Choosing the best way to make a Bevel Gear 1

[CarlosEstinos]

I’ve been tasked at work to make 20 Bevel gears, each weighs roughly 20KG.
They are used on the drive mechanisms for large penstock valves, they are operated by hand using a key which interfaces with the input shaft. The gear will run at a relatively low speed
I’m trying to weigh up all my options cutting them either outsourcing or in house on a CNC using a CAM system.
The other option I’m looking at is to get a pattern made and cast them.
The environment in which they will be used is chlorine rich so any material that is used has to have good resistive properties against corrosion from chlorine
The originals were made out of cast iron. Does anyone have any experiences of casting gears? What types of materials would be better to use etc.
Any feedback on this subject would be gracefully received

 

[TVP]

What are the basic dimensions of the gear?

 

[CarlosEstinos]

The max radius is approximetly 300mm, tapering in to 200mm. The max height is about 120mm.

 

[MikeHalloran]

Have them made by a real gearcutting house.


Mike Halloran
Pembroke Pines, FL, USA

 

[gearcutter]

20 is a very small quantity for casting.
Have a gear shop make them for you.
Use a gear shop that doesn't use a 'two tool' bevel generator as they are not cost effective for this quantity.
A bevel generator which uses rotary cutters will get you a more cost effective solution.
I'd forget about CNC milling them as you'll encounter far too many geometry issues.


Ron Volmershausen
Brunkerville Engineering
Newcastle Australia

http://www.aussieweb.com.au/email.aspx?id=1194181

 

[tbuelna]

carlosestinos,

If you can produce a high fidelity surface model of your gear, it can be cast economically in limited quantity using rapid prototype tooling. The most dimensionally accurate casting method for ferrous metals is investment casting, but even investment casting would not likely give you the accuracy you need "as cast".

There are also specialty shops (

http://spiralbevel.com/gear_cutting)

that will accurately CNC bevel gears, but it's not cheap.

As other posters recommend, your best option for 20 gear sets is a conventional gear house.

Hope that helps.
Terry