Etching serial numbers on steel

pmrobert

I'm looking for information regarding etching serial numbers on steel, specifically fuel injectors. Volume is low, averaging 15-30 per day. This is relevant, in a bit of a stretch, in that the testing device uses a Prop to accurately generate various width pulses at various periods for various lengths of time. Fuel injectors are cylindrical (10-25mm diameter) so this makes things a little difficult re marking them.

Thanks!

Publison

I have used item like these with good results when a hard stamp would not work.:

http://www.seton.com/hand-held-engraver-cs60.html?fr=1

NWCCTV

Have you ever used chemical etching? We use to mark certain aircraft parts that way. You can probably find a used kit on EBay.

kwinn

Electro-etching is another option to consider. You might even be able to DIY your own etcher. I saw one at a customer site that was made from from an old dot matrix printer. The etching electrode was mounted on the print carriage and the paper roller was replaced with a mechanism to hold and turn the part to be etched.

Too_Many_Tools

How many digits in the serial number?

Laser engraving is likely what you want.

While one can pick a laser engraver on the surplus market, I would think the cheaper route is to outsource it.

pmrobert wrote: »

I'm looking for information regarding etching serial numbers on steel, specifically fuel injectors. Volume is low, averaging 15-30 per day. This is relevant, in a bit of a stretch, in that the testing device uses a Prop to accurately generate various width pulses at various periods for various lengths of time. Fuel injectors are cylindrical (10-25mm diameter) so this makes things a little difficult re marking them.

Thanks!

Paul K.

Instead of etching try punching. Make a simple fixture & stamp it on the height of the cylinder. Ideally laser engraving is what your looking for. The parts we make for the automotive industry usually get etched via laser second hand with a part number.

Too_Many_Tools

Punching may deform the injector.

Paul K. wrote: »

Instead of etching try punching. Make a simple fixture & stamp it on the height of the cylinder. Ideally laser engraving is what your looking for. The parts we make for the automotive industry usually get etched via laser second hand with a part number.

W9GFO

A regular CO₂ laser can mark steel pretty well. If you want the marking to really stand out you can use the laser with a material called Cermark, it makes a shiny black marking that is bonded to the metal.

CuriousOne

If you need to write on cylindrical surface, you need an engraver optimized for such tasks, such as Roland EGX-360, which retails from $18000. So I suggest to outsource the task, if you need professional look, or simply use glas ruling pen, filled with acid.

LoopyByteloose

I think that if you are using a chemical etching process, the main issue is what do you use as your acid resist and how do you apply it to the surface.

You could simply apply a cost of oil-based paint, and then scratch your number into it by hand or more elegantly by machine. And then brush it with acid to get your etch.

There are a lot of things that are known to resist acid and many are a very thin coat. You can see this with iron-on laser printer ink and markers used to create an acid resist for etching printed circuit boards. So you don't have to be chemist orvuse rocket-science to find some sort of paint that can be applied, let dry, and then removed... all sorts of material will do fine.

You may want to use a shellac. It dries quickly and is removed easily with alcohol. It can be tinted with a color to be more obvious contrast.

Or you can just use bitumen tar dilluted with mineral spirts. It is soft, but it you are working quickly and carefully it will work. Fine artist use this with etching copper plates for printing.

If you are willing accept writing serial numbers by hand, you could also have the craftman that fabricated the piece personally sign his or her initials.

For etching steel. I suppose muratic acid or nitric acid are your choices. Nitric acid cuts fast and deep and takes more effort to control. There are other acids, but they are either more costly or much slower or are very toxic.

pmrobert

Thank you ALL for some excellent input. Plan A is to use a Dremel engraver for now with a search for a place to outsource the parts for professional laser or chemical etching to follow. The numbers are only 4 digits and can be very small as they will only be needed to verify it's my work in the case of returns. Once in a while I get a return of a device I KNOW I didn't previously work on but can't prove it. A simple mark denoting it came through my shop would work but I generate a detailed report on each injector and am going to serialize them so I can correlate my stored data directly with each particular injector.

Genetix

What about Ink Stamping?

Mark_T

Before considering any kind of acid process check if the steel in question is subject to hydrogen embrittlement (most aren't
but a few specialised ones are).

LoopyByteloose

pmrobert wrote: »

Thank you ALL for some excellent input. Plan A is to use a Dremel engraver for now with a search for a place to outsource the parts for professional laser or chemical etching to follow. The numbers are only 4 digits and can be very small as they will only be needed to verify it's my work in the case of returns. Once in a while I get a return of a device I KNOW I didn't previously work on but can't prove it. A simple mark denoting it came through my shop would work but I generate a detailed report on each injector and am going to serialize them so I can correlate my stored data directly with each particular injector.

Having a Trademark followed by the letters TM doesn't require government approval (the 'circle r" represets a Registered Trademark) and can be useful to both identify fakes and to eventually establish a registered trademark. Serial numbers can be faked as well. A personal initial set as proof of origin is a nice touch.

It wouldn't hurt to actually etch a barcode as anyone that desires to fake something will have to sort out what you are doing with the barcode.. it just makes it a bit harder to bother with. Methinks that 4 digits isn't really enough for protection as proof of orign... Code in the Month, the Year, and the Location (maybe a zip code?) and encrypt the obvious info to no longer be an obvious serial number. but provide the obvious serial number to confirm that the encrypted data conforms.

pmrobert

Thanks again to all of you. Ink stamping probably is a nonstarter due to the fact that the injectors are usually mounted in a rubber collar of sorts (under that collar, which seals the injector pocket and absorbs vibration, is where the stamping needs to be placed) and live in a hot environment that usually contains airborne hydrocarbons aka solvents. I don't think ink would survive the hostile, abrasive environment for very long. H2 embrittlement - excellent point, thank you! The injectors are usually made of regular old steel with high Ni stainless alloys used for the flexfuel/ethanol applications. I think I'll avoid acids for that reason as H2 embrittlement is uncharted territory and some of these injectors are parts of very expensive vehicles. Mechanical engraving raises the specter of creating multiple stress risers in the metal. I've only seen mechanical failures very rarely, it's almost always electrical or the nonreplaceable body seal leaks. I'm thinking a light glass beading of the engraved area will mostly make the stress riser potential go away. I'm already using a CCD microscope to read the part number and check the pintle, etc., for physical damage and it's only a keystroke away to capture the image of the part number and engraved ID and add it to the database for that particular injector. As it's hand engraved, it would be quite difficult to exactly replicate the engraving. Sorry for the rambling, this is just a stream of ideas I'm throwing out here.

NWCCTV

I think the Chemical etching may be your best option. The parts we used it on were to be located inside aircraft fuel tanks, etc. and worked very well for that purpose.