How are worm gearboxes produced

Worm gearbox is a power transmission device that uses the speed conversion of gears to decelerate the speed of the motor to the desired speed and obtain a larger torque, it is widely used in various industries. Because of its simple structure and relatively low cost, the worm gearbox is more popular than other types of reducers.
Shengjie has been specialized in manufacturing worm gearboxes for more than ten years and is a leading manufacturer and exporter of worm gearbox in China. This article mainly explains how the worm gearboxes are precision produced in Shengjie.

Processing of each component

The basic structure of a worm gearbox consists of a housing, worm wheel, worm, covers, shaft, bearing, fasteners and seals. The precise processing and quality control of each component is the basis for producing a quality worm gearbox.

Housing processing

housing processing

The housing casting purchased from the casting factory will be finely finished in our housing machining center, including the big hole, small hole and bottom foot of the housing. Then they will be moved to the CNC drilling machine for large hole, small hole, bottom foot, oil plug hole, oil marker hole processing. After testing qualified, they are moved into parts warehouse.

Worm wheel processing

gear hobbing processing

The worm wheel consists of a cast iron wheel core and a bronze wheel rim. The wheel core casting will firstly be finished on the inner hole, outer diameter and thickness of the wheel core at our CNC lathe area. Then the copper cladding process will be carried out by the copper casting factory. Then they will be processed at our CNC machining area, and processed on our hobbing machine, finally moved into storage after inspection.

Worm processing

steel cutting

tooth grinding processing

Worm is component made of steel through rough machining, thread milling machining, heat treatment machining, external cylindrical grinding machining, thread grinding, keyway milling machining, etc.

The raw steel material will be cut according to different specifications at the sawing machine processing area, then be rough machined by CNC lathe. And our workers will conduct to thread milling according to different speed ratios. After testing, they will be put into storage.

The heat treatment of worm will be processed by heat treatment factory, which can improve the hardness of the worm, improve the wear resistance, and extend the service life.

After that, our workers will carry out external cylindrical grinding processing on tooth, bearing carriers and input shaft carrier of worm. Next will be grinding process. The thread grinding is to make the worm wheel & worm be meshed better with low noise.

Finally they will be processed at keyway milling machine, enabling gearbox connect with other parts through the shaft and key pin.

After testing qualified, the worms will be moved into the warehouse.

Cover processing

cover processing

drilling machine processing

The covers of worm gearboxes include big cover, output cover, oil marker cover and input cover. The cover castings will be fine machined at our CNC lathe, for the seal carrier, housing big holes connecting carrier and bearing carriers of the big cover and output cover, and for housing small holes connecting carrier and oil seal carriers of the oil marker cover and input cover. The precise dimensions can prevent the worm gearbox from oil leakage and overheating problems.

Finally drilling process of covers will be done at the drilling machine processing area, enable the covers and the housing connect by fasteners.

After inspection, qualified covers will be put into storage.

Shaft processing

housing processing

external grinding machining

Shaft is a component completed by steel through the process of rough machining, external cylindrical grinding machining and milling machining. Similar to worm processing, the steel is firstly cut by sawing machine, then rough machined at the CNC lathe area, including bearing carrier, worm wheel carrier, output shaft carrier. Then moved to the external grinding processing area for fine process. Finally the shafts will be milling processed. After testing qualified, the shafts will be moved into the warehouse.

Bearings, fasteners, seals

Our bearings, fasteners, seals and other accessories are supplied by well-known manufacturers, such as bearings from C&U, HRB, oil seals from NAK, SKF and other brands, fasteners are with grade 8.8, we can upgrade the bearings, oil seals, and fasteners according to customer needs.


The assembly of a worm gearbox greatly affects its operating effect. Correct assembly can make the worm gearbox run smoothly with low noise, control the temperature rise, minimize the possibility of oil leakage in later use and extend the service life of worm gearboxes. All assembled gearboxes are subject to strict testing by our QC team before leaving our factory.



The assembly of worm gearbox is relatively simple, according to the model and quantity of each order, our assembly workers will get the corresponding parts including housing, worm, worm wheel, shaft, bearings, seals and fasteners from the warehouse.

Step1: Clean the housing, worm wheel, worm and shaft.

Step2: Press the worm wheel and both bearings onto the shaft by hydraulic press, and press other two bearings onto the worm.

Step3: Press the oil seal onto the oil seal cover, set the seal ring onto the big cover, assemble the big cover to the housing with fasteners.

Step4: Put the sub-assembly set of shaft, bearing and worm wheel into the housing, fix them into the bearing carrier of the big cover, then assemble the output cover to the housing with fasteners. Assemble the oil marker cover to the housing with fasteners. Assemble the worm into housing slowly, after ensuring the worm and worm wheel are meshed well, then assemble oil seal cover to the housing by fasteners.

Step5: Finally install the oil release hole screws, the assembly of worm gearbox is completed.


air tightness test

After assembly, all worm gearboxes need to be tested at Shengjie.

Firstly our QC will test the air tightness through the air tightness testing instrument, if there is air leakage, the instrument will prompt the alarm. And we will further recheck manually, the most intuitive way is to place the worm gearbox into the water, by pressurizing into gearbox,  we will observe whether there are bubbles in the water, and find the leakage position, we will repair the gearbox or replace some parts based on the situation.

Then fix the worm gearbox on the testing platform and connect it to the motor, run it without any load, check if its operation and vibration are normal, and use a decibel meter to detect whether the noise is within the normal range.

Painting & Packaging

Our paint spraying line is environmentally friendly and certified by the Environmental Protection Agency. After the worm gearboxes are tested and qualified, the painting workers will paint the surface of gearboxes for beautiful appearance. The default color is green/blue, and various colors can be customized according to customer requirements.

After painting, our workers will nail or paste the nameplate on the worm gearbox, the nameplate should contain the gearbox model, speed ratio, production year and month, company information, etc.. And affix the warning sign of refueling, then pack them by 5 layers of cartons, and indicate the gearbox model specification on the carton. We will also use plywood case, wooden pallets and other forms of packaging according to different model and qty of gearboxes.


Shengjie strictly regulates the raw materials of each component, performs real-time inspection and quality control at every stage of production, and implement strict inspecitons on each product, in order to produce high performance and durable worm gearboxes. Shengjie consistently focuses on the product and strives for excellence, demonstrating our leadership position in the manufacture of worm gearboxes.

0 replies

Leave a Reply

Want to join the discussion?
Feel free to contribute!

Leave a Reply

Your email address will not be published.