ISO 606 Chain Drive — Roller Chain Selection & Sprocket Geometry Calculator
ISO 606 — Short-pitch transmission precision roller and bush chains, attachments and associated chain sprockets
ISO 606 is the international standard for short-pitch precision roller and bush chains, their attachments, and the associated sprocket geometry. It defines the chain pitch series (from 04B at 6 mm pitch through 48B at 76.2 mm pitch), the minimum breaking load for each size and strand count, the sprocket pitch-circle, tip and root diameter formulae, and the lubrication type requirements (Types A–D) that must be met for the tabulated power ratings to be valid. ANSI B29.1 is the North American counterpart and uses the same underlying geometry with a different designation system (ANSI No. 25–240).
In practice, ISO 606 is the reference a designer reaches for when sizing a chain drive: the chain is selected by comparing the design load (nominal power × service factor) against the chain's minimum breaking load divided by a speed-dependent safety factor, and the sprocket geometry is then computed to the ISO 606 tooth-form formulae. MechanixCalc implements the complete selection, geometry, polygonal-effect and wear-life method in the browser and generates a method-cited PDF engineering report suitable for design review handover.
Calculators that implement ISO 606
What ISO 606 covers
- Chain pitch series and dimensional parameters — pitch, roller diameter, inner width, plate thickness and minimum breaking load (Tables 1–3 of ISO 606)
- Sprocket geometry — pitch-circle diameter, tip (addendum) diameter and root diameter formulae for all tooth counts
- Lubrication type classification: Type A (manual), Type B (drip), Type C (bath/disc) and Type D (forced/spray), keyed to chain speed and power
- Multi-strand capacity — strand efficiency factors per ISO 10823 (duplex η = 0.95, triplex η = 0.90) that account for load-sharing inequality
- Service factor application and the speed-dependent safety factor used to select the minimum chain size for the design load
- Replacement criterion — the ANSI 1.5 % pitch-elongation limit that triggers chain renewal (referenced alongside ISO 606 in chain manufacturers' application guidance)
Governing formulas
d = p / sin(π / z) [mm]where d = pitch-circle diameter (mm); p = chain pitch (mm); z = sprocket tooth count. The tip (outer) diameter follows da = p · (0.6 + cot(π / z)), and the root diameter df = d − d_roller, where d_roller is the roller diameter from ISO 606 Table 1.
v = z₁ · p · n₁ / 60 000 [m/s] ; MBL_req = (P_d · 1000 / v) · SF / (strands · η_s · 1000) [kN per strand]where v = chain speed (m/s); z₁ = driver tooth count; n₁ = driver speed (rpm); P_d = design power = P · Ks (kW); SF = speed-dependent safety factor; strands = number of chain strands; η_s = ISO 10823 strand efficiency (1.00 / 0.95 / 0.90 for simplex / duplex / triplex)
δv = (1 / cos(π / z₁) − 1) × 100 %where δv = peak-to-peak speed variation (%); z₁ = driver tooth count. At z₁ = 17 teeth δv ≈ 1.66 %; at z₁ = 19 teeth δv ≈ 1.38 %; at z₁ = 25 teeth δv ≈ 0.8 %. ISO 606 recommends ≥ 17 driver teeth, with an odd count to distribute roller-seat wear evenly around the sprocket.
Frequently asked questions
What is ISO 606 used for?
ISO 606 defines the geometry and minimum breaking loads of short-pitch precision roller chains and the associated sprocket tooth forms. Engineers use it to select the right chain size for a given power and speed (by checking the required breaking load against the tabulated value), to compute sprocket pitch-circle and tip diameters, and to determine the required lubrication type. It is the standard cited in chain-drive calculations throughout Europe and internationally; ANSI B29.1 is the North American equivalent.
How do I select a roller chain to ISO 606?
Multiply the nominal transmitted power by the service factor Ks (1.0 for smooth load, up to 1.75 for heavy shock) to get the design power. Compute the chain speed v = z₁ · p · n₁ / 60 000 m/s, then the required minimum breaking load MBL_req = (P_d × 1000 / v) × SF / (strands × η_strand × 1000) kN, where SF is a speed-dependent safety factor. Select the smallest standard chain whose tabulated breaking load meets MBL_req. Because a larger pitch changes v and therefore MBL_req, this is an iterative (fixed-point) calculation — the MechanixCalc chain calculator solves it automatically.
What does the polygonal (chordal) effect mean and how do I reduce it?
Because a sprocket is a polygon, the chain speed rises and falls once per tooth pitch even at constant input speed. The variation is δv = (1/cos(π/z₁) − 1) × 100 %. At z₁ = 11 teeth δv ≈ 4.2 %, causing noticeable vibration and noise; at z₁ = 17 teeth it drops to ≈ 1.66 %, and at 25 teeth to ≈ 0.8 %. ISO 606 recommends at least 17 driver teeth. An odd tooth count on the driver sprocket distributes roller wear evenly because each roller contacts a different tooth on successive revolutions.
What lubrication type does ISO 606 require?
ISO 606 and ANSI B29.1 classify lubrication into four types by chain speed and power: Type A (manual grease or oil) for slow, lightly-loaded drives; Type B (drip feed) for moderate speeds (roughly up to 4 m/s); Type C (oil bath or disc) above 4 m/s; and Type D (forced/spray) above 8 m/s or above 15 kW. Providing the correct lubrication type is a prerequisite for achieving the tabulated power rating — it does not credit additional capacity, but failing to provide it shortens chain life significantly.
Is the ISO 606 chain calculator free?
You can run a full chain selection and geometry calculation during a free 30-minute preview session with no sign-up required. A free 14-day account trial gives access to every MechanixCalc tool — no credit card needed. The branded PDF engineering report with the full ISO 606 method and selected chain data, and saved calculations, are part of a paid plan.
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