4 Dyeing Quality Issues with Rope Dyeing Machine

Rope dyeing machine, also known as rope dip dyeing machine. It is a type of equipment for interweaving thin silk, wool, cotton, and chemical fiber materials with loose, normal temperature rope dip dyeing. It is appropriate for many textile printing and dyeing operations, including loose rope scouring, dyeing, washing, and others. (An additional rope dyeing machine utilized in the denim facility will not be included in this article.)

Types of rope dyeing machine

Wool, silk, cotton, and their mixed knitted textiles, as well as chemical fiber imitation fabrics that are unsuitable for tension and pressing, are the major materials rope dyeing machines are used for.
Additionally, it may be used to scrub, bleach, soap, and wash various silk, cotton, and cotton-blend knit materials. This is due to the elongation, chafing, and loosening that certain textiles are prone to. Dyeing and processing machinery should meet the special requirements of these fabrics with low tension and low friction.
At present, there are several sorts and variations of this apparatus. Ordinarily, there are four types of the dyeing equipment:

1. Normal temperature and normal pressure rope dyeing machines.
2. Normal temperature and normal pressure overflow dyeing machines.
3. High temperature and high pressure overflow dyeing machines.
4. Jet dyeing machines.

Dyeing Quality Issues

Knitted fabrics are pre-treated, colored, and finished mostly in rope dyeing machines. The brief duration of this process is one of its distinguishing features. In a tubular shape, the knitted cloth can be directly pre-treated and coloured. During the processing, the tension on the fabric is minimal. And the rope dyed knitted fabric has a nice feel to it.
However, because of the influence of the dyeing process and the structural characteristics of the rope dyeing machine itself, this type of method will also have dyeing quality issues. Dyelot chromatism, tube difference, stripes, and wrinkles are some examples.

1．Dyelot chromatism

Rope dyeing of knitted materials mostly use batch dyeing equipment, which are appropriate for small batches and a wide range of colors. Unlike the continuous dyeing machine, the batch dyeing machine has a restricted one-time cloth capacity. If the capacity of a single machine is exceeded by a batch of the same dyed fabric, it will be dyed in different cylinders or batches.
Dyelot chromatism will occur even if the same tank is dyed in batches or the same dyeing procedure is completed in different tanks of the same model. The reason for this is that the conditions of use differ. Differences in water, steam, electricity, and industrial operations are examples. And the equipment operation circumstances of multiple machines at different periods or different machines all at once. Even the features of different main circulation pumps of the same type, as well as the production and performance of components, may differ.
Of course, in actual applications, the dyelot chromatism generated by this reason must be kept within an invisible to the naked sight range.
As a result, in order to eliminate the influencing elements in this regard, the present knitted fabric rope dyeing machine is trending toward a multi-tube or multi-dyeing tank design. The dyelot chromatism exists whether in the same tank or in other tanks of the same model.
However, in actual applications, separate cylinder dyeing (finger colouring the same fabric) is unavoidable; instead, investigate how to better manage the dyelot chromatism within the permissible range.
The dyelot chromatism can be regulated within the prescribed range if the reasonable dyeing process and the specified operation technique are combined with a dyeing machine with good structural performance and sophisticated control, and the entire dyeing process is fully automatic controlled.

2．Stripes

Knitted fabric stripes are classified as weft (crosspiece) or warp (longitudinal). Warp stripes are common in pure cotton knitted textiles. This is because the weft-knitted tubular fabric is not blown open as it exits the guiding roller. And the stripes appear in areas that have not been opened and folded in a long time. Another issue is that the nozzle aperture is too tiny, causing the fabric to be excessively tight when passed through in a bundle. As a result, the cross-sectional area of the rope-like knitted fabric should ideally not exceed two-thirds of the nozzle diameter.
Weft and warp stripes appear on polyester knitted garments. The reasons are not only related to cylindrical expansion and nozzle diameter, but also due to structural tensions created during the weaving process. This structural tension is released during initial wet work at a certain temperature. If the pretreatment is rope-like, it produces weft or warp prints. And there will be streaks during the coloring process.
As a result, real experience demonstrates this. When using the open width pretreatment as the initial wet treatment. It has the ability to completely relax the structural tension of retracting knitted materials, preventing stripes during rope dyeing. In most cases, this procedure may be carried out concurrently with refining.

​This blog is reproduced from 4 Dyeing Quality Problems of Rope Dyeing Machine.