PDA

View Full Version : drilling real small holes



plunger
10-16-2013, 05:38 PM
It was while I was testing the spray patterns on my tractors injectors that I realized how small the holes are in the injector nozzles. I can not see these holes with my 50 year old eyes and can only see them with an optivisor.
It led me to think of two questions.
How do they drill such a small hole
With this hole being so small I am surprised injectors aren't getting blocked all the time.
I have just bought a new t6 ford ranger and was reading about a guy who filled up at a petrol station called budget diesel. He put in 15 liters and the pick up died. Fords road side assistance towed it to the workshop to find all five of his injectors need replacing at a cost of $4800.
They say the diesel was contaminated and he will not be covered by warrantee. His insurance is also refusing to pay out and he has no recourse against the garage where he bought the diesel as he cannot prove he bought the diesel there.
I will never buy diesel at these dodgy independent no name unbranded garages after hearing this story. The ford dealers drained the tank and you can see the diesel is contaminated by what looks like rusty water.

daGrouch
10-16-2013, 07:21 PM
I think EDM is used to make the holes. What was the 2nd question?

I would be asking Ford why a set of injectors cost as much as a crate motor.

boslab
10-16-2013, 08:14 PM
Ive drilled 19 thou holes thrugh 1/4 steel bar, they were for the pins of a tiny comb to be injection moulded, beleive it or not they were for womens eyelash combs!, i thought it was mad too but they do use them. The pins were inserted into the holes in the bar, then loaded into a mould cavity with the bar sticking out, the moulder closed and injected polyprop around the pins to form a handle, the whole lot was then manually unloaded.
They used to make millions of nit or louse combs by the same method, boring work to say the least.
The drill used was a high speed horizontal twin spindle cnc, originally made for drilling holes in injectors and spray nozzles, the bits were held in collets and were solid tungsten carbide, what was amazing was the speed the drills were shoved through steel, it was about 100 holes a min.
Great if the drill was good but on cheap bits the holes would run out all over the place, the best ones were titan or skf.
Mark

TGriffin
10-16-2013, 08:48 PM
I've milled pockets with .005" end mills and I'm pretty sure they make drills in the .002-.003" range. All it takes is a really small tool (drill) and a whole lot of rpm.

Tom

vpt
10-16-2013, 08:59 PM
The holes in diesel injector tips are so very tiny. I would say down in that .002-.001 or even less range.

The smallest I ever went with power was around the .010"ish area.

http://img855.imageshack.us/img855/545/dieseljets016.jpg

http://img683.imageshack.us/img683/1264/dieseljets019.jpg

http://img508.imageshack.us/img508/6807/dieseljets021.jpg

CCWKen
10-16-2013, 09:17 PM
Didn't the truck have a fuel filter? That's what they're for.

Dealers don't "fix" anything any more. They remove it and replace it with a new part. I've cleaned electronic injectors before by just reverse flowing. I use a 5v power supply to open them and pump solvent through them. Diesel injectors have to be disassembled since they won't back-flow. Some can't be disassembled.

At $4800, I think the owner is being taken for a ride.

J. R. Williams
10-16-2013, 10:04 PM
Almost 60 years ago I worked at a crude oil pump station powered by large diesel engines. One job was to use a small drill and clean the injector nozzles. It had six holes in the tip that were cleared with a 0.020 inch dia drill. The nozzle was set to open at 3750 psig. The fuel being used was light crude oil.

Jaakko Fagerlund
10-16-2013, 10:09 PM
The small holes can be done with either drilling or if the size, shape or material doesn't allow drilling, then with small hole EDM or in some cases with ECM which will leave a polished hole.

BigBoy1
10-17-2013, 05:31 AM
Many years ago I had an Oldsmobile diesel station wagon and the injectors needed to be replaced. I was at the parts store and sales-counter person had pulled up the information on the injectors I needed on his computer screen. He didn't realize that his screen was angle so I could read what was on the screen. One screen was very interesting and I'll try to reproduce it below. It was a break-down of the injector's costs.

Mfg. Cost.........Wholesale Price........ Dealer Price..........Retail Price
.....$30...................$60.................... ....$120..................$240

What I thought was interesting as the price doubled with each step. Who says there is a profit to be made with parts!

J Tiers
10-17-2013, 08:49 AM
Many years ago I had an Oldsmobile diesel station wagon and the injectors needed to be replaced. I was at the parts store and sales-counter person had pulled up the information on the injectors I needed on his computer screen. He didn't realize that his screen was angle so I could read what was on the screen. One screen was very interesting and I'll try to reproduce it below. It was a break-down of the injector's costs.

Mfg. Cost.........Wholesale Price........ Dealer Price..........Retail Price
.....$30...................$60.................... ....$120..................$240

What I thought was interesting as the price doubled with each step. Who says there is a profit to be made with parts!

And now you know the REAL reason shops will NOT use any parts that you supply...... Of course they CLAIM it is because they "must be sure it is the right part".

The real reason is that they want that $120 dollar per unit price boost to go to them, since they generally get a discount closer to the dealer price.

vpt
10-17-2013, 08:53 AM
Didn't the truck have a fuel filter? That's what they're for.

Dealers don't "fix" anything any more. They remove it and replace it with a new part. I've cleaned electronic injectors before by just reverse flowing. I use a 5v power supply to open them and pump solvent through them. Diesel injectors have to be disassembled since they won't back-flow. Some can't be disassembled.

At $4800, I think the owner is being taken for a ride.



I was lucky to receive the manual for 99-03 ford diesel injectors for tear down and rebuild. It is like a 60 page book by itself. I am waiting to get a spare injector to tear into some day and see if it is even possible for me to tear it down and rebuild it properly before I even think of attempting the ones in my truck. They are electronically triggered and oil driven injectors. Lots of little parts in them and they all have to be perfect.

Here is a parts explosion.

http://www.mylexinternational.com/images/partsdiagram.gif

ikdor
10-17-2013, 09:03 AM
The small holes can also be machined with a laser, much more accurate than the mechanical drills.
See for instance here:
http://www.oxfordlasers.com/laser-micromachining/applications/fuel-injector-production/

Ever shorter pulses allow for neater hole finishes:
http://info.raydiance.com/Portals/196988/images/holes_evolve1.gif

And according to the manufacturer they can drill an injector hole with a femtosecond laser in 1 second.

Igor

bborr01
10-17-2013, 09:34 AM
The plant that I retired from used to make injectors for large diesel engines. Back in the day they hand drilled the holes with sensitive drill presses. Probably in about the late 60's they started to burn them with tungsten wire in a purpose built EDM.

The EDM's were fairly well automated and saved a lot of tedious labor. I would think they likely use lasers now for speed.

Brian