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Another tip – how to engrave metals without an engraver
If you have a vinyl cutter , you can do doctors plaques , stainless plates, alumminiun signs and a lot of other articles in metal with lettle or no expense.
You use a technique called chemical etching. Metals are eaten away by various mordants (acids or the like) and if you protect areas of a plate the mordant does not attack them , however most of us dont really want to work with acids as they release toxic fumes and are pretty hazardous materials , but there is a relatively mild product called ferric chloride (not really an acid , used to make printed circuit boards) that is cheap and wont burn you
(It is VERY messy and will stain your hands and clothes yellow or orange, it is not completely safe , is not really suitable for flushing down the drain etc – so be carefuyl , gloves overalls , eye protection open containers of ferric in your workshop will ataack all metals (like the bearing rails of you super duper 10kw overhead router:)
This is available from just about any chemical supply house in crystal or liquid form , get the liquid and ask for about 46 baume concentration – they will know exactly what you mean or should.The simple steps are this
Take a sheet of the metal you want to etch , give it a good rubdown and wash with something like a scotchbrite abraisive pad , design a graphic and weed OUT what you want etched inwards , make the graphic border a little smaller then the plate. Now apply the square with the lettering or graphics removed to the plate , making sure you apply it nice and square and then roll it or squeegee it down , pay LOTS of attention to where the edges of the graphics you have cut out meet the brass , IE you are going to dip this plate in something that attacks metal , the Vinyl is the resist – thus if for example you have a bubble or wrinkle where a letter is cut out , the mordant (etch) is going to seep under it.Then take some parcel tape or vinyl and coat the back of the plate and the exposed eges or ANY area you want to remain protected
Make sure you havent got “leak holes” or anything where the plate is taped up
The next step is to take a plastic or glass caserole type dish , bigger than the plate and fill it with enough ferric to cover the plate – if you can heat the ferric to about 40 degrees c – all the better , it works tons faster than room temp.
You put the plate in , face up (tho face down is better but more difficult to work with) and using a brush swish the ferric over the plate , using the brush to remove the byproducts of the etch , within seconds you will see the letters darken and if you leave the plate in long enough(about 15 mins with heated stuff and constant swishing brushing) and strip the vinyl tape etc off it , you will have a stunningly etched plate with crisp edges and contours an engraving machine couldn’t cut , let alone a etched surface finish that a machine cant do (which aids paint filling.)
Dont try this first on aluminium as it needs a weaker ferric mix , about 1/3rd strength otherwise it fizzes and bubbles and overheats , brass is ideal
Stainless requires a longer time to etch. If you dont heat the ferric , it can take a long time to etch any metal)
At worst , to try this can cost you a few pounds , and like us , you might end up building semi automated hot spray etching machines (for our own use , I will post instructionsto build a better more production type etcher if anyones interested)Obviously if you cant weed something , you cant etch it , thus the smallest finest detail is dictated to by your weed or cutting capability.
Etched plaques sell for very high prices and can be made very quickly , very cheaply.
There are various other nethods of doing this , some etchers screen an acid resistant ink onto the metal for large repetitve runs , we often laser engrave a polyester resist away , cos the laser can engrave VERY fine detal and then ettch for jobs where high detaill or even halftone photographs are needed.
You get various photsensitve resists you laminate onto playe and expose directly usining a possie etc.
Try it , you will be amazed -
26 Replies
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Rodney – Thanks for sharing this. This is something I always wanted to try, and with your help I can now have go. Right where’s me gas mask and gloves (hot) Booooooooooooooooooooommmmmm!!!
🙁
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Now that was interesting, have just spent over £800 on etching some stainless signs, I think the company was taking the mick a bit but time did not allow me to shop around.
I have a small bronze sign to do (120x120mm) but it has 3 logos on and the small lettering of the logos only come out less than 2mm high. Any bright ideas how to produce the masking for this one.
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Thanks a great deal for sharing this with us
I read this with great interestI am definitely going to give this a try just for the sheer fun of it 😀
As you say its not going to cost a lot to give it a go 😀Oh! Welcome to the boards 😀
good to have you with us
John
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The small graphics need to be done photographically , take the plate to the local PC board makers and ask them to laminate , expose and wash out the image – the image need to be sent to them in black and white – they use VERY high DPI plots – like 2400 or better and basically use the same type of technology as screening when you make screens.
The alternative is to find someone with a laser near you and use a polyester vinyl over the engraved areas (Laser guys don’t want to laser engrave ordinary vinyl – they dont mind cutting it , but vaporising large areas realease toxic vapors and chlorine into a laser and the chlorine combines with vapour to form hydrochloric acid which in the long term attacks laser parts) and send them the image to laser.
Settings for a 25-30 watt laser (most common power) are about 100% power and 50% speed.
the only hassle with this is the slight glue residue the laser leaves behind , but a few seconds in a fine grit blaster clears this.If you want your business to soar – buy a laser , especially if there is no one in your area with one curently , there is a huge amount you can do with them to offer your customer what was previously impossible.
I can write a short sort of “what a sign guy can do with a laser ” type thing if any one is interested.
Lasers are VERY pricey , but IMHO a licence to print money. The new Generatation lasers are marvellous , the new Gcc Laserpro Explorer is a wonderful machine with a bed size of 1m x 500mm (1m x unlimited with pass thru) and tru production engraving speed. -
quote Rodney Gold:Stainless requires a longer time to etch. If you dont heat the ferric , it can take a long time to etch any metal)
At worst , to try this can cost you a few pounds , and like us , you might end up building semi automated hot spray etching machines (for our own use , I will post instructionsto build a better more production type etcher if anyones interested)OK Rodney…We certainly want to know how to build a semi automated machine…please tell us..
kindest regards
Fizgig ( Peter ) -
Hmmmmmmm!
I remember thisCould be interesting this production type etcher
Is it complex Rodney? -
This post should be a demo.
-Marek -
Completely agree Marek
That’s if Rodney’s up to doing one
It sure would be great -
I agree with Marek & Little John, it would be a different string to our bow if you know what i mean.
It is an ideal subject for a demo Rodney.Long John
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I was thinking that earlier.. Rodney, can you get some photos and maybe do a demo for us, would be rather interesting and this then could be moved to Demos section
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I will do some diagrams and dig up the CDR drawings of what we did to make ours
Its fairly complicated
I will try to give exact plans I think I have photos of our very first prototype somewhere which will be more useful than those of the current machine where a lot of the workings are under splash guards etc and would require some dissasembly to show more detial , the prototype is all exposed.
You will have to give me a little time on this one , say tue or wed next week.
I reckon it would cost about 1000+ quid to build one of these. -
I just meant a demo on how to do the engraving. 😀
A demo on the machine would be to follow.
You already basically gave a demo of how to do it, but a couple of pictures and having it posted on the main page would be great so we could actually see what you are describing.
-Marek -
I’ll second that Rodney – would be cool if you could find time to write it up as a demo with a couple of pics maybe ?
I’d love to have a bash at doing my own engraving and filling on metals – seems one of the frustrating things about having a laser and not being able to do them.
I was thinking about making a decent sized shallow container for the etching – could you use acrylic or would the chemical attack it ?
Nigel
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Polycarb is the best nigel , acrylic will work , but its far cheaper to get something like a photo developing dish or a babys bath, pyrex oven dish or something like that. In general the etchant which is ferric chloride solution needs to be heated to 40 deg C and the hot ferric doesnt treat acrylic nicely , it promotes stress cracks where the acrylic has been machined and making an acyric tank to hold hot etchant waterproof is a misson. The mess and damage ferric all over a workshop floor and on machinery can cause is huge. Its not an acid but stains everything orange and leaves a rust like deposit on everything and attacks ALL metals barring titanium or gold and some others.
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Thanks Rodney, I’ll maybe knock one up from some titanium then :lol1:
Nigel
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i reckon i’ll try this just for the sake of it !!!
can i heat it using a a glass fish tank heater ? obviously ionly submeging the glass section of it ! common sense tells me this is ok as of course the dish i made of glas …. doh ! 😮
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quote Hugh Potter:can i heat it using a a glass fish tank heater ? obviously ionly submeging the glass section of it ! common sense tells me this is ok as of course the dish i made of glas …. doh ! 😮
Good idea… I was going to stick it in the microwave 😕
That would take a while to heat up though wouldn’t it with a low power heater…and do they go up to 40 degrees ?Nigel
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I used an etching fluid on aluminium years ago. It didn’t need heating, just agitating occasionally, but did take an hour or so to eat its way in enough. Does anyone know of a supplier of this chemical over here?
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try http://www.maplin.co.uk/Module.aspx?Mod … 7&doy=18m9
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tropical tank heaters (ones i use anywy) are available up to 300w, and would warm a gallon of the stuff in only a few min’s i’d reckon, i have a 300w in the tank here next to me, only comes on about once an hour, for around 2 or 3 mins, then goes off again, keeps it at 27degs all the time !
i’m sure it goes to around 35 degs, but allowing for the time the heather itself takes to cool down, i would imagine it’d continue to heat above that mark.
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We have a removal rate of .1mm per minute with the hot etchant spray , just about any chemical supply house can supply ferric chloride in crystal or liquid form.
Aluminium needs a diluted solution and should be initially etched in caustic soda (nasty stuff) to go thru anodising (you can use caustic for the full etch)
We initially did use multiple 300w aquarium heaters and had a large manifold tank , but it takes a long time to heat up and unless you use huge manifold tanks (reservoirs) the etchant cools quickly when its sprayed and doesnt reheat fast enough depending on the throughput. The solution is to use titanium industrial element type immersion heaters. If you use a dish system , place the dish with the etch into anouther dish filled with hot water – a bain marie type system.
The key to good etching is to heat the solution and to have it the correct Baume density (density of ferric to water). Cold solution can take 10-100x longer to etch. You need to etch to depth quickly as the resist that stops etching can get adversely affected over time in the ferric and come adrift – a quick hot etch stops this and whats called “undercutting”.
there are additives one can add , like citric acid that aid etching times and keep the etch with its original bite for much longer.
Fresh etch will bite a lot more , so ideally you need to add about 10% spent etch into it or add a small piece of brass and wait for it to disolve a little. One can use other stuff like nitric acid etc as an etch , obviously using acids is much more hazardous!!!
Cold etchant will tend to crystalize so with spray type machinery , one has to be careful of piping , orificies and the pumps
Either let the machine have a standbye mode where etchant is partially heated and cycle the pumps a few times a day or drain the etchant into the manifold and flush the system with water. The pumps required to get decent pressure over large areas and to pump the liquid which is quite viscouous are very expensive , we use 3 phase magnetically coupled acid pumps for ours and a small one costs around 500 quid. -
We are all waiting with baited breathe 😎
regards
Peter
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Just read with interest on etching with ferric chloride. I have been manufacturing printed circuits for 20 years now and decided to get into signs as another business for my sons to have an interest in.(big mistake after a couple of grand on machines and materials all they have made are stickers for there motorbikes with no sales).
Maplin are a good source for etching materials, however if you run a business you will require a waste discharge liscense as any chemicals discharged into drains will attract attention and a large fine.
We etched quite a few brass plates as nameplates but as cnc engraving machines became cheaper our profits were too small to justify competing.
Just hope the sign business doesnt go as the circuit board business has declined with the cheap imports from China. -
Hello Col
quote :quote col:Just read with interest on etching with ferric chloride. I have been manufacturing printed circuits for 20 years now and decided to get into signs as another business for my sons to have an interest in.(big mistake after a couple of grand on machines and materials all they have made are stickers for there motorbikes with no sales).
Maplin are a good source for etching materials, however if you run a business you will require a waste discharge liscense as any chemicals discharged into drains will attract attention and a large fine.quote :We etched quite a few brass plates as nameplates but as cnc engraving machines became cheaper our profits were too small to justify competing.What do you exactly mean with this ? Is it too expensive to etch a plate as against CNC it ? Where would you see the break even point on this one ?
quote :Just hope the sign business doesnt go as the circuit board business has declined with the cheap imports from China.This one is inevitable..Australia is in the process of signing up a free trade agreemant with China, as well as currently overhauling all the Industrial relations laws and system for the first time since 1904..The end result will be minimum wage negotiations between employee and employer, with basically all awards being dismantled..The system will be loosely based on the USA’s system …
China are the single largest consumer base on earth, they will overwhelm the rest of the planet with cheap production, mass production and consumerism. The affects are already being felt in Australia.
Competition with India gearing up as the next sleeping giant will see the developed countries turn into unemployed /slave wage wastelands, their will be simply no other way to compete with those two giants…
regards
Peter -
Sorry I havent done the write up etc in more detail , but I dont really have the time right now. In terms of large scale etching , most co’s wont flush down a drain and have hazmat and waste management proceedures in place.
The only time one would use CNC machining to take the place of etching is for very small production and the cost of a CnC machine is substantially more than a simple etching setup.
Etching is substantially faster than CNC work and can do stuff that cannot be done with a cnc machine. Removal rates are in the order of .1mm per minute with hot spray etchers and a huge plate can be etched in literally minutes , often 100x faster than a CnC machine.
It is possible to screen 100’s of plates very quickly for etching and of course an etch can give line widths that are simply not possible with a CnC setup without multiple tool changes. Of course sharp corners are possible with etching that are not possible with a tool that has a radius. Surface quality of the engraving of an etched plate is way better than machined plates. Some materials cannot be effectively mechanically engraved and can be etched a lot easier (hard steels , stainless , titanium etc) Double sided and full pierced etching can be done , no CnC machine can do that as effectively and apart from anything else , etched plates require no hold down and are not subject to the stresses or forces machining has.
Productivity and the cost of production is where business competes , it’s not as tho china didnt exist and businesses here didnt know about the vast labour pool in those populous countries , so losing out to cheaper production was not unforseen. If one can no longer compete , one either has to modify ones business or change direction. The biggest problem is ignoring this type of stuff and relying on protectionist mechanisms for survival , both will sink you. -
Looking forward to your in depth machine layout Rodney. We are now going thru the throws of basic etching as you have previously described.
The results are incredible and we are very happy with them..We would like to develop a semi automated or totally automated system..
Current price for a system out of UK is Australian $ 50,000 or approx. GBP 17,000.. Similar from the USA..
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