Machining pockets with thin flats

[Kevin W@Accurate]

Hey all,

 

I am machining large pockets out of .5" AL plate. The pockets end up at .100" thick. I am using surface rough pocketing because there are some varying depths and features. When I get down near final depth the part starts vibrating badly. What I would like to do is pocket the inside to finish depth, step out, pocket to finish depth and repeat until I reach my full pocket size. I am looking a toolpath method to do this or other strategies for machining large pockets with thin bottoms. I appreciate any tips all of you can give me. Thank You!

[Jean-Simon]

A thing we do here, might look weird, but reverse your spindle and pass an extra fine sand paper on your end mill for a few seconds. Reduce your rpm. there's no speed and feed data for that kind of work, you go with the noise!

 

HTH!

 

Simon

[Jean-Simon]

BTW Welcome to the forum!!

[Mike Whitten CAD/CAM Contractors]

Kevin,

 

Here is a few:

 

-Start with thicker material. Mill the pockets then wack the back off.

 

-Double back tape something on the back of the part.

 

-Clamp the part down on a fixture plate so that the back of the part is supported properly.

 

-Use smaller tools.

 

- Use a very free cutting em such as an OSG 2flt HSS or HSCO.

 

-Slow down the speeds and feeds.

 

-Make the last "Z" finish pass much larger then normal and pocket it out starting from the center.

 

Mike

[Mike Whitten CAD/CAM Contractors]

Oooh!,

 

Welcome to the Forum Kevin!

 

To answer your question more directly, you will just have to use separate contour or pocket cuts/chains.

 

Mike

[billystein]

sounds like you could use a vacuum plate.

[Kevin W@Accurate]

Hey-

 

Thanks for all the responses! I think I have a good way to go about machining these parts now. Thatnks for the welcome, I'm glad to be here.

[Bob_Looney]

i do a lot of thin wall/floor stuff. if you're vibrating it sounds like the part needs to be bolted down to a plate to keep the floor from vibrating.

also, if you are able to hold the parts in a vise but the pocket floor vibrates, pocket from the inside out, this will keep the floor thickness up till you get towards the outer edge and then the pocket walls will help keep the vibration down.

I never use tape.

[cblythe3d]

What a wealth of experience here.

 

I must not have been paying attention in machinist school or they forgot this lesson.

 

3M has the bomb double back tape. Acetone both sides before applying.

 

A R/H cut L/H spiral mill pushes down while cuttin around. Often used on composites to prevent de laminating. High velocity air aimed down the flute really helps evacuate cuttings.

 

Charlie

 

"No Brain = No Pain" Nope- still hurts