[4]

Tapping Aluminum

[3]
[10] Like what you see?
Click here to donate to this forum and upgrade your account!

Rex Smith

Newbie
Registered
Joined
Jun 14, 2015
Messages
13
Likes
1
#1
I am about to tap a bunch of 10/32 x 3/4" blind holes in aluminum. I have some good quality HSS 2-flute taps and a floating tapping head that I got for the occasion. I've studied the procedure and think I know how to approach it. I looked up the feeds and speeds on the CNC zone calculator and am suspicious they are too high. I know that the speed and feed need to be compatible with the thread pitch, but the speed it's giving me is over 32 ipm. Does that make sense? I'm visualizing the tap breaking at that speed in aluminum as the tap gets galled. I don't seem to have a pecking option. I'll be using Hangsterfer's coolant in the process.
thanks, rex
 

gradient

Gradient
Registered
Joined
Aug 9, 2014
Messages
27
Likes
9
#2
Rex,
I just checked GWizard and got 891 RPM with a feed of 27.6 ipm. This is the conservative setting. The aggressive setting is 905 RPM and 29 ipm.
Regards,
 

gradient

Gradient
Registered
Joined
Aug 9, 2014
Messages
27
Likes
9
#3
Rex,
You didn't say, but you are using spiral flute taps for the tapping, head I hope. Standard hand taps are not meant to be used for machine tapping. :)
GWizard also calls for flood or mist use during the operation.

Marty
 

Rex Smith

Newbie
Registered
Joined
Jun 14, 2015
Messages
13
Likes
1
#4
I have a Hertel 2 flute spiral point tap. Same thing? It says it's good for thru and blind holes.
I have misting on the machine. Sounds like I'm good to go?
 

FLguy

H-M Supporter - Gold Member
H-M Supporter - Gold Member ($25)
Joined
Jan 11, 2016
Messages
243
Likes
137
#5
You have the right tap but I would slow down to approx. 500rpm. Put some fluid in the blind hole.
 

Rex Smith

Newbie
Registered
Joined
Jun 14, 2015
Messages
13
Likes
1
#6
That's what I was wondering about the speed. It seems to me that GWizard is a little too aggressive. It doesn't offer speeds that low for this configuration.
 

Rex Smith

Newbie
Registered
Joined
Jun 14, 2015
Messages
13
Likes
1
#7
Is there a good reference about tapping feeds and speeds, so I can understand the logic?
 

wawoodman

himself, himself
H-M Supporter - Gold Member ($25)
Joined
Mar 19, 2011
Messages
931
Likes
711
#8

Kernbigo

Active User
Registered
Joined
Apr 8, 2012
Messages
727
Likes
207
#9
use a express tap or also called shrinker tap for aluminum, they don't cut but extrude the metal. I used to work for Besly tap co.
 

woodchucker

Registered
Registered
Joined
Nov 25, 2015
Messages
1,504
Likes
1,036
#10
I sense a disturbance in the force. A spiral TIP tap is for through holes, since it moves the chips forward. In a blind hole, this is a not-good thing. A spiral FLUTE tap, OTOH, is for blind holes, since it pulls the chip backwards.

Look at page 3: https://www.yamawa.com/en/support/catalog/pdf/understanding-the-basics-of-spiral-fluted-taps.pdf
I wanted to like your post, but LIKE is not showing up for some reason, so ... I totally agree with what you said, sprial is for through, spiral flute is for blind, or through.
 

Rex Smith

Newbie
Registered
Joined
Jun 14, 2015
Messages
13
Likes
1
#11
I sense a disturbance in the force. A spiral TIP tap is for through holes, since it moves the chips forward. In a blind hole, this is a not-good thing. A spiral FLUTE tap, OTOH, is for blind holes, since it pulls the chip backwards.

Look at page 3: https://www.yamawa.com/en/support/catalog/pdf/understanding-the-basics-of-spiral-fluted-taps.pdf
Interesting that the MSC web page for that tap says it's for thru or blind holes. Anyway, I tested it on a thru hole and noted that it was pushing the chips through the bottom of the hole. So, for this particular work-piece, thru holes were fine, so I drilled them through and then tapped. It worked great btw.
 

Silverbullet

Gold
Registered
Joined
May 4, 2015
Messages
3,419
Likes
1,662
#12
I don't think I'd be running my taps that fast. Of course I'd just set up my tapping head in my drill press with a depth stop. With aluminum I'd be using a fast spiral tap . Kero or wd40 for cutting fluid. May not be CNC but they work great.
 

FLguy

H-M Supporter - Gold Member
H-M Supporter - Gold Member ($25)
Joined
Jan 11, 2016
Messages
243
Likes
137
#13
Wawoodman is correct. I do a LOT of blind holes so spiral to me is lifting the metal up out of the hole. I'm sorry! After about 50 years of doing this stuff you can get a bit sloppy on correct names to use. I have 2 tapping heads and they don't get used much as I do 8-24 and up under power at 100rpm. Never a problem with thru holes and for blind I pay attention to the DRO so I don't bottom out. It works for me but maybe a bit harry for the younger guys.
 
[6]
[5] [7]
Top