Checking and Control Points of Dyeing:
Dyeing is a method which imparts beauty to the textile by applying various colors and their shades on to a fabric. Dyeing can be done at any stage of the textile manufacturing, such as fiber, yarn, fabric or a finished textile product including garments and apparels. It is one of the complex processes in textile industry. So, dyeing textile materials is definitely complex task for textile engineers. Crucial factors during dyeing are leveling, dye penetration, and authenticity. During dyeing operation, textile engineer should give deep concern on the some points and controls. He should give proper instruction to his supervisor or operator to do all the work as per schedule. If any faults occur during dyeing operation then it will impact on overall process.
Fig: Dyeing mill
It is important to have clarity on the points to be controlled in dyeing to achieve the targets and those to be checked to ensure the process in control. These checking and control points need to be reviewed from time to time and modified to suit the requirements of individual factories and their targets. Each mill should prepare its own ‘Checking Points and Controlling Points’ and display them in the work area so that the people refer and follow. The control points and checkpoints are to be decided by the type of the machine, the type of fabric processed, normal customer complaints and the problems faced earlier in the process.
List of Checking and Control Points of Dyeing Process:
Checking points and control points of dyeing process are point out below-
Checking points of dyeing operation:
a) Material related:
The fabrics received against the plan received for dyeing
The quantity of fabric received for loading in dyeing machine – meters and kilograms
b) Machine related:
The condition of the machine
The working of various valves and controls
Condition of the spray nozzles
c) Setting related:
The speed set
Number of ends (runs) set
The recipe prepared
d) Performance related:
Uniformity of shade throughout the fabric
The shade obtained against the requirement
Fastness properties of the dyed materials
e) Documentation related:
The design number and the shade dyed
Quantity dyed
f) Work practice related:
The cleaning of the dyeing machine thoroughly before loading the material.
Proper alignment of the batch while loading on to machine.
Proper closing of the door while dyeing process is on in case of vat and reactive dyeing.
Proper cleaning of spray nozzles.
Removing of the water completely and refilling with fresh water in each wash.
g) Logbook related:
Machines working
Starting time of the running lots
Activities done and to be done
h) Management information system related:
Dyeing machine number
Design number
Number of meters
Weight in kilograms
Color used
Chemicals used
i) General:
Use of safety gadgets such as gloves and gum shoes while handling chemicals
Removing the completed batch and delivering to the next process
Control points of dyeing process:
1. The raw material type and quality, dyes and chemical’s requirements for the orders received and placing indents.
2. Deciding and selection of process parameters, viz., machine setting, mercerising time and temperature, stretch%, stretching time and temperature, caustic lye concentration, washing and neutralising sequences, batch size and liquor ratio.
3. Water quality, the softness, turbidity and purity.
4. Employing qualified and trained employees.
5. Reviewing the dyeing capacities and planning activities for the orders received for dyeing.
6. The package dimensions required depending on the capacity in dyeing machine.
Providing the required containers, balances and safety equipments.
10. The dyeing operation sequence.
11. Deciding on chemicals and their quality to be procured.
12. Evolving production norms.
13. Evolving norms for consumption of chemicals, water and steam.
14. Deciding on quality of raw materials to be procured.
15. Deciding the dyeing operation sequence, time, temperature, steam pressure, liquor ratio, number of cycles, number of washes, etc.
16. Determination of after treatment depending on the dye and depth.
17. Determination of acceptance criteria for fastness, friction values, shade variation between and within lots, whiteness index in case of bleaching, and the physical properties of final yarn.
References:
Handbook of Value Addition Processes for Fabrics By B. Purushothama
Handbook on Fabric Manufacturing: Grey Fabrics: Preparation, Weaving to Marketing by B. Purushothama
Training and Development of Technical Staff in the Textile Industry by B. Purushothama
Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. Mr. Kiron is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.
