How to set up the Zinc Phosphate Process?

A. Very few people use a home brew for phosphating. Step 1 is which of the three general types of phosphate do you want to do? Next is to contact two or more vendors with the type of metal and amount that you want to phosphate and ask for quotes for equipment and chemicals. Ask what tech service they provide on a routine and an emergency basis. Find out what you are going to need for in house lab testing to control the tanks. They will provide operations data sheets that has the ranges of all of the parameters.

After that, the secret of successful phosphate operations is bring the temp up fast, keeping metal in the tank as much as possible and dropping the tank temp as soon as done. I always saved the last water addition for evaporation until the last load was out. You can not overwork a phosphate line, but it will go sour rapidly if it is at temperature with no load or a series of loads that are too small for the tank volume. The Ti modifier in a rinse tank is necessary if you are going to acid etch the parts. Phosphate works best with freshly blasted parts.

A. It is my feeling that it is difficult to overload a phosphate tank. BUT!
If you have a huge weight of parts, the tank temp will drop and you will not get a good phosphate, so you will need a larger tank OR huge heaters OR add parts a few at a time and remove the ones that are done and immediately add more IE, you sequence the parts rather than an entire load at one time.

Unless you have an unusual loading, chemical additions probably will not need to be done during a shift.

A tank at temp with no load in it is the worst thing that you can do for a phosphate tank. It really messes up the acid ratio which is a key for good work.

A. Dear Mr. Paton Zinc phosphating process has pretty many parameters to be taken in consideration and it also costs more; so I can easily say it is not that easy to set up a bath by yourselves but I can suggest another kind of phosphating process: iron phosphating. First you should investigate if iron phosphating is suitable for your parts and, of course, for the later processes. The rest is quite easy compared to zinc phosphating. There are 5 important parameters to be taken in consideration. Temperature, Pressure (for spraying), Time, pH, Total Acid level. These should be settled in the charge of a process engineer or a chemist, otherwise getting the proper result will be harder. Best Regards, Levent Aliustaolu - Bursa, TURKEY 2004

"Phosphating of Metals"
by Werner Rausch

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A. For drill stem the object is usually make/break lubrication, in other words the phosphate coating is primarily sacrificial, intended to crush and provide lubricity so that the stem can be disassembled on removal. The common treatments for this are manganese phosphate and heavy zinc phosphate. The immersion time will vary from 2 to 10 minutes and the temperature of the bath will vary from 130 to 170 °F.

Use a ready-made chemical from a vendor that can help you set up the bath. The equipment is pretty basic, just a series of heated tanks and a hoist (programmed hoist for high volume). The phosphate tank will have to be stainless, like 304L or 316. Everything else can be mild steel or plastic.

I hope this helps,

A. Dear Mark,

A typical phosphating process is minimum seven step process. Additional steps may be required depending upon structure and job conditions. For selecting suitable bath size, component details and quantity is required. Further a suitable process has to be selected from low zinc phosphating, heavy zinc phosphating and manganese phosphating. Bath controls are very simple.