Industrial roller chain is not bicycle chain. That distinction matters, because if you search for "roller chain" or "sprockets" online, bicycle components dominate the results — different pitch, different load ratings, different standards entirely. This guide is about industrial roller chain: the ANSI and ISO/BS series chain used in conveyors, agricultural equipment, mining machinery, printing presses, manufacturing lines, and wherever real power transmission is required at low to moderate speeds.
Industrial roller chain is one of the oldest and most dependable power transmission methods in engineering. It is direct — no slip, no elastic creep, no tension-sensitive efficiency curve — and it is versatile enough to span centre distances that would make a gear set impractical and speeds that would overheat a flat belt. The trade-off is that it requires accurate alignment, correct tensioning, and consistent lubrication. Miss any one of those and the chain will tell you quickly.
This guide covers everything you need to specify, install, maintain, and replace industrial roller chain: how to decode the numbering system, how to match chain to sprocket, how to size a drive, and what to do when things wear out.
This guide is part of AIMS Industrial's curated Engineering Reference Charts library — 78 reference articles across fasteners, threading, bearings, lubrication and safety standards.
Roller chain anatomy
Understanding the components of a roller chain helps when diagnosing wear, comparing grades, and specifying replacements.
A standard roller chain consists of alternating inner links and outer links connected by pins:
- Inner link plates — the two flat side plates that hold the inner link assembly. They carry the tensile load and resist fatigue.
- Outer link plates (pin link) — the two flat side plates that hold the pins. On standard chain, these are the "master link" plates used to connect chain ends.
- Rollers — the cylindrical components that engage the sprocket teeth. They rotate freely on the bushes, reducing wear on both the sprocket teeth and the chain. The roller diameter determines the sprocket tooth form.
- Bushes — pressed into the inner link plates, the bush is the bearing surface for the roller. The inner diameter of the bush accepts the pin.
- Pins — the pivot points of the chain. Pin diameter and bush bore are the primary contact surfaces for articulation wear. This is the joint that elongates as the chain wears.
The pitch is the distance from the centre of one pin to the centre of the next. It is the single most important dimension for chain-to-sprocket compatibility — pitch must match exactly. Everything else (roller diameter, plate width, pin diameter, breaking load) is determined by the chain standard, but pitch is the non-negotiable match point.
Attachment chain
Standard roller chain is available with attachment plates — inner or outer link plates with extended tabs, holes, or bent flanges machined in. These are used in conveyor, elevator, and positioning applications where you need to fix a product carrier, bucket, or guide to the chain without breaking into the chain structure. Attachment designations (K1, K2, A1, A2, etc.) are defined in both ANSI and ISO standards.
The ANSI and ISO/BS numbering systems
Two major standards govern industrial roller chain in Australia: ANSI/ASME B29.1 (the American system, dominant in most industrial catalogues and stocked by most suppliers) and ISO 606 / BS 228 (the metric-origin system used in European machinery and some agricultural equipment).
ANSI chain numbering
ANSI chain numbers are two or three digits. The logic:
- The first one or two digits indicate pitch in eighths of an inch. Chain #40 has a pitch of 4/8" = ½" (12.7 mm). Chain #80 has a pitch of 8/8" = 1" (25.4 mm). Chain #120 has a pitch of 12/8" = 1½" (38.1 mm).
- The last digit indicates roller width and type: 0 = standard (roller width ≈ 5/8 × pitch), 1 = lightweight (narrow roller width), 5 = rollerless (used in some agricultural applications).
- Suffix -2 or -3 after the number indicates duplex or triplex (e.g. #40-2 is duplex #40 chain).
ISO/BS chain numbering
ISO/BS chain uses a different code. A designation like 10B-1 breaks down as:
- The number (10) indicates pitch in 1/16" increments. So 10B has a pitch of 10/16" = 5/8" (15.875 mm).
- The letter B denotes British Standard (metric pitch, imperial-origin dimensions). Some ISO chain carries an A suffix for ANSI-compatible dimensions.
- The final digit (-1, -2, -3) is the strand count: simplex, duplex, triplex.
ANSI and ISO/BS chains are NOT interchangeable at the same nominal pitch. An ANSI #80 chain (1" pitch) and an ISO 16B chain (1" pitch) have different roller diameters, plate widths, and pin dimensions. The sprocket tooth form differs too. Always confirm which standard applies to the existing drive before ordering replacement chain or sprockets.
Chain size reference chart
The table below covers the most commonly stocked industrial sizes in both ANSI and ISO/BS standards. All dimensions in millimetres.
| ANSI # | ISO/BS equivalent | Pitch (mm) | Roller dia. (mm) | Inner width (mm) | Approx. breaking load (kN) — simplex |
|---|---|---|---|---|---|
| 25 | 04C / 04B | 6.35 | 3.30 | 3.18 | 3.1 |
| 35 | 06C / 06B | 9.525 | 5.08 | 4.78 | 7.8 |
| 40 | 08A / 08B | 12.70 | 7.92 | 7.85 | 14.1 |
| 50 | 10A / 10B | 15.875 | 10.16 | 9.40 | 22.2 |
| 60 | 12A / 12B | 19.05 | 11.91 | 12.57 | 31.8 |
| 80 | 16A / 16B | 25.40 | 15.88 | 15.75 | 56.7 |
| 100 | 20A / 20B | 31.75 | 19.05 | 18.90 | 88.5 |
| 120 | 24A / 24B | 38.10 | 22.23 | 25.22 | 127.0 |
| 140 | 28A / 28B | 44.45 | 25.40 | 25.22 | 172.4 |
| 160 | 32A / 32B | 50.80 | 28.58 | 31.55 | 222.4 |
Breaking loads are approximate for standard-grade single-strand chain. Enhanced and heavy series chain carries higher ratings. Always apply a service factor to design loads before specifying a chain size — a minimum 7:1 safety factor on breaking load relative to maximum working load is typical for general industrial use.
Simplex, duplex and triplex chain
Multi-strand chain is simply two or three parallel chains sharing a common set of pins and outer plates. The strand count multiplies the load capacity without changing pitch — a useful option when you need more capacity in a compact width than a single large-pitch chain would allow, or when a single strand at the next pitch size up would require a larger sprocket than the shaft arrangement permits.
| Configuration | Strands | Capacity vs simplex | Notes |
|---|---|---|---|
| Simplex | 1 | 1× | Standard. Widest sprocket range. |
| Duplex | 2 | ~1.7× | Not exactly 2× due to load sharing tolerances. |
| Triplex | 3 | ~2.5× | Requires careful alignment across all three strands. |
The practical limit is triplex for most industrial applications. Beyond three strands, chain alignment becomes very difficult to maintain and a larger single pitch chain is usually the better engineering choice.
Multi-strand chain requires multi-strand sprockets — the sprocket hub width accommodates all strands simultaneously. You cannot run duplex chain on a simplex sprocket.
Stainless steel roller chain — and other material variants
Standard industrial roller chain is made from medium-carbon steel with quenched and tempered components for optimum strength and wear resistance. For most dry indoor industrial applications, that's the right material — strongest, lowest cost, longest service life. But carbon steel chain rusts. In wet, humid, washdown, food-contact, chemical, marine, or high-temperature applications, the rust progresses fast and the chain fails before its mechanical wear life is reached. The answer is stainless steel chain (or one of several alternative corrosion-resistant variants).
304 stainless vs 316 stainless
Two grades of stainless cover almost all roller chain applications:
| Grade | Composition | Corrosion resistance | Price premium | Typical use |
|---|---|---|---|---|
| 304 (AISI 304 / 18-8) | 18-20% chromium, 8-10.5% nickel, no molybdenum | Excellent for water, mild chemicals, dry chloride exposure, food and pharmaceutical washdown | 3× the price of plain carbon steel chain | The default stainless roller chain — food processing, beverage, pharma, dry chemical, industrial washdown. Sugiyama (SY) and KCM use 304 across all chain components (pins, bushings, rollers, plates). |
| 316 (AISI 316) | 304 + 2-3% molybdenum | Better than 304 in saline, marine, acid, and aggressive chloride environments — molybdenum resists pitting corrosion | 25-80% premium over 304 (so roughly 4-5× plain carbon) | Marine, coastal, salt-spray, pool chemistry, aggressive cleaning chemistry, some pharmaceutical processes that involve chlorides |
| 316L | 316 with reduced carbon (<0.03%) | Same as 316 but better suited to welded fabrication | Similar to 316 | Where chain components are welded into custom assemblies — uncommon for stock roller chain. |
The grade identification trick: 304 is slightly more magnetic than 316 due to its nickel composition. A strong rare-earth magnet picks up 304 noticeably; on 316 the pull is significantly weaker. This is a quick field check, not a definitive test — for a guaranteed grade match, look for the manufacturer's marking on the chain plate or the material certificate from the supplier.
Stainless is NOT a drop-in replacement for carbon steel chain
The most common — and most costly — buying mistake on stainless roller chain is treating it as a same-spec replacement for carbon steel chain. It is not. Stainless steel roller chain has 50-70% of the working load capacity of equivalent carbon steel chain at the same pitch. The reason: stainless cannot be quenched and tempered to the same hardness as carbon steel without losing its corrosion resistance. The pins, bushings and plates are softer, the surface hardness is lower, and the maximum allowable working load drops accordingly.
This means:
- Drive design uses working load tables, not horsepower tables. Carbon chain is sized from horsepower charts (drive HP at sprocket RPM). Stainless chain is sized from working load — calculate the chain pull force at the smaller sprocket, then select stainless chain rated above that load with appropriate service factor.
- Step up a chain size where loads are critical. If a carbon steel #50 (5/8" pitch) carries the calculated load, the stainless equivalent may need #60 (3/4" pitch) for the same service factor.
- Chain wears faster than carbon steel. Lower hardness means faster pin and bushing wear under the same conditions. Stainless typically reaches the 1.5% elongation replacement threshold sooner than carbon — plan for shorter service intervals.
- Sprockets must match. Standard mild-steel sprockets work fine with stainless chain, but in a corrosive environment that's defeating the purpose — pair stainless chain with stainless sprockets to keep the entire drive corrosion-resistant.
Premium stainless roller chain — heat-treated and pre-stressed
Some manufacturers (Sugiyama SS series, Renold SS, Tsubaki SS) produce a heat-treated and pre-stressed stainless variant that recovers some of the strength gap to carbon steel chain. The heat treatment is a controlled process that hardens the pin and bushing while preserving stainless corrosion resistance, and the chain is pre-stretched at the factory to remove the initial elongation that occurs in the first hours of running. This raises the working load to roughly 80-85% of carbon steel equivalent — closer parity, but at a price premium over standard 304 stainless chain.
For applications where stainless is mandatory (food, pharma) but the load is at the upper end of standard stainless capability, premium pre-stressed stainless is the practical step up before having to oversize the chain pitch.
Stainless chain sizing — same pitch, different rating
Stainless roller chain follows the same ANSI and ISO/BS pitch standards as carbon steel chain. A stainless #50 chain has the same 5/8" pitch as carbon steel #50, the same roller diameter, the same overall geometry. It will mate with the same sprocket and run on the same drive layout. What changes is the working load rating — not the dimensions.
Common AU stocked stainless roller chain sizes:
- BS metric simplex: 06B-1SS (3/8" pitch), 08B-1SS (1/2" pitch), 10B-1SS (5/8" pitch), 12B-1SS (3/4" pitch), 16B-1SS (1" pitch)
- BS metric duplex: 08B-2SS, 10B-2SS, 12B-2SS
- ANSI imperial simplex: #25SS, #35SS, #40SS (1/2" pitch), #50SS (5/8" pitch), #60SS (3/4" pitch), #80SS (1" pitch)
- ANSI imperial duplex: #40SS-2, #50SS-2, #60SS-2, #80SS-2
- Double pitch: C2050SS, C2060HSS — for slow-moving conveyor applications where 2× pitch is acceptable
Other corrosion-resistant chain variants
| Variant | How it differs | Use case | Cost vs carbon |
|---|---|---|---|
| Nickel-plated chain | Standard carbon steel chain electroplated with a thin nickel layer for corrosion resistance | Light corrosion environments where full stainless is not justified — equipment exposed to washdown, light moisture | 1.5-2× carbon |
| Zinc-plated / galvanised chain | Hot-dip or electroplated zinc finish | Outdoor exposure, light marine. Zinc gradually sacrifices to protect the steel beneath | 1.3-1.5× carbon |
| Self-lubricating chain | Sintered bushings impregnated with oil — chain runs lubricant-free | Food contact (no drip lubricant required), clean rooms, applications where re-lubrication is impractical | 2-3× carbon |
| Polymer / plastic chain | POM or nylon links with stainless steel pins, or fully plastic chain | Light loads, high humidity, food contact, clean room. Quiet operation. Limited load capacity. | Variable — fully plastic is cheaper than stainless, hybrid (plastic plates / stainless pins) sits between |
| FRAS-rated chain | Standard chain meeting Fire Resistant Anti-Static specification | Underground mining conveyors and drives — AS/NZS standard for AU mining | Premium — typically 2-3× carbon |
Stainless drive chain at AIMS Industrial
AIMS stocks the standard stainless roller chain range from two premium manufacturers:
- Sugiyama (SY) SS series — all chain components (pins, bushings, rollers, side plates) made from AISI 304 stainless steel for full corrosion protection. Available in BS simplex, ASA simplex and double-pitch variants. Suitable for food, pharma, dry chemical, washdown.
- KCM stainless steel chain — BS Simplex and ASA Duplex stainless variants in 10-foot box lengths. The standard production-grade stainless chain for general industrial use.
Both brands are produced to ISO 606 / DIN 8187 (BS) and ANSI B29.1 (ASA) specifications, fully interchangeable with their carbon steel equivalents at the same pitch — but with the load derating noted above. For a specific application — particularly where stainless sprockets, food-grade lubricant, or premium pre-stressed variants are required — call our team on (02) 9773 0122 or contact AIMS Industrial for the right specification.
How to measure and identify your chain
If you need to replace chain and don't have the documentation, here is how to identify it in the field:
Step 1: Measure the pitch
With the chain held taut (lay it on a flat surface with the strand straight), measure the distance across exactly 10 links from pin centre to pin centre, then divide by 10. This gives you the pitch. Ten-link measurement averages out any minor elongation and gives a more accurate result than measuring a single link.
Step 2: Measure the roller diameter
Use calipers to measure the outer diameter of one roller. Combined with pitch, this uniquely identifies whether you have ANSI or ISO/BS chain of a given size — the two standards have different roller diameters at equivalent pitches.
Step 3: Count the strands
Simplex, duplex, or triplex — count the number of parallel rows of rollers across the chain width.
Step 4: Check for a stamped mark
Many chains have the chain number stamped into the outer link plate. Clean the side plate with a rag and look for a two- or three-digit number. If present, this is your confirmation.
Connecting links and offset links
A connecting link (also called a master link) joins two chain ends. It has an outer plate that clips or cotters onto the pins after threading through the inner link. Most connecting links use a spring clip — always install the spring clip with the closed end facing the direction of chain travel. The spring clip is the failure point; never reuse an old or distorted clip.
An offset link (also called a half link) is used when your calculated chain length requires an odd number of pitches. Offset links introduce a slight asymmetry into the chain and are a source of reduced fatigue strength — avoid them in high-load or shock-load applications where possible by adjusting centre distance to use a whole-link count.
Sprocket types
The sprocket is the toothed wheel that the chain wraps around. Sprocket selection is closely linked to chain selection — the two must match in pitch and must be specified for the same standard (ANSI or ISO/BS).
Plate sprockets
The simplest form: a flat steel disc with machined teeth. Plate sprockets are usually bore-to-size or supplied with a pilot bore for machining to the required shaft diameter. They are used on smaller drives and where the shaft arrangement is fixed. They do not allow for easy removal without disturbing the shaft or bearings.
Hub sprockets
A sprocket with a machined hub that extends to one side (single-hub) or both sides (double-hub) of the tooth plate. The hub provides a longer bearing surface for keyway engagement and better support on longer spans. Hub sprockets are the standard form for most industrial drives and are available in a wide range of tooth counts.
Taper lock sprockets
Taper lock sprockets use a split taper bush (the same system used in V-belt pulleys and timing belt pulleys) to secure the sprocket to the shaft. The advantages are substantial: the sprocket can be fitted, removed, and repositioned without disturbing the shaft, bearings, or adjacent components. Taper lock bushes are available in a range of bore sizes to suit most shaft diameters. This is the preferred mounting method for any drive where sprocket maintenance or replacement is anticipated. If you're specifying a new drive, taper lock is worth the marginal extra cost in most industrial environments.
For more on taper lock and keyway sizing, see our guide to Tooth count and drive ratio
The drive ratio is determined by the ratio of sprocket tooth counts: Ratio = Driven sprocket teeth ÷ Driver sprocket teeth A 19-tooth driver sprocket and a 57-tooth driven sprocket gives a 3:1 reduction ratio — the driven shaft turns at one-third the speed of the driver shaft, with three times the torque. The minimum recommended tooth count for a driver sprocket (the input, typically on the faster shaft) is 17 teeth. Below 17T, the polygon effect becomes significant: as chain wraps a small-diameter sprocket, the links articulate through a larger angle per engagement. This accelerates wear on the pin-bush joint, increases noise, and causes speed variation (chordal action). For high-speed applications (above approximately 300 RPM chain speed), a 19T or 21T minimum is more appropriate. For driven sprockets, the maximum is practically limited by the space available and the need to keep the chain velocity reasonable. A very large driven sprocket combined with a small driver sprocket produces a large velocity ratio — feasible, but the chain speed may become too low for effective hydrodynamic lubrication, and the wrap angle on the driver sprocket will be reduced. Odd tooth counts (17, 19, 21, 23, 25, etc.) are preferred for driver sprockets. Combined with an even link count, an odd tooth count ensures every chain link engages a different sprocket tooth on each revolution, distributing wear evenly across all teeth. Even tooth counts, by contrast, can cause repeating engagement patterns that accelerate localised wear. For a two-sprocket drive, the wrap angle on the smaller sprocket should be at least 120°. Drives with wrap angles below 120° risk the chain jumping off under load or vibration. Where geometry constrains the wrap angle below 120°, an idler sprocket on the slack strand can restore adequate wrap. Most industrial roller chain drives follow a straightforward design process. Here are the key steps: Start with the design power (kW) and the driver speed (RPM). Apply a service factor based on load type and duty cycle — smooth loads and continuous running use a factor of 1.0; light shock (pumps, fans, light conveyors) 1.3–1.5; moderate shock (metal machining, heavy conveyors) 1.5–1.7; heavy shock (crushers, presses, rock drills) 1.7–2.0 or higher. Multiply the rated power by the service factor to get the design power. Using the design power and driver speed, select a chain size from the manufacturer's power rating table. Chain power ratings are given as a function of speed and tooth count — a higher tooth count on the driver sprocket generally allows a smaller chain pitch for the same power. The goal is the smallest pitch chain that handles the design power with adequate safety margin. Select tooth counts to achieve the required ratio, respecting the 17T minimum on the driver sprocket. Most industrial drives work well with ratios up to 6:1 on a single reduction. Beyond 6:1, consider a two-stage reduction (two chain drives in series, or combine with a gearbox). The ideal centre distance is 30–50 times the chain pitch for most applications. Very short centre distances (below 20 × pitch) result in excessive chain wear due to the high frequency of link articulation; very long centre distances require more tensioning capacity and are vulnerable to vibration. Calculate chain length in pitches: L = 2C/p + (N1+N2)/2 + ((N2−N1)/(2π))² × (p/C) Where: L = length in pitches, C = centre distance, p = pitch, N1 = driver teeth, N2 = driven teeth. Round up to the nearest even number of pitches to avoid an offset link. For belt drive applications where chain is not the right fit, see our guide on choosing between belt and chain drives. For timing belt specifications, see the Chain lubrication
Lubrication is the single most important maintenance factor for roller chain life. The wear that causes chain elongation occurs at the pin-bush interface inside the inner link — a contact zone that is inaccessible without some form of penetrating lubricant. Inadequate lubrication can reduce chain life to a fraction of its rated value. For a full guide to lubricant types, application methods and re-lubrication intervals, see our Chain Lubrication Guide. The correct lubricant for roller chain is oil, not grease. This is a common mistake. Grease does not penetrate the pin-bush clearance; it stays on the surface and actually seals dirt into the joint. Chain oil needs to be thin enough to flow into the joint under capillary action or by spray force.Minimum tooth count — the 17T rule
Preferred tooth counts
Wrap angle
Drive design basics
1. Define the power and speed requirements
2. Select the chain size
3. Choose the drive ratio and tooth counts
4. Set the centre distance
Lubrication methods by chain speed
| Method | Chain speed | Description |
|---|---|---|
| Manual / drip | Up to ~4 m/s | Apply oil by hand or drip oiler to the slack strand. Minimum every 8 hours of operation. |
| Oil bath | Up to ~12 m/s | Lower runs of chain dip into an oil bath in a sealed housing. Level should be at the pitch line of the lower strand. |
| Forced circulation / spray | Above ~12 m/s | Oil pump delivers a jet of oil to the chain. Required at high speeds to prevent overheating and foaming in bath systems. |
| Aerosol / spray lubricant | Any (maintenance/repair) | For drives that cannot be enclosed or for maintenance application. Apply to inner face of chain so it penetrates the joints. |
Lubricant selection
For most general industrial chain drives, a medium-viscosity mineral or synthetic chain oil (ISO VG 68–100) works well. In wet, dusty, or food processing environments, specialty products are required:
Morey's Chain Lube — A general-purpose aerosol chain lubricant for industrial and agricultural drives. Penetrates the pin-bush joint and leaves a protective film that resists fling-off. Suitable for open drives, conveyors, and agricultural machinery operating in standard environments.
CRC Food Grade Chain Lube (340 g) — NSF H1 rated lubricant for drives in food processing, beverage, packaging, and pharmaceutical environments where chain may contact food or food-contact surfaces. Meets FDA and USDA requirements. Leaves a clear, odourless film.
CRC TAC2 Adhesive Lubricant (300 g) — A tacky, adhesive chain lubricant that stays on the chain and resists fling-off at higher speeds and in high-contamination environments. Well suited to drives exposed to water, dust, or grit where a standard oil would be washed off quickly.
Browse the full range: Chain and Sprockets
Lubrication interval
As a starting point, apply lubricant every 8 hours of operation for open drives in moderate environments. Increase frequency in hot, dusty, wet, or high-load conditions. The tell-tale sign of inadequate lubrication is a reddish-brown rust discolouration on the link plates combined with stiff, reluctant articulation at rest. At that point the chain is already damaged — prevent it, don't react to it.
Tensioning and chain elongation
Correct chain sag
Roller chain drives should not be run tight. The correct installation is with a deliberate amount of sag on the slack strand. A general rule of thumb: the slack strand should have a sag of approximately 2% of the centre distance. For a 500 mm centre distance, that is about 10 mm of vertical deflection at the midpoint of the slack strand under light finger pressure.
Running chain too tight causes unnecessary loads on shaft bearings, accelerates pin and bush wear, and increases power consumption. Running too slack causes the chain to bounce, jump teeth, or slap the housing — which also accelerates wear and causes noise.
For vertical drives (chain running vertically between two sprockets), there is little or no sag provision — a take-up adjuster or tensioner is required to maintain consistent tension as the chain wears.
Chain elongation — the wear indicator
As the pin-bush clearance grows with wear, the effective pitch of the chain increases — commonly called "chain stretch" or chain elongation. This is not actually the metal stretching; it is wear in the bearing surfaces of each link joint accumulating across the full chain length.
The standard replacement threshold is 1.5% elongation relative to the nominal chain length. Beyond 1.5%, the chain pitches no longer match the sprocket tooth form correctly — the rollers ride up and over the teeth rather than seating in the root. This accelerates sprocket tooth wear dramatically and increases the risk of the chain jumping or breaking under load.
Measuring elongation
To check elongation, measure a length of taut chain over a minimum of 12–20 links (the more links measured, the more accurate the result). Compare the measured length to the theoretical length (number of pitches × nominal pitch). If elongation exceeds 1.5%, replace the chain.
A dedicated chain wear indicator (a simple gauge available from most industrial distributors) makes this check fast and requires no calculations. Check at every scheduled maintenance interval.
Replace chain and sprockets together
When a worn chain is replaced, always inspect the sprockets. Worn sprockets have a characteristic "hooked" or "shark fin" tooth profile. Running new chain on worn sprockets accelerates wear on the new chain, because the roller does not seat correctly in the distorted tooth root. In a high-use application, replace chain and sprockets simultaneously.
Frequently asked questions
What is the difference between industrial roller chain and bicycle chain?
Industrial roller chain follows ANSI or ISO/BS standards and is designed for continuous power transmission in machinery. The smallest common industrial size (ANSI #25, 6.35 mm pitch) is already larger than a standard bicycle chain (½" × 3/32" or ½" × 1/8"). Industrial chain is heavier, thicker, has higher breaking loads, and uses rollers designed to seat on industrial sprocket tooth forms. Bicycle chain is not a substitute for industrial applications — the load ratings, fatigue strength, and lubrication requirements are entirely different.
What does the number on a roller chain mean?
For ANSI chain, the first one or two digits give the pitch in eighths of an inch: #40 = 4/8" = ½" pitch, #80 = 8/8" = 1" pitch. The last digit indicates type: 0 = standard, 1 = lightweight. A suffix of -2 or -3 means duplex or triplex (two or three strands). For ISO/BS chain, the number indicates pitch in sixteenths of an inch and the letter B or A indicates the standard.
How do I measure roller chain pitch?
Lay the chain flat and taut. Measure from the centre of one pin to the centre of the pin 10 links away. Divide by 10. This gives you the pitch in millimetres. Measuring over 10 links averages out minor elongation. Cross-check against the roller diameter with calipers to confirm the exact chain standard and size.
What is the minimum number of teeth for a drive sprocket?
The minimum recommended tooth count for a driver (input) sprocket is 17 teeth. Below 17T the polygon effect causes speed fluctuation, excessive noise, and accelerated pin-bush wear. For drives running above 300 RPM chain speed, a 19T or 21T minimum is more appropriate. There is no strict minimum for driven sprockets, though very small driven sprockets on slow shafts will also wear faster.
How do I know when roller chain needs replacing?
The primary indicator is elongation: measure the chain over 12–20 links and compare to nominal length. Replace at 1.5% elongation. Other signs include stiff or seized links (visible when the chain is laid flat and flexed), corrosion or rust staining, cracked or deformed link plates, and roller damage. A worn chain riding up on sprocket teeth — visible as the chain pulling away from the sprocket root — means replacement is overdue.
Should I use oil or grease on roller chain?
Oil. Not grease. The wear in roller chain occurs at the pin-bush interface inside the joint. Grease is too viscous to penetrate this clearance — it sits on the outside of the chain and can actually seal dirt into the joint. A light to medium chain oil or aerosol chain lubricant penetrates the joint and lubricates where it is needed. For food-safe environments use an NSF H1 rated food-grade chain lubricant.
What is the difference between simplex, duplex and triplex chain?
Simplex chain has one strand of rollers — the standard configuration. Duplex has two parallel strands sharing common pins, giving approximately 1.7× the load capacity of simplex at the same pitch. Triplex has three strands, giving approximately 2.5× simplex capacity. Multi-strand chain requires matching multi-strand sprockets. Duplex and triplex chains require very accurate shaft alignment across all strands to share load correctly.
Can ANSI and ISO/BS chain be mixed?
No. ANSI and ISO/BS chains use different roller diameters, plate widths, and pin dimensions even at nominally similar pitches. For example, ANSI #80 and ISO 16B both have 1" (25.4 mm) pitch, but the roller diameter and inner link width differ. Running the wrong standard chain on a sprocket will cause improper roller seating, accelerated wear, and eventual failure. Always match chain and sprocket to the same standard.
How tight should roller chain be?
Not tight. The slack strand should have a sag of approximately 2% of the centre distance. For a 500 mm centre distance, that is about 10 mm of deflection under light finger pressure at the midpoint. Running chain too tight overloads shaft bearings and accelerates wear. The chain naturally takes up slack as the drive runs; the sag allowance absorbs this. For vertical drives, use an adjustable tensioner to maintain consistent tension.
How do I calculate roller chain length?
Chain length in pitches: L = 2C/p + (N₁+N₂)/2 + ((N₂−N₁)/(2π))² × (p/C), where C is the centre distance, p is the pitch, N₁ is driver teeth, and N₂ is driven teeth. Round up to the nearest even number to avoid needing an offset link. Then adjust the actual centre distance to achieve the correct sag with the calculated chain length.
What causes roller chain to wear out quickly?
The four main causes are: (1) inadequate or wrong lubricant — the most common cause; (2) running an undersized chain for the applied load; (3) misalignment between driver and driven sprockets, causing the chain to run at an angle and load one side of the rollers and link plates preferentially; and (4) insufficient or inconsistent tensioning, allowing the chain to bounce and shock-load the joints. Abrasive contamination (grit, dust, swarf) accelerates all four mechanisms.
Can I use a half link (offset link) in roller chain?
An offset link allows you to use an odd number of pitches when the chain length calculation falls between whole-link values. Offset links are legitimate but introduce a small reduction in fatigue strength compared to the rest of the chain — the asymmetric geometry creates a stress concentration. Avoid offset links in high-load, high-speed, or shock-loaded applications. Instead, adjust centre distance to accommodate a whole-link count if possible.
Do I need to replace sprockets when I replace chain?
Inspect the sprockets. If the tooth flanks show a hooked or shark-fin profile (the tooth tip is curving in the direction of chain travel), the sprockets are worn and should be replaced at the same time. Running new chain on worn sprockets dramatically shortens the life of the new chain, because the rollers cannot seat correctly in the distorted tooth root. In high-cycle applications, replacing chain and sprockets simultaneously is the more economical choice over the full maintenance cycle.
Browse our full range of chain, sprockets, and accessories or contact the AIMS team for application-specific advice.
Can I replace my carbon steel roller chain with stainless steel chain at the same size?
Stainless steel roller chain has the same pitch and dimensions as carbon steel chain at the same designation (#50SS = #50, 12B-1SS = 12B-1) — it will fit the same sprockets and the same drive layout. However, stainless chain has only 50-70% of the working load capacity of carbon steel chain at the same size. Stainless cannot be quenched and tempered to the same hardness as carbon steel without losing its corrosion resistance, so the pins, bushings and plates are softer. To replace carbon chain with stainless safely, recalculate the drive load using stainless working load tables (not horsepower tables), apply the appropriate service factor, and step up to a larger chain size if the calculated load exceeds the stainless rating at the original pitch. For premium pre-stressed stainless chain, the strength gap closes to about 80-85% of carbon steel — but standard stainless requires careful re-rating.
What is the difference between 304 and 316 stainless roller chain?
304 stainless steel contains 18-20% chromium and 8-10.5% nickel, with no molybdenum. It provides excellent corrosion resistance for water, mild chemicals, food and pharmaceutical washdown, and dry chloride exposure. 316 stainless adds 2-3% molybdenum to the 304 composition, which significantly improves resistance to pitting corrosion in saline, marine, and aggressive chloride environments. 316 typically costs 25-80% more than 304. For most industrial roller chain applications (food processing, beverage, pharma, general washdown), 304 is sufficient and is the standard stocked grade from KCM and Sugiyama. 316 is selected for marine equipment, coastal installations, swimming pool environments, and aggressive cleaning chemistries that contain chlorides. A rough field test for grade identification: 304 is slightly more magnetic than 316 — a strong magnet picks up 304 noticeably while the pull on 316 is much weaker.
Does stainless roller chain need lubrication?
Yes — stainless roller chain still requires lubrication, just like carbon steel chain. The corrosion resistance of stainless steel does not eliminate the need for lubricant between the pin and bushing surfaces, where wear occurs. Without lubrication, stainless chain wears faster than carbon steel chain because the stainless surface hardness is lower. For food contact applications, use NSF H1 food-grade chain lubricant — these lubricants are formulated to be safe for incidental food contact and are widely available in spray and brush-on forms. For non-food applications, standard chain lubricant is fine. Self-lubricating stainless chain is available (with sintered bushings impregnated with oil) for applications where re-lubrication is impractical or where drip-free operation is required — but this is a different specification, not a drop-in replacement for standard stainless chain.
