Home » Karl Mayer Sizing doc , Learning Doc » GUIDE FOR USING THE SIZING MACHINE
Sizing was created to give the threads forming the warp the following features:
· sufficient resistance to abrasion
· even elongation and tension
· outer coating to reduce their hairiness as much as possible.
These features must aid a smooth passage of the sized thread along the loom path (warp stop-motion, heddles and comb) to ensure a perfect formation of the step thus achieving a fault-free fabric, or at least the best possible fabric. For a correct sizing the type of used yarn must always be considered, as well as the type of weaving by which it has been produced; in the end the weave used in the loom to obtain the fabric (cloth, twill, sateen...). The choice of the sizing products is also very important, as well as their concentrations and application methods to avoid unwished rheologies in the following processing steps.
For example, if the fabric must be dyed it is indispensable to use completely biodegradable sizes to avoid unpleasant effects of moirè colours or uneven shades. Again, some products cannot be compatible with the following treatments: the use of polyvinyl alcohol at certain concentrations without a previous suitable washing at the singeing could polymerize the PVA residues with crystallizing effects of the products on the fabric, with negative results.
Other example, sizing products - that can be hardly removed at low temperatures, during the dyeing steps in continuous lines with few preliminary washing tanks - can jeopardize the dyeing itself.
Besides the above remarks, it is clear the sizing aids, together with other factors, the weaving output and quality; thus, the sizing operator must know everything concerning the re. yarn: physical features, previous and following treatments and on which machine types to obtain the product final step.
Please, consider that each type of fiber and thread requires different products, machinery, processings and methods.
This little guide will deal and clear the use of a sizing machine for short fibers (cotton, wool, blends... ) with drier with water steam heated cylinders, with size boxes with one or two soakings and simple or double squeezing. There are 3 control parameters for the thread physical features:
1) elongation
2) resistance to abrasion and dynamometric resistance
3) hairiness
1) First of all, it is always to be considered that the sized yarn must have a residual elongation equal to 70% of its original elongation; this requirement can be achieved only if all threads show the same tension already while forming the warp beam.
Thus, a good sizing requires a perfect warping, needing in its turn a bobbin winding as careful as possible.
Considering that a perfect finished products can be influenced by yarns coming from different lots, all this indicates how much careful each step of the textile processing must be. Coming back to warping, yarns coming from the same lot should be used, forming bobbins with even tension and the same meterage.
Creels should be equipped with suitable tension units according to the tensions to be exerted on the single threads to guarantee an unwinding and winding on the fractional or sectional beam as much perfect as possible (for cotton, on beams flange 1000, the peripheral difference should not exceed 3 mm); they should also be equipped with more sensitive machine stop systems, as accurate as possible, for a warper fast and accurate intervention to restore any breakage. After these initial remarks, a steady control of the thread tensions in every section of the sizing machine is needed to check the its draft % that can influence directly the size absorption in the size box.
2) The resistance to abrasion and the dynamometric resistance are factors ensuring an efficient treatment on the weaving machines; the choice of the sizing products, together with a more and more perfect control of the processing parameters ensures output standards that are higher and higher and above all reproducible.
Considering the remarkable influence of the products on the warp behaviour in the machine, it is always recommended to discuss or process recipes with the suppliers (above all when processing new items very different from the previous ones).
The positive effect by the use of paraffin treatment or the use of special products, such as antistatics or others, to improve the friction coefficient in the loom yarn guide components should also be considered.
3) The thread outer hairiness is a factor that can be improved and solved with suitable measures and using suitable products; the correct values for squeezing, drying cylinder temperatures and warp tensions in the separation table are thus fundamental. It can be easily understood that a sudden opening of the various thread layers, above all if still too wet, besides breaking the outer film of the applied size, also significantly increases the presence of surface fibers not wound in the thread body, that while weaving could originate the defect of inwound dust, increase the warp breakage and thus decrease the loom output, increase the dustiness in the loom rooms.
As for the squeezing, the right compromise must be searched for each warp type between size penetration inside the thread and outer coverage of the thread itself. The thread twist coefficient is thus extremely important; a yarn oe should usually have a @ of 115-150, while a ring yarn 100-110 (cotton base).
Before considering the setting of the different working parameters it is advisable to consider a few fundamental basis for a perfect warp preparation. It is thus recommended:
· to check the alignment of the fractions on the creel;
· to unwind the warp beams carefully, possibly fixing the layer of threads of each single fraction with some adhesive tape to prevent thread overlaying or crossing;
· the sequence of the various beams must be made according to the required treatment type, if sizing with 1 or 2 size boxes according to the number of threads, always considering that a high density of threads/cm over 85% jeopardizes a good sizing. This is why it is advisable to separate the warp for the passage in 2 size boxes.
Coming back to the arrangement of the warping beams there are several possibilities, all correct and functional, even if some ensure an even easier intervention for repairing the broken or crossed threads, and some other are more suitable for the continuous dyeing - sizing lines.
Let's see the most used ones:
1) this is the most used solution, enabling an even unwinding of the warp beams
2 ) this is the solution used most frequently in the continuous systems, where a safe splitting is strictly necessary
3 ) this unwinding ensures a perfect intervention possibility, giving the operator the possibility of restoring the breakage without any interference among beams
4) this is the ideal solution for linen yarns, both with dry and wet process.
Many other solutions can be adopted, but it is anyway advisable to not to make the beams rotate in the same direction, so as to avoid possible warping faults to multiply while sizing; another important factor is the easy availability of separation or classifying bands (usually, thin bands of twisted yarn in polyester or nylon are used, even better a flat braided cord).
It is also advisable to separate the 2 halves practically to aid the selection in the dry splitting range.
While sizing, the threads could break and wind on the size box rollers, above all on the squeezer lower rollers.
In this case the operator will notice a sudden separation of the warp chain on the drying cylinder, clearly indicating a breakage with relevant thread winding. First of all, the operator must separate the layer of threads entering the size box, so as to insulate on the side the thread ring formed on the cylinder.
Now the machine can be stopped and it is possible to intervene cautiously: have the system started up with the aid of another operator using the installed man push button.
To remove wound thread, it is advisable to use the suitable curved knife taking care not to etch nor to dent the squeezing cylinders and the teflon-coated cylinders; thus, the blade must always be laid flat making the knife slide on the surface and thus cutting the thread.
Special care must be paid to introducing the suitable separation wires: they must be introduced while starting between the fraction layers, starting from the center line (the one dividing the upper and lower layers).
Be careful and avoid some threads to deviate from their position and to cross reciprocally.
The comb rising is also very important, as it must occur only when the layers are well separate and stretched and the threads are well parallel.
This operation can be made following different methods according to the warp coming from a sectional or fractional warper.
In the first case some operators use a comb with flat teeth and positioning it at the exit of the drying cylinders, immediately after the passage of the so-called cross-piece, they take it up to the comb of the head and lift it.
In the second case, instead, a valid system is positioning some adhesive tape on the cylinder before the waxing device after all the classifying and adhesive tapes applied to each single layer have passed; take it up to the comb taking care not to disarrange the thread carpet.
Another system, always for chains coming from fractional warpers, is dividing the threads on the comb starting from the center and, after a suitable calculation for an exact splitting, then arranging them in suitable number on each teeth passage.
After this operation (both introducing the wires and separating the comb) the warp length is adapted according to the height of the loom beam; obviously, also the choice of the pressing rollers must adapt to the loom beams.
A parameter for a machine correct operation, but above all to ensure an excellent thread treatment both while sizing and later while weaving, is the preliminary setting of the tensions in the various machine points according to the item being processed. Considering the total number and the count of the warp threads, first of all the weight in g/m and the coverage degree are calculated. With these 2 parameters it is possible (by using the enclosed tables) to set the machine operating values and to understand if the type of machine available is the most suitable one for the required treatment.
The decision of using 1 or 2 size boxes depends on the coverage degree (threads/cm * working table); for size boxes with double traditional squeezing this value must not exceed 85%; with the new prewetting systems (our type MPD - PW) it must be equal to 105%.
If the value of the coverage degree is higher, it is necessary to split the warp in 2 layers and then operate on 2 size boxes.
· sufficient resistance to abrasion
· even elongation and tension
· outer coating to reduce their hairiness as much as possible.
These features must aid a smooth passage of the sized thread along the loom path (warp stop-motion, heddles and comb) to ensure a perfect formation of the step thus achieving a fault-free fabric, or at least the best possible fabric. For a correct sizing the type of used yarn must always be considered, as well as the type of weaving by which it has been produced; in the end the weave used in the loom to obtain the fabric (cloth, twill, sateen...). The choice of the sizing products is also very important, as well as their concentrations and application methods to avoid unwished rheologies in the following processing steps.
For example, if the fabric must be dyed it is indispensable to use completely biodegradable sizes to avoid unpleasant effects of moirè colours or uneven shades. Again, some products cannot be compatible with the following treatments: the use of polyvinyl alcohol at certain concentrations without a previous suitable washing at the singeing could polymerize the PVA residues with crystallizing effects of the products on the fabric, with negative results.
Other example, sizing products - that can be hardly removed at low temperatures, during the dyeing steps in continuous lines with few preliminary washing tanks - can jeopardize the dyeing itself.
Besides the above remarks, it is clear the sizing aids, together with other factors, the weaving output and quality; thus, the sizing operator must know everything concerning the re. yarn: physical features, previous and following treatments and on which machine types to obtain the product final step.
Please, consider that each type of fiber and thread requires different products, machinery, processings and methods.
This little guide will deal and clear the use of a sizing machine for short fibers (cotton, wool, blends... ) with drier with water steam heated cylinders, with size boxes with one or two soakings and simple or double squeezing. There are 3 control parameters for the thread physical features:
1) elongation
2) resistance to abrasion and dynamometric resistance
3) hairiness
1) First of all, it is always to be considered that the sized yarn must have a residual elongation equal to 70% of its original elongation; this requirement can be achieved only if all threads show the same tension already while forming the warp beam.
Thus, a good sizing requires a perfect warping, needing in its turn a bobbin winding as careful as possible.
Considering that a perfect finished products can be influenced by yarns coming from different lots, all this indicates how much careful each step of the textile processing must be. Coming back to warping, yarns coming from the same lot should be used, forming bobbins with even tension and the same meterage.
Creels should be equipped with suitable tension units according to the tensions to be exerted on the single threads to guarantee an unwinding and winding on the fractional or sectional beam as much perfect as possible (for cotton, on beams flange 1000, the peripheral difference should not exceed 3 mm); they should also be equipped with more sensitive machine stop systems, as accurate as possible, for a warper fast and accurate intervention to restore any breakage. After these initial remarks, a steady control of the thread tensions in every section of the sizing machine is needed to check the its draft % that can influence directly the size absorption in the size box.
2) The resistance to abrasion and the dynamometric resistance are factors ensuring an efficient treatment on the weaving machines; the choice of the sizing products, together with a more and more perfect control of the processing parameters ensures output standards that are higher and higher and above all reproducible.
Considering the remarkable influence of the products on the warp behaviour in the machine, it is always recommended to discuss or process recipes with the suppliers (above all when processing new items very different from the previous ones).
The positive effect by the use of paraffin treatment or the use of special products, such as antistatics or others, to improve the friction coefficient in the loom yarn guide components should also be considered.
3) The thread outer hairiness is a factor that can be improved and solved with suitable measures and using suitable products; the correct values for squeezing, drying cylinder temperatures and warp tensions in the separation table are thus fundamental. It can be easily understood that a sudden opening of the various thread layers, above all if still too wet, besides breaking the outer film of the applied size, also significantly increases the presence of surface fibers not wound in the thread body, that while weaving could originate the defect of inwound dust, increase the warp breakage and thus decrease the loom output, increase the dustiness in the loom rooms.
As for the squeezing, the right compromise must be searched for each warp type between size penetration inside the thread and outer coverage of the thread itself. The thread twist coefficient is thus extremely important; a yarn oe should usually have a @ of 115-150, while a ring yarn 100-110 (cotton base).
Before considering the setting of the different working parameters it is advisable to consider a few fundamental basis for a perfect warp preparation. It is thus recommended:
· to check the alignment of the fractions on the creel;
· to unwind the warp beams carefully, possibly fixing the layer of threads of each single fraction with some adhesive tape to prevent thread overlaying or crossing;
· the sequence of the various beams must be made according to the required treatment type, if sizing with 1 or 2 size boxes according to the number of threads, always considering that a high density of threads/cm over 85% jeopardizes a good sizing. This is why it is advisable to separate the warp for the passage in 2 size boxes.
Coming back to the arrangement of the warping beams there are several possibilities, all correct and functional, even if some ensure an even easier intervention for repairing the broken or crossed threads, and some other are more suitable for the continuous dyeing - sizing lines.
Let's see the most used ones:
1) this is the most used solution, enabling an even unwinding of the warp beams
2 ) this is the solution used most frequently in the continuous systems, where a safe splitting is strictly necessary
3 ) this unwinding ensures a perfect intervention possibility, giving the operator the possibility of restoring the breakage without any interference among beams
4) this is the ideal solution for linen yarns, both with dry and wet process.
Many other solutions can be adopted, but it is anyway advisable to not to make the beams rotate in the same direction, so as to avoid possible warping faults to multiply while sizing; another important factor is the easy availability of separation or classifying bands (usually, thin bands of twisted yarn in polyester or nylon are used, even better a flat braided cord).
It is also advisable to separate the 2 halves practically to aid the selection in the dry splitting range.
While sizing, the threads could break and wind on the size box rollers, above all on the squeezer lower rollers.
In this case the operator will notice a sudden separation of the warp chain on the drying cylinder, clearly indicating a breakage with relevant thread winding. First of all, the operator must separate the layer of threads entering the size box, so as to insulate on the side the thread ring formed on the cylinder.
Now the machine can be stopped and it is possible to intervene cautiously: have the system started up with the aid of another operator using the installed man push button.
To remove wound thread, it is advisable to use the suitable curved knife taking care not to etch nor to dent the squeezing cylinders and the teflon-coated cylinders; thus, the blade must always be laid flat making the knife slide on the surface and thus cutting the thread.
Special care must be paid to introducing the suitable separation wires: they must be introduced while starting between the fraction layers, starting from the center line (the one dividing the upper and lower layers).
Be careful and avoid some threads to deviate from their position and to cross reciprocally.
The comb rising is also very important, as it must occur only when the layers are well separate and stretched and the threads are well parallel.
This operation can be made following different methods according to the warp coming from a sectional or fractional warper.
In the first case some operators use a comb with flat teeth and positioning it at the exit of the drying cylinders, immediately after the passage of the so-called cross-piece, they take it up to the comb of the head and lift it.
In the second case, instead, a valid system is positioning some adhesive tape on the cylinder before the waxing device after all the classifying and adhesive tapes applied to each single layer have passed; take it up to the comb taking care not to disarrange the thread carpet.
Another system, always for chains coming from fractional warpers, is dividing the threads on the comb starting from the center and, after a suitable calculation for an exact splitting, then arranging them in suitable number on each teeth passage.
After this operation (both introducing the wires and separating the comb) the warp length is adapted according to the height of the loom beam; obviously, also the choice of the pressing rollers must adapt to the loom beams.
A parameter for a machine correct operation, but above all to ensure an excellent thread treatment both while sizing and later while weaving, is the preliminary setting of the tensions in the various machine points according to the item being processed. Considering the total number and the count of the warp threads, first of all the weight in g/m and the coverage degree are calculated. With these 2 parameters it is possible (by using the enclosed tables) to set the machine operating values and to understand if the type of machine available is the most suitable one for the required treatment.
The decision of using 1 or 2 size boxes depends on the coverage degree (threads/cm * working table); for size boxes with double traditional squeezing this value must not exceed 85%; with the new prewetting systems (our type MPD - PW) it must be equal to 105%.
If the value of the coverage degree is higher, it is necessary to split the warp in 2 layers and then operate on 2 size boxes.