Focusing on the design, manufacturing processes, heat treatment techniques, and key quality control points for all types of standard and non-standard gears.
| Parameter | Specification Range |
| Module / DP Range | M1 ~ M25 / DP 1 ~ DP 25 |
| Accuracy Grade | GB/T 10095 4~8, equivalent to AGMA 10~14 / ISO 4~8 |
| Max. Outer Diameter | ≤ 1000mm |
| Helix Angle Range | 5° ~ 25° |
| Bore Diameter Range | φ10mm ~ φ400mm |
The full name of the external helical gear is external helical cylindrical gear. It is a widely applied category of cylindrical gear in the field of parallel shaft transmission, and also the mainstream selection for medium-high speed and heavy-duty industrial transmission scenarios.
Its gear teeth are evenly distributed on the outer circumferential surface of the cylinder, and the direction of the tooth trace forms a certain helical included angle with the gear axis (namely the helix angle). When assembled in pairs, it meshes tangentially with another external helical gear on the outside, and can smoothly transmit power and motion between two parallel shafts. After meshing, the input shaft and the output shaft rotate in opposite directions.
Compared with external spur gears, the teeth of external helical gears engage and disengage progressively, with a higher contact ratio. Therefore, they feature smoother transmission, lower meshing noise and stronger load-carrying capacity, and are often used in equipment such as gear reducers, machine tool spindles and high-speed gearboxes that have requirements for transmission smoothness and noise control. The disadvantage is that axial thrust will be generated during meshing, which requires matching thrust bearings, and the structural design and manufacturing cost are slightly higher than those of external spur gears.
The tooth profile adopts the industry-standard involute tooth form with a standard pressure angle of 20°. The core difference from spur gears is that the teeth are distributed along the helical path, and the tooth trace forms a fixed included angle with the gear axis, namely the helix angle, which generally ranges from 8° to 20° in the industry. The larger the helix angle, the higher the meshing contact ratio, but the greater the axial thrust generated during operation.
The teeth engage and disengage progressively. More teeth remain in mesh simultaneously compared with external spur gears, delivering a higher contact ratio. During transmission, impact is minimal and meshing noise is low; running stability is significantly superior to spur gears, with stronger load-carrying capacity, making it more suitable for high-speed and heavy-duty transmission conditions.
This is the most distinctive structural feature of external helical gears: an axial force component is generated along the axis direction during meshing. For this reason, matching bearings must be selected from types capable of withstanding axial loads, and the housing structure must also be reinforced accordingly. In engineering practice, symmetrically mounted herringbone gear sets are often used to counteract bidirectional axial thrust.
The mechanical transmission efficiency is approximately 97% to 98%. Due to axial sliding on tooth flanks and additional friction from bearings, it is slightly lower than that of external spur gears of the same precision grade. Its overall advantages are concentrated in smooth operation and low noise under high-speed and heavy-duty conditions, while its limitations lie in higher machining and assembly complexity, as well as higher manufacturing costs than external spur gears.
| Parameter | Standard Mass Production (General Service) | High Precision Custom (Precision Transmission) |
| Core Dimensional Specifications | ||
| Module / DP Range | M1 ~ M25 / DP 1 ~ DP 25 | M1.5 ~ M12 / DP 2 ~ DP 16 |
| Number of Teeth (Z) Range | Z10 ~ Z250 | Z12 ~ Z150 |
| Max. Outside Diameter | ≤ 1000mm | ≤ 800mm |
| Face Width Range | ≤ 300mm | ≤ 250mm |
| Bore Diameter Range | φ10mm ~ φ400mm | φ12mm ~ φ300mm |
| Secondary Machining Options | Keyways, splined shafts, stepped bores and end-face threaded holes available in one production flow | Full-process single-setup machining, strictly ensuring concentricity and tooth alignment accuracy |
| Tooth Profile & Accuracy Specifications | ||
| Tooth Profile Standard | Involute profile, available in both metric and inch standards | Involute profile, custom non-standard profiles available |
| Standard Pressure Angle | 20° (default), 14.5°/15° customizable | 20°, 14.5°/15°/22.5° and other non-standard angles customizable |
| Helix Angle Range | 8°~20° (standard) | 5°~25° customizable, with strict helix angle deviation control |
| Hand of Helix Customization | Left-hand or right-hand available on request | Left/right hand customization available, paired gears can be manufactured synchronously |
| Accuracy Grade | GB/T 10095 Grade 7~8Equivalent to AGMA Grade 10~11 / ISO Grade 7~8 | GB/T 10095 Grade 4~6Equivalent to AGMA Grade 12~14 / ISO Grade 4~6 |
| Tooth Profile Modification | Standard profile, basic tip relief available | Tip relief, lead crowning and helix modification available |
| Tooth Surface Roughness | Ra 3.2 ~ 6.3μm | Ra 0.8 ~ 1.6μm |
| Remarks | The above are the standard machining parameter ranges of our external helical gears. Special specifications and non-standard structures can be customized based on your drawings.For quotation, please provide module, number of teeth, helix angle, hand of helix, outside diameter, material, accuracy grade, quantity and other information. We will provide an accurate quotation within 12 hours. | |
High-quality blanks are forged and normalized to eliminate internal stress and stabilize material structure.
Turning, milling and hobbing/shaping are applied to form the target tooth profile with strict accuracy control.
Carburizing quenching or tempering processes to improve tooth surface hardness and core toughness.
Grinding of tooth flanks, bores and datum faces to correct deformation and enhance meshing precision.
Full-dimensional verification by gear measuring center and CMM to qualify products before release.
Professional anti-rust and protective packaging to keep products intact during storage and transit.
High-precision gear grinding delivers tooth surface roughness as low as Ra 0.4, with tight meshing, low vibration and noise for smoother equipment operation.
Premium materials matched with precise heat treatment ensure wear-resistant tooth surfaces and impact-resistant core, cutting maintenance and replacement costs.
Custom solutions for high-speed heavy load, corrosion resistance and food-grade scenarios, eliminating trial-and-error costs in product selection.
Scaled production supports tiered pricing for bulk orders with consistent quality; full-process control guarantees stable lead time and complete after-sales support.
Representative grade: 45 Steel)
High-quality carbon structural steel is the standard base material for external helical gears. After quenching and tempering, it strikes a balance between strength and toughness, with excellent machinability and strong cost-effectiveness. Its tooth surface hardness can be boosted via high-frequency induction hardening, making it ideal for medium-speed, medium-load applications. It has limited hardenability, performs poorly under heavy impact loads, and provides no rust protection.
Representative grades: 20CrMnTi, 40Cr, 20CrMo
Alloy structural steel offers far better hardenability than carbon steel. Treated by carburizing & quenching, or quenching & tempering plus surface hardening, it delivers both tooth surface wear resistance and tooth root fatigue resistance, suitable for high-speed, heavy-duty and high-impact operating conditions. It is widely used in high-precision, long-life transmission systems, and carries relatively higher material and heat treatment costs.
Representative grades: 304 & 316 Stainless Steel
Stainless steel provides excellent rust and corrosion resistance. Food-grade grades meet clean production requirements, and it is commonly used in food processing, pharmaceutical equipment, chemical machinery and outdoor humid corrosive environments. Grade 316 is engineered to withstand strong acid and alkali corrosion. It comes at a premium cost, has limited load capacity, and is not intended for high-speed heavy-duty service.
Representative materials: Tin Bronze, Brass H62
Copper alloy delivers exceptional friction and noise reduction performance, which pairs perfectly with the low-impact meshing of helical gears to achieve dual noise dampening. It also features corrosion resistance and non-magnetic properties, with easily attainable machining precision. Tin bronze offers superior wear and friction reduction, and is mostly applied in light-load, low-speed, precision small-module transmission scenarios.
Representative materials: POM, PA66, PEEK
Engineering plastics are lightweight with built-in self-lubricating properties. Combined with the progressive meshing of helical gears, they further enhance noise and vibration damping and deliver strong corrosion resistance. High-end PEEK grades are compatible with special industrial environments featuring high temperatures and severe corrosion. They are mainly used in light-load, low-speed applications, with low load and speed ceilings, and are prone to creep under sustained loading.
Representative grades: Gray Cast Iron HT200, Ductile Cast Iron QT450
Cast iron is easy to cast and cost-effective, with excellent inherent vibration and noise damping performance. Gray cast iron fits steady-load operating conditions, while ductile cast iron provides improved strength and toughness for higher load capacity. It is mostly used for large, open-type helical gears running at low speeds with steady loads. It has weak impact resistance and is susceptible to tooth breakage under shock loads.
As the most core application scenario, external helical gears are widely used in the medium and high-speed stages of precision parallel-shaft gear reducers and hard-surface gearboxes. Compared with spur gears, they deliver a higher meshing contact ratio, stronger load capacity, and lower vibration and noise during high-speed operation, meeting the continuous high-speed transmission needs of fans, pumps, industrial production lines and other equipment. Heavy-duty gear reducers also frequently adopt helical gear designs to extend service life.
External helical gears are universally applied in the spindle gearboxes of CNC lathes, machining centers and high-precision grinding machines. They ensure smooth transmission with minimal impact at high speeds, effectively suppressing machining vibration and safeguarding workpiece accuracy. The simultaneous meshing of multiple teeth also distributes tooth surface loads more evenly, making them well suited for precision equipment running long-duration continuous machining cycles.
They are extensively deployed in high-speed sorting lines, precision packaging machines, new energy conveyor lines and similar equipment. Compared with standard spur gears, helical gears run quieter and transmit more smoothly, satisfying workshop noise reduction targets while supporting higher operating speeds — ideal for high-volume, high-cycle continuous production environments.
Alloy steel external helical gears are the dominant choice for power shift transmissions in excavators, loaders, bulldozers and other heavy equipment. Their multi-tooth meshing characteristic boosts overall load capacity, delivers superior tooth surface fatigue and impact resistance, and stands up to the complex, harsh heavy-duty variable load conditions typical of construction machinery.
Helical gears are the preferred option for drive mechanisms in elevator traction machines, precision winches and medical lifting systems. Their key strengths include low meshing noise and smooth, jerk-free operation, which meet the comfort and stability requirements of passenger-carrying and precision handling applications, and they offer better long-term operational reliability than spur gear alternatives.
External helical gear designs are standard in automotive manual transmissions, differentials and diesel locomotive drive gear sets. At medium and high speeds, they effectively reduce transmission noise and shifting shock for smoother performance, while their higher load capacity also accommodates the complex power output demands of vehicles.
Inner VCI vacuum anti-rust process fully seals tooth flanks and critical machined surfaces, effectively resisting salt spray and moisture during ocean and air freight to keep precision gears corrosion-free throughout long-distance transit.
We select cost-effective logistics channels with stable transit time and controlled costs. Full logistics tracking is available with real-time status updates to ensure reliable and punctual delivery.
All products are covered by a 1-year warranty. Quality defects caused by non-human factors are fully guaranteed, removing your procurement concerns.
Our professional technical and after-sales team is always available to respond quickly to inquiries and after-sales needs, and efficiently resolve issues during installation and operation.
We support full-parameter OEM/ODM customization based on 2D/3D drawings or physical samples, including module, tooth profile, material and heat treatment specifications. You only need to provide core gear parameters, detailed drawings or physical samples to start the customization process.
You can send physical samples to us via international courier. Upon receipt, we will complete full-dimensional measurement and parameter verification, then arrange sample production after confirming the solution, ensuring the finished product fully matches the original in installation dimensions and transmission performance.
Prototype orders usually ship within 15–25 days, subject to heat treatment and grinding scheduling. Lead time for bulk orders will be confirmed after process finalization, with stable and well-managed production schedules.
We adopt a tiered pricing policy — the larger the order quantity, the more favorable the unit price. All orders follow the same production and quality inspection standards with strict accuracy control. Quality will never be compromised for larger order volumes.
We can include dimensional inspection reports, hardness test records and material certificates with each shipment. For high-precision key projects, professional inspection data from CMM and gear measuring centers is also available.
All products come with a 1-year warranty covering material defects and manufacturing quality issues under normal use. We also have a professional technical team to provide full-process consultation and selection support.
Spur gears feature a simple structure and no axial load, ideal for medium-low speed general transmission with higher cost-effectiveness. Helical gears run smoother with lower noise and higher load capacity, suitable for high-speed heavy-duty applications. We can recommend the optimal solution based on your actual requirements.
+86 184 3796 0706 
info@destinytrans.com 
