Example 1 Manual Immersion Coating of Threaded Fasteners in a Zinc Phosphating Solution

An example of equipment requirements and process cycles can be found in a company that produces threaded fasteners, zinc phosphates, and oil dips at an average of 3600 kg (8000 lb) of these parts each 8 h shift. One worker operates the entire immersion phosphating line. All parts are cleaned and pickled before being phosphated.

Production requirements for the manual immersion zinc phosphating of fasteners are listed below:

Requirement

Value

Weight of each piece, kg (lb)

0.013 (0.029)

Weight of each load, kg (lb)

193 (425)

Average weight processed per hour, kg (lb)

454 (1000)

Average number of pieces per hour

34,483

Equipment specifications required for manual immersion zinc phosphating are given in Table 9.

Table 9 Equipment specifications for typical manual immersion zinc phosphating coating of threaded fasteners

Component

Quantity

Unit capacity

Weight

Volume

kg

lb

L

gal

Work-handling equipment

Workbasket for cleaning(a)

2

230

500

Perforated drums for phosphating(b)

3

230

500

Drum loading stand

1

230

500

Hoists

2

910

2000

Loading chute

1

230

500

Cleaning equipment

Alkali soak tank

1

760

200

Acid tank (sulfuric acid)

1

760

200

Rinse tank

3

760

200

Phosphating equipment

Phosphating tanks(c)(d)

3

760

200

Rinse tank

1

760

200

Chromic acid rinse tank(d)(e)

1

760

200

Centrifuge for drying®

1

Oil dip tank®

1

380

100

(a) Stainless steel.

(a) Stainless steel.

(b) Motor-rotated.

(c) Heated by stainless steel steam plate coil.

(d) Automatic temperature control.

(e) Heated by steam plate coil.

(f) Equipped with hot-air blower driven by 2.2 kW (3 hp) motor.

(g) Corrosion resistant

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