Textile

Quality control: a guidebook

Processes
0
798

The application of the Quality Control Guidebook is essential so that the spinning textile products possess all quality requirements able to meet the market demand. The proposed model refers to cotton spinning and is also valid, with appropriate corrections, for all other types of textile fibers spinning

Today, a modern textile fibers spinner requires a valid and efficient quality control of raw materials, semi-finished and finished products.

The function of the Quality Control is to maintain a constant and scheduled control of all technical operations related to the production, by logically gathering together the surveyed values and comparing them with quality standards; in this way it can cooperate with the Spinning Direction and provide qualified assistance to the technical Department.

In this view, within each company, the formulation of a Control Guidebook is to be considered as an essential tool for Quality Assurance in all textile fiber spinners.

The Quality Control Guidebook herein proposed, applicable in combed cotton spinning, consists of:

1) Plan of lab tests, with time and work schedule.
2) Control Methods.
3) Calculation formulas.
4) Handouts for results’ registration.
5) Comparison with qualitative standards.

Plan of lab tests (table 1)

Department
Control type           
Control frequency
Sample size
Card
Title and CV%
Uster%
Neps
Weekly
Weekly
Weekly
5 samples by 7 yds/card
1 test/card
1 test/card
Drawing frame
1° pass.
Title and CV%
Uster%
Daily
Daily
5 samples by 7 yds/capita
1 test/capita
Winder
rpm canvas
Weekly
1 test by 1m/canvas for 5 canvas
Combing machine
Title and CV%
Deviation
Uster%
Neps
Weekly
Weekly
Weekly
Weekly
5 samples by 7 yds/card
1 test for combing machine
1 test for combing machine
1 test for combing machine
Drawing frame
2° pass.
Title and CV%
Uster %
2 times/r
Daily
5 samples by 7 yds/capita
1 test/capita
Bench
Title and CV%
Uster %
Daily
Daily
2 samples by 10 yds/spool for 5 spools
5 spools/bench
Spinning machine
Title and CV%
Uster %
Resistance
Twist
Progressive in spinning machines
Progressive in spinning machines
Progressive in spinning machines
Progressive in spinning machines
10 reels by 120 yds/spinning machine
10 reels by 120 yds/spinning machine
10 reels by 120 yds /spinning machine
10 reels by 120 yds /spinning machine

The Plan of laboratory tests indicates, for each department and from carding to spinning operations, the kind of controls to be carried out on semi-finished products or on the yarn, the sampling frequency and the size of the samples.

The Plan in the example could include other equally useful tests, such as percentage of waste, the monitoring of machine failures or the calculation of inactive spindles but, as it is designed, the Plan is already absolutely valid for the enterprise’s quality assurance.

Logically, the implementation time of all controls depends on the automation degree of the lab equipment and the training degree of the operators. Once the time for each test is set, it is possible to fill in a document that highlights the total weekly time for the realization of the Plan. The work schedule results from the Plan of tests and Implementation Time; it plans daily schedules and assigns an operator to each test.