Worm gear sets
Now online available!
This video illustrates the advantages of our online shop.
- Custom production according to customer request
- Diameter from 15 to 300 mm, axial distances from 17 to 210 mm, module from 0.5 to 10, shaft length up to 500 mm
- Material selection according to customer requirements (steel, bronze, fabric laminate or plastic)
- All process steps (turning, hobbing, annealing, flank grinding, grinding, measuring) from a single source
Our worm gear sets cover a wide range of applications. We demonstrate our years of experience and high level of capacity by producing more than 1 million worm gear sets every year in-house, most of which are created according to custom specifications.
Our catalog of worm gear sets in line with the Framo Morat standard have diameters ranging from 20 to 135 mm and axial distances of 17 to 80 mm. In addition, we offer custom worm gear sets with diameters of up to 300 mm and center distances of up to 210 mm.
The catalog of worm gear sets can generally be supplied ex warehouse in a wide selection of axial distances and gear ratios with fine degrees of differentiation. We can also calculate and produce customer-specific axial distances and gear ratios at the plant. We prefer to produce worm gear sets for right-handed users, but these sets can be designed for left-handed users on request.
We perform all major soft and hard machining steps in-house, including annealing in our own ovens. Thanks to extensive production depth, we are able to execute even highly complex machining tasks precisely according to customer expectations and in the highest quality. Learn more about it here.
The worms are made of case hardened steel with ground bore and worm profile. The worm gears are made of a special alloy (copper-zinc alloy with additives of aluminum, silicon and manganese). It is treated for better sliding characteristics. The chemical resistance is very high due to aluminum additives.
Brass worm gears
Brass worm gears have good corrosion resistance, high strength, good sliding properties and high wear resistance.
Since July 21, 2021, the exceptions of the EU Directive 2011/65/EU (RoHS II) regarding the use of lead as an alloying element in steel (Exception 6a in Annex III) and in copper alloys (Exception 6c in Annex III) expire. In order to give our customers legal certainty with regard to the requirements of the RoHS directive, we have decided to gradually convert our standard worm gear sets to alloys with a lead content of ≤ 0.1% by weight.
You can find an up-to-date overview of the materials that have already been converted on the product pages in our online shop. You can recognize these by the ° marking and by the new item numbers without spaces (e.g. new: R17U80B° / e.g. old: R 17U 80B).
Plastic worm gears
Plastic worm gears are suitable for low sliding speeds (< 1.5 m/s) and medium tooth pressure due to their bad thermal conductivity. Worms have to be hardened and ground.
The thermal expansion coefficient is appr. 4 times higher than with brass. Therefore the backlash shouldn’t be too small.
Bronze worm gears
Cu Sn 12 DIN EN 1982
Comparatively soft material with good wear resistance, suitable for high sliding speeds.
Cu Sn 12 Ni DIN EN 1982
Comparatively soft material with very good wear resistance, suitable for very high sliding speeds.
CuAl10Fe5Ni5 DIN EN 1982
Comparatively hard material for high torque and low speed.
Cast iron worm wheels
EN-GJS-400-15 DIN EN 1563 / EN-GJL-250 DIN EN 1561
Only suitable for low planing speeds.
Please find more details at our Worm gear set catalog.
Self-locking is affected by the lead angle, the roughness of the flanks, the sliding speed, the lubricant and increases in temperature. Self-locking can be dynamic or static.
Dynamic self-locking: lead angle up to 3° with grease lubricant; lead angle up to 2.5° with synthetic oil lubricants.
Static self-locking: lead angle from 3° to 5° with grease lubricant; lead angle from 2.5° to 4.5° with synthetic oil lubricants.
No self-locking facility is available for lead angles over 4.5° or 5°.
Jarring and vibration can prevent gears from self-locking. Self-locking can also be adversely affected if sliding conditions are particularly good. This can be caused by a number of factors relating to the lubricant, sliding speed and loading. For this reason we are unable to assume any warranty obligations for self-locking.
- Installing the worm gear
The reference surface tolerances will determine the lateral positioning of the worm gears. The lateral tolerance “c” must not exceed 0.15 mm for any centre distance.
You can tell if the worm gear is in the correct axial position by checking the position of the tooth contact pattern when the gear wheel is installed. If possible the tooth contact pattern should be towards the run-out side. When the gear is turned in the other direction (reverse operation) the tooth contact pattern should be towards the centre.
The efficiency of the worm gear set generally depends on the following parameters:
- Lead angle of the worm
- Sliding speed
- Surface quality
- Installation conditions
The larger the centre distance, the greater the degree of efficiency. Sliding bearings are often used with gears with smaller centre distances to save space and reduce costs. The sliding bearings have higher coefficients of friction, which can have a considerable effect on the overall efficiency of the gear. Efficiency data can be obtained from the manufacturer or our catalogue.
Additional information to efficiency factors are available in our worm gear sets catalog.
- Helical gearing
A helical gearing is a spur-type gearing which is inclined at the same angle as the lead angle of the worm. The sliding surface corresponds to a point contact, which means that a reduced torque can be transmitted compared to the worm gear teeth or the service life is reduced.
Catalog worm gear sets
Center distance 17mm
2,25 – 80:1
1,0 – 2,8 Nm
Center distance 22mm
3 – 40:1
2,2 – 5,8 Nm
Center distance 25mm
4 – 50:1
5,1 – 9,3 Nm
Center distance 31mm
2,5 – 100:1
4,4 – 15,7 Nm
Center distance 33mm
3,5 – 75:1
10,1 – 21,3 Nm
Center distance 35mm
2,78 – 90:1
6,6 – 25,6 Nm
Center distance 40mm
6,75 – 90:1
25,2 – 46,5 Nm
Center distance 50mm
4,25 – 69:1
34 – 117,3 Nm
Center distance 53mm
4,75 – 75:1
45 – 141 Nm
Center distance 63mm
6,1 – 70:1
89 – 258 Nm
Center distance 65mm
6,25 – 75:1
101 – 288 Nm
Center distance 80mm
6,75 – 80:1
150 – 522 Nm
Customized worm gear sets are produced in various designs and materials according to customer specifications.
Framo Morat supplies customized gear sets in axial distances of 17 to 210 mm at a max. worm gear diameter of 300 mm. If necessary, Framo Morat calculates the toothing data, defines materials and the surface treatment and provides consultation with respect to lubrication and torque loads.
For this purpose, there is a calculation program, which is oriented to the DIN standard. Framo’s 40 years of experience in manufacturing worm gear sets showed that our customers rely primarily on existing gear cutting tools, particularly when dealing with short delivery times and low unit quantities. As a result, the procedure must be checked on a case-by-case basis. To do so, you can contact us personally or use the request form.
The gear variety designed as a duplex worm gear set is especially suited for drives that require positioning at precise angles with high gear ratios. A plus factor is that the gearing backlash can be adjusted repeatedly. If after a longer period of operation the circumferential backlash increases, the gearing can be readjusted so that it is low backlash. For this purpose, the worm shaft is shifted axially in the gear housing by small increments. This is done, for instance, using shim rings when installing the fixed bearing or by means of adjusting screws in the housing cover. The duplex gearing is distinguished by tooth flanks with different helix angles. Axial adjustment of the worm shaft results in low backlash engagement of the worm tooth pitch with the teeth of the worm gear. Worm gear sets by Framo Morat that can be adjusted for low backlash are available from module 0.3 through module 8.
Duplex gearing is used, for instance, in rotary and swivel tables that position components for processing or for automated assembly. In addition, low backlash worm gearing sets optimize optical and mechanical instruments in measurement and medical technology. Because the gearings are adjustable, instruments, components to be measured and optics can be precisely positioned throughout their entire service life.