Cutting 5/8" material questions

[grindergary]

I need to cut some 5/8 inch material and would like your suggestions on cutting.

These are lift lugs for a company that will buy over 100 a year. They are in metric but 4" wide and 6 inches tall rounded top with a 2" hole on the top middle.

On previous 5/8 cuts most worked well. At 85 amps 34 IPM at 134 volts worked well for the most part. On the 2" hole, would you reduce cut speed as you would on smaller holes?

I will post a drawing as soon as I figure out how to do that.

Gary

http://i153.photobucket.com/albums/s230 ... iftlug.jpg.

[beefy]

Gary,

the general "book" recommendations are 60% cut speed, and THC off. However, some seem to do OK and others don't. I personally haven't had any luck with that formula yet. I get a lot of inwards taper at the bottom of the hole.

Jim Colt did a pdf file on hole cutting. Here's one link

http://www.metalwebnews.com/howto/plasm ... tation.pdf

Do some tests on scrap and see how you go with all the "book" recommendations and from Jim Colts writeup.

A plasma table manufacturer I know of recommended lowering the normal cut height in an attempt to get more flare at the bottom of the hole. Perhaps give that a try also and even lower the cut speed much more than 60%. Basically experiment and see what works.

Keith.

[grindergary]

Thanks Beefy,
I will read Jims article.

I got brave and made a new tool in SC at 15IMP for the hole. I worked well for that hole cut other than the little edge left when the cut meets back up with the cut and the slug drops right out. I then went and changed the gcode to slow down the cut at the top rounded corner. Worked very well and very little taper.
Customer was happy with the cut and got an order for 42 more.

Thanks for the help

Gary

[jimcolt]

Are they supposed to look like this? This was 3/4" cut at 85 amps.

Jim Colt

[grindergary]

Are they supposed to look like this? This was 3/4" cut at 85 amps.

Jim Colt

IMG_0624.jpg

IMG_0626.jpg

Yup looks the same. They are cutting really nice at 65 amp at 23 ipm with slowdown to 15 ipm on the hole and the curved top. Seems like lots of dross on the backside but falls right off when I drop them on the floor.

Tho only other issue is the small amount of material left when the hole is cut on the start stop. Using the long lead in and a short lead out but leaves a small amount of material. Hit it with a cone stone and it is gone in seconds.

Thanks for all your help Jim.

Gary