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Drilling 40xD holes in UHMW. How to not get melty melty

rk9268vc

Aluminum
Joined
Dec 2, 2021
Location
Minnesota
Good morning,

I have a bunch of small diameter, but deep holes to drill in UHMW that are roughly 40 times D deep
They are 21ga (.159) blind holes 6.25in deep. The only drill I could find this long only has flutes the first 1.5in so i have to peck. Object moved
I also have a bunch of smaller diam holes down to 60ga. This part is like swiss cheese

Whats the best way to get at this without making the hole all full of little melty hairs? Print wants the holes to be completely free of little hairs etc

What I have been doing is peck drilling them at 3K rpm with .039" pecking depth (depth chosen by fusion) But it is kinda melty and stringy
My thought was to peck it slowly to give the bit/ material time to cool. Is this the right mindset?

Should i be spinning slower or taking deeper pecks etc?
I dont have through spindle coolant, so that isnt an option.

Thanks
 

Milland

Diamond
Joined
Jul 6, 2006
Location
Hillsboro, New Hampshire
Coolant inducer toolholder. Coolant through drill. Low RPM, play with feeds and pauses (not withdrawal) to break chips (might have to hand code).

Have fun...

["Have fun" seems to be a theme]
 

CITIZEN F16

Titanium
Joined
May 2, 2021
Rpms create heat, I would trying slowing down and peck deeper to start and then progressively more shallow. What kind of drills are you using? By the way UHMW sucks in my opinion, who picked that as a material? Is there another option?
If you don't have coolant at least rig up air blow. If the drill is still getting hot pause between pecks.
 

rk9268vc

Aluminum
Joined
Dec 2, 2021
Location
Minnesota
I have expressed that UHMW sucks to the customer, but they want it for the slippy ness. They make label applicators and the label slides on this surface.
The holes are all for mounting and pneumatics and vacuum.

I dont think the lockline air blower puts out enough air, so i rigged up a high flow air wand and it doesnt seem to help. The drill is so deep in the part that air and coolant cant get to it.

I will try lower rpm and see how it goes. This long holes all intersect a whole bunch of other ones for pneumatics, so i cant have the hole wandering at all
 

rk9268vc

Aluminum
Joined
Dec 2, 2021
Location
Minnesota
Coolant inducer toolholder. Coolant through drill. Low RPM, play with feeds and pauses (not withdrawal) to break chips (might have to hand code).

Have fun...

["Have fun" seems to be a theme]

I tried dropping it to 1K rpm and it seems to help so far
I dont have coolant through spindle capabilities on this mill.
As mentioned in post, I have to do full retracts because only the first inch or so of the drill has flutes and im going 6.25 deep
 

CITIZEN F16

Titanium
Joined
May 2, 2021
I tried dropping it to 1K rpm and it seems to help so far
I dont have coolant through spindle capabilities on this mill.
As mentioned in post, I have to do full retracts because only the first inch or so of the drill has flutes and im going 6.25 deep

You need to get a drill with much longer flutes, the rubbing is building up heat, and you are recutting swarf.
I would get both parabolic style and standard flute. Weren't you the guy that had a down machine for a while, now you have it running to do a UHMW job? Man, you are having a crappy stretch.
 

Milland

Diamond
Joined
Jul 6, 2006
Location
Hillsboro, New Hampshire
I tried dropping it to 1K rpm and it seems to help so far
I dont have coolant through spindle capabilities on this mill.
As mentioned in post, I have to do full retracts because only the first inch or so of the drill has flutes and im going 6.25 deep

That's why I suggested a coolant inducer toolholder:

Tool Holders, Mill Holders, Collets: Collis Toolholder Iowa

Lots of companies make them, they allow a side coolant inlet to a union that allows the holder to get fed directly from the pump. Obviously pressure's not great (~40-60 psi) with a regular flood pump, but you could add a second pump (~200-300 psi or so) just for that use.

It'll cost you, but make it up in better speed/feed/hole quality.
 

rk9268vc

Aluminum
Joined
Dec 2, 2021
Location
Minnesota
That's why I suggested a coolant inducer toolholder:

Tool Holders, Mill Holders, Collets: Collis Toolholder Iowa

Lots of companies make them, they allow a side coolant inlet to a union that allows the holder to get fed directly from the pump. Obviously pressure's not great (~40-60 psi) with a regular flood pump, but you could add a second pump (~200-300 psi or so) just for that use.

It'll cost you, but make it up in better speed/feed/hole quality.

oh thats pretty slick!
Ill have to check it out, i didn't know that was a thing
might be a bit of a pain though with the tube hanging off with an auto tool changer. just have to load that one manually.
thanks chief
 

Milland

Diamond
Joined
Jul 6, 2006
Location
Hillsboro, New Hampshire
just have to load that one manually.
thanks chief

There are setups to allow auto tool changing, but it's easier and safer to just do a manual change. If this is a ongoing aspect of your work, then talk with the toolholder provider on what options they have for auto-coupling (or whatever they call it).

[And I'm not a chief, I'm a corporal. Corporal Punishment, that's what the grunts call me...]
 

dlaw

Plastic
Joined
Jul 27, 2012
Location
Minnesota USA
Parabolic drills might work for this type of a job. However I have never used a parabolic drill on UHMW. My jobs for them was for 30 to 40 diameters deep in 60-61 aluminum.
 

13engines

Hot Rolled
Joined
Jun 30, 2015
Location
Saint Paul
Titex Extra Length 1722 ("Super 22")

4mm OAL @ 8-21/32" with flute length of 5-29/32"

EDP# 215961

WALTER TITEX A1722-4 Walter Titex - Extra long deep-hole drill | eBay
----------------------------
Think Snow Eh!
Ox

This drill is more the ticket. Even if you have to resort to your present one for the last inch. Try running it dead slow. Like 100 to 400rpm if even. Use unheard of feed like you're running one of those big ole wood auger bits that you drive with the egg beater type thing. Do the whole depth without a peck. You'll likely have to pull the chips at least partly out of the hole by hand after each hole. Adjust your feed to fill the flute almost full. Whatever it takes to get the chips to spiral out of the hole in two continuous lengths. I do this with bigger drills like a 9 or 11/32. But should work here also if you can find the right numbers. Slow and fast should do it with a drill like this.

One thing to remember too is the hole is likely to shrink back after drilling. Might need to drill oversize if you're really shooting hard for nominal.
 

TeachMePlease

Diamond
Joined
Feb 11, 2014
Location
FL
It's plastic. You don't even need a fancy drill, you just need a better drill than what you have.

Here's a drill from McMaster. $20 and it'll save you that in time and frustration.

Object moved
 

Mtndew

Diamond
Joined
Jun 7, 2012
Location
Michigan
I have expressed that UHMW sucks to the customer, but they want it for the slippy ness.
As much as I dislike when people say to tell your customer to use a different material, I wonder if suggesting Teflon to them might work? Or maybe delrin dipped in Teflon (can that be done? I don't know).
But TeachMePlease has it right, you just need a better drill, and get the speeds n feeds right.
Coolant thru is always a good choice here.
 

Chip Chester

Diamond
Joined
Dec 13, 2007
Location
Central Ohio USA
As much as I dislike when people say to tell your customer to use a different material, I wonder if suggesting Teflon to them might work? Or maybe delrin dipped in Teflon (can that be done? I don't know).
But TeachMePlease has it right, you just need a better drill, and get the speeds n feeds right.
Coolant thru is always a good choice here.

Sometimes that's the right thing to do, though. Perhaps suggest a metal main structure with a UHMW overlay. Still slippery, but the holes could be more shallow.

Part of the sales pitch could be that they can change the orifice size in the overlay (for fine-tuning, different materials, etc.) without re-making and re-plumbing the whole base structure. Maybe.
 








 
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