Leather manufacturing process technology with flow sheets

The manufacture of leather follows the same general steps for a great variety of leathers (figure below). The largest category of hides tanned is cattle hides . Of the cattle hides chrome tanning of unhaired hides is by far the dominant system used throughout the world. The tanning of other types of hides and skins requires variations in the systems used for cattle hides.

Fig: Process flow diagram for the production of chrome-tanned cattle hides leather

Curing:

Crust Leather Production Process with flow sheet

Raw Materials

The main raw materials for production of crust leather from wet-blue leather stage are wet-blue leather, oils, synthetic tannins, vegetable tannins, aniline dyes, sodium bicarbonate, sodium acetate and formic acid.

Flow sheet of crust leather production

LEATHER GARMENT PRODUCTION

Production Process

The process of leather garment production does not involve complex unit operations. The machinery and equipment required are simple, and the process required for such operations as preparation of designs and cutting to required sizes, sewing, pasting, button hole making, button fixing and other necessary operations. The specifications of leather garments to the export market are mainly related to the colour of the leather and its colour fastness, softness and resistance to moisture and cold. Other specifications like design and pattern for leather garment to be exported are, in most instances, provided by the buyer.

The pieces of leather that remain as by-products are highly needed by other industries as useful inputs. Bricks factories make use of the by-product as sources of energy for fired-furnaces. The by-products can also be used as inputs to micro and small scale industries. Thus, production of leather garments does not have negative impact on environment.

Finished leather production Process

The processes involved for the production of finished leather from the crust leather stage are presented as follows. 

Conditioning by uniformly increasing the water content in the dried leather is necessary before staking. Grain-damaged leather can be improved considerably by butting the grain surface with fine abrasives, and the resulting product is called corrected leather. After butting, the leather dust has to be removed because it would interfere with a proper finishing.

After dusting, the leather is waxed, or treated with pigments, dyes, and resins to achieve a smooth, polished surface and the desired color; or lacquered with urethane for glossy leather. Plating is then used to smooth the surface of the coating materials and bond them to the grain. Hides may be embossed.

Embossing is a way of pressing a specific pattern, e.g., a reptile grain, into the cattle hide grain. The new pattern will cover many grain damages and is consequently used primarily on the lowest leather qualities. Before dispatch, the product will be sorted and measured. Since finished leather production starts from crust leather most of the waste has been removed in the pre-crust processes. Therefore the wastes expected in processing crust leather are minimal.

Equipments

Drum with 5HP motor shaft pulley Electrical Unit Heater for Stuffing Drum 5HP Shaving Machine - single width Electrical Hand Operated Setting Out Machine Lace Cutting Machine Spraying Machine with Dryer Hydraulic Press Brushing Machine with Drier Related posts Crust Leather Production Process with flow sheet LEATHER GARMENT PRODUCTION Leather manufacturing process technology with flow sheets

Laminated leather belt making steps

Portions of chrome-tanned leather, free from cuts are used for the fabrication of laminated leather beltings.

First, dried splits of chrome tanned leather are cut into straps at right angle in a round-strap cutting machine. A long roll is made by joining leather pieces of equal sizes with suitable adhesive cement applied to the end after splicing. The joint portion is kept under pressure in a cold press to ensure proper bonding.

The ready leather roll is fed into the splitting machine to cut appropriate sizes suitable for uniform sandwiching. The flesh side is buffed and a polymer resin is applied. The final operation is insertion of nylon flesh in between two leather rolls under hot hydraulic press. Both leather and nylon film are kept under heat and pressure for a certain period of time in order to produce a long roll of leather nylon sandwiched belting.

The final roll after lamination is mounted on a winding frame for a few days and thereafter ends of the roll are trimmed by using a circular knife and subsequently buffed on a buffing machine in order to clear unwanted material and gloss if produced during the process of lamination. The process does not have any adverse impact on environment.

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Finished leather production Process

 LEATHER GARMENT PRODUCTION

Crust Leather Production Process with flow sheet