Also on the drawing will be indication of who produced it ask them.

This is a case of my customer has to ask their customer who has to ask their customer. The question has been asked, but it is a long chain and I am in the middle of quoting a bunch of jobs.

Garyceng,

50.8 micrometer converts to 0.002", but that's got to be the thickest Type I anybody has ever seen. Type I is more like 0.0002" or 0.0005" or such. Hard coat will go to 2 mils, but not Type I. Sounds like you've got somebody that converted a spec without understanding it.

The other week I was working with a drawing that somebody had converted from metric to American and there was a sheet metal bend with seven decimal places!

I think you may be right about someone mis-understanding the spec. The draftsman who drew the parts also called out bar stock that is actually under-size to the print dimension on several of the drawings in the package that I am working on. I think what happens is that they are working with a combination of English and Metric and don't take the conversions out to enough decimal places or round them off to fit into a standard on the tolerance block. It is just laziness and very frustrating but I must deal with it because it could represent enough work for my business for the next 2 years.

Can you point me to a conversion chart or equation so I can discuss this intelligently with my customer?

I think the draftsman may have misapplied the spec and communicating with your customer may be enhanced when using the commonly regarded specs of the application with explanation.

Exactly! I normally try to find information myself before asking for help. My search for info on this hwever led me mostly in circles. I asked my customer's purchasing manager for the info and he couldn't find it either. On Tues. I can ask my plater. In the meantime I posted the question on CR4 to see if anyone is familar with the spec., and can offer some info.

Roger that, asking for a review of the spec may be your route for as TVP45 indicated and I agree the thickness is way out of line.

Thanks Guys,

My experience with anodizing is that if you build up more than .0007 then the process starts to reverse and eat away at the material. If any of you have the conversion ratio between thousandths and micrometers, I would find it useful.

Hello garyceng:

http://en.wikipedia.org/wiki/Anodising The bold type below is taken from this site:

I understand the spec' given to you was wrong. But a quick read through these bits may help and, if not the chart you asked for is on one of my last posts. They are spec's' so are correct

In typical commercial aluminium anodization processes, the aluminium oxide is grown down into the surface and out from the surface by equal amounts. So anodizing will increase the part dimensions on each surface by half of the oxide thickness. For example a coating that is (2 μm) thick, will increase the part dimensions by (1 μm) per surface. If the part is anodized on all sides, then all linear dimensions will increase by the oxide thickness. Anodized aluminium surfaces are harder than aluminium but have low to moderate wear resistance, although this can be improved with thickness and sealing.

I worked out my chart from this site: http://www.convertit.com/Go/ConvertIt/Measurement/Converter.ASP

It goes from 00001 to 0004, converting these 'inches' into Microns. It is correct as it is a specification. The convertion factor is: 0.00001 inch = 0.254 micron.

So you need about 4 times this to reach 1 Micron ! Or with your method: 00004"

I will paste some stuff on plating below which you may find udeful. It mentions build-up tolerances. The site I got it from:

http://www.mail-archive.com/sundial@uni-koeln.de/msg11819.html

I am not sure if it will work but, there is a button a few lines down that you can click to email the writer. 'tloc54452'.

If you go to the site it should work fine. This is a site about sundials and there makers. But some people are using Aluminium and anodizing it, which is why you may find it useful.

sundial

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tried hard anodizing?

tloc54452
Wed, 17 May 2006 06:54:59 -0700

Has anyone tried hard anodizing? I used to use tefloned hard anodizing on 6061 for mechanical parts subject to sliding. It has a duller, grayer finish. I wonder how it does in the weather. I have regular anodizing, water sealed, on my 12" (30 cm) bowstring equatorial. Fine weather resistance, but... The equatorial surface is really a concave cylindrical mirror, so it's pretty darn bright to the eye from some norrmal viewing positions. Hard anodizing might be the cure. Anyone tried it? For those unfamiliar with hard anodizing, but curious, googling found: http://www.techplate.com/hard_anodize.htm Thanks, John B --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial

• tried hard anodizing? tloc54452
• Re: tried hard anodizing? JOHN DAVIS
• AW: tried hard anodizing? hannes
• Re: AW: tried hard anodizing? JOHN DAVIS
• Re: tried hard anodizing? Larry McDavid
• Re: tried hard anodizing? tloc54452
• RE: tried hard anodizing? Fritz Stumpges
• Re: tried hard anodizing? tony moss
• Re: tried hard anodizing? tloc54452
• Re: tried hard anodizing? Larry McDavid
• AW: tried hard anodizing? hannes

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Larry McDavid
Thu, 18 May 2006 10:31:33 -0700

tony moss wrote:

I must admit that this is the first time I have encountered the term 'hard' anodising and the webpage referred to gave only general information of the process...

Tony, both "anodize" and "hard anodize" coatings are routinely used here; they are quite different!

Almost everyone here refers to a US Military Specification, MIL-A-8625E, which encompasses a range of anodize processes. The MIL spec is routinely referenced even in commercial uses; it is so commonly specified that every plater certifies to it.

There are two anodize coatings used. The very common "anodize" is identified in the spec as "Chromic Anodize" and is specified as MIL-A-8625E Type I; Class 1 is non-dyed and Class 2 is dyed with a specified color. It is "intended to improve surface corrosion protection under severe conditions or as a base for paint systems." The build-up is specified as 0.00002 to 0.0003 inch (the high end of this range is uncommon). In other words, there is essentially no build-up on the surface. Open pores in the Al2O3 coating are usually "sealed."

But, the "hard anodize" coating is quite different. It is specified as MIL-A-8625E Type III, or sometimes just "Type III Anodize." Class 1 is non-dyed and Class 2 is dyed with a specified color. "Color will vary from light tan to black depending on alloy and thickness. Can be dyed in darker colors depending on thickness.

Coating PENETRATES base metal as much as it build up on the surface. The term THICKNESS includes both the buildup and the penetration. Provides very hard ceramic type coating. Abrasion resistance will vary with alloy and thickness of coating. Do not seal coating where main function is to obtain maximum abrasion or wear resistance. When used for exterior applications requiring corrosion resistance but permitting reduced abrasion resistance, the coating shall be sealed (boiling deionized water or hot 5% sodium dichromate solution)."

"The Type III process can be controlled to very close thickness tolerances. Hard coatings vary in thickness from 0.0005 to 0.0045 inch. Yes, that's 4 mils (this means 2 mil penetration and 2 mil buildup). Thus, "hard anodize" or Type III Anodize is much thicker than regular or Type I anodize."

I'm quoting from a plater's quick reference wall chart.If you want to saw cut a piece of aluminum that is hard anodized, expect to dull a saw blade in the process! It's tough stuff! It is fairly common to Teflon impregnate the hard anodize coating. This provides lubricity and some additional weathering resistance. It also makes wiping off bird droppings easier. The red fire retardant material dropped from airplanes does not wipe off so easily. Yes, I have personal experience with each from my desert astronomy site. I have used the Teflon-impregnated hard anodize coating for infrequently-moved sliding surfaces. It is sometimes used for light bearing applications. It really is nothing like the common anodize. I'm quite sure this hard anodize coating is available to you; you just have to find out how it is specified in England--it may have a different name. Most aluminum alloys when hard anodized look light gray with perhaps a bit of tan color. It can be (and often is) dyed black. Other colors don't look great on hard anodize.

stay safe

babybear

Ya need a calculator? Here ya go.

http://www.martindalecenter.com/

Have fun.

1 micrometer is equivelant to .001 millimeter...so 50.8 micrometers = .0508 millimeter.

Hope this helps.

Roger

Hello garyceng:

1 µ (micron) or micrometre is 1 millionth of an inch.

So there is 25.4µ (microns) to 1/1000" 25,400µ (microns) to an inch.

Your ref' of 50.8µ (microns) equates to 2/1000"...........Or '2 thou'. From that you can do the Maths on no offence!

I have pasted a chart below which equates things like sand, cement dust etc to its size in Microns and Inches. Not very useful but, just remember 25,400 microns to an inch........ 25.4µ = 1/1000"

Please note: I have seen many other supposed conversions in looking for this chart and almost all are wrong. I know this is correct, OK? I am not showing off, and no affence to anyone. Good luck.

Stay safe

babybear

The chart is as follows:

Mesh-Micron-Inch Conversion Chart

Mesh Sizes and Microns

What does mesh size mean? Figuring out mesh sizes is simple. All you do is count the number of openings in one inch of screen (in the United States, anyway.) The number of openings is the mesh size. So a 4 mesh screen means there are four little squares across one linear inch of screen. A 100 mesh screen has 100 openings, and so on. Note, therefore that as the number describing the mesh size increases, the size of the particles decreases. Higher numbers = finer powder. Mesh size is not a precise measurement of particle size. Screens can be made with different thicknesses of wire. The thicker the wires, the smaller the particle passing through that screen, and vice versa.

What do the minus ( - ) and plus ( + ) plus signs mean when describing mesh sizes? Here's a simple example of how they work. –200 mesh aluminum would mean that all particles will pass through a 200 mesh screen. A +200 mesh aluminum means that all the particles are retained on a 200 mesh screen

How fine do screens get? That depends on the wire thickness. But the supplier of our screens does not offer any screens finer than 500 mesh. If you think about it, the finer the weave, the closer the wires get together, eventually leaving no space between them at all. So, beyond 325-400 mesh, we usually describe particle size in "microns."

What is a micron? A micron is another measurement we use for measuring particle size. A micron is one-millionth of a meter or one twenty-five thousandth of an inch.

This table is adapted from a post made by Ken Kosanke to the PML and previously published in a PGII Bulletin.

U.S. Standard * Space between wires

Sieve Mesh No. Inches Microns** Typical material

14 0.056 1400

28 0.028 700 Beach sand

60 0.0098 250 Fine sand

100 0.0059 150

200 0.0030 74 Portland cement

325 0.0017 44 Silt

400 0.0015 37 Plant Pollen

(1200) 0.0005 12 Red Blood Cell

(2400) 0.0002 6

(4800) 0.0001 2 Cigarette smoke

A micron is one millionth of a meter, not one millionth of an inch.

Hi Guest,

you are right.

I rewrote my post after searching for a chart and pasted the wrong bit after 'one to many'!

It is quite amazing how many different conversions from a micron to an inch or visa versa, are totally wrong. At least I made an 'obvious' mistake.

take care

babybear

The official definition of an inch is 25.4 mm. Because it is a definition, it is an exact conversion, meaning as many zeroes as required can be added after the 4, and it still remains a correct conversion.

Unfortunately, many people are either lazy or ignorant, or both, and keep too many digits after converting. The 50.8 was clearly the result of multiplying 25.4 by 2, without correct rounding. As a previous post indicated, 0.002" * 25.4 = 0.0508mm, which is the same as 50.8µm, or microns. This should have been rounded off to 50 microns - There is no way any ordinary coating is going to have a thickness of 50.8 microns (meaning greater than 50.3 and less than 51.3, or something similar, depending on rounding practices)

That's not totally true as far as the plateing aspect goes....platers define plating in two ways... thickness and buildup...therefore you can actually do both with .002 thousands...I have it done to parts I make all the time..I have .002 buildup which would means .004 on diameter and .008 on threads. I do a lot with hardcoat then Teflon impregnation. Like I said I have this done quite often as that is what I do for a living..Design and fabricate specialized equipment for the bio-medical industry. Most of the problem here is when you convert to inch....in the metric system all you do is move the decemal point...hense..1.0 micron= .001 milimeter=.00003937 inches...but in the end your right and the callout is for .002 plateing...the most comon callout is .0005/.00075 thickness and this comes with 45+ years of dealing with platers from all over the country..

Regards

Roger

This is why I was hoping to find someone who is familiar with the spec.. When I googled the spec. I did find some reference to teflon impregnation, but could not get anything specific about thickness tolerances. I have also done some hard anodize myself in the past and had lots of parts plated using various processes. If the conversion formula is correct then they are asking for a .002 buildup. The next question is: is the plating thickness including impregnation and buildup or just buildup, and what tolerance can they hold?

I am looking at a drawing with a 28mm counterbore. The tolerance is +.01/-.00mm or in English +.0004/-.0000. on an aluminum part. The plating tolerance would take up more than the machining tolerance. I think I need to no bid this one until someone moves a decimal point!

Hello Gary,

1 Micrometer=1 micron

1 Micrometer=3.937x10^-5 Inch. You can take it from there,

Wangito.

Hello garyceng:

Below is my original post............Which I wrote three times and still copied the wrong version to post! I apologise !

Note: 1 µ (micron) or micrometre is 1 millionth of a Metre

Most plating is under 20µ (Microns). In fact more like 6 to 10µ. This is nowhere near enough plating to smooth out any surface roughness. So the surface has to be good first.........................

Sorry for the mistake.

babybear

0000000000000000000000000000000000000000000000000000000

1 µ (micron) or micrometre is 1 millionth of an inch.

So there is 25.4µ (microns) to 1/1000" 25,400µ (microns) to an inch.

Your ref' of 50.8µ (microns) equates to 2/1000"...........Or '2 thou'. From that you can do the Maths on no offence!

I have pasted a chart below which equates things like sand, cement dust etc to its size in Microns and Inches. Not very useful but, just remember 25,400 microns to an inch........ 25.4µ = 1/1000"

Hello garyceng:

http://www.convertit.com/Go/ConvertIt/Measurement/Converter.ASP

I went to this site and had to type 'inch' after the figures below, copied from your post. Typing (") was not understood.

As you can see the 'conversion factor is ± .254µ (Microns).

Hope this is of help.

0.00001 inch = 0.254 micron

0.00002 inch = 0.508 micron

0.00003 inch = 0.762 micron

0.00004 inch = 1.016 micron

0.00005 inch = 1.27 micron

0.00006 inch = 1.524 micron

0.00007 inch = 1.778 micron

0.00008 inch = 2.032 micron

0.00009 inch = 2.286 micron

0.0001 inch = 2.54 micron

0.00011 inch = 2.794 micron

0.00012 inch = 3.048 micron

0.00013 inch = 3.302 micron

0.00014 inch = 3.556 micron

0.00015 inch = 3.81 micron

0.00016 inch = 4.064 micron

0.00017 inch = 4.318 micron

0.00018 inch = 4.572 micron

0.00019 inch = 4.826 micron

0.0002 inch = 5.08 micron

0.00021 inch = 5.334 micron

0.00022 inch = 5.588 micron

0.00023 inch = 5.842 micron

0.00024 inch = 6.096 micron

0.00025 inch = 6.35 micron

0.00026 inch = 6.604 micron

0.00027 inch = 6.858 micron

0.00028 inch = 7.112 micron

0.00029 inch = 7.366 micron

0.0003 inch = 7.62 micron

0.00031 inch = 7.874 micron

0.00032 inch = 8.128 micron

0.00033 inch = 8.382 micron

0.00034 inch = 8.636 micron

0.00035 inch = 8.89 micron

0.00036 inch = 9.144 micron

0.00037 inch = 9.398 micron

0.00037 inch = 9.398 micron

0.00039 inch = 9.906 micron

0.0004 inch = 10.16 micron

stay safe

babybear

You right, anodizing is usually between 5 and 10 microns max.

The micron is a metric standard in the rest of the world outside the USA

One micron is millions of a meter.

One micron is = to 0.000001of a meter or 0.001 of a millimeter = 0.000039 Inches

So the normal anodizing should be 0.00025 Inches

It must be an error in the spec

I hope this helps

One day the USA will go metric ???

A micrometre (American spelling: micrometer; symbol µm) is one millionth of a meter, or equivalently one thousandth of a millimeter. It is also commonly known as a micron. It can be written in scientific notation as 1×10⁻⁶ m, meaning 1/1 000 000 m.

Chromic anodize, commonly referred to as Type 1 anodizing, is formed by using an electrolytic solution of chromic acid that is about 100° F and a density of 1.5 to 4.5 A/ft2. The process will run for 40 to 60 minutes. This will produce a clear to gray coating, depending on sealing and alloy used, that is about 2 µm. One third of the coating thickness will build up per surface and 2/3 will be penetration.

Thickness of .00005" to .00030". is equal to 1.27 µm & 7.62 µm resp.