I need to find cosmetic and surface finish standards 1

[BusaJames]

Please help. I've been assigned to find cosmetic and more importantly surface finish standard so that my company can put together a document to send out to our suppliers. I found ASME B46.1 standard but I'm not sure if it has what I need. I don't want to spend the $ if its not usable.

Thanks,

 

[KENAT]

For general use in the US ASME B46.1 is the surface finish spec.

However, it may not cover what you want to know about 'cosmetic'surface finishes.

Our standard note is:

7. SURFACE ROUGHNESS TO BE ____ RMS PER ASME B46.1.

Sometimes we'll indicated required 'grain' direction.

We also have large 'brushed' stainless panels. These use a number system such as #4 if I recal correctly. I'm not sure what standard defines these off the top of my head.

 

[BusaJames]

Thanks. It makes me feel better to hear it from somebody else. I've been looking all over and every search seems to end up at the B46.1 so I'll tell the boss I think

 

[Heckler]

Also, the Machinery's HDBK has a chapter on Surface Texture. We have both but I lean towards the Machinery's HDBK because it's on my desktop.

Heckler
Sr. Mechanical Engineer
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(In reference to David Beckham) "He can't kick with his left foot, he can't tackle, he can't head the ball and he doesn't score many goals. Apart from that, he's all right." -- George Best

 

[IRstuff]

The more relevant question is what do you NEED?

If you don't a high level of smoothness, why pay for it?

TTFN

FAQ731-376

 

[BusaJames]

Exactly right. But we need to be able to go to a supplier and say we want a Class II finish, for example, and they know exactly what we mean by that. Then, we also have a way to check that we're getting what we want other than just eyeballing it.

 

[mechengdude]

Sometimes eyeballing it is exactly what you want. Similar to a paint brochure you may want to consider obtaining samples of exactly what you are looking for and putting them in a binder/brochure of some sort.

 

[drawoh]

BusaJames,

Get yourself a surface finish gauge. That way, you will know what you are talking about.

I call up the finish I want on my drawing using surface finish symbols. These are explained in the Machinery's Handbook. I can look at my surface finish gauge and see which finish I want.

125 and 63 microinch finishes are popular to call up, and they do not look very good.

JHG

 

[BusaJames]

I definately agree that every piece should be examined for obvious defects but we wanted some kind of standards doc that refferences more detail that we can hold our suppliers to. I think the plan is to put together a pdf and send it to all of our suppliers.

 

[IRstuff]

But, rather than randomly asking for specs, you need to determine what you absolutely need, then ask for the spec that most closely matches that.

TTFN

FAQ731-376

 

[BusaJames]

That's one of the reasons we're looking for a big book of specs. Then we can attach what we need now and for new products later.

 

[BusaJames]

Thanks for all the input by the way. I think the boss has decided to buy the B46.1 standard, hopefully the machinery's handbook, and then collect all the docs we already use in house. We'll take all of these and make one complete doc.

 

[KENAT]

If I understand what your saying I'd be tempted come up with an internal spec to tell you what surface finish to use/specify when.

For instance for non cosmetic finishes maybe 125 is OK where as for Cosmetic you may want 63 or better. In some cases you may also want to indicate 'grain' direction.

You could come up with some standard notes for drawings that state your requirements for each case, these notes should probably include reference to the ASME spec.

This way your actual drawings are just referring to the industry spec and you don't have to worry about a separate document that may get lost by the vendor, not sent by purchasing etc. Just my 2C though.

The 'pallet' of samples will be very useful if you can get one. They're not always cheap but if your main concern is cosmetic then they may be really useful in showing you what finish you need.

Do a google search for surface chart and you’ll find some useful information.

http://www.google.com/search?hl=en&q=surface+roughness+chart

Also one of these says ISO 1302:1992 uses N numbers, I’m not totally sure this is what I mentioned our suppliers specify their sheet metal in but it may be.

http://www.roymech.co.uk/Useful_Tables/Surface_Texture/Sur_Fin_Values.html

 

[unclesyd]

You might want to take a look at this booklet. I would order the hard copy.

http://www.ssina.com/publications/spe_fin.html

 

[BusaJames]

The document I'd like to put together would aid in choosing surface finish on our end and make it very clear to our suppliers what we want. Hopefully it would help communications between us. The SSINA book is helpfull. I just need to collect info like it for plastic, painted, cast, etc.