Finished Bore Sprockets Asian Standard

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Korea Ever-Power Asian standard finished bore sprockets conform to JIS B1801 — the Japanese Industrial Standard for roller chain sprockets, which is the basis of the Asian standard used throughout Japan, South Korea, Taiwan, China and Southeast Asia. The JIS chain dimensions differ from both ANSI B29.1 and DIN 8187 in roller diameter and inner width, requiring a specific tooth profile — Asian standard chain and sprockets must always be matched to the same standard.

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25B – 120B

Εύρος μεγέθους αλυσίδας

FBN / FBK

Type FBN (B) & FBK (B+F)

JIS B1801

Asian Standard

ISO 9001

Πιστοποιημένη Ποιότητα

Asian Standard Finished Bore Sprockets – Product Overview

The finished bore range is produced in two hub types: FBN (Type B) — a straight hub with a bore, keyway and setscrew, supplied with the keyway centred on the tooth centreline (not between teeth as in some other standards). The keyway-on-tooth-centre arrangement allows the key to be visible from above when the sprocket is mounted on the shaft, making alignment checks easier. FBK (Type B+F) — the same hub with an additional flange, used for applications requiring positive lateral retention or attachment to a shaft shoulder.

The range covers chain sizes 25B (3/16" pitch) through 120B (1½" pitch), in simplex. Material is C45 carbon steel with induction-hardened teeth for sizes 35B and above. For 25B light-duty chain, the sprocket is un-hardened plain C45. Stainless steel (SUS304) variants are available for 25B (food and pharmaceutical) — designated SUSFBP. For the Asian stock bore range (NK type) see our Asian stock bore sprockets. Browse the πλήρης κατηγορία γραναζιών.

 

Korea Ever-Power Asian standard JIS B1801 finished bore sprockets FBN FBK

🌏 Asian vs ANSI vs European — same pitch, different chain

For the same pitch (e.g. ½″ / 12.7 mm), the three standards have different roller diameters:

Pitch ½″ Roller Ø Πρότυπο
40B (Asian/JIS) 7.92 mm JIS B1801
#40 (American) 7.95 mm ANSI B29.1
08B (European) 8.51 mm DIN 8187

⚠️ Do not mix chain standards — the larger DIN 08B roller will not seat correctly on Asian or ANSI tooth profiles.

Keyway Location — Asian Standard Difference

Asian standard sprockets have the keyway machined on the tooth centreline — aligned with the midpoint of a tooth, not between teeth. This is a different convention from European DIN 8187 and American ANSI B29.1 sprockets, where the keyway is typically positioned between teeth. The difference matters for two reasons:

✔ Visual Installation Confirmation

With the keyway on the tooth centreline, the engineer can confirm correct installation position by looking at the top of the installed sprocket — the tooth directly above the key should be centred over the keyway mark on the shaft. This visual check is particularly useful during installation of large sprockets where gauging the sprocket position is difficult.

⚠️ Do Not Substitute European/ANSI Sprocket

A European or ANSI sprocket cannot be substituted for an Asian standard sprocket on Asian chain, even if the pitch and bore are the same. The tooth profile — seating curve radius, tooth width and tooth angle — differs between standards. Running mismatched chain and sprocket causes poor roller engagement, accelerated wear and premature sprocket failure within weeks of installation.

📐 JIS B1301 Keyway Standard

Keyway dimensions conform to JIS B1301 (revised 1976) — the Japanese standard for parallel keys and keyways in metric bore sizes. This is dimensionally close to DIN 6885 but uses slightly different depth proportions for small bore sizes (below 22 mm). Always use a JIS B1301 or DIN 6885 key in Asian standard sprockets — do not use ASME B17.1 inch keys, which have different width-to-depth ratios.

Key: Z = teeth  |  De = tip diameter (mm)  |  Dp = pitch circle diameter (mm)  |  BD = bore diameter options (mm)  |  BL = bore length (mm)  |  a = keyway width (mm)  |  FBN = Type B hub; FBK = Type B with flange; SUSFBP = SUS304 stainlessFinished Bore Sprocket Specifications — 35B through 100B

 

35B  |  Pitch 9.525 mm  |  Roller Ø 5.08 mm  |  Inner width 4.78 mm  |  C45 hardened

Ζ De (mm) Dp (mm) BD options (mm) BL (mm) a keyway (mm)
9 32 27.85 *21.5 (pilot) 20 6
11 38 33.81 *27 (pilot) 20 6
13 44 39.80 10, 12, 14, 15, 16 20 4–5
17 56 51.83 10, 12, 14, 15, 16 20 5
25 80 76.00 14, 15, 16 20 5

40B  |  Pitch 12.70 mm  |  Roller Ø 7.92 mm  |  Inner width 7.85 mm  |  C45 hardened

Ζ De (mm) Dp (mm) BD options (mm) BL (mm) a keyway (mm)
9 42 37.13 *28 (pilot) 22 5
12 55 49.07 10, 12, 14, 15, 16, 17 22 5
15 67 61.09 12, 14, 15, 16, 17, 18 22 5
17 75 69.11 12, 14, 15, 16, 17, 18, 19, 20 22 5
20 88 81.19 14, 15, 16, 17, 18, 19, 20 22 5
25 108 101.33 14, 15, 17, 18, 19, 20 22 6

60B  |  Pitch 19.05 mm  |  Roller Ø 11.91 mm  |  Inner width 12.07 mm  |  C45 hardened

Ζ De (mm) Dp (mm) BD options (mm) BL (mm) a keyway (mm)
9 63 58.10 32 35 8
11 76 71.56 30, 32, 35 35 8
13 89 84.92 30, 32, 35, 38, 40 35 10
17 114 109.97 32, 35, 38, 40, 42, 45 35 10
21 139 135.64 35, 38, 40, 42, 45, 48 40 12

80B  |  Pitch 25.40 mm  |  Roller Ø 15.88 mm  |  Inner width 15.88 mm  |  C45 hardened

Ζ De (mm) Dp (mm) BD options (mm) BL (mm) a keyway (mm)
9 84 77.52 44 (pilot) 42 12
13 117 113.27 40, 42, 45, 48 42 12
17 151 146.28 42, 45, 48, 50 42 14
21 186 180.75 45, 48, 50, 55 50 14

* = pilot bore (no keyway). Full bore range and stainless SUSFBP25B variants available — contact us. 50B, 100B and 120B also available. Specify chain size, tooth count, type (FBN or FBK) and bore diameter mm when ordering.

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JIS B1801 Tooth Profile

The tooth profile conforms to JIS B1801 — required for correct engagement with Asian standard roller chain. The seating curve radius and tooth width differ from DIN 8187 and ANSI B29.1 because the Asian standard roller diameter is slightly different from both. Running Asian chain on European or American sprockets (or vice versa) causes incorrect roller seating and premature wear even where the pitch is identical. Pair with JIS B1801 Asian standard roller chain.

C45 with Hardened Teeth — 35B and Above

All FBN and FBK sprockets in 35B through 120B are C45 carbon steel with induction-hardened tooth flanks at 52–58 HRC. The bore is machined before the heat treatment cycle and confirmed dimensionally after hardening. 25B sprockets are lighter duty — plain C45 without tooth hardening, suitable for the light loads in 25B drive applications. SUS304 stainless variants (SUSFBP prefix) are plain bore only and are unhardened by material.

FBK Flange Type — Lateral Retention

The FBK type adds a flange face to the hub, providing a bearing face against a shaft shoulder or collar. This is required in applications where the sprocket must be retained axially on the shaft by its own geometry rather than relying entirely on the setscrew. FBK is the standard type for chain drives in Japanese agricultural machinery and material handling equipment where the sprocket position is located by a shaft step rather than by a setscrew alone.

Korea Ever-Power for Asian OEM Drives

Korean industrial machinery uses JIS-based chain standards for all domestic drives. Korea Ever-Power Asian standard finished bore sprockets are the correct replacement for drives in Korean-manufactured equipment across all sectors — construction machinery, agricultural equipment, industrial conveyors and textile machinery. The same hub geometry, bore sizes and keyway dimensions as the original Korean OEM specification.

Αλυσίδα Συνδυασμού & Σχετικά Προϊόντα

JIS B1801 Asian standard roller chain 40B 60B 80B for finished bore sprockets

Matching Asian Standard Roller Chain

Match your FBN/FBK sprocket with JIS B1801 Asian standard roller chain in the same chain number (35B, 40B, 60B, 80B etc.). Standard, H-series, self-lubricating and SUS304 stainless variants available. Never run European DIN 8187 or ANSI B29.1 chain on Asian sprockets.

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Request a Quote — Asian Standard Finished Bore Sprockets

Specify chain size (e.g. 60B), tooth count, type (FBN or FBK), bore diameter in mm. Stainless SUSFBP available for 25B. Response within one working day.

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