INSTALLATION The initial installation is the most critical event in the overall program for better chain life. The break-in period, and how the product is installed will determine whether the system will run trouble free, or will be subject to frequent periods of minor problems. If the proper foundation is set, and some pre-installation practices are followed, the overall chain life could be increased by 25 to 50%, depending on the application. Listed below are some of the preliminary steps that should be considered before, and during the installation process: 1. Select a chain manufacturer that you feel comfortable with and one who

can help you select the proper product to use. Communicate regularly and establish a personal relationship so that ideas can flow easily and with trust. There are many chain producers, some making outlandish claims about their products and service, anything to make a sale. But what we really want and need is that trust and degree of confidence that comes from a joint working relationship.

2. The cost of the chain should not be the sole determining factor. As

maintenance people, you want to give yourself the best opportunity for success, so you need to understand and evaluate the features and benefits available to improve the chances of success. The added cost of these extras are minimal when compared to the cost of a single breakdown. As a general rule, it is better to over-specify than to skimp and hope.

3. Lubrication is so important, especially in the joint area that I normally

recommend an extra cost feature that will insure proper lubrication during the critical break-in period. The recommendation is to have the pins pre-greased prior to assembly. The actual operation is to dip the pins into grease and to add some grease into the barrel cavity so that the grease is trapped into the cavity between the barrel and the pin. By doing this, you obtain some very helpful insurance, and some extra protection from the corrosive environment that may exist in your operation. Although there are more lasting features to combat corrosion, this idea will give some temporary relief and almost guarantee some added chain life.

4. As stated above, pre-lubing a chain before installation can add months

and years of life to the chain. There are many ways this can be done, but

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possibly the easiest way is to immerse the chain into a barrel of ordinary motor oil of the proper viscosity for the prevailing conditions. Let the chain sit for some time to allow the oil to seep into the chain joints and the barrel cavity.

Then, install the chain, run it for a period of time to set the joints, and you

should have a chain that will out-perform anything you have tried before. Through regular periodic lubrication in the months ahead, you will have a chain that will last, reducing your maintenance and downtime costs.

5. Remember sprockets. It is a good practice to replace the sprockets when

installing new chain. The sprocket interface is probably the greatest contributor to excessive chain wear, so if you want to improve chain life, give extra care to sprocket selection. Some rules of thumb to consider:

A. Smaller sprockets are harder on chains than larger sprockets. If

you have room in your drive or envelope consider using a larger sprocket with more teeth. Increasing a sprocket by even two teeth will help improve chain life.

B. Try to use sprockets with an uneven number of teeth. Chain tends

to strip off the bottom of the sprocket better, especially with a 180 degree wrap installation.

C. We generally recommend the diameter of the sprocket to be about

4 times the chain pitch. D. Be particular about the chain return. The chain should have a

catenary of from 5-10% of the center distances between the sprockets.

The next step to consider in the initial installation is to have the chain run in the proper direction. Because welded steel chains have a “fixed barrel”, it is important that the chain run with the chain links open end forward. By doing this, the pin rotates inside the barrel and there is no movement of the barrel and less tendency to wear. Once seated on the sprocket tooth, no wear will take place on either the tooth or the barrel O.D. There are so many variations of welded steel chains that should be considered depending upon the operating conditions. Some will add chain life, while some are a waste of money even though they sound good on the surface. As a helpful hint section, I have compiled a list of some of the best add-ons, and some of the worst. In all of our thinking, we should remember that the pin is the most critical part of a chain, so anything we do to make the pin better will be a plus for the chain.

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1. Induction Hardened Pins…An excellent plus for Welded Steel Chains because induction hardened pins have good core strength for toughness, and a very hard outside surface for added wear qualities.

2. Alloy Steel Pins…An excellent plus because Alloy Steel is made to

exacting standards and has the chemicals that insure uniform hardness in the part after heat treating.

3. Stainless Steel Pins…Only if necessary for very severe corrosive

conditions. Stainless steel pins generally do not have the hardness or toughness required for the tough applications. It is generally better to check out the degree of corrosion, and then us a plated pin with a specific plating material that works well in your environment.

4. Stainless Steel Sidebars…Not usually worth the money. Although

required for some food handling applications, the cost / benefit relationship is usually unfavorable and can be avoided.

5. Case Hardened Barrels…Not a very good alternative on welded steel

chains. Very costly and prone to crack. 6. Induction Hardened Sidebars…A total waste of money except in very rare

instances where there is a heavy load placed directly on a chain that is running over a bed of very abrasive materials. Usually the joint parts of a chain wear before the sidebars, so in most cases induction hardening the edges of sidebars add cost but no real benefits.

7. Split Sprockets…Although costly is usually an excellent idea for many

forest products applications. The cost of replacing sprockets will be substantially reduced through the use of this design sprocket.

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PREVENTATIVE MAINTENANCE

CHECK LIST

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BETTER CHAIN LIFE

PREVENTATIVE MAINTENANCE CHECK LIST Chain and sprockets should be inspected after three months service and six month intervals thereafter. These mostly visual inspections will uncover potential problem areas before they become more serious. Always correct apparent problems as they are uncovered to assure all steps are taken to guarantee long life and trouble free service. INSPECTION CHECK LIST 1. Wash chain and sprockets with a heavy stream of clean water or steam

to remove excess material buildup which can cause improper seating on the sprockets resulting in accelerated wear. Direct the water spray to flush out the joints that could clog and prevent the entry of lubricants, or cause tight joints through a buildup of corrosion.

2. Inspect the sprockets for usual or excessive wear, or an uneven wear

pattern on the sprocket teeth, deep grooves in the pockets, a hooking wear pattern on the teeth, or for any other indications of misalignment. Inspect for cracked welds, and retighten set screws or other ring bolts if you are using segmental sprockets.

3. Check the inner face of the sidebars of the chain for a shiny surface

which could signal a misalignment problem, especially if the wear is more prevalent on one side than the other. Misalignment problems should be corrected as soon as possible. The chain should run freely and without interference with the sprocket teeth. (note: We frequently see poor sprocket / chain interaction because the sprockets are not properly matched to the chain). It is a good idea to purchase chain and sprockets from the same source and to have the chain wrap checked prior to shipment.

4. Check for loose, cracked, or unseated or rotating pins. Any of these

conditions indicate a danger signal that can lead to chain breaks, work stoppages, and lost productivity. Check for signs of corrosion, or corrosive buildup which can lead to tight joints, and fatigue breaks. If a bad situation is present, the condition may require some special action to reduce the corrosion causing conditions, or possibly special pin treatment to reduce the damaging effects of corrosion. Corrosive conditions are one of the leading causes of pin breakage in Welded Steel

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Chains. (Note: See page 19 for an in depth discussion of the effects of corrosion on pin life with some suggestions for corrective actions.)

5. Check bushings for signs of uneven or excessive wear, cracks, or broken

welds. These conditions usually indicate sprocket scrubbing, misalignment, overload, or improper tooth design. The conditions can sometimes be corrected by adjusting the take-ups, and by paying more attention to the amount of chain sag, but usually trial and error, or just plain good judgment are all that it takes once there is understanding that chain sag is necessary for good chain performance.

6. Check the chain joints for signs of “wallowing out”, which is excessive

wear of the sidebars at the pin location. This condition can cause chain stretch, jumping of sprocket teeth, a conveyor surge, early pin breakage, and also create a dangerous situation. When a condition like this is noticed, the link should be removed and replaced. If there are several links with this problem, the chain should be replaced. Wallowing out usually occurs because of a poor press fit of the pin in the sidebars. This could occur because of poor control of the pin diameter, or more likely improper piercing of the sidebars.

Frequently maintenance personnel replace pins in chain, to increase

chain life. Because of the difficulty in maintaining a press fit, some grind or turn the pin to get an easier replacement. This, of course, reduces the life of the chain and the loose pins begin turning, which then leads to the wallowing out process.

7. Lubricate the chain immediately. To be effective, the lubricant should be

directed into the chain joint area where it is most effective. Adequate lubrication is the most important element in long chain life, so care should be taken to insure the lubricant seeps between the pin and bushing, and between the pins and the sidebars. The extra time it takes to do a complete job pays very big dividends in trouble free operation.

If possible, some type of oiling system should be installed to keep the joints in contact with some type of lubricant. Because clean water has some lubricating qualities, some run a stream of water over the joints with enough force to remove buildup, and to keep the joints clean. A petroleum based lubricant is better, but clean water can also be used effectively.

8. Run the chain to seat the joints and to check for any signs of pulsing, or

surging. The chain should run smoothly over the sprockets and along the tracks. Tight joints will not articulate over the sprockets and can be readily observed and immediately replaced or repaired. Usually surging chain indicates a potential problem and the need for corrective action. Some possible causes of surging:

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A. Take-up tension is too tight or too loose. Best solution is to try to adjust the take-up until the chain runs smoothly without jerks or surges.

B. Improper sprocket design or number of teeth. As a general rule,

use sprockets with as many teeth as practical, and use a sprocket with a diameter of 3-4 times the chain pitch.

C. If the conveyor is running at a very slow speed, try increasing the

speed to overcome the frictional forces that could cause the surges. D. Check sprockets for excessive wear patterns. Worn sprockets can

cause chain to jump teeth or catch in the pockets. E. Check the loading of the chain and try to eliminate very rough

loading onto the chain. Dropping heavy logs onto the chain is very destructive. A better method is to slide the load onto the chain without the impact of a high drop. Chains were not designed to accept a rough loading that causes the chain to jump or bounce.

9. Check all the attachments for cracked welds, tighten bolts, and look for

signs of inappropriate wear. Loose attachments are particularly dangerous so make sure they are properly welded. Because most chain sidebars are heat treated, the welding of attachments becomes more critical. Use a low hydrogen rod, pre-heat the parts to be welded, and then slow cool. A good method is to toss a heavy blanket or canvass over the new weld until it cools naturally in this controlled atmosphere. Rapid cooling will cause stress cracks with will lead to premature fatigue failures.

10. Remember the importance of the three and six month inspections, and

remember to keep the chains well lubricated. These rules are guidelines that are sure to increase chain life, reduce failures, and improve the productivity of your operation.

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PIN CORROSION: EFFECT

AND PREVENTION

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BETTER CHAIN LIFE

PIN CORROSION: EFFECT AND PREVENTION Corrosion is very common in chains that operate in Forest Product applications. Especially the green area where the chain comes in frequent contact with water and the various acids from the logs being processed. In normal operation, when a load is placed upon the chain, the pin flexes in a back and forth motion, and a condition develops that makes the pin very susceptible to pitting from corrosion. The pitting becomes a very serious problem because as the pin moves back and forth, the pits become cracks, getting bigger over time until there is a failure. This is often called a fatigue failure. Corrosion cannot be eliminated entirely, nor can fatigue breaks, but there are actions that can be taken to reduce the amount and extent of the corrosion. Depending upon the degree of the pollutants that are attacking the pins, steps such as water resistant lubricants, various plating processes such as Zinc, Cadmium, Nickel or Electro less Nickel have all proven to be effective. Under some conditions induction hardened pins have shown some effectiveness because the induction process places the pin in compression. While in compression the pin will not be subject to the corrosive attack. Because induction hardened pins are so beneficial from a strength, wear and corrosion attack, they are almost a must for the buyer who wants better chain life. Stainless steel also offers good resistance to corrosion attack, but the amount of resistance properties of the stainless depends upon the grade of stainless selected. The more resistant, the more expensive and the less strength as a chain component so even if stainless is selected there has to be a compromise between resistance and strength. If stainless is the apparent answer, talk to your chain supplier about the different grades and the pros and cons of each.

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INDUCTION HARDENED PINS

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INDUCTION HARDENED PINS

THE SECRET TO CHAIN LIFE

In my opinion, the single most important, cost effective option you can specify for your welded steel chains would be to have the chain produced with induction hardened pins. It is a relatively low cost extra that pays real big benefits in reducing corrosion fatigue, improving chain wear and reducing downtime. I usually recommend induction hardened pins for most applications because “Done Right,” the induction process adds so many benefits to a chain pin, that I find it difficult to recommend anything else. I say, “Done Right,” because that is the key. The pin is the most important part of a chain because it takes the most severe beating in operation. The pin flexes and is subjected to tensile stresses, and in many applications, it also operates in a corrosive environment. In most cases the quality of the pin determines the life of the chain, and where there is tensile stresses and a corrosive environment the importance of the pin is multiplied many times over. To be “Done Right,” the induction hardened pins should have several very important characteristics. A good pin will have a very tough core strength necessary to insure toughness and the ability to flex and carry the load. Then, the pin should have a surface hardness that is deep enough and hard enough to improve the wear resistance, but not cause brittleness. Finally, the pin should be put into a state of compression by imparting residual compressive stresses in the surface of the pin. This can be done by induction hardening. This process will give you several benefits, but the most important is that you cannot have a fatigue failure while the pin is in compression. Since the induction hardened process leaves residual compressive stresses in the surface of the pin, you cannot have a fatigue failure until a crack develops and goes through the induction hardened surface. To gain toughness the pin should be heat treated, oil quenched, and drawn back to provide a hardness throughout of 28/32 Rc. This hardness provides the inner toughness to the pin. The same pin is then passed through a series of induction coils which will heat the outside surface of the pin to a predetermined “Red-Hot” temperature, and this surface will immediately be water-quenched. The combination of a predetermined “Red-Hot” temperature and a severe water quench produces a very hard outside surface. To prevent brittleness the depth of the induction

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hardness surface is controlled to about 10% of the pin diameter. The outside hardness is 42/47 Rc which gives the pin superior wear capabilities. The combination of first through hardening, and then induction hardening, produces a pin with inner hardness for strength, and an outside hardness for improved wear characteristics. If you were to cut an induction hardened pin in half, you would have a pin cross section that appears as in sketch A. SKETCH A This is a cross-section of a typical WH132 pin that illustrates the difference between an induction hardened pin and the standard through hardened pin. If you were to cut an induction hardened pin in half, you would actually see the black ring as illustrated.

Core hardness Pin hardness

28/32 Rc 32/37 Rc

Outer throughout

surface is

approx.

42/47 Rc

Depth .100

Induction Hardened Standard Heat-Treat

WR132 Pin WR132 Pin