Limbowhale
Mechanical
- Jun 24, 2008
- 10
First the problem:
We make a ring gear that is not durable enough for our customer application. They have made their own gear which they claim lasts longer. We want to get the business back which means we have to make a gear that is equal to or better than theirs but have to be price competitive.
The facts:
The gear is 21" od x 19-1/2" id x 1-1/4" thk with external gear teeth. We make it from through hardened 4140 HT 320BHN forgings. The process we use is to machine the hardened ring and gearcut it. The problem is that at less than 320BHN the gear is not durable enough
In the distant past,we did make ring gears from carbon steels had problems with warpage when they were quenched so we reverted to buying the material that is through hardened to a hardness that is just below what the gearcutter can handle. This was OK for almost all our customers but in this application they are wearing our gears out in one year.
Our customer makes his gear from A36 stl which they carburize and quench to 52RC. They claim their gear outlasts ours 2:1 and they buy it at the same price.
As an experiment, we carb & quenched 2 of our 4140 gears on the gear teeth only (stop-off paint on everything but the teeth) and the gears did stay flat and the teeth did get a case so I assume they will be much better than the A36 gears.
My fear is that just because 2 gears done as an experiment by the heat treater stayed flat is no guarantte that if I send 24 gears they will all be flat
Our local heat treater cannot flame harden the gear due to the size and the cost to tool for it.
His quench press is too small. I am hesitant to send the gears out of the area because of time and cost considerations
Does anyone have any ideas?
We make a ring gear that is not durable enough for our customer application. They have made their own gear which they claim lasts longer. We want to get the business back which means we have to make a gear that is equal to or better than theirs but have to be price competitive.
The facts:
The gear is 21" od x 19-1/2" id x 1-1/4" thk with external gear teeth. We make it from through hardened 4140 HT 320BHN forgings. The process we use is to machine the hardened ring and gearcut it. The problem is that at less than 320BHN the gear is not durable enough
In the distant past,we did make ring gears from carbon steels had problems with warpage when they were quenched so we reverted to buying the material that is through hardened to a hardness that is just below what the gearcutter can handle. This was OK for almost all our customers but in this application they are wearing our gears out in one year.
Our customer makes his gear from A36 stl which they carburize and quench to 52RC. They claim their gear outlasts ours 2:1 and they buy it at the same price.
As an experiment, we carb & quenched 2 of our 4140 gears on the gear teeth only (stop-off paint on everything but the teeth) and the gears did stay flat and the teeth did get a case so I assume they will be much better than the A36 gears.
My fear is that just because 2 gears done as an experiment by the heat treater stayed flat is no guarantte that if I send 24 gears they will all be flat
Our local heat treater cannot flame harden the gear due to the size and the cost to tool for it.
His quench press is too small. I am hesitant to send the gears out of the area because of time and cost considerations
Does anyone have any ideas?
