GOVERNMENT OF THE PEOPLE’S REPUBLIC OF BANGLADESH BANGLADESH COLLEGE OF LEATHER ENGINEERING AND TECHNOLOGY
PURPOSE OF INDUSTRIAL TRAINING In our institution we learn the theoretical aspect of leather production. Industrial training provides us a chance to compare our theoretical knowledge with large commercial production of industry. The purpose of industrial training can be outlined under the following topics: • • • • • •
To get an idea about the vast commercial production. To observe the management system of the industry. To observe the process of product development and quality control. To observe the plant layout of the industry. To observe the production of various leathers. To introduce with the factory environment.
DESCRIPTION OF THE INDUSTRY 1. Name of the Industry 2. Location
: Samina Tannery (Pvt.) Ltd. : 36/1, Kalunagar, Hazaribagh, Dhaka-1209.
Post: 1. Managing Director 2. General Manager 3. Chief Leather Technologist 4. Leather Technologist
: Abdus Samad : Moktar Hossain : Mohiuddin Ahmed : a) Md. Fazlul Haque Tutul b) Md. Rafiqul Islam
5. Wet Blue Tanner
: Md. Siraj
6. Mechanical & Electrical Engineer
: Eng. Salatun Nabi
Others: 1. Number of Foreman Instructor 2. Number of Feeder Man 3. Number of the workers i) Wet Blue ii) Crust iii) Finish
: 01 : 02 : 40 : 20 : 15
Administrative Management Chairman/Managing Director General Manager Production Manager Leather Technologist Mechanical & Electrical Engineer Machine Operator Labor
The tannery has following sections:
1. Wet blue.
2. Crust. 3. Finishing. The Tannery has the following machineries: Wet blue section: Name: Drum 2. Fleshing machine Crust section: 1.
Name: 1. 2. 3. 4. 5. 6. 7. 8.
Drum Shaving machine Setting machine Vacuum dryer Toggle dryer Vibration staking machine Testing drum Milling drum
Number : 20 : 01 Number : 08 : 01 : 01 : 01 : 01 : 01 : 01 : 01
Finishing section: Name: 1. 2. 3. 4. 5. 6. 7. 8.
Auto spray Hand spray Polishing machine Roto roller Kiss plate machine Buffing machine Measuring machine Hydraulic Press
Number : 01 : 01 : 01 : 01 : 01 : 01 : 02 : 01
PRODUCT RANGE: All kinds of drum dyed crust & finished leather such as:
1. Full chrome, semi chrome, full vegetable, natural & dyed crust. 2. Glazed shoe upper. 3. Softy shoe upper. 4. Garments leather 5. Nappa leather
Pull up, nubuck and burnished leather. Brush off leather. Lining leather. Shrunken grain leather. And also specific leather on customer's choice.
6.
7. 8. 9. 10.
Production Capacity: Daily Production: Wet Blue : 20,000 sq. ft Crust
: 20,000 sq. ft
Finish
: 4,000 sq. ft
Annual Production Capacity: Finish
: 20%
Crust
: 80%
Sister Organizations: Contact: Telephone
: +88029663815, +88029660384
: samina1@dhaka.net
Fax
: +88028614989
Responsible Technologists: 1.
Md. Rafiqul Islam
COMMENT ON TANNERY
The main feature of Samina Tannery (Pvt.) Ltd. is that it is very well-managed, disciplined and its plant layout is quite reasonable. It provides worker comfort and appraises customer satisfaction with great concern. They are very much devoted to quality improvement and quality maintaining. All the above factors were instrumental for this zenith position of Samina Tannery (Pvt.) Ltd. This tannery plays pivotal role in our leather industry and one can take Samina Tannery (Pvt.) Ltd. as a model of resurgent leather sector.
A BRIEF DESCRIPTION OF TANNERY WORK & OUR TRAINING Day: 01 13.11.2010 Introduction: Our training started on the 13 th November 2010. We were five students in a group. On the very first day our guide teacher ABDULLAH-AL-MAHMUD went to the tannery with us and introduces us with Mohiuddin Ahmed the senior technologist of SAMINA TANNERY LTD. We were also introduced with the authority and other personnel concerned with production. I was trained at the Wet blue section from 13-11-2010 to 06-12-2010. Leather technologist Md. Rafiqul Islam was our instructor. He was quite helpful to us. At this section we observed the following operations and mechanical process. WET BLUE Day: 02 14.11.2010 In wet-blue section, Technologist Md. Rafiqul Islam told us briefly about the tannery, its rules and regulation and different operations and functions of cow wet-blue section. He also helped us to observe the wet-blue section. We saw that the tannery was arranged sequentially. Day: 03 15.11.2010 In this section have about 40 workers. It has 20 industrial drums, and 1 fleshing machine. All the drums and machines are set-up sequentially. We saw large amount of raw hide is processed here every day. Many people work there and the Technologist, Tanner and supervisors guide them. All people worked very
attentively and carefully. We also observed that a large number of Raw or wetsalted cow hides piles in raw storage and selection and cow wet-blue piles in wetblue storage section. We are pleased and enjoyed to observe the leather manufacturing process in large production and acquired vast knowledge and idea and interested to do our training regularly. Day: 04 16.11.2010 Raw cow Hides Selection Today we observed the selection of raw and wet salted cow hides. Main selector with workers was engaged for this purpose. He selects the hides with eye observation and experience. He found out different defects from hides and made different lots of different grading. Grain damage, old ages, pin marks, flaying cut, damage by insets and birds, pox, virus, small size, action of hot water, scratch marks etc. were mentionable defects found in raw hides. Then we observed different machines.
Day: 05 17.11.2010 Trimming, curing, and weighing: This is the first operation which is performed after the entry of raw H/S (cured) into the tannery. In case of fresh H/S curing is also done. Weight is taken before starting chemical operation. Day: 06 18.11.2010 Soaking Operation Today we observed the soaking operation of cow hides. Soaking is the first tannery operation. During curing, hides and skins are large amount of its physiological content of water and unless the former regains this water during soaking operation, good quality leather cannot be produced. It is best done in two stages such as pre-soaking and main soaking. Pre-soaking which removes dirt,
dung and curing salts from hides and skins. The main soaking rehydrates the hides. Presoaking: In this process raw H/S are washed with water in drums or paddles. Main soaking: It is also washing of H/S with water and some chemicals which are wetting agents (LD607), bactericide (Busan-40L), and soda ash etc. It is done in drums. Objects of Soaking o
To remove the dirt, blood and dung from the hides and skins.
o
To remove the curing salt in case of salted hide and skins.
o
To rehydrate the skin protein.
o
To open up the contracted fibrous structure of the skins
o
To clean off surface filth.
o
Softening the hides and skins.
Recipe for Soaking Operation Presoaking:
200% Water Run 60 min. Drain well.
Main soaking:
Day: 07 20.11.2010 Liming:
200% Water 0.25% Wetting agent (LD-607) 0.2% Bactericide (Busan-40L) 0.25% Soda ash Run 30 min Run 2 min each hour Total time: 12-14hrs.
It is the treatment of H/S with milk of lime and sharpening agents. The intensity of liming is varied with the final product. Liming of cow hides and goat skins are done in drums. Buffalo hides are limed in paddle. The chemicals used in liming are liming auxiliary (Busperse 7743L), sharpening agents (Na2S) and lime (CaO). Objectives of Liming o
To remove simply hair.
o
To remove cementing substances.
o
Splitting up of fiber bundles.
o
To remove fat and grease.
Recipe for Liming Operation: 200% Water 0.5% Liming Auxiliary 0.25% Wetting Agent, Run 10 min. +2.0% Na2S 2% Lime , Run 60 min. +2% Na2S 2% Lime, Run 30 min. Total time: 16-18 hrs.
Day: 08 21.11.2010 Fleshing: It is done by fleshing machine. After fleshing the pelts are weighed. This weight is known as pelt weight. Next all the percentages of chemicals used are based on this weight. Scudding: This mechanical process is done to remove the hair roots. It is done with blunt knife.
Day: 09 22.11.2010
Weighing Operation After fleshing the pelt, trimming was done and then took weight and send for the next operation. We observed the weighting process. We saw 50 kgs weights were on one side of the balance and on the other side the pelt were measured. Day: 10 23.11.2010 Deliming: In this process lime used in liming is removed by washing with water and deliming agents. This process is also done in drums. In deliming mainly ammonium sulphate (NH4)2S04, sodium metabisulphite, ammonium chloride (NH4C1). Objectives of Deliming o
To remove most of the lime and alkaline materials from the pelt.
o
To reduce the swelling of the pelts.
o
Solubilization of Ca-soaps.
o
To remove flesh, scud etd.
o
To prepare for different Tannages.
Recipe for Deliming Operation
Day: 11 24.11.2010
50% Water 2% (NH4)2S04 0.5% Na-meta bisulphate 0.5% SNA Liquid, Run 45 min Check Cross section, with phenolphthalein Check PH: 8.3-8.2
Bating: It is a treatment of delimed pelt with enzyme and other chemicals to make the final leather soft, pliable and stretchy. Temperature is an important factor for this operation. It is done in drums. The chemicals used in this operation are alkaline bate (Oropon-G) and acid bate (Oropon BRS).
Objectives of Bating o
To make the grain surface of the finished leather clean, smooth and fine.
o
To remove some of the non-leather forming proteins materials like albumins, globulins.
o
The scud of dirt, short hairs, greases and lime soaps, dark colored pigments and traces of epidermis are all loosened and are easily to make the final leather soft, pliable and stretchy.
o
To allow the splitting up of collagen fibers.
Recipe for Bating Operation 0.8% Bating agent 0.5% Alkaline bate (Oropon-G), Run 60m +0.5% Acid bate (Oropon-BRS), Run 30-45 min +1.0% Degreasing agent (FA- 607), Run 15 min
Day: 12 25.11.2010 Pickling: It is the treatment of the bated pelt with acid and salt. This process makes the leather suitable for chrome tanning. Concentration of salt and acid is an important factor for this operation. P is another factor in this operation. It is done in drums. Objectives of Pickling o
To bring the delimed or bated pelts to a require degree of acidity before chrome tannage, even vegetable tannage.
o
To reduce the pH.
o
To modify the fiber structure.
o
To reduce the astringency of chrome tanning agents,
o
To preserve the leathers and to achieve the special effect.
Recipe for Pickling Operation 80% Water 8% Salt, Run 10 min, Check Bo: 6-7 + 0.25%Impropal CO, Run 10
+ 0.25%Formic acid, Run 15 min + 1.2%Sulphuric acid, Run 120 min + 0.25 Hypo, Run 20 min, Check PH: 2.6-2.8
Day: 13-14 27-28.11.2010 TANNING OPERATION In leather manufacture the most outstanding process is Tanning. The process of converting putrescible hides and skins into un-putrescble leather is called Tanning. The materials which are used for tanning are called tannins. There is various process of tanning such as chrome tanning, semi-chrome tanning, Vegetable tanning, Aldehyde tanning, Oil tanning, Zr-Tanning, Alum-Tanning, Wet-white Tanning etc. Objectives of Tanning o
To convert the putrescible hides and skins into un-putrescible leather.
o
To raise the shrinkage temperature and to increase the resistance to hot water of the leather.
o
To reduce the ability to swell when wet back.
o
To increase the strength properties of leather.
o
To stabilize the leather against enzymatic degrading.
Chrome tanning: It is the treatment of leather with chrome powder and then with basifying agent to fix the chrome. It is done in drums. Recipe for Chrome tanning: Drain half of the pickle bath + 1.0% Ingrasente 99E, Run 20 min + 4.0% Chrome, Run 1 hour + 4.0% Chrome Run 1 hour +0.5% SF Liquid, Run (0+10+10+40) min +0 .25% Busan 30 L, Run 15 min +1.0% NaHCO3, Run 2 hours +0.5%NaHCO3, Run 1 hour Check PH: 3.6-3.7, Unload and Pile up
Day: 15 29.11.2010 Name of some wet-blue chemicals used in Samina Tannery (Pvt.) Ltd. : •
LD 600 (ACI)
•
Busan 40L (Buckman)
•
Busan 30L (Buckman)
•
Soda Ash
•
Formic Acid (BASF)
•
Basic Chromium Sulfate (LANXESS)
Day: 16-20 30.11- 05.12.2010 Wet-Blue Leather Selection Today we observed the wet-blue leathers. After pre-tanning with Basic chrome powder the hides and skins are called wet-blue leather, as the color of the leathers is Bluish-Green. We saw many piles of wet-blue leathers in the tannery. It is necessary to age the wet-blue leathers for few days for better chrome fixation. Then we observed the selection of wet-blue leathers. Selector told about selection. He selected the leathers in accordance with grading. The leather of Grading 1,2,3 are kept in one lot, Grading 4,5,6,7,8 are kept in another lot and the much defected leathers are included in grading 9 and 10. The crust and finished leathers are manufactured from these wet-blue leathers according to customer’s demand.
Day: 21 06.12.2010
Drawing Plant Layout of wet-blue section of the Tannery: That day we drew the plan layout of Wet-Blue section of Samina Tannery (Pvt.) Ltd.
FLOW CHART OF THE PRODUCTION OF WET BLUE LEATHER FROM RAW HIDE & SKIN
Raw Hides & Skins Selection Trimming Weighing Presoaking Soaking Unhairing Liming Deliming Bating Pickling Chrome Tanning Wet Blue
Crust section
Responsible Technologists: 1.
Md. Fazlul Haque Tutul
2.
Md. Rafiqul Islam
CRUST I was trained in crust section from 07-12-2010 to 27-12-2010. Here we acquired detail knowledge of the following operations:
Day: 01 07.12.2010 Selection & Grading Today we observed the selection of finished and crust leather. The selector selected the leather according to grading. Good quality leathers were kept in grading1,2 & 3. Less defected leather in grading 7,8,9,10 or rejected according to the type of leather.
Day: 02 08.12.2010 Sammying to Shaving Today we observed the sammying, splitting and shaving machines and their functions. In this section there are sammying machine, splitting machine and shaving machine. Objectives of Sammying machine o
To reduce water from the leather.
o
To add the chemicals for next operation
Splitting The band knife splitting machine split the leather into two of more pieces if the leather is too thick. The object is to get the require thickness. Example: for shoe upper leather thickness = 1.3-1.4mm. Shaving The wet-blue leather are shaved to get require thickness. After shaving wet-blue Leathers are sent to crust section of Samina Tannery Ltd. for manufacturing of crust and finished Leather.
Day: 03 09.12.2010
Trimming and Weighing Day: 04 11.12.2010 Wet Back & Re-Chroming Operation Before retanning it is necessary to wet back the shaved wet blue/wet white leathers. It is done with acid, wetting agent and water. Acid is used to boring the leather of optimum pH for re-chroming. Re-chroming is done to increase the strength of leather, to fix more chrome into the leather, to increase the hydrothermal stability and shrinkage temperature, to improve the softness, fineness of the grain etc. 1. Acid Wash: This is the washing of wet blue/wet white leather with acid in drums. 2. Rechroming: Here chrome tanned leather is again treated with chrome and chrome syntan in
drums. Day: 05
12.12.2010 3.Neutralization: It is done to prepare the leather for succeeding operation i.e. dyeing and fat liquoring. P" of leather is strictly controlled in this operation. It is done in drums. Objectives of Neutralization o
To remove the neutral salts and uncombined chromium salts from the leather.
o
Neutralization of free acid in leather formed by the hydrolysis of the chrome complex.
o
To control the affinity of the leather for anionic materials, particularly dyestuff and anionic oil emulsions by regulation its electrostatic charge.
Day: 06 13.12.2010 4. Retanning: This process is done to impart combination of leather tannage to the leather.
Objectives of Re-Tanning Operation o
To fill the loose and softer parts of the leathers to produce leathers of more unirorm physical properties.
o
To allow for the production of unlined footwear.
o
The retannage may improve the chemical stability of the leather, particularly its resistance of alkalis and perspiration.
Day: 07 14.12.2010 Dyeing: Leather is treated with dye of required color. It is done in drums. Day: 08 15.12.2010 Fat Liquoring: 6.Leather is treated with emulsion of fat, fish oil etc. for softness of leather. Temperature is an important factor for this operation. Objectives of Fat Liquoring: o To improve the softness of the leather. o To improve the sliding properties of the leather. o To improve the toughness, water-repellent properties of the leather.
Day: 09 18.12.2010 Preparation of Production Recipe
Recipe for The Production of Black Shoe Upper: Shaved at: 0.9-1.0mm (Finally 1.1-1.3)
Acid Wash: Water
:
250%
Degreasing Agent (Busperse 7738)
:
0.2%
Acetic Acid
:
0.2%
Water
:
100% at 35째C
Formic Acid
:
0.2%
+Chrome Powder
:
5.0%
Chrome Syntan (Retaral CRO)
:
3.0%
Sodium Formate
:
1.0%
Chrome Stable Fat (Atlasol 177C)
:
1.0%
Run 60min
+Polymeric Tanning Agent (ICATAN 204)
:
2.0%
Run30min
+Water
:
50% at NT
Sodium Formate
:
1.0%
Run 15min
+Sodium Bicarbonate
:
0.8%
Run (10+10+40) min
Run 30min
Re-Chroming:
Run 10min
Check ph: 3.7-3.8 Leave Over Night Next Morning Run 15min, Drain & Wash
Neutralization: Water
:
100% at 35째C
Neutralizing Syntan (Tamol NA)
:
2.5%
Sodium Formate
:
1.0%
Run 30min
+Sodium Bicarbonate
:
0.5%
Run (15+30)min
Check pH:
4.5-4.8
Drain & Wash
Re-Tanning & Fat Liquoring: Water
:
100% at 35째C
Acrylic Resin (AR)
:
5.0%
Run 30min
+Mimosa
:
4.0%
Quebracho
:
2.0%
Tanigan OS (Replacement Syntan)
:
3.0%
Basyntan AN (Amphotaric)
:
3.0%
Neosyn N (Naphthalene)
:
1.0%
Run 30min
+Dye Leveller
:
0.6%
Run 10min
Dye (Black 3 TN)
:
2.5%
Run 60min
Check: Ø Penetration +Dicyandiamide (Syntan DF585)
:
5.0%
Run 60min
+Water
:
100% at 60°C
Synthetic Fat (Synthol FL327)
:
3.0%
Semi Synthetic Fat (Atlasol 23kpm)
:
3.0%
Sulphite fish oil (Vreka 400R)
:
1.0%
Lecithine (Provol BA)
:
1.0%
Lanoline (Vreka GFN)
:
1.0%
Neats Foot oil (Atlasol 30CT)
:
1.0%
Run 60min
+Styrene Maleic Resin (Raaral RST)
:
4.0%
Run 30min
+Formic Acid
:
2.5%
Run (10+10+30)min
Drain & Wash
Top Dyeing: Water
:
200% at 60°C
Basic Black LNI
:
0.8%
Acetic Acid
:
0.4%
Run 15min
+Basic Dye (5TN)
:
0.8%
Run 15min
+Formic Acid
:
0.8%
Run 15min
+Black Dye (5TN)
:
0.8%
Run 15min
+Formic Acid
:
1.5%
Run (5+5+30)min
Drain & Wash +Water
:
200% at NT
Cationic Fat (Catalix GS)
:
0.6%
Neats foot oil (30CT)
:
0.4%
Run 15min
Drain/Horse up O/N
Recipe for The Production of Shoe Lining: Acid Wash Same as Upper
Re-Chroming: Same as Upper
Neutralization: Water
:
100% at 35째C
Neutralizing Syntan (Tamol NA)
:
2.0%
Sodium Formate
:
1.5%
Run 15min
+Sodium Bicarbonate
:
1.0%
Run (15+15+45) min
Check pH:
5.2-5.5
Drain & Wash
Re-Tanning & Fat Liquoring: Water
:
100% at 35째C
Acrylic Resin (AR)
:
3.0%
Run 20min
+Fish Oil (400R)
:
2.0%
Run 10min
+Mimosa
:
3.0%
Tanigan OS (Replacement Syntan)
:
2.0%
Basyntan AN (Amphotaric)
:
2.0%
Neosyn N (Naphthalene)
:
1.0%
Run 30min
+Dye
:
0.6%
Run 30min
+Dicyandiamide (Syntan DF585)
:
3.0%
Run 60min
+Water
:
100% at 60째C
Synthetic Fat (Synthol FL327)
:
4.0%
Semi Synthetic Fat (Atlasol 23kpm)
:
3.0%
Sulphite fish oil (Vreka 400R)
:
4.0%
Lecithine (Provol BA)
:
4.0%
Neats Foot oil (Atlasol 30CT)
:
1.0%
Run 90min
+Styrene Maleic Resin (Raaral RST)
:
2.0%
Run 20min
+Formic Acid
:
2.5%
Run (10+10+30) min
Drain & Wash
Top Dyeing: Water
:
200% at 60째C
Basic Black LNI
:
0.8%
Acetic Acid
:
0.4%
Run 15min
+Basic Dye (5TN)
:
0.8%
Run 15min
+Formic Acid
:
0.8%
Run 15min
+Black Dye (5TN)
:
0.8%
Run 15min
+Formic Acid
:
1.5%
Run (5+5+30)min
Drain & Wash +Water
:
200% at NT
Cationic Fat (Catalix GS)
:
0.6%
Neats foot oil (30CT)
:
0.4%
Run 15min
Drain/Horse up O/N
Recipe for F/C Natural Leather: Acid Wash: Water
:
250% at NT
Degreasing Agent (Busperse 7738)
:
0.2%
Oxalic Acid
: Drain, Wash
0.6%
Run 30min
Re-Chroming: Water
:
100% at 35째C
Formic Acid
:
0.1%
+Chrome Powder
:
5.0%
Chrome Syntan (Retaral CRO)
:
3.0%
Sodium Formate
:
1.0%
Chrome Stable Fat (Atlasol 177C)
:
1.0%
Run 60min
+Polymeric Tanning Agent (ICATAN 204)
:
2.0%
Run30min
+Water
:
50% at NT
Sodium Formate
:
1.0%
Run 15min
+Sodium Bicarbonate
:
0.8%
Run (10+10+40) min
Run 10min
Check ph : 3.7-3.8 Leave Over Night Next Morning Run 15min, Drain & Wash
Neutralization: Same as Upper
Re-Tanning, Fat Liquoring & Dyeing: Water
:
100% at 35째C
Acrylic Resin (AR)
:
5.0%
Run 30min
+Bleaching Syntan (Syntan SA)
:
5.0%
Bleaching Syntan (Basyntan DLF)
:
3.0%
Tanigan OS (Replacement Syntan)
:
5.0%
Run 30min
+Dicyandiamide (Syntan DF585)
:
5.0%
Run 60min
+Water
:
100% at 60°C
Synthetic Fat (Synthol FL327)
:
4.0%
Semi Synthetic Fat (Atlasol 23kpm)
:
4.0%
Neats Foot oil (Atlasol 30CT)
:
1.0%
Run 60min
+Styrene Maleic Resin (Raaral RST)
:
5.0%
Run 30min
+Syntan SA
:
2.0%
Run 20min
+Formic Acid
:
2.0%
Run (10+10+30) min
Drain & Wash +Water
:
200% at NT
Cationic Fat (Catalix GS)
:
0.6%
Neats foot oil (30CT)
:
0.4%
Run 15min
Drain/Horse up O/N
Day: 10 19.12.2010 Name of some crust chemicals used in Samina Tannery (Pvt.) Ltd.: •
Busperse 7738 (Degreasing Agent)
•
Chrome Syntan (Retaral CRO)
•
Chrome Stable Fat (Atlasol 177C)
•
Polymeric Tanning Agent (ICATAN 204)
•
Neutralizing Syntan (Tamol NA)
•
Acrylic Resin
•
Mimosa
•
Quebracho
•
Tanigan OS (Replacement Syntan)
•
Basyntan AN (Amphoteric)
•
Neosyn N (Naphthalene)
•
Black 3TN (Dye)
•
Dicyandiamide (Syntan DF585)
•
Synthetic Fat (Synthol FL327)
•
Semi Synthetic Fat (Atlasol 23Kpm)
•
Sulphite fish Oil (Vreka 400R)
•
Lecithine (Provol BA)
•
Lanoline (Vreka GFN)
•
Neats Foot Oil (Atlasol 30CT)
•
Synthetic Maleic Resin (Retaral RST)
•
Cationic Fat (Catalix GS)
Day: 11 20.12.2010 Setting Operation: Today we observed the setting operation. It is done to reduce water and crease from the leather. There is a setting machine here. We saw that the operator and wprlers were busy for setting the Ecological tanned leathers, Black lining leathers, yellow lining leathers, black upper leathers in setting machine. Two rollers in setting machine pressed the leather. Objectives of Setting Operation: o
To reduce water from the leather.
o
To increase the area of the leather.
o
To remove the crease.
o
To increase the compactness of the leather.
Day: 12
21.12.2010 Vacuum Dryer: In order to dry the leather, Vacuum dryer is used where leather is dried under certain temperature and pressure. There is a vacuum dryer in this section. Four operators are engaged in these purposes and the workers helped them. They worked very rapidly. After every 30 seconds the platform of vacuum dryer pressed the leather and thus dried it. The pressure was 5 bars and temperature was 60째c. After vacuum, the leather was partially dried and produced smooth grain.
Day: 13 22.12.2010 Staking Operation Today we observed the staking operation. Staking is done to make the leather soft and smooth. There is a vibration staking machine in this tannery. Four operators were engaged for this purpose and four workers helped them.
Day: 14 23.12.2010 Toggle Drying: After staking, the leathers were sent to toggle dryer for drying. There was a continuous toggle dryer here. The object of toggling is to dry the leather by passing hot air into the toggle dryer and to stretch the leather i.e. to increase the area of the leather. Eight people were engaged for this purpose and six people helped them. They worked so fast with experience.
Day: 15 26.12.2010 Trimming: It was done to give the leather a suitable shape and to cut out the defected area of the leather.
Kiss-Plate:
This machine has another name hydraulic press machine. This machine applies heavy weight with plane plate on the leather. As a result, Smooth and glossy grain surface is appeared on the leather. There is an only hydraulic press in this tannery. By changing the plate of different design, the appearance of that plate produced on the leather.
Day: 16 27.12.2010 Observation of Leather Machines: Today chief mechanical engineer helped us to observed different machines present in this tannery and shortly described their functions.
Drawing Plant Layout of Crust section of the Tannery: That day we drew the plan layout of Crust section of Samina Tannery (Pvt.) Ltd.
FLOW CHART OF THE PRODUCTION OF CRUST LEATHER FROM WET BLUE/WET WHITE Acid Wash
Rechroming Neutralization Retanning Dyeing Fatliquoring Setting Vacuum Hang Drying Staking Toggling Trimming Plating Crust Leather
NEXT MORNING: Setting
Vacuum Drying at 60oC 1 min
Hang Dry (1 day)
Staking (2/3 pressure)
Toggle
Trimming
Plating
Crust Leather
Responsible Technologists: 1.
Mohiuddin Ahmed
2.
Md. Fazlul Haque Tutul
3.
Md. Rafiqul Islam
FINISHING From 29-12-2010 to 05-01-2010 I was trained in finishing section. He has given us a good overview of the finishing process. Day: 01
16.12.2010 Study on Finishing Definition of Finishing The last & most important operation in a tannery today is finishing where the Leather surface is coated with nice looking, colored or colorless, flexible, stretchy, durable film of some film forming materials. Finishes on Leather also serve as a protective coating.
Purpose of Finishing (1) Levelness of color on the Leather. (2) Uniformity of shape from Leather to Leather. (3) Changing the color to that which is required. (4) Giving a surface to the Leather varying from Matt to gloss. (5) Adding a transparent film through which the natural appearance of the Leather may be viewed. (6) Render the Leather fast to acids, alkalis & perspiration. (7) Render the Leather resistant to repeated flexing.
Different types of Leather Finishes: There are three different types of Leather Finishes, which are commonly used by Leather Finishes— (1)
Water type Finishes: --These may be based on pigments protein binders, such as casein, shellac, gelatin, egg & blood albumin, waxes & mucilaginous substances.
(2)
Solvent type Finishes: -- In contrast to water type Finishes solvent based Finishes contain as a binder either polyurethane or collodion cotton. These Finishes are dissolved in organic solvents such as butyl acetate, cyclohexanone etc.
(3)
Emulsion type Finishes: -- Emulsion type Finishes consists of emulsions of mtrocellulose’s or resins.
Preparation of the Finishes: Finishes should be prepared in the following order of additions: -(a) Pigment pastes & aniline dyes. (b) Plasticizers of the soluble oil type. (c) Protein binder thoroughly mixed with wax emulsion when desired (d) Mucilage’s, thickeners. (e) Water for dilution (f) Resin dispersion binders. (g) Fixatives (formaldehyde etc).
(h) Preservatives (para chloro- meta- cresol)
Day: 02 16.12.2010 Samina Tannery (Pvt.) Ltd. performs various types of finishing: 1. Aniline Finish: In Aniline Finish they use almost 100 dyes and no pigment. The leather produced in this way is of A to C grade. 2. Semi-Aniline Finish: In Semi-Aniline Finish they use 50 dyes and 50 pigments. The produced leather is of C to F grade. 3. Pigmented Finish: In Pigmented Finish they use almost 100 pigment and no dyes. The produced leather is of under F grade.
In finishing operation on crust leather they apply the following three coats: 1. Staining coat 2. Polishing coat 3. Season coat
In Season coat the following ingredients are generally used: 1. Casein 2. Resin 3. Wax 4. Filler 5. Poly Urethane 6. Modifier 7. Water
For finishing operation they use the following machinery: 1. Auto Spray 2. Polishing machine 3. Roto roller 4. Kiss plate 5. Buffing machine
Day: 03
16.12.2010 Auto Spray Machine: Today we observed the auto spray machine and its functions. There is an only auto spray machines in this tannery. In finishing this tannery specialize in natural looking aniline & semi-aniline finishes with good look & feel, following the latest market trends. The ranges of their finish products are: Aniline, semi-aniline, Glazed, Embossed, Plate, Milled, Burnish, Polished leathers etc. Today we observed the semi-aniline finish of cow leather by auto spray machines. This machine has microprocessor unit, which maintain the whole process and also has some spray gun that move roundly and spray on the leather. The leather is moving over the belt, the microprocessor. Then it gives instruction to the spray guns. When the leather passes through the spray gun chamber they continuously spray on the leather. Then it passes through for drying. All the operation is done automatically. The process is done in the following way:
Recipe for Semi-Aniline Finish: 1. Staining Coat:
Chemicals
Amounts in grams
Supernil HK Black (Clarient)
XX
Water
XXX
Iso Propayl Alcohol (IPA)
XX
1X Spray, Then Dry. 2. Season Coat:
Chemicals
Amounts in grams
Melio Resin 777A
XX
Melio Resin 931A
XX
Melio Resin 943A
XX
Lustraral UT
XX
Melio Top 288
XX
SFT F 6004
XX
Melio Wax 180
XX
Water
XX
Melio Promul 70
XXX
Pigment, Black PA
XX
Dye, S.HK. Black
XX
2X Spray, Then Dry. Sand Blast 70째C, 150 Pressure Again same solution 4-5X Spray, Then Dry well. 3. Top Coat:
Chemicals
Amounts in grams
Melio WG 348
XXX
Water
XXX 2X Spray, Then Dry. Check: 100% fastness
Day: 04 16.12.2010 Staking: There is an only staking machine here. Staking is done here by plain plate in staking machine at 70째C Temperature and 30-Bar pressure. Then staking by staking machine to make the leather soft and smooth.
Roto-Press Machine: Today we observed the roto-press machine. It is used to given glazy appearance on the leather. We observed the roto-pressing on cow shoe upper leathers. It is done at 110째C temperature and 40-Bar pressure.
Day: 05 16.12.2010 Selection & Grading:
Today we observed the selection of finished and crust leather. The selector selected the leather according to grading. Good quality leathers were kept in grading 1, 2& 3. Less defected leather in grading 7, 8, 9, 10 or rejected according to the type of leather.
Measuring: Today we also observed the measuring of finished and crust leather. There are two measuring machine here. The machines measure the whole area of the leather in square-feet. It can measure quickly and accurately. Then the value is calculated.
Day: 06 16.12.2010 Packaging: Finally the leather is packed for export according to buyers order.
Name of some finishing chemicals used in Samina Tannery (Pvt.) Ltd. : 1.
Luster (EARN SHOW)
2.
KT (EARN SHOW)
3.
CM 502(ALPA)
4.
FN (EARN SHOW)
5.
RA 2394 (STAHL)
6.
BAN (BASF)
7.
RU 3989 (STAHL)
8.
ARU (BASF)
9.
Etc
Day: 07 16.12.2010 Drawing Plan Layout:
That day we drew the plan layout of finishing section of Samina Tannery (Pvt.) Ltd.
Some Finished Leather Produced in Samina Tannery (Pvt.) Ltd.:
Report Preparation: Day: 01 08.01.2011 Information Collection: That day collect the information which is necessary for preparing our industrial training report.
Day: 02-05
09-12.01.2011 Report Preparation: Day 2-5 we prepared our training report and make the report signed by the trainer Md. Rafiqul Islam, Technologist of Samina Tannery Ltd.
Day: 06 13.01.2011 Report Submission: The day we submit our training report to our departmental office after making the report signed by our guide teacher.
Training Duration: We were introduced to the leather industry, Samina Tannery Ltd. and the technologist on 13th November 2010 by our honorable guide teacher Abdullah-al-Mahmud. Our industrial training started from that day and it lasted after two month 13 th January 2011.
Tannery Problems: Since tannery is a large production area, so it is natural to have some problems of it. Some problems that we noticed in the tannery are following: o
The environment of the tannery is not suitable for health.
o
The tannery has no Effluent Treatment Plant (ETP)
o
There is no proper drainage system.
o
The number of technologist is very few.
o
The salary of the leather technologist & workers is very low.
o
There is not proper air circulation system in the tannery.
o
They have not enough facility for research.
Conclusion: Leather Industry in Bangladesh is highly potential sector. Bangladesh has a large pool of cheap labor force and adequate supply of raw materials in this leather sector. Further hide and skin of Bangladesh have good demand in international market, because of
their fine fiber structure and grain. But it could not prosper much because of proper planning, well skilled manpower and executive skilled leather technologists.
REMARKS: From my point of view the sixty days industrial training is a very significant part of the coarse B. Sc in Leather Engineering. By attending this training our knowledge of leather manufacturing became more improved and matured. I think the college authority may arrange such training at the end of every year. During my training I found the sequencing quality controlling process supervision working efficiency of workers and technologist of Samina Tannery Ltd. is really appreciatable but their waste management industrial environment is up to the mark. The authority must be more concern about these. Finally all the best of Samina Tannery Ltd. and once again thanks for their friendly co-operation