Home /
T.O.C.
FAQs
 
Good
Books
Ref.
Libr.
Advertise
Here
Help
Wanted
Current
Q&A's
Search 🔍
the Site

Chime right in! (no registration req'd)

-----

"Tight fits, aluminum, anodize and galling"



2002

I have a situation where 12 round plates 3.75" in diameter and anywhere between .250" and .625" high need to be stacked into a machined bore roughly 6" deep. We control the form and size of our parts to assure clearance under all conditions is at least 0.001". This may not be increased.

We have continual problems with the parts galling during installation and teardown as they pass into and out of the bore. The bore is 355 cast aluminum and the plates are 6061 aluminum.

The only solution we have to galling so far is to AMS A8625 [withdrawn / link is to spec at TechStreet] type I anodize all parts prior to assembly. This is expensive. Are there any less expensive and time consuming alternatives to assure the parts do not gall together?

We suspect the advantage to anodize may only be from the 'acid deburring' of the parts. We are considering leaving the plates uncoated and placing an AMSA8625 Type III hardcoat on the bore. There must be a better way.

Thank you.

Peter Nickerson
- Ayer, Massachusetts
^


2002

For installation, it is no sweat. Store the parts in a freezer and install cold. For a little easier, remove the plates the night before and store on dry ice. For a fast even looser fit, use dry ice and methyl or ethyl alcohol. PS, this is really cold , handle with appropriate caution.

Coating the bore with a fluorocarbon mold release agent from a spray can may be enough to keep it from galling during the removal.

The typical anti-galling procedure is to make one surface hard and one surface soft--Your hard coat the bore. The inverse of that procedure would be to coat the plate edges with tin or silver. This could be done with a brush plating setup in your shop (mechanized)(mobile) very easily. Silver has a disposal problem, so I would go with the tin. You can do thin coats of anodize with it also, but requires refrigeration of a pumped solution.

James Watts
- Navarre, Florida
^


2002

Aluminum and anodized aluminum have terrible lubricity and are prone to galling. Electroless nickel plating all the parts should eliminate galling problems. Electroless nickel costs more than anodizing. The coating price should be very small compared to making new parts.

Todd Osmolski
- Charlotte, North Carolina, USA
^


sidebar

2002

Then why do they use aluminum for light bulb bases? I would pay an extra couple of cents for a brass socket. Sounds like a great place for a class action suit against bulb manufacturers by all who have cut their fingers on the bulb after the base gets stuck in the socket. I mean, what expert witness could deny that aluminum is an awful choice?

tom pullizzi animated    tomPullizziSignature
Tom Pullizzi
Falls Township, Pennsylvania
^


2002

Aluminum is a very active metal and untreated aluminum will quickly corrode with white corrosion pores that could presumably be .001" high, so that isn't the answer. But Mil-C-5541 [link is to free spec at Defense Logistics Agency, dla.mil] chromate conversion coating might be fine, and there are any number of non-chromate corrosion inhibitors available from such companies as Everbrite [a finishing.com supporting advertiser], International Chemical Products, and Sanchem which might provide sufficient corrosion resistance.

Yes, you would be willing to pay a few more cents for brass. That's why some manufacturers work so hard to use exactly the right chromates and dyes that their aluminum bulb bases will look enough like brass to hoodwink you :-)

I haven't personally cut myself removing a broken bulb in several years, so I can't join that hypothetical class action suit. But using metal finishing to dupe the consumer should be punished rather than rewarded, and it is a continual petty aggravation to constantly struggle with stuck bulbs because aluminum is disguised to look like brass although it doesn't function like brass, so I'd love to see the suit go forward :-)

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
^


2002

Count me in on that. I can't understand why the bulb manufacturers are not required to use the Best Available Technology.

Todd Osmolski
- Charlotte, North Carolina, USA
^


April 12, 2012

Ever since Congress passed the law to dictate what type bulbs we use, the companies who make incandescents have been shutting down their lines, or moving offshore. I believe it is for that reason that some incandescents are getting harder and harder to find, even bulbs of lower wattage than the ban entails. We can't find brass based 40W incandescents for our JennAire oven. Florescent bulbs won't handle the heat. Nor I doubt, will LED or Halogen bulbs. JennAire insists on brass bases, because the heat will weld an aluminum base bulb into the socket.

I've driven to at least 12 different stores. If it was the intention of congress to reduce power consumption, they haven't done it, because I've used at least 4 gallons of gas doing this. While we won't probably toss our modern stove for lack of a bulb. I imagine quite a few Americans will just buy a new stove, and send the old one to the dump prematurely. What is THAT going to do for the environment?

Besides the problem with oven bulbs, I have noticed that the florescent bulbs won't start up in any application where it's too cold - like the unheated crawlspaces we have in some areas of our plant. They also won't survive the high temperatures of the rooms we use to cure our coatings on circuit boards. And they won't take the vibration of certain types of machinery.

Congress should get out of the business of mandating technology!

Jim Vincent
- Tully, New York, USA
^


April 13, 2012

Hi, Jim.

Yes they should, but they won't because we keep voting for democrats and republicans no matter how poorly served we are.

I use mostly CFLs and a few LEDs, but where incandescents are appropriate, that's what I want to use. As small electric heaters, incandescent bulbs are ultra efficient, ultra cheap, ultra reliable, ultra compact, and ultra safe. We'll now have to buy dangerous, clunky, expensive, non-waterproof electric heaters for those small heating jobs (like germinating seeds) that incandescent bulbs were doing so wonderfully.

Regards,

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
^


April 13, 2012

You're absolutely right, they do make good localized heaters! Lost in all the talk about the low efficiency of incandescent bulbs is the fact that the energy isn't always wasted - especially in the northern climates. Incandescent bulbs heat our rooms during the winter. How much energy are we going to save, if instead of sitting under that warm reading lamp, we get up, and reset the thermostat to warm up the entire house?

Jim Vincent
- Tully, New York, USA
^

none
finishing.com is made possible by ...
this text gets replaced with bannerText
spacer gets replaced with bannerImages

Q, A, or Comment on THIS thread SEARCH for Threads about ... My Topic Not Found: Start NEW Thread

Disclaimer: It's not possible to fully diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations might be harmful.

If you are seeking a product or service related to metal finishing, please check these Directories:

 
Jobshops
Capital
Equipment
Chemicals &
Consumables
Consult'g, Train'g
& Software


About/Contact    -    Privacy Policy    -    ©1995-2021 finishing.com, Pine Beach, New Jersey, USA