Mech311
Non-Tradional Machining
What is the principal cause of tool wear in ECM?
There is no tool wear to speak of in ECM as the tool is protected cathodically during the process. There may be some chemical reaction between the tool and the electrolyte when the power is off, depending upon the materials involved.
What is the nature of the surface obtained by electro discharge machining?
The surface is heated by the sparks to either melt or even vaporize metal. The melted metal is washed away by the dielectric. The sparks cut small, spherical shaped, cups into the surface. The surface is covered with recast (melted and resolidified) metal. Thus, there will always be a hard, brittle, surface layer on EDM part surfaces.
What process would you recommend to make many small holes in a very hard alloy where the holes will be used for cooling and venting?
Again, LBM is good for small holes in hard metals and since they are being used for venting, the recast layer should not be a problem. The low MRR rate may make for long machining cycles, so ECM may be preferred. EDM is not preferred for small holes.
ECM able to drill really small holes, and has a 50:1ratio in high-strength with no residual stress on the surface.
Broaching/Sawing/Filing
What is the main function of a gullet in the broach in the broach during a broaching operation?
Gullet must take the excess chip, which allows the operator to collect the unwanted chips.
Name two advantages of shell construction for a pull broach?
- Possible to make these with really lose cost steels
- If any wear occurs, we can only replace that shell without replacing the whole thing.
Name one adv. one disadv. for broaching and two examples.
- Quick
- Can be expensive
Slots,
What is the principal cause of tool wear in ECM?
There is no tool wear to speak of in ECM as the tool is protected cathodically during the process. There may be some chemical reaction between the tool and the electrolyte when the power is off, depending upon the materials involved.
What is the nature of the surface obtained by electro discharge machining?
The surface is heated by the sparks to either melt or even vaporize metal. The melted metal is washed away by the dielectric. The sparks cut small, spherical shaped, cups into the surface. The surface is covered with recast (melted and resolidified) metal. Thus, there will always be a hard, brittle, surface layer on EDM part surfaces.
What process would you recommend to make many small holes in a very hard alloy where the holes will be used for cooling and venting?
Again, LBM is good for small holes in hard metals and since they are being used for venting, the recast layer should not be a problem. The low MRR rate may make for long machining cycles, so ECM may be preferred. EDM is not preferred for small holes.
ECM able to drill really small holes, and has a 50:1ratio in high-strength with no residual stress on the surface.
Broaching/Sawing/Filing
What is the main function of a gullet in the broach in the broach during a broaching operation?
Gullet must take the excess chip, which allows the operator to collect the unwanted chips.
Name two advantages of shell construction for a pull broach?
- Possible to make these with really lose cost steels
- If any wear occurs, we can only replace that shell without replacing the whole thing.
Name one adv. one disadv. for broaching and two examples.
- Quick
- Can be expensive
Slots,