Custom Forged Gear Shaft Manufacturer | 18CrNiMo7-6 Gearbox Shaft Supplier | HHF

Forged Gear Shafts | 18CrNiMo7-6, OD 120–1200 mm | HHF

Forged Gear Shafts for Heavy-Duty Gearboxes

A gearbox shaft must transmit torque while maintaining alignment between connected components. In wind power equipment, mining drives, marine transmissions and other heavy-duty machinery, shaft performance depends on more than nominal strength. Steel cleanliness, forging quality, heat treatment and the condition of the finished surface all influence service life.

Henan Zhongyuan Heavy Forging Co., Ltd. (HHF) produces large forged gear shafts with outside diameters from 120 mm to 1200 mm. The standard material for this product range is 18CrNiMo7-6 case-hardening steel. Manufacturing can follow customer drawings, with engineering support available for projects that still require dimensional development.

Factors‍‌‍‍‌ Affecting the Service Life of a Gear Shaft

The failure of a gear shaft rarely starts off with the full break of the component. Depending on the environment where it is being used, the first symptom can be the appearance of pitting on the gear teeth, the presence of cracks around the tooth base area, the excessive bending/deflection of the shaft or the damage to the fatigued spots, especially in the places with high stress.

These types of complications may have their origin in various aspects. For example, improper heat treatment may result in the case being harder than can be supported by a core at a reasonable level through the depth. The presence of inclusions in the material or the existence of the internal flaw can lead to the fatigue crack starting points. Besides that, the dimensional variations and the machining errors are the other factors that may influence the load-sharing behavior between the teeth of the gear set. For big shafts, it would be a good idea to give these problems the proper attention before the final machining. The part may be compliant to the specifications but, if its internal structure or properties of material differ from those specified in design, the further examination can be necessary.

HHF considers gear shaft manufacturing as a series of associated operations. The steel choice, open-die forging, heat treatment, machining and inspection are treated as different stages, the process requirements are determined in respect to the component's sizes and application.

Why Consider 18CrNiMo7-6 for Gear Shafts?

18CrNiMo7-6 steel is an alloy type of case-hardening steel which is a nickel-chromium-molybdenum variant and which gets a great use among all heavily loaded gears and other transmission parts. In this way, the composition of the material permits a case hardening that is very common while the core of the material remains tough enough to survive loads that come at the working time especially after the material is treated to the required conditions.

What the gear shaft needs isn't just a surface with higher hardness. The hardened layer should resist contact wear adequately and the unhardened part (i.e. the underlying material) has to take care of the applied twisting moment and bending moments.

The actual features of a piece of material depend mainly on the details of heat-treatment that will be employed, the effective case depth, design of the component and its inspection requirements. All these details should be agreed beforehand not assumed from steel grade alone.

HHF employs a 10,000 ton hydraulic press for large open-die forgings. Heat treatment is planned bearing in mind the real section sizes while material and mechanical testing are carried out in the company's physical and chemical laboratory.

Customers may ask manufacturers for the corresponding documents confirming that equipment or parts have been inspected when considering a new supplier or before placing a production ‍‌‍‍‌order.

Forged Gear Shaft Manufacturing Range

The diameter range covers a broad selection of industrial transmission components. Final feasibility depends on the shaft length, weight, geometry, forging ratio, machining allowance and required finished dimensions. Customers with unusually long or complex shafts should submit a drawing for a technical review.

From Steel Stock to Finished Shaft

Large gear shafts require coordination between several manufacturing stages. The sequence below describes the main operations; the actual route is determined by the order specification and component design.

1. Material selection and incoming inspection

The steel grade and required supply condition are established before production. Chemical composition is checked against the applicable material specification, with additional tests arranged where the order requires them.

2. Open-die forging

The selected steel is forged to develop the required blank geometry and internal structure. Forging dimensions and machining allowances depend on the shaft design and the amount of material that must be removed during subsequent operations.

3. Heat treatment

The treatment route is selected according to the steel grade, section size and specified mechanical properties. Quenching and tempering may be required for the core condition, while case hardening is specified where the finished gear design calls for a hardened working surface. The required sequence must be confirmed for each component.

4. Machining

Machining brings the forged blank toward the required dimensions, bearing fits, concentricity and other drawing tolerances. Rough machining and final machining are scheduled according to the manufacturing route.

5. Inspection and release

The finished or intermediate component is checked against the agreed acceptance criteria. Depending on the order, these may include dimensional inspection, chemical analysis, tensile and impact testing, hardness measurements and additional nondestructive examination.

This process-based approach gives procurement and engineering teams a clearer basis for reviewing a shaft before it enters gearbox assembly.

Cutting-to-Size‍‌‍‍‌ Gear Shafts That Adapt to Operating Requirements

A shaft used in a wind turbine's gearbox may not, in contrast, be exactly the same in terms of dimensional accuracy, load bearing characteristics, as its counterpart for example a gear shaft of a marine transmission or a mining unit drive. Torque levels, revolutions per minute, bending load, space limitations, and the frequency of maintenance work are just some of the variables that might influence the gear shaft design.

We are always ready to take on the challenge provided you send us the drawings and/or the customer technical specifications with HHG. However, in case your project is only at the concept stage, our team of engineers will be happy to look over your mechanical requirements and help you develop the drawings, as long as it is based on the information you gave and we agreed on what the project entails.

Different from one application to the other, the subject of the discussions can vary a lot:

• Shaft dimension: length, outer diameter, etc., shoulders, journals and connection geometry.

• Steel grade and steel supply condition that material should meet.

• Core material properties and surface-hardening requirements.

• Allowed deviations in sizes - machining tolerances, and roughness.

• Preliminary testing without causing damage, how often the inspection is done and what the standards are that should be met.

• Stamps, identification, containers and foreign shipping papers.

Different materials can be made available if you contact us. The suitability of a proposed alternative should be checked against the specification of the part and the use, but should not be accepted simply because it has approximately the same strength ‍‌‍‍‌value.

Chemical Composition of 18CrNiMo7-6

The following values are the composition figures supplied for this product page. Before placing an order, the applicable steel standard and material certificate should be used to confirm the acceptance limits.

Material note: Hydrogen content and hardness are not chemical composition percentages. They should be treated as separate material requirements, with the relevant sampling method, test stage and acceptance condition stated in the purchase specification. The silicon limit and the other listed ranges should also be checked against the exact governing standard and grade designation before publication or procurement.

Material selection remains subject to the customer's requirements and the technical review of the specific shaft.

Inspection‍‌‍‍‌ and Quality Documentation

For a massive forged part, inspections must agree on the inspection requirements, including production steps. Different applications may require combining different methods of mechanical testing, hardness measurement, dimensional control and internal-defect detection.

HHF has its own National ClassII physical and chemical lab. Its capabilities are limited to chemical analysis, mechanical properties and hardness testing. Customers wishing to make a purchase can get records of inspections from the product they ordered, provided the type of inspection is within mutual agreement between them and the supplier.

If you have been offered an opportunity to become a supplier and want to know what is in production documentation, you can ask for sample reports from the company that will produce the items and check whether the type of tests described here will be carried out during the regular production. If a third-party inspection agency as SGS or BV is needed, the arrangements can be negotiated before the order is made.

HHF's official certificates include API Q1, API 7-1, CSSC and ISO/TS 29001 together with ISO 9001:2008 as per our supplied company details. However, the certifying scopes as well as the validity of each certificate must still be matched or confirmed to fit the particular purchase requirement at ‍‌‍‍‌hand.

Warranty‍‌‍‍‌ and Technical Support

HHF has announced the warranty period for their forged gear shafts as two years from the date of dispatch. According to the documents provided by the company, warranty includes manufacturing defects which occurred during the production stages like material handling, forging, and heat treatment procedures. The repair, replacement or giving a credit, whichever suits best, is the way to respond for acknowledged claims as mentioned in your agreement.

Better half of the technical questions can expect being addressed within one working day. In addition, buyers can consult third-party inspections and documentation aspects pre-shipments.

To preserve the uniformity in manufacturing between lots, it will be of assistance if customers, in the case of reorders and replacement parts, keep the old drawing, the specification of the material, heat treatment requirement, and inspection records on hand. The design or specification changes which cannot be made from an earlier order by informal means should rather be formally captured in writing.

Lead Time, Payment and Delivery

Manufacturing lead time

The normal lead time for the company is about 45 days from when the purchase order is received and the down payment has been made. This is simply the company's expected planning period for the most straightforward manufacturing cycle which involves getting the raw materials, forging, heat treating, machining, and quality inspection at the end. However, the exact schedule will heavily depend on how soon the material can be gotten, the size of the part, what type of processes are to be carried out, and of course, when production is planned.

For orders where the product has to be replaced as early as possible or when the delivery has to be completed at a fixed date the delivery date should also be stated during quotation.

Payment conditions

The usual payment term is 30% deposit payment to initiate production and the balance 70% to be paid at the time of shipment.

We accept either T/T or L/C.

Sight L/C or other forms can be arranged at buyer's request for our regular and qualified customers subject to mutual agreement.

Delivery condition

Quarantines are allowed FOB, CFR and CIF. Once you select the delivery condition it will be written into the sales contract and together with a named location, the agreement of freight, insurance, and delivery duties is going to be stated.

Shipping and loading

The company mentions that deliveries can be made through ports in Shanghai, Ningbo, Tianjin, Qingdao, Guangzhou and factory loading also is possible.

Different shipping routes, which will suit best a customer’s needs, is a combination of many conditions: cargo size, shipment weights, destination, and the buyer’s choice of the freight forwarder.

Buyer can coordinate the export documentation and loading arrangement with us prior to the dispatchment.

Export Packaging for Large Forgings

When it's time to handle, ship or store such products as heavy steel shafts, these objects are required to have adequate supports. HHF has listed wooden crates as one of the major forms of export packaging; the shipment arrangement also decides whether secure metal boxes or crates will be used or not along with metal support structures if any.

The actual choice of packaging and support should take into account the shaft's weight, lifting points, the surfaces which will be machined and the likely transport conditions. If such components are to be put into storage prior to their installation, then the customer can, for instance, even request that support arrangements should be made keeping in view that the shafts would be properly aligned and the likelihood of a damaged finished surface minimized.

If the customer has his own packaging design or handling instructions he may, however, submit them for ‍‌‍‍‌approval.

About Henan Zhongyuan Heavy Forging Co., Ltd. (HHF)

Established in November 2004, Henan Zhongyuan Heavy Forging Co., Ltd. is based in Jiyuan City, Henan Province, China. The company operates a heavy forging facility covering approximately 150 mu, with three large open-die forging lines built around a 10,000-ton hydraulic press, two die-forging lines, large CNC machining equipment, heat treatment facilities and a National Class II physical and chemical laboratory.

According to the company information provided, HHF has an annual large-forging capacity of approximately 50,000 tons and can produce individual forgings weighing more than 30 tons. Its workforce numbers around 500, including more than 50 engineers and technical specialists.

The company's product portfolio serves power generation, mining machinery, shipbuilding and heavy equipment applications. Named customers and industry relationships in its supplied company profile include CITIC Heavy Industries, China First Heavy Industries, Taiyuan Heavy Industry, Goldwind and Envision Energy. International mining equipment names listed in the profile include Joy Global, Hitachi Mining, Komatsu and Caterpillar. These references describe the supplied company profile and should not be interpreted as confirmation that every named company currently purchases this particular gear shaft.

HHF reports exports to more than 20 countries and regions.

Frequently Asked Questions

How‍‌‍‍‌ quickly will HHF produce a quotation for the fake gear shaft?

The quoted time period is three working days once the technical info is submitted.

Drawings of the required gear shaft together with materials, dimensions, quantity, and inspection requests are necessary to enable the technical department to produce a thorough and accurate quotation.

Is it possible to manufacture according to our drawings?

No problem. If a drawing has already been completed HHF is in principle ready to accept it. If the drawing is not yet completed the engineering department will assist with the design of the component based on the information that you provide.

What is considered as the typical material?

The product is usually made out of 18CrNiMo7-6. The other grades can be considered depending on the design of the component and its intended operating conditions.

What external diameters can you supply?

From 120mm to 1200mm, the given outside diameter range for a forging gear shaft.

However, the feasibility of making the required shaft will depend on its other factors like length, weight, geometry, and machining demands, if any.

What is the typical production lead?

It takes about 45 days after a customer's PO and deposit are received. The final timeline, depending on the production methods and material ready, will be agreed.

Which tests and reports can be requested?

The laboratory has capabilities to perform chemical analysis, hardness testing and mechanical testing. The inspection plan, final report, its content and delivery shall be decided on the basis of the procurement specifications.

Is it possible to get the inspection handled by an independent inspection company?

Yes, SGS, BV and another inspection company which is mutually agreed may be introduced prior to production or shipment, provided the inspection coverage and timeframe are agreed.

What about the payment terms?

A typical payment arrangement is payment 30% upfront, and 70% one before delivery of goods.The seller accepts T/T and L/C only, and any other payment methods need mutual agreement.

Which ports are able to deliver the goods?

Possible ports are Shanghai Port, Ningbo, Tianjin, Qingdao, or Guangzhou Port. The factory can arrange the factory delivery as well.

Discuss your Forged Gear Shaft Requirements

In order to issue the quotation, you just need to send the sketch, outer diameter, length, material grade, order quantity along with the delivery address. You need also to add the mechanical properties, heat treatment condition and inspection standard if these are already decided.

At the outset of the project when you have limited data, a good way to begin developing the technical requirements is by using the rough estimations of the size, operating mode, and general characteristics.

After the agreement of the manufacturer on the method and material requirements, acceptance of the product, inspection procedures, documents delivery, schedule and commercial conditions of the manufacturer have been made known, the parties shall get them finalized.

Call up HHF to get a forged gear shaft that suits your gearbox ‍‌‍‍‌application.

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