Boring dream? 1

[antknee]

Well I was thinking of a technique to machine stainless that involved laser drilling the holes then boring them to remove the taper. The catch is that the laser drilled holes have an entry diameter of 60 microns and exit diameter 30 microns, so the drill bits for bore need to be around 60 microns diameter. Boring on this scale is going to be specialist.

Now I think somewhere in the dim and distant past I saw a company that could bore with 60 micron bits. But now I can't find any sight nor sound of this industry let alone that company. Did I dream this?

Thanks,

Ant.

 

[SnTMan]

My dreams are boring too

Regards,

Mike

 

[fegenbush]

I don't know if it would be possible to bore to 0.002", but it may be possible to ream to that diameter.

 

[btrueblood]

We've had parts drilled to .0015" diameter at about an L/D of 10 before, to create a flow orifice at a flow tolerance of a ridiculous nature (so we needed tight control on diameter and inlet edge break). We tried EDM, laser drilling, and mechanical drilling. Of all the options, mechanical drilling won - but it depended on finding the right shop to do the work. Reaming a laser or EDM drilled hole was a non-starter, as the rough recast layer tended to "hook" into the drill/reamer flutes and break them too readily.

There are machines made to do micro hole drilling, and these had some success for us (I think our yield was 80% or so on the above hole size). Guhring makes a line of micro-size drills that are very well made. Even better was to find a shop with experience and tooling for micro hole drilling - this was National Jet in Maryland, strongly suggest you give them a call, better yet just visit their website, the photo there ought to convince you they know their business.

http://najet.com/

 

[antknee]

It is interesting to read your post, i too have to make nozzles. I was thinking it would be better to laser drill these first because i couldn't see how i could drill through stainless without the drill bits breaking or it taking hours, my stainless is 0.008" thick. I presume from your post your material was metallic, about 0.015" thick and you purchased a micro drilling machine. How long did it take to get through the 0.015 inches? And how many holes did you have to drill per part for a yield of 80%? I've had a look at National Jet and they are definitely the route to take.

Best regards,

Ant.

 

[dgallup]

You have 30 microns of taper in a 200 micron long hole? That sounds way out of line for a good laser. Also, why are you concerned about taper? Depending on what you are doing with your nozzle, taper can be unimportant or even useful. We never try to do secondary operations to laser or EDM holes, we don't even measure the size. We just measure the flow rate. We don't even consider drilling or machining.

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[antknee]

The last order for laser drilled parts I had in the 200 micron material had an entry of 30 microns and exit of 10 microns, I took advice from another company and they couldn't do any better taper in the stainless. They used an ND Yag as far as I know, but could be wrong. The taper is important because it is at the heart of some patents that I need to avoid, I need some complex internal geometries to get around them - I think. I also need low friction nozzles because I'm working with AA battery power.

 

[btrueblood]

"I was thinking it would be better to laser drill these first because i couldn't see how i could drill through stainless without the drill bits breaking or it taking hours, my stainless is 0.008" thick. I presume from your post your material was metallic, about 0.015" thick and you purchased a micro drilling machine. How long did it take to get through the 0.015 inches? And how many holes did you have to drill per part for a yield of 80%? I've had a look at National Jet and they are definitely the route to take.

Yes, the holes were from 10 to 20 L/D in stainless steel. Drilling time was about 10 minutes per part maybe longer, it's been more than 10 years, but most of the time was spent in setup (getting zero spin-out on the drill bit end is a bear with the tiny bits).

The micro-drilling machine was made in japan, and had pre-programmed numerical control for micro drilling. We rented the machine on a demo basis, and ended up returning it after we found Nat. Jet. The drilling machine used a peck drilling cycle, and had a sensor that detected the torque on the drill chuck, and would try to back out if the torque rose beyond a preset limit - but it still broke drill bits from time to time, and the effect of a broken bit was a scrapped part for us.

When I took parts to Nat. Jet, they let me visit a very narrow area of their shop, and had tarps put up so that all I got to see was one drilling machine, manually controlled. They used jeweler's microscopes to view the drill bit, and had trained operators to set up and run the parts. They completed a job for us of 30 parts, zero scrap, in about 3 or 4 hours (I left, and came back later in the day to check in and the parts were finished). They were very protective of their knowledge, and rightly so in my mind. We had very good success with them as a vendor. I do remember they sent me their business card, and it had a sample hair with a wire threaded through it taped to the back. That card was pretty useful in convincing others in our shop that they could do the job for us, prior to giving them the work.

 

[antknee]

It is nice to get a quality job done although it doesn't happen to me often, to be fair I never know exactly what I want from a subcontractor so they don't have much chance of sending it. R&D is just one long series of mistakes I found the company that I could only vaguely recall, they are called Microcut Ltd.

http://www.microcut.ch/en/index.php

They don't appear to be able to drill small diameters but they can ream them to very high quality, I'm not exactly sure what Surface roughness Rx = 0.2um means (anyone want to enlighten me?) but it gives the impression of being very smooth. It looks like they are using a diamond tool and some kind of CNC control, most likely of a similar sort to the machine that you hired. I was particularly impressed where it says on the website "we use rotation and translation such that the holes are more cylindrical than the tool used."

How many holes did you have drilled in each part? For example if you had 30 parts and 10 holes per part that would be 300 holes.

Thanks,

Ant.

 

[btrueblood]

One hole per part.

"I was particularly impressed where it says on the website "we use rotation and translation such that the holes are more cylindrical than the tool used."

Um. Sounds clever...but then, a standard twist drill isn't very cylindrical, it forms a cylindrical hole by virtue of combined rotation and translation. :/

 

[msquared48]

Mining engineers have boring dreams.

Mike McCann
MMC Engineering