Kwa nini ISO VG inatofautiana na SAE?

ISO VG (Viscosity Grade) classifies industrial lubricants by kinematic viscosity at 40°C. SAE grades are used for automotive oils: SAE crankcase grades (e.g. 10W-30) are based on viscosity at 100°C, while SAE gear grades (e.g. 75W-90) use a different scale. The systems measure at different temperatures and serve different markets.

Kwa nini kuna viwango tofauti vya viscosity?

Sekta tofauti zilitengeneza viwango vyao kwa kujitegemea. ISO VG (ISO 3448) inatumika kwa vilainishi vya viwandani, SAE J300 kwa mafuta ya injini za magari, SAE J306 kwa mafuta ya gia za magari, na AGMA 9005 kwa gia za viwandani. Kila kiwango kiliundwa kwa matumizi maalum na kina hali tofauti za majaribio.

AGMA (American Gear Manufacturers Association) inafafanua viwango vya vilainishi kwa gia za viwandani kulingana na AGMA 9005. Viwango vya AGMA 1-8A vinalingana takriban na ISO VG 46 hadi VG 1000. Mfumo wa AGMA unatumika sana Amerika Kaskazini kwa kubainisha vilainishi vya gia.

Tofauti kati ya cSt na cP ni nini?

cSt (centistokes, mm²/s) is kinematic viscosity — it measures flow under gravity. cP (centipoise, mPa·s) is dynamic viscosity — it measures resistance to flow under applied force. They are related by: cP = cSt × density (g/cm³). For most lubricating oils with density ~0.87 g/cm³, cP ≈ 0.87 × cSt.

Jinsi ya kusoma mafuta ya SAE ya viwango vingi (multigrade)?

Mafuta ya SAE ya viwango vingi kama 10W-30 yana nambari mbili: nambari ya 'W' (Winter/Baridi) inaonyesha viscosity wakati wa kuanza kwa baridi, na nambari ya pili inaonyesha viscosity kwenye joto la uendeshaji (100°C). Mafuta ya 10W-30 hutiririka kama 10W kwenye joto la chini lakini hutoa ulinzi wa kiwango cha 30 kwenye joto la uendeshaji. Mafuta ya viwango vingi hutumia viboreshaji vya kielezo cha viscosity ili kufikia tabia hii.

Zana ya Uhandisi Isiyolipisha

Kibadilisha Viscosity

Rejeleo kati ya viwango vya ISO VG, SAE crankcase, SAE gear, na AGMA. Pia badilisha kati ya vitengo vya cSt, cP, na SUS.

ISO VG SAE J300 / J306 AGMA 9005 cSt ↔ cP ↔ SUS

Results

ISO VG Grade

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Kiwango cha SAE Crankcase

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SAE Gear Grade

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AGMA Grade

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Mwelekeo wa Viscosity

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Viscosity ya Nguvu (Dynamic)

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SUS (Saybolt Universal)

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Mfano wa Msalaba wa ISO VG / SAE / AGMA

Usawa wa takriban kati ya mifumo ya upimaji wa mnato. Hizi si ubadilishaji halisi — kila mfumo hutumia hali tofauti za upimaji.

ISO VG	Masafa ya cSt (40 °C)	SAE Crankcase	SAE Gear	AGMA

Fomula za Ubadilishaji wa Vitengo

Dynamic viscosity (cP) = Kinematic viscosity (cSt) × Density (g/cm³)

Where: 1 cP = 1 mPa·s, and 1 cSt = 1 mm²/s. Oil density is typically 0.85–0.90 g/cm³ (850–900 kg/m³) at 15 °C.

SUS ≈ cSt × 4.635 (approximate, for cSt > 50)

Takriban ya Saybolt Universal Seconds (SUS) ni sahihi kwa mnato zaidi ya ~50 cSt. Kwa mnato wa chini, fomula ngumu zaidi inahitajika, lakini fomula iliyo juu hutoa matokeo yanayokubalika kwa mafuta mengi ya kiviwanda.

Kuhusu Mifumo ya Upimaji

ISO VG (ISO 3448) — Industrial lubricants; 18 grades VG 2 to VG 1500; kinematic viscosity at 40 °C ± 10%.
SAE Crankcase (SAE J300) — Mafuta ya injini za magari; daraja kama 10W, 20, 30, 40, 50; hupimwa kwa 100 °C.
SAE Gear (SAE J306) — Mafuta ya gia za magari; daraja kama 75W, 80W-90, 140, 250; hupimwa kwa 100 °C.
AGMA (AGMA 9005) — Vilainishi vya gia za kiviwanda; daraja 1 hadi 8A; inalingana na ISO VG.

⚠️ Important: Cross-references are approximate. ISO VG measures at 40 °C while SAE measures at 100 °C. Always verify with the specific oil product data sheet for exact viscosity values at your operating temperature.

Viscosity Converter | ISO VG ↔ SAE ↔ AGMA

Published by Nikolai Shelkovenko on Febuari 15, 2026 Febuari 15, 2026

Results

Mfano wa Msalaba wa ISO VG / SAE / AGMA

Fomula za Ubadilishaji wa Vitengo

Kuhusu Mifumo ya Upimaji

Duka

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