Ελικοειδή γρανάζια ενανθράκωσης μηχανημάτων εξόρυξης — σφυρήλατα 18CrNiMo6, κατηγορίας DIN 6 για βιομηχανικούς κινητήρες υψηλής αντοχής

Mining Machinery Carburized Helical Gear — Overview

The mining machinery carburized helical gear from Korea Ever-Power Worm Gear Co.,Ltd is a heavy-duty power transmission component manufactured specifically for the demanding shock and abrasion conditions found in underground mining equipment, surface excavators, conveyor gearboxes, and ore-processing machinery. The combination of 18CrNiMo6 nickel-chromium-molybdenum alloy steel, forged blank production, and a full carburizing-and-grinding manufacturing sequence produces a gear with a hard, wear-resistant case over a tough, shock-absorbing core — exactly the mechanical property profile that mining drives require. Standard spur or through-hardened ελικοειδή γρανάζια do not provide this combination: a hard-through gear is brittle under impact, while a soft gear wears rapidly under abrasive dust contamination. Case carburizing solves both problems simultaneously.

The reference gear for this product is a right-hand ελικοειδές γρανάζι κοπής with module M=9, 33 teeth, an 8° helix angle, 20° pressure angle, and a profile shift coefficient of x=0.2. This tooth geometry has been selected to balance tooth bending strength with smooth engagement characteristics for the gearbox input speed ranges typical of mining machinery. Korea Ever-Power's manufacturing capability extends to external gears up to 2,500mm outer diameter and 45mm module for tooth-ground finishes, covering the full size range of mining and metallurgical gearbox applications from compact shearer drives to large mill pinion gears. For customers who need a direct ελικοειδή γρανάζια κοπής replacement for an existing worn component, reverse engineering from sample gear or drawing is a standard service.

Product Specifications and Manufacturing Capabilities

Gear Basic Data — Reference Configuration

Manufacturing Capabilities — Internal Gears and Internal Splines

Manufacturing Capabilities — External Gears and External Splines

Carburizing and Heat Treatment — Why 18CrNiMo6 Matters for Mining Drives

18CrNiMo6 is a case-hardening alloy steel with chromium and nickel additions that give it two properties essential for mining gear applications: high core toughness and deep hardenability. The chromium content (1.5–1.8%) improves hardenability, ensuring that carburizing produces a consistent hardened case even on large-diameter gear bodies. The nickel content (1.4–1.7%) maintains core ductility after quenching, so the gear can absorb the shock loads from ore crusher drives or conveyor overloads without brittle fracture through the tooth root.

The Carburizing Process in Sequence

The complete manufacturing sequence for this carburized helical gear is: forging → rough machining → carburizing (gas atmosphere furnace, case depth 1.5–2.5mm for module M9) → quenching → stress-relief tempering → plane and internal grinding (to correct heat-treatment distortion on reference surfaces) → tooth grinding (to DIN class 6 final accuracy, Ra 0.6 tooth flank) → wire cutting (for keyway, spline, or relief features requiring tight dimensional tolerances after hardening). The tooth grinding after heat treatment is the critical step: it removes the profile error introduced during carburizing distortion and brings the tooth flank to the final accuracy class, ensuring that the gear operates at its designed contact ratio and load distribution from the first hour of service.

Forging vs Casting — Why Forged Blanks Are Specified for Mining Gears

Forged helical gear blanks have grain flow that follows the contour of the gear cross-section, which aligns the material's strongest direction with the principal stress direction in the tooth root. Cast blanks, by contrast, have random grain orientation and often contain internal shrinkage porosity or inclusions that act as stress concentration points under cyclic loading. For mining drives that experience regular shock loads — such as a conveyor belt starting under full load, or a jaw crusher encountering an oversize rock — a forged blank can absorb significantly more impact energy before crack initiation at the tooth root than a cast blank of identical nominal composition. Korea Ever-Power specifies forged 18CrNiMo6 blanks as standard for all mining and heavy-industry ελικοειδή γρανάζια above module M6 and for any gear subjected to impact loading, regardless of module.

Gear Failure Modes in Mining Environments — and How Carburizing Addresses Them

Surface Pitting and Spalling

Pitting is the progressive formation of small craters on the tooth flank surface under cyclic Hertzian contact stress. It begins at sub-surface crack nucleation sites — often just below the depth where maximum shear stress occurs under normal contact loading. A high-hardness carburized case (HRC 58–62) raises the allowable contact stress limit significantly compared to a through-hardened gear (HRC 48–54), pushing the fatigue threshold well above the normal operating stress range. The residual compressive stress introduced by the quench process further suppresses crack propagation, so carburized gears resist pitting initiation for considerably longer service intervals than alternative hardening methods.

Tooth Root Bending Fatigue

The tooth root is the highest-stress location in a gear under load — bending stress peaks at the root fillet. In mining drives with frequent start-stop cycles and load reversal (such as reversing conveyors), the tooth root experiences fully reversed bending stress, which reduces the allowable stress amplitude to roughly half the one-way bending fatigue limit. The combination of a hard case (which raises the surface fatigue limit) and a tough core (18CrNiMo6 with 1.4% Ni provides good fracture toughness even at lower temperatures) gives the best combination of surface resistance and bulk toughness available from a case-hardening alloy. Shot peening of the root fillet after grinding can further increase the root fatigue limit by introducing beneficial compressive residual stresses — available on request.

Abrasive Wear from Contaminated Lubricant

In underground mining environments, fine mineral dust inevitably enters the gear housing through seals, particularly on conveyor drives and heading machine gearboxes. Mineral particles harder than the tooth flank surface act as a three-body abrasive between the mating tooth flanks. A carburized case at HRC 58–62 is harder than most common rock minerals (quartz has a Vickers hardness of approximately 1100 HV; the carburized case reaches 700–750 HV) — so the carburized surface resists abrasive wear far better than a hobbed-and-normalized gear at HB 220–280. Combine this with a fine-ground tooth surface (Ra 0.6) that holds a stable oil film more readily than a rough-cut surface, and the result is markedly reduced wear rates in contaminated lubricant conditions.

Core Performance Advantages

 

Industrial Applications for Carburized Helical Gears

Underground Mining Machinery

Continuous miners, longwall shearer drives, and heading machines transmit hundreds of kilowatts through compact gearboxes operating in environments with coal dust, mineral particles, and limited maintenance access. The carburized hard case on the tooth flanks resists abrasive wear from dust contamination, while the tough 18CrNiMo6 core handles the shock loads from cutting through rock strata. Gearboxes designed to replaceable specification (drop-in pinion and wheel sets) are a standard supply format — provide the existing gear's drawing or worn sample for a matched replacement.

Ore Processing and Mill Drives

Ball mill and SAG mill gearboxes use large-module ελικοειδή γρανάζια — module M12 to M45 is common in this sector — running continuously under high torque with periodic shock from uneven ore feed. The external tooth grinding capability to module 45mm and OD 2500mm covers the full size range of these mill pinions. For the primary drive stage, carburized and ground gears in 18CrNiMo6 match the service life targets set by mill operators who calculate cost per tonne of ore processed as a key maintenance metric.

Metallurgical Rolling Mill Gearboxes

Steel and aluminum rolling mills subject their gearboxes to large cyclic torque variations as each billet or slab enters and exits the roll gap. The transient torque spike at entry can reach three to five times the mean running torque. Carburized helical gears in 18CrNiMo6 are the standard specification for rolling mill pinion stands and roughing mill gearboxes because the material's combination of high core toughness and surface hardness handles both the peak entry torque and the prolonged steady-state rolling loads. Find the full range of industrial-grade ελικοειδή γρανάζια κοπής and options at κατασκευαστής ελικοειδών γραναζιών Korea Ever-Power.

Our Service Process — Before, During, and After Production

 

Pre-Production

• ▸ Customer provides detailed drawings or sends worn gear for reverse engineering
• ▸ Korea Ever-Power evaluates drawing, communicates technical and quality questions, and issues quotation
• ▸ Unresolved technical questions addressed via direct communication before PPAP file preparation

In-Process

• ▸ Detailed technical questions arising during production communicated and resolved promptly
• ▸ Traceability marking applied at each process stage for full manufacturing audit trail
• ▸ Complete production flow and transportation packing plan prepared and documented before shipment

After-Sales

• ▸ Application performance monitored following delivery
• ▸ Quality complaints acknowledged within 24 hours; 8D report issued within 48 hours; on-site support available if required
• ▸ Continuous process improvement to reduce lead times and improve dimensional consistency
• ▸ Annual customer visits abroad to maintain technical, quality, and commercial alignment
• 

Τύποι Εξοπλισμού από την Κορέα Ever-Power

Korea Ever-Power Worm Gear Co.,Ltd manufactures a comprehensive range of gear types beyond helical gears. Whether your application requires a different configuration or a complete drive system combining multiple gear types, our team can assist:

• ⬡ Εργαλείο ώθησης: Straight-cut teeth for low-to-moderate speed parallel shaft drives where noise is not a primary concern. Simple geometry and lower manufacturing cost than helical types.
• ⬡ Γωνιακός οδοντωτός τροχός: Transmits power between intersecting shaft axes — typically at 90°. Widely used in differential drives, right-angle gearboxes, and hand tool drives.
• ⬡ Εργαλείο σκουληκιών: Right-angle non-intersecting shaft drives with high single-stage reduction ratios. The ατέρμονα κοχλία series covers standard center distances and reduction ratios with self-locking capability.
• ⬡ Διπλό ελικοειδές γρανάζι: For heavy-duty parallel shaft drives requiring zero axial thrust at the bearings. The διπλό ελικοειδές γρανάζι series is used in marine, turbine, and rolling mill gearboxes where thrust bearing cost and complexity must be minimized.
• ⬡ Εσωτερικό γρανάζι δακτυλίου: Internally toothed annular gears for planetary gearboxes and compact epicyclic stages used in drilling heads, mill drives, and compact industrial reducers.

For applications requiring a complete assembled drive rather than loose gears, Korea Ever-Power also supplies ελικοειδές κιβώτιο ταχυτήτων reducer units. Contact us with your torque, speed, ratio, and mounting configuration requirements for gear type selection and supply format recommendations.

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