Mold Polishing - New Learnings

[@knowledgeabundant]

I have to applaud you for sharing this. I think your the only one showing how to clean an aluminum mold cut from a cnc. I'm working on a project myself and needed some guidance. Thank You, I look forward to looking at your other videos and keep these coming. I'm hoping you have a way to reduce the scallops from the center as well, maybe I'll run another finishing cut.

[@JohnSL]

Some time ago, I asked a person I know who makes injection molds for model trains how he polished the molds. His answer is that he doesn't. Instead, he lets the machine "do it" by running smaller end mills with small step overs. When I've done this it really helps with the surface finish. I don't remember whey I didn't do that in this case.

[@jonmct3507]

Thanks for the continued documentation of your discovery process!

[@JohnSL]

My pleasure!

[@nareshsharma9509]

Where I receive this polish and tool for polish mold

[@PatrickSmith-kd3fs]

John,a lot of blokes on hear might mean well but there is a correct procedure to follow. Unless you want anSPI 1 2 or 3 finish then you can do it with a stick and wet and dry.Start of with P320 paper under your stick ,rub in one direction until most of your tool marks are out.Clean the grit of the mould .Select P600paper and rub at 90 degrees until 320 scratches are out. Clean mould .Select P800 rub with stick lightly t get 600 marks out. It's all about putting in a controlled scratch in(320) and then working through the grades to remove those scratch s.All depends what finish your customer wants. An SPI 1 finish (mirror finish) as used on optical moulds requires finishing with a diamond paste but thats another story. You got there in the end, you an get good advice on the net. Polishing is very rewarding job,I'm retired now ,but do a bit of sub/contracting. All the best Paddy

[@GoodCicero]

I love your videos! Thank you.

[@anderskarlsson9881]

I have polished a few aluminium molds recently. I found that the step that is most important is to be sure that ALL toolmarks are removed. I start with 120 grit emery cloth (80 if needed). When i'm really sure that all toolmarks are gone, i go up in steps: 180, 240, 320, 400, 600, 800, 1000, 1200, 1500 and 2500. I keep it wet with WD-40. Then i switch to diamond paste, and use 45, 15, 6 and 1. All is done by hand. This will give you a mirror finish. Going through all these steps actually makes the work go faster. Trying to get a surface with a to fine grit takes way longer than using many grits in steps.

[@deanneumann8594]

John, I don't do any molds but I do frequently machine parts from aluminum that I subsequently polish to high finish. I always media blast the tool marks off first to achieve a uniform (but matte) finish, then pollish the uniform finish to a mirror finish. 100% aluminum oxide is too abrasive though... it will abrade the material away, changing your mold's dimensions. There are all kinds of alternative media, from walnut shells to blends. I'm sure one of those alternatives will remove tool marks without changing part dimensions. A blend of 80% glass beads with 20% Aluminum oxide is quite good at creating a uniform surface finish in aluminum without changing surface geometry. You may even find that the polishing step isn't necessary if you follow the media blasting with a liberal coating of mold release spray... In that case the whole thing is a 30 second process :)

[@ppassal]

Hey man i like how your giving it a go, im a professional mold polisher (at least i like to think so but apparently my paycheck doesn’t think so) but just like to say nice job, and just watch your edges with sand paper or stones/ what ever tools your using. Also for a “diamond polish” go up to the 800 grit paper and instead of going at it 90deg crossing use like 35 ish deg chris crossing and dont work in one are to long you will notice a “hole” starting. Then use the pllishing compound you had at the beginning but if you can get 5 micron and use the felt wheel. And finish it off with the mothers polish and a wool or cotton buffing pad. Sorry for the long post cool video

[@JohnSL]

Thanks for the detailed reply. I always appreciate this type of information.

[@tedhicks6416]

I’ve been benching and polishing molds for over 30 years and you are absolutely right. You must remove all tooling marks with a stone and sandpaper first then polish. Bristle brush and then buff.

[@victorfernandez4475]

​@tedhicks6416 hi. Can i pick your brain about polishing a really small mold. Our concern is breaking aluminum off and i dont know what to use to get into the crevices.

[@rayblankenship432]

I use 400 and 800 grit sandpaper and follow it up with a brown scotchbright pad for some of my aluminum parts. That process works pretty good to get out the tooling marks. Thanks for sharing Brother!!!

[@JohnSL]

Thank you. I'll have to try scotchbright pads.

[@ramontria8628]

You did a good job, I'm also a plastic injection moldmaker, I worked 17 years in Saudi Arabia. I did different mold steels like 1.2080, 1.2016 which were also called stainless steel due high chrome contents. Some aluminium ones for blow moulding and thermoforming molds. For cosmetics molds, they required glass finished. For that kind of work that you did, you to make a small wooden stick formed like a chisel. A 30 or 45 degrees angle will do or what is comfortable to you. You put the sandpaper 400 grit under the wooden stick. Move forward and backward and put WD40 or any light oil will do. Then 800 to 1000 grit to finish, another 1200 grit would be better. Thanks bro.,,. good luck to your KZbin channel.

[@tinkertom3683]

A quick tip, you need to thoroughly clean the parts with solvents before using another grit 😊

[@billb295]

I’m machining some molds that will be used for cold cast urethane. Very complex organic surface models with deep pockets. Why couldn’t you chuck up these felt bits in the mill and create tool path that does the polish work for you. That’s what thinking about trying. I used to polish toy sculpting wax (sculptures) like this when I used to work in the toy industry as sculptor and model maker. I could get the surface to a high buff polish like it was done by hand all on the mill. High polish was always a requirement for a final toy sculpt Seams doable in 6061? Any comments would be great. The video was helpful for sure. Do they make mold cavity polishing end mills?

[@DUCKS2525]

Hey that’s an awesome video! You definitely have to get the tooling marks out before polishing. I apologize for not being more specific. Working up from 400, 800, 1000, 2000 them mothers will get a mirror finish! A cotton cloth gets rid of all the polish better than paper towels. Thanks again for the video and experimenting different alternative! Love it!

[@JohnSL]

Thanks for the original suggestion. I'm glad I tried Mothers directly, as it was a good learning experience. I can see how cotton cloth would be better, and definitely something I'll use if I need a mirror finish in the future.

[@capnthepeafarmer]

You don't need to start as low as 400 grit. With a low cusp height from ball end mill you are really already at a 600-800 grit surface roughness equivalent.

[@coulterjb22]

i love the progression, it helps us viewers a lot.

[@dicelabiblia7461]

I can not stop your videos, I REALLY enjoy them. Thank you!

[@JohnSL]

He he, that's part of my plan. Glad you enjoy them.

[@tedhicks6416]

Tip, start off with a Boride t4 aluminum stone at 600 grit with mineral spirits to remove tooling marks and keep all your details crisp. Cross out stone marks with 600 wet sand paper and the buff with compound.

[@waynespyker5731]

The dry stones will obtain a flat surface quickly. High speed rotary tools can produce ripples. Just use a progression of grits crossing direction 90 degree to the next, ending with the last in the direction of draw. Avoid finger backed steps, could produce ripples or gouges. Shape a common wood dowel on the belt sander to a chisel shape, wide for large areas or narrow for small areas or corners, to back your paper. Please note a cold mold can change the color and gloss of the part. Thanks for sharing your experiment, I will be watching for the first shots.

[@JohnSL]

Yes, I did see ripples when I used the rotary tool. I do have some Gesswein stones on order, but it will be a week or two before they arrive. Can you provide more information about cold molds changing the color? I have a mold heater, but haven't hooked it up yet, so I'm curious to learn more. Finally, at the end I show some molded parts I made with a mold that was just sanded on one side.

[@waynespyker5731]

@@JohnSL Test the softer ones first, again dress the corner away on your disc sander to form the chisel flat working surface. Run your mold temperature to the material supplier's recommendations as well as all parameters. We run automotive cabin parts 24/5 and check the color and gloss each shift. Many are textured, a colder mold produces more parts but can reduce the texture quality. Mold temperature settings are the first request from our colorant supplier troublshooter. The color shift is minimal but may be noticable if the parts are mated in assembled. Side note: I am somewhat color blind in the aqua hues. One morning the quality inspector stated when I placed a black seat back adjusting knob on the gloss meter, "Boy, where did all that green come from?" I couldn't see the difference. It was a supplier compounding issue, they replaced the colorant.

[@OldIronShops]

Hi John we met at the bash I'll be looking at your catalog of videos should get the creative juices flowing.

[@billb295]

Are the swabs your using sand paper surface, felt or just sponge they look really helpful.

[@almostanengineer]

That want to try different things, even when you’ve found a solution is the Engineer in you 🙂

[@JohnSL]

Guilty :-).

[@RobertWelchman]

can you do any of this in the mill? Seems like you ought to be able to chuck up the dremel style polishing pads, add some paste, then just run a path on the floor? Keep the grit out of your machine by using very little and even add some containment if necessary...?

[@JohnSL]

Possibly. However, with sand paper, it doesn't take that long. And I enjoy the process.

[@tilakkk3091]

Aluminium used should be 6000 series of higher for better finish. What we do O investment casting tooling is. First removing the tooling marks with sand paper starting as low as 200 and going fine to 1200. Later steel wool for finishing with or without mold polishing paste.

[@tymz-r-achangin]

The air pencil "tended to fling the paste all over the place" Then don't apply so much at a time. Use less of the polishing compound and let it 'absorb' or worked into the polisher. A little goes a long ways especially when doing soft metals like aluminum It's kind of like using a buffer wheel... you dont want to load too much of the polishing compound in the buffer wheel or it will be wasted by getting flung in your face and all over the back wall

[@JohnSL]

Thanks. Wish I'd known that ahead of time :-).

[@kamaruddinboto8908]

Thk for information polish mould,

[@dennisf.macintyre117]

Instead of something as course as fine sandpaper, are you familiar with emery paper? or a paper car body/people use with water? also crocus cloth. I remember my father using jeweler's rouge in stick form on a 5 or 6 inch diameter cloth wheel on a mandrel. I used to scrape the jeweler's rouge into a mixture of silvo and brasso to polish my brass when in the army. The rouge would keep the brash from tarnishing longer. For a courser medium to polish with, what about valve grinding compound from an auto parts store? All my best! / dennis

[@justinchurch8440]

You need to purchase a Nakanishi ultrasonic (sheenus neo) from ARTCO. This will improve your process greatly. I’m a professional mold polisher

[@michaelmayo3127]

A tool maker would use different grades of diamond-past and a piece of balsa wood 5x5 m/m to apply the past with.

[@JohnSL]

Thanks. It's good to know what others do.

[@scienceandtechnologyst8134]

I don't want mirror finish I want rough surface in my mold how could I achive that surface ? Help help

[@JohnSL]

My understanding is that you can use sand blasting to achieve that type of finish. I haven't tried it yet, but it's on my backlog.

[@Aruljabez]

Place show polishing process of pipette mould

[@GlassGuy89]

You should revisit this and use rubber polishing wheels from the dental industry

[@armarmo964]

Ultrasonic polishing systems work well but expensive

[@JohnSL]

That does sound nice--and expensive.

[@mahmutcetin2928]

Thank you good

[@johnmarkel8160]

Try simichrome polish with toilet paper

[@TurnRacing]

Awesome

[@JohnSL]

Thanks Zach.

[@ryansagisi492]

What about media blasting w/ aluminum oxide or glass bead?

[@JohnSL]

I believe that would produce a matte finish rather than a smooth finish. It's something I want to try at some point.

[@ryansagisi492]

You can work your way down in grits. If you want to try send me a mold and I can blast for you. No charge, just cover shipping.

[@David_11111]

yay

[@VincentFogarty]

Air tools are to fast you should invest in NSK

[@Zebra66]

The polishing shouldn't start until you've ground or filed off the tooling marks. You'd be better off starting with 40 or 60 grit sand paper and working up.

[@compassprecision]

Boy, that air pencil is noisy! Good video.

[@JohnSL]

Thanks. It certainly is noisy!

[@gregkennedy5554]

I would 400 stone first to remove tooling

[@johnhatcher2449]

Try 0000 steal wool

[@bitsurfer0101]

Be careful using wheel polishes. Some of them contain ammonia which will corrode aluminum.

[@JohnSL]

Thanks. I always clean the mold with mineral spirits after the polish to try to remove all the residue from polishing.

[@annakrupnik9239]

Hello guys, incidentally I have seen this video created by John. We are a producer of diamond pastes that allow to receive absolutely amazing results considering speed of polishing and quality of polishing. We are located in Houston, TX, and produce our compounds in house. If anybody of you is interested I will be happy to send some free samples.

[@yxxvbnm6143]

I'd like to try them out. What is contract info. Thanks

[@rnedevelopmentsSA]

Use fine scotch-brite with lube instead of sand paper then with mothers polish. You will thank me later.

[@JohnSL]

Thanks. I'll try that next time.

[@stevebulmann8366]

If you are using a rotary tool you are doing this wrong. We are not polishing cars or paint. You can not hide anything you will see it in the molding process.

[@JohnSL]

The parts turned out well...

[@bradjunes1610]

This video show why mold making is so expensive.--- I use stainless dies and electropolish to micro finishes. Much easier.