Seq of operation

[caddone]

Al Extrusion need some presiding drilling and anodizing. What's best sequence. Drilling or anodizing ?

 

[caddone]

Please ignore typo presiding ; it should be reading precision.

 

[IRstuff]

But what kind of precision, i.e., what tolerances are you trying to maintain?

TTFN
faq731-376

 

[rb1957]

anodizing "only" coats the parent material, no?

isn't the question whether or not you want to anodize the bore of the hole ?

if a 0.001" or two of anodize deposit in the bore of the hole affects your precision, then account for it in the hole diamater.

if your precision is so tight, what'll happen inservice when the anodize wears off ??

 

[caddone]

Here is a print..

 

[caddone]

here is machining extrusion print

 

[caddone]

RB,
thanks for responding. from that it appears to be no problem to anodize at thd end od sequesnce..

 

[rb1957]

what (exactly) was your original concern ?

did you think anodizing would distort the part ?

 

[TVP]

You should confirm with your customer that it is ok to have an anodized layer inside the holes, otherwise the part should have the holes masked and then anodized.

 

[caddone]

TVP we are the end user & its OK to have layer inside holes if its as little as rn1957 was talking about.
I am actually concerned if the anodizing can leave much thicker deposits like sometimes it happens in powder coating.

 

[TVP]

No, anodizing is not as susceptible to thickness variation like powder coating. And the coating will actually taper off (less thickness) around corners, not increase in thickness.

 

[caddone]

The blind holes you are seeing on the print are holes ready to take a thread forming screws. Now Iam feeling confident to try the anodizing at the end if the operation. Thanks.

Is it right that during the process they immerse the entire extrusion into a chemical tank?

 

[mfgenggear]

caddone

run a test part thru anodize.measure before, then after.
the thickness of anodize will result in half penetration & half buildup.
so if the hole requires .001" anodize per surface".002 total" there will be approximate
.001 build up on the diameters., in other words the diameter will be .001" smaller after anodize.
the reason to measure before & after as RB 1957 suggest, the anodize will plate less in
recesses, holes, & so on. so there may be less build up in these areas.
anodize adds to protection for wear, & helps the base material.

this part is very liberal far as tolerance, and should be no issues.

Good Luck
Mfgenggear

 

[mfgenggear]

I wanted to add that the machining needs to to tighten up before anodize,& also that it was TVP who said that there will be less plate in the edges.
Generally as rule of thumb is if the tolerance is less then .001" tolerance then it has to be machined after. IE chase theads, hone or ream holes.
or like said above mask off less plate.

Mfgenggear

 

[KENAT]

Not an option if you're the manufacturing engineer or similar, but from as design point of view...

Say you do want the holes free of anodize.

Do you really care if they get drilled before anodize and masked, or made after anodize?

Generally the answer is a resounding 'no'.

In which case just put a note on the drawing 'HOLES SHALL BE FREE OF ANODIZE'. Then the machine shop & plating shop can decide which order works best for them - I've had parts done both ways for various reasons.

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