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- Modeling 3d crown face gears in NX7.5 tutorial.

    Crown Face gear is often a good alternative to a bevel gear: “...revolutionary way to increase transmission power in the Apache helicopter ... Today any cnc machine shop can make crown face gears. Cutting gears on universal milling machines has become a standard with an an accurate 3d gear model from our MS Excel program. CNC gear machining provides advantages.

This design advantage would benefit any other high endurance applications, for example, rock crushers, rotary tables and other.

Unlike bevels, crown gears do not require accurate axial position of the input pinion. If you need quick and easy pinion replacement Crown Face gear is a better option compare to spiral bevel. There is no axial force on cylindrical pinion, which increases life of pinion bearings. Cylindrical pinion for a crown gear set is about 70% less expensive to make compare to a spiral bevel pinion. Cylindrical pinion is easy to find and faster to make if you need a replacement. Unlike spiral bevels, Crown gears and pinions do not need to come in sets because Crown gears mesh with standard involute pinions. With Crown face gear you do not need to buy high cost replacement sets. You would need only spur pinions with standard involute tooth form. Because of higher pressure angle Crown gear tooth has about 50% higher load capacity compare to a traditional bevel gear tooth. On the impact load applications such as rock crushers Crown gear can be as much as 200% stronger compare to traditionally used bevel gear because of the more advantageous high pressure angle on the gear tooth. The mating pinion, if machined on a CNC can be also made in heavy duty configuration for additional torque:

Because Crown gear tooth practically never fails and mating standard cylindrical pinion is low cost and easy to find, many equipment users will benefit from significant reduction of operating cost during the life of machinery. There is no dependency on bevel gear suppliers since the Crown gear will not fail as spiral bevel and the mating cylindrical involute pinion is easily available from nearly any machine shop since it can be hobbed, milled or wire EDM.

Here is an example of accurate simulation of the tooth contact pattern between a spur pinion and a crown gear that was generated in Inventor with help of our Excel program:

This method of combined contact pattern visualization is based on surfaces (enveloping tapes) generated by our Excel program.

     Crown face gears will become more common on crushers, thrusters and rotary tables due to reduction of operating cost. The reason why they are not standard yet is because CNC gear tooth cutting technology has become available just recently. Before, crown face gears have been cut on gear shapers so the size of the gear was limited. Today, Crown face gears can be cut on universal CNC milling machines from 3d CAD models. We are offering software and 3d models for crown face gears. 
We assist in correct selection of design parameters of crown gear and provide accurate 3d CAD model of the gears for CNC machining.
     Crown face gears are more practical for tooth cutting. Often, you need 5-axis CNC milling machine for a spiral bevel pinion tooth cutting. You need only 3-axis to cut crown face gear teeth. The mating cylindrical spur pinion can be machined by many different methods. Wire EDM is probably the most cost effective. But traditional hobbing and CNC milling are also inexpensive for spur pinions. Our software provides 3d CAD model for the mating cylindrical pinion as well if you are interested to mill the pinion from a 3d model.

x,y,z crown gear tooth surface coordinates table output on Sheet2 for CMM inspection:

This option allows to study resulting gear tooth surface in details using MS Excel.

Because this program is based on DDS method the accuracy of the finished surface depends on calculation time. Within 3 seconds the program generates accurate model - the following samples: download gear and pinion in iges.

This software can be used in manufacturing for prediction of the final gear tooth surface. Input x,y,z coordinates of the shaper cutter or coordinates of the continues grinding wheel (cutting hob). This program will generate the gear tooth surface exactly identical to what would be produced in real manufacturing. The undercut areas on the root and on the toe will be accurately calculated in 3d identically to production gears.