CHEMWIT PRODUCT DATA AND PROCESS INFORMATION

ZINPHOSCON 500 TP     ZINPHOSCON 525 NTP     ZINPHOSCON 550 SP

THE PRODUCTS

ZINPHOSCON 500 TP is formulated for zinc phosphate conversion coatings on metal surfaces by thermal dip process.

ZINPHOSCON 525 NTP is formulated for zinc phosphate conversion coatings on metal surfaces by non-thermal (at room temp.) dip process.

ZINPHOSCON 550 SP is formulated for zinc phosphate conversion coatings on metal surfaces by spray process.

FUNCTIONAL IMPORTANCE

phosphate conversion coatings by zinphoscon 500 tp/525 ntp/550 sp are widely used in the manufacture of metal surfaces for following principal merits:

• to precondition metal surfaces for better bonding of paints and plastic coatings.
• for superior performance in retarding the lateral creep of corrosion between the organic coating and the metal originating at a scratch through the coating to the metal.
• a phosphating coating itself can act as cold forming lubricant as well as a carrier of lubricants such as oil.
• almost all the automotive and appliance manufactururing and some deep draws would be virtually impossible without the use of phosphate coatings

SPECIFICATIONS

• chemical composiotion: blend of phosphates, zinc, nitrates, activators etc.
• nature : acidic
• volatality : non volatile
• solubility : easily soluble
• flash point : nil
• toxicity : nil
• handling : to avoid splash and body touch while pouring

OPERATING PARAMETERS

• bath makeup : 3 to 5 liters of zinphoscon 500 per 100 litres
• of bath capacity.
• bath pointage : 24 – 34
• temperature : 65⁰ to 75⁰ c
• toner/accelerator : 20 gms/100 liters of bath
• dip time : 7 to 15 minutes

PROCESS CYCLE

• degreasing in greaserid 200 hd bath
• running water rinse
• derusting / descaling in rustrid 300 hd bath
• running water rinse
• surface activation in conconditioner 410 bath
• phosphating in zinphoscon 500 tp bath
• running water rinse
• passivation in passichem 900 bath
• forced drying by hot air blowing on work pieces

PREPRATION OF ZINPHOSCON 500 TP BATH

fill the tank upto 2/3 of operating level with water and switch on the heaters. when the temp is about 60 degree add about 5 lit. of zinphoscon 500 tp in the bath per 100 lit. of bath capacity. fill the tank upto the operating level with water.

AGEING THE ZINPHOSCON 500 TP BATH

the freshly made-up bath tends to produce coarce and uneven coatings on the first few loads of work processed. to overcome this, it is adviseable to awaken (also called break-in the bath) the bath with dummy pieces (about 50 sq. ft. of surface area) of scrap. now the bath is matured and ready for use.

ADDING OF ACCELELERATOR/TONER

add about 20 gms of proacceler 600 zpc per 100 lit. of bath. test by inserting starch iodide paper. appearing of blue colour confirms sufficient added amount.

if starch iodide paper remains white it shows insufficient quantity of proacceler 600 zpc in the bath

black and dark blue colour of starch iodide paper denotes excess of accelerator/ toner in the bath.

TESTING AND CONTROL OF ZINPHOSCON 500 TP

TOTAL ACID POINTAGE

pipette 10 ml. of bath soln. in a conical flask. add 5 to 8 drops of phenolphathalein indicator to it and titrate against n/10 naoh until pink colour appears. the burrete reading of ml. of naoh used denotes the pointage of the bath.

REPLENISHMENT OF BATH

add about 150 ml of zinphoscon 500 tp per 100 lit bath capacities for each point below required pointage.

SLUDGE FORMATION AND ITS REMOVAL

sludge is formed in the bath in due course of operation and should be removed periodically by means of a hoe or any other suitable means.

the loss in pointage should be repleished in proportion of150 ml. of zinphoscon 500 tp for each point below required pointage.

EQUIPMENT

the bath tank should be fabricated with 3 to 5 mm thick ms plates with continuous convection current heating system.

FINAL SEALING

phosphate coating alone do not protect from rusting for long and requires sealing with paint immediately after phosphating for proper protection.