Barrel plating dangler problems and alternatives

A. Hi Daniel. If you're pretty sure that the bending is happening while the screws are in the plating barrel rather than in material handling, I can think of two approaches:
1. Danglers must snake their way through the parts as the barrels rotate, and this can cause snarls of parts, which then bend. Plating barrel manufacturers do offer barrel styles which do not have danglers. They tend to be a bit more complicated and require more maintenance because they use a sort of contact brush system on the hanger arm so there is nothing stationary to twist up within the barrel.
2. Many years ago, one manufacturer offered doorless barrels to facilitate automation; I think they called them "rack and roll". In order that the parts not fall out during plating, the barrels only rotated 180°or so before reversing. You would not need to go doorless, but could simply install a timing mechanism and reversing contactor to reverse the rotation of all your existing barrel drives, so they rock back and forth 180° to 270° and the danglers don't wind up.
Luck & Regards,


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

A. Hi again Daniel.
Yes, barrel contacts of that general sort rather than with danglers is what I was speaking of. Sorry that it doesn't help enough.
Since the plating barrels have doors and won't spill, it shouldn't matter if several are ganged off the same motor or starter. Maybe just try a timer arrangement where you rotate for 6-10 seconds in one direction, stop for a second or two, then rotate 6-10 seconds in the opposite direction, and repeat. Ideally, the motors should be duty-rated to insure they can do this without overheating, but If I were you I would try it anyway :-) Luck & Regards,


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

A. Most "vibratory" barrels are employed on electronic parts 25 times smaller than yours.

Parts tangling together is a perennial problem in barrel plating and there are only partial solutions, which include: different contact styles (cones, bars, external buttons, etc.) in lieu of danglers, small loads (like you are running), and periodic reversing starters so the barrels only rotate a few seconds in each direction.

A. Vibratory barrels may be a good option, but they are expensive. May I suggest trying a barrel with button danglers, and also using conductive plating media or some other zinc plated parts that can be mixed with the hooks and separated later.

A. A common reason a dangler snarls up when plating nesting parts is that the dangler does not rotate with the barrel and the mass of parts; it must keep snaking its way through the mass. So, the hope is that a style of contact that rotates with the barrel--so there is nothing stationary in the revolving barrel--will minimize the snarling.

So, what you are trying to do is get the electricity to the parts without leaving anything stationary like a dangler inside the barrel or mass of parts. The buttons, or contact bars, or cones, or whatever, are fixed to the cylinder and rotate with it and the parts.

It is difficult to do yourself because this requires some kind of informal "electrical brushes" arrangement whereby the contact surfaces (fixed inside the barrel) get their current from a contact on the hanger arm. All plating barrel manufacturers are able to supply such contact arrangements for dangler-free contacts though. Good luck.

A. Hi Rodrigo Salinas,

If you're looking for a long term solution for plating these hooks I would suggest you to go for rack plating. I guess you can expect uniform deposition and faster plating rate. It's possible to rack and unrack these hooks quickly.

A. Hi Pravin. You could try electropolished stainless steel dangler knobs. Electropolished parts have very little "tooth" and are quite passive, so it's generally easier to remove deposits from them. Good luck.

A. Titanium is a terrible conductor of current, so it would not work as a dangler.

A. Natasha,
As Jon mentioned Ti is not used for danglers because of lower conductivity and higher contact resistance. Copper is the 2nd best conductor, I think brass is the 6th best, at room temp of course. As you said Ti is more expensive. Based on these two facts alone, what kind of contacts would you put on danglers? Ti is used for hooks and baskets mainly for its strength, heat and corrosion resistance, it is compatible in certain plating solutions.

A. Hi. There's a bit of a semantics issue here. The dangler as a whole is a heavy copper cable with heavy plastic insulation and a bare contact knob on the end. I'm sure Natasha is speaking only of making the knob out of titanium, not the whole cable.

I could be wrong but I think the actual problem is not conductivity or wear, but polarity. My belief based on practical experience is that titanium is not actually resistant to the acids used in plating: rather, the titanium oxide coating it develops from being anodic is what is acid resistant. Dangler knobs are cathodic and I think they will quickly dissolve in the plating baths.

Luck & Regards,

A. Who decided that they are hazardous waste, Mike?

I'm not sure that you're interpreting the regulation correctly. I'd need to restudy it myself, but I don't understand why you can't strip the rubber off, triple rinse it and dispose that part as simple waste while selling the copper as scrap. What is the reasoning you are using, or others are giving you, that causes you to equate a dangler with a sludge? The components that you plate are not hazardous; why should the danglers that you plate be considered hazardous?

In the case of a disputed interpretations, common sense should always prevail; and it tells me it is an environmental travesty to landfill electrolytically pure copper metal! At the least, anyone who issues such an order should sign their name on said order :-)

A. Dear Gupta,
Use a tight PVC sleeve over the solder Joining point (Dangler and the cable).

All the best.

A. Hi Mike. Just brainstorming here, but I am not yet convinced that plain button contacts wouldn't work. They could be made of electropolished 316 stainless steel, which is both very passive and very free of tooth; I think with luck the plating would fall off or almost fall off.

As for deplating, I don't think you will attack the substrate of the buttons if you keep the voltage low.

Regards,

A. Why not use a nitric acid stripper formulation instead of ammonium bifluoride? It would not attack the stainless steel. Other than the fumes, it may have less concerns about human exposure.

A. Hi Sam. Can you send a photo to mooney@finishing.com for posting here? I'm not sure what you mean by "the copper rod". Most plating barrels have danglers. But some plating barrels have, instead, a copper rod running from the center of one hub to the center of the other, from which you can dangle something to bring current to the parts. But making a suggestion how to improve what you have when I don't really know what you have is tough :-)

Luck & Regards,

A. Hi Åukasz,
I think regular dangler contacts would be best, but that the barrels should be 11" internal diameter or less so there is no way the spikes can get vertical but must essentially remain horizontal.

Luck & Regards,