The authoritative public forum
  for Metal Finishing since 1989
-----

Detailed operational parameters for 7-tank phosphating process

July 19, 2008

DEAR SIR,

Please give me the details of each seven tank i.e. types of solution, its pH, its temperature etc. This information to help me to installation of seven tank in my small scale paint application unit.

Thanks.

Sujitkumar Prajapati
Paint shop - Baroda, Gujarat, India

---

July 21, 2008

Hi, Sujitkumar. Most people installing a phosphatization line would go to a specialty supplier for a co-ordinated cleaner, zinc phosphate, and final dip. We would advise you to strongly consider that route as you would not only receive detailed operational instructions, but the quality of your product would be better, the vendor would be keeping you abreast of changing requirements like RoHS compliance, and the smaller the shop the less practical it is to formulate your own chemistry.

But if you will be formulating your own processes and trying to optimize them, I think you will find the kind of information you seek in Samuel Spring's Preparation of Metal for Painting ⇦[this on on Amazon affil links] or "Phosphating of Metals" ⇦[this on Amazon or AbeBooks affil links]by Rausch. Good luck.

Regards,

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

---

SIR
I HAVE FORMULATED 3 IN 1 CHEMICAL FOR PRE TREATMENT CHEMICAL BUT MY CUSTOMER IS INTERESTED IN 7 TANK PROCESS AS MY 3 IN 1 HAS PROBLEM OF GETTING REDDER TONE AFTER APPLICATION AS SURFACE GETS ACCTIVATED.KINDLY GUIDE IN ABOVE LINE OR LET ME KNOW IF 7 TANK SYSTEM IS MORE APPLICABLE THAN 3 IN 1(DEGRESING DERUSTING & PHOSPHATE COATING)

DEVANG CHHAPAWALA
MANUFATURER - ANKLESHWAR, GUJARAT, INDIA
August 8, 2008

---

July 2, 2011

Sir,

Kindly clear my doubt about 7 TANK HOT PHOSPHATING PROCESS CHEMICAL mixing procedure.
What are the chemicals mixed in the 7 Tanks? Please notify the chemical names and strength of each tank.

Thanks

AV KUMAR
MANAGER - CHENNAI, TAMILNADU, INDIA

---

July 6, 2011

Hi, AV.

Letter 21461 asserts that the seven stages are degreasing, pickling, zinc phosphatizing, and the associated rinses.

Letter 32095 asserts that it would best as two-stages of cleaning, no pickling, phosphating and plenty of rinsing; but that writer is probably thinking of iron phoshatization.

Letter 50907 asserts that the process is degreasing, rinse, derusting, rinse, activate, phosphating, passivation.

Although I personally feel that the phrase "7 tank" implies zinc (or di-catioic or tricationic) phosphating, the best answer may be that a supplier could sit with you to pick what ought to go in each of the seven tanks based on your particular parts. To assume that the answer is fixed and independent of the parts you are trying to process is incorrect, I believe.

Good luck.

Regards,

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