बेकिंग ओवन के कन्वेयर बेल्ट के लिए वर्म गियरबॉक्स

At 70 °C ambient, the oil sump temperature will reach 90–100 °C under continuous operation. ISO VG 460 PAO synthetic maintains adequate viscosity (target ≥ 20 cSt at operating temperature) in this range, whereas standard VG 220 mineral oil would thin to approximately 14 cSt — below the minimum film thickness requirement for the worm gear contact. Always use VG 460 PAO or higher for drive installations where ambient exceeds 50 °C.

Options in order of preference: (1) VFD at reduced frequency (25–35 Hz) on a standard worm reducer with ratio 80:1 — easiest and most flexible; (2) double-stage worm reducer (two worm stages in series) achieving ratios 400:1 to 3 600:1 without VFD; (3) single worm stage ratio 100:1 with a secondary chain/sprocket reduction — simple but adds maintenance points. For belt speeds below 1 m/min (enrobers, cooling tunnels), option 2 (double-stage) is recommended for reliable splash lubrication at near-zero output speed.

Repeated thermal cycling (cold start → operating temperature → shutdown) can stress housings and cause seal compression set over time. Cast-iron housings (low thermal expansion) are significantly more resistant to thermal cycling fatigue than aluminium. FKM seals resist compression set at elevated temperature far better than NBR. High-temperature silica-gel breathers prevent the vacuum effect during cool-down that can draw ambient air (and flour dust) through shaft seals. These three measures — cast iron, FKM, high-temp breather — are our standard specification for tunnel oven applications.

It can be bolted directly to the oven frame, but this is not recommended for ovens where the frame reaches >50 °C. We recommend an insulating mounting bracket (10–15 mm fibre-reinforced PTFE or ceramic-filled polymer pad) between the reducer foot and oven frame. This thermal break reduces conductive heat transfer to the reducer housing by 40–60 %, keeping the oil sump temperature within the rated range of standard synthetic lubricants. We supply these brackets as an optional accessory.

With PAO 460 synthetic lubricant at sump temperatures ≤ 100 °C: first oil change at 500 hours (run-in period); subsequent changes every 4 000–5 000 hours or annually, whichever comes first. Inspect shaft seals visually every 6 months for weeping — replace at first sign of oil film on shaft exterior. Check breather filter condition every 3 months — replace when discoloured. In very high flour-dust environments, increase inspection frequency to monthly for the breather and seals.

For belt speeds below 3 m/min with a 300 mm drive sprocket (output speed <3 rpm), a single-stage worm at ratio 100:1 with a VFD-reduced motor speed is generally preferred over a double-stage unit — it is more efficient, generates less heat, and is simpler to maintain. However, if the output speed must be controlled without a VFD (e.g., in a hazardous area or very old installation), a double-stage worm reducer is the right choice. A double-stage unit also provides a larger reduction margin for future belt speed adjustments without changing the reducer.