finishing.com logo
    HOME / sitemapFAQsBOOKSHelp WantedsAdvertiseContact   you are here: Hotline/Forum => Letter 29547
most fun in metal finishing

Roughness in acid copper while plating gravure cylinders

adv.     

++++

Sir, we plate gravure cylinders in acid copper bath and use normal copper anodes with the bath composition of 250 gm/lt copper sulphate, and 25-30 ml/lit of sulphuric acid, as the cylinder dips in the copper solution only 15-20% and run the bath at 4 amp/dm2.Now my problem is upon operation with the above conditions the cylinder is getting rough deposit on the surface,I suspected suspended particles , and filtered the solution, and even carbon treated the solution. I suspected high current, and controlled and operated at 4 amp/dm2, I even suspected the copper anodes, as it found black , so replaced with phosphorized copper anodes, still problem persists.copper metal and acid are in range. So I kindly request the professionals to suggest , what could be the problem , and how to get rid of this roughness. Awaiting for the reply, in detail.

Thanking you, Sincerely yours,

Panjala Mukesh
     fashion jewelry mfgr.
Hyderabad, India

++++

FIRSTLY I WOULD SUGGEST TO ANALYZE YOUR BATH PROPERLY. KEEP PROPER CONC. OF SULPHURIC ACID IT HELPS IN REDUCING THE TENDENCY FOR ROUGH & TREED DEPOSIT. KEEP CONC.AS COPPER SULPHATE 160-225 GM/LTR SULPHURIC ACID 50-75 GM/LTR USE GOOD QUALITY CHEMICALS FILTRATION CONTINUOUS, WITH PROPER AGITATION TEMP ROOM.

START CURRENT DENSITIES:- 1-3 AMP/DM2 ANODE PHOSPHORIZED .02-.04% A BLACK ADHERENT ANODE FILM IS FORMED WHICH ENCOURAGES UNIFORM ANODE DISSOLUTION AND REDUCE PARTICLE FORMATION DUE TO ANODIC DISINTEGRATION. USE ANODE BAGS P.P

GOOD LUCK

Ajay Raina
Punjab, India

++++

Bath concentration is perfect , double checked, copper sulphate is 250 gm/lt and sulphuric acid 30 ml/lt, operated at 4 amps/dm2 at these conditions even deposition for 500 microns it is taken around 15 hrs with rough deposit, normal copper anodes turning black , so replaced with phosphorized copper and inducted 60 ppm chloride, with continuous bath filtration , and even solution hot carbon treated and filtered , still the problem of roughness persists. Kindly advice is the bath composition is correct? or do we need to change the bath composition to avoid this roughness and for speedy deposition. We do not use any additives in the bath.

Any one in this expertise , kindly suggest.

Panjala Mukesh
     fashion jewelry mfgr.
Hyderabad, India

++++

The usual reason for a rough coating is a contaminated bath. I would suggest you use a 0.5 micron (or smaller) filter and use a flow rate of at 6-8 tank volumes per hour. (If I was electroforming, I would use 8-10 T/O per hour). Make sure you have good polypropylene anode bags that have not got holes in them. Operate the copper bath at 220 g/l CuSO4 and 50 ml/L H2SO4 (SG 1.84). Increase the chloride to 100 ppm. The temperature should be between 25 and 30 C. The anode area should be about double the cathode area. The cathodic CD should be OK at what you have.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK


++++

Problem seems in your filtration. CHECK FOR LOW ACID CONTENT. EXCESS CURRENT, LOW TEMP, LOW CHLORIDE CONTENT, CHLORIDE CONC.60-100 PPM. WHEN COPPER IS TO BE DEPOSITED FROM ACID BATHS ON STEEL MUST FIRST RECEIVE A CYANIDE COPPER OR NICKEL STRIKE THE STRIKE MAY BE AS THIN AS 2 MICRONS.AFTER THE STRIKE PARTS SHOULD BE DIPPED IN A DILUTE SOLUTION OF SULPHURIC ACID TO NEUTRALIZE SOLUTION RETAINED FROM THE ALKALINE STRIKE BATH .THE PARTS SHOULD BE THEN RINSED BEFORE ACID COPPER PLATING. INCREASE SULPHURIC ACID CONC.30-45 ML\LTR.

Ajay Raina
Punjab, India

First of two simultaneous responses -- ++++

Thanks for the reply , I have tried by increasing the solution turnover and kept 5 micron filter cartridge, still my problem persists, if I operate it 4 amp/dm2 , rate of deposition is very low , I want an accelerated rate , so kindly suggest what kind of bath concentration to be used for gravure cylinder plating , and how to wrap the PP cloth to the anodes. If any additional information is appreciated .

Panjala Mukesh
     fashion jewelry mfgr.
Hyderabad, India

Second of two simultaneous responses -- ++++

PROBLEM SEEMS IN YOUR FILTRATION. ROUGH DEPOSIT CAUSES:- LOW ACID, EXCESS CURRENT, LOW TEMP, LOW CHLORIDE CONTENT, SUSPENDED IMPURITIES IN THE BATH. FOR AIR AGITATED BATH CHLORIDE 60-100 PPM. INCREASE SULPHURIC ACID CONC. 30-45 ML/LTR. WHEN COPPER IS TO BE DEPOSITED FROM ACID BATHS ON STEEL, MUST FIRST RECEIVE A CYANIDE COPPER OR NICKEL STRIKE,THE STRIKE MAY BE AS THIN AS 2 MICRONS. AFTER THE STRIKE PARTS SHOULD BE DIPPED IN A DILUTE SOLUTION OF SULPHURIC ACID TO NEUTRALIZE SOLUTION RETAINED FROM THE ALKALINE STRIKE BATH. THE PARTS SHOULD BE THEN RINSED BEFORE ACID COPPER PLATING.

Ajay Raina
Punjab, India

++++

Mukesh it sounds as if your acid level is too low. Check it out. I also think your filters are too large, use 0.5 micron filters, not 5 micron. Thirdly, I take it you are not using anode bags as you ask how to wrap polypropylene around the anodes. Anode bags are what they say, they are bags that the anodes go into. You MUST use anode bags with copper anodes, otherwise you run the risk of getting particulates into your solution and this will result in a rough deposit. Once you have the bath and process in specification, then the ccd and throwing power should be OK.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK


++++

Hello Mukesh,

Check for iron impurity , and also the chloride may be less, causing you treeing effect. I would suggest you use an organic brightener which are specially used for this kind of application where you built up such a high thickness and work and which will allow you to work at higher current density. I hope you can follow my views and check with the best supplier located nearby you.

Thanks and reg,

Praveen Kumar
    plating process supplier
Mumbai, India

++++

Dear Mukesh,

Add about 10 gms./ltr Potash Alum to your bath. Alternatively you can try Poly Ethylene Glycol for fin grain , Roughness free deposit.

RAMESH KHARE
- Mumbai


++++++

Pitting and drill problem

DEAR RAMESH KHARE

You said ''Add about 10 gms./ltr Potash Alum to your bath. Alternatively you can try Poly Ethylene Glycol for fin grain , Roughness free deposit.''

you said me what is the potash alum.formula.(alike CuSO4)
What is the poly ethylene glycol do changing in the bath.how amount poly ethylene glycol for litre.

BEST REGARDS

AHMET ÇUHACI
- ISTANBUL, TURKEY
ADD a Q or A to THIS thread START a NEW THREADView This Week's HOT TOPICS

disclaim

 seek

JobshopsCapital Equip. & Install'nChemicals & Consumables Consult'g, Train'g, SoftwareEnvironmental ComplianceTesting Svcs. & DevicesUsed & Surplus


©1995-2014 finishing.com     -    Privacy    -    Search