Rectangular Broach

[BrianP.]

Here we do a ton of flanges for microwave applications. Usually we get away with being able to put a .015 radius in the corner but one customer is insisting on .008 max. The parts are over .200 thick so I'm thinking a .016 endmill over 10x diameter might be a small challenge and time consuming. Our Haas VF2 has the spindle orient option so I can program it to orient at any angle. I would like to broach the rectangle to size while forming the corner radii. The size is pretty small .140 X .280 with a +/-.001 tolerance. I would mill the slot to with in .003-.005 with a .047 endmill leaving a .0235 radius in the corner to broach out. Has anyone done anything like this? I have seen a bunch of keyway broaching while researching this but nothing really like the application I am looking at broaching a rectangle. The feature is through and the material is Aluminum.

 

  

Thinking about something like this custom made for the size we need. Place to purchase?

[Guest]

Brian,

I did a TON of this while at Cobham/Kevlin Microwave.....

Slater Tools....find a broach that is the right size...

I would use a drill path and after milling down to .0235 rad, I would draw a line out of each corner at 45°....break it into as many points as I wanted and create points at endpoint....then pick them in the order to approach the corner....done, square corner...use can use a .005 step early, then drop to a .002 with a free pass or 2...(hint-disable Filter out duplicates to get free passes....

 

 

Edited September 12, 2017 by Guest

[mkd]

haven't worked microwave parts since the mid 90's. Used to love those .02" pocket floor thicknesses, flat within .002

Never broached on a haas mill but iv'e always  been  paranoid about the servo dithering when "locked"

[BrianP.]

1 hour ago, mkd said:

haven't worked microwave parts since the mid 90's. Used to love those .02" pocket floor thicknesses, flat within .002

Never broached on a haas mill but iv'e always  been  paranoid about the servo dithering when "locked"

Yeah. Everything is +/-.001 and true position of .002-.005. Even the clearance holes for screws. Frickin engineers.

[Machineguy]

Hey Brian,

There is a reason for that. I did a lot of that stuff when I worked at Hughes.

I got a nice education on how it all works. Its tight for a reason.

[K20]

All youhave to do is to lock your spindle,programme a slot with an endmill the same size of the broach and(transform) (rotate) the plane of work

you can control the depth of pass and the with an length of the rectangle.

See the attache mcx file

Cheers

broach.mcam