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Zamak components for textile machineries
In this post we analyze proprieties and applications of Zamak components for textile machineries. The textile sector is indeed an interesting sector considering the continuous technological research which makes indispensable the use of high-performance components capable of responding to high technical and production requirements.
Properties of Zamak components for the textile industry
In previous posts in this blog we described the properties of Zamak for the application in different industries, including: lighting, building, electronics, electromechanical, household appliances. As we have already observed, the chemical and physical properties of the raw material and the surface and finishing treatments to which the components can be subjected therefore make Zamak a versatile material, capable of satisfying various types of aesthetic, mechanical or safety requiremensts. For applications on textile machineries also.
The properties required to Zamak components for textile machineries are mainly mechanical: the components must be able to dampen the vibrations of the machinery on which they are installed, to resist the strong wear caused by the sliding of the wires on them and they must have, already during the casting phase as to reduce costs, a precision with very narrow tolerances of the shapes.
In this sector of application also, the fluidity of Zamak is therefore fundamental because it allows to obtain a high degree of detail and complex shapes directly during the casting phase. Moreover, it is also fundamental the excellent surface quality of the Zamak die casts.
Let’s now see in detail these three characteristics of Zamak that are so important for textile machineries components.
In the textile industry Zamak components are employed in rotor spinning with a single spinning head technology: a technology that can overcome the limits of belt drive and in which the use of antivibration materials is essential. Textile machineries of this kind can in fact have rotor rotation speeds up to 180K revolutions per minute, with an output speed of up to 300K thousand revolutions per minute. This is why it is fundamental to employ HIDAMET (High Damping Metals) raw materials, such as zinc alloys, to make components subjected to this kind of stress. Zinc alloys, in fact, have an excellent damping capacity and this is why they prove to be a perfect choice for this field of application.
To find out more on the anti-vibration properties of zinc alloys we suggest to read the essay of I. Ritchie, Z. Pan e F. Goodwin, Characterization of the damping properties of die-cast zinc-aluminum alloys that can be found here.
Wear resistance is a fundamental requirement for components installed inside textile machineries. The sliding of the yarn on the component in fact subjects it to strong stresses which, over time, could damage it by eroding it.
Wear resistance in Zamak components is achieved through different strategies. First of all, the die-casting technology with which the zinc alloys are treated allows to obtain a surface layer, called “foundry skin”, of about 0,2-0,3 mm. The dense fine-grained microstructure of the “foundry skin” gives the zinc components a wear-resistant surface, as reported in the table below.
|Abrasion Index (mm tenths)||Abrasion Index (mm tenths)||Abrasion Index (mm tenths)|
|Load 10 kg||Load 20 kg||Load 50 kg|
The tests were conducted on cylindrical specimens of 15 mm in diameter pressed on a hard cast iron disk, dampen with water carrying fine sand with a variable load. After a number of turns corresponding to a path of 10K cm, the thickness of the removed layer is measured. The value, expressed in tenths of a millimeter, provided the relative abrasion data. Zamak alloy, in the conditions in which the tests were carried out, is less consumable than ordinary brass while it is lower only than the 90/10 bronze. (The reported data derive from: L. Andreoni, Quaderno della colata a pressione delle leghe di zinco, Le leghe di zinco, Zama, ed. Edimet, Brescia, 1998).
Another strategy to increase the resistance of Zamak components for textile machineries is to subject them to specific surface treatments. In this case the components are placed on a tray immersed in a chemical bath where, thanks to the rotation given to the tray, they are able to absorb the chemical agent which, depositing itself on the surface, turns into a protective coating.
Possibility to obtain complex shapes and surface quality
The fluidity of Zamak allows to fill even the smallest cavities of the mold obtaining, already during the casting phase, small details and complex shapes. This property proves to be fundamental in an industry, such as the textile industry, in which the tolerances are very narrow and the components, to fulfill their mechanical function, are assembled together.
To deepen your knowledge on these themes we suggest you to read Thin walls thickness: a competitive advantage in zinc die casting.
Surface quality is also an important requirement for components intended for textile machineries. In fact, surface defects such as irregularities, bubbles or burrs could damage the yarn breaking it. Even in an industry such as the textile industry, where the requirements for the components are mainly mechanical, the possibility of obtaining an excellent surface quality directly during the casting phase and of being able to carry out various types of treatments and processes is therefore important.
To find out more on the surface treatments that is possible to carry out on Zamak components we suggest to read Coating, plating and other kind of surface treatments and Processing techniques for metal finishing.
Review of Zamak components for textile machineries
After analyzing the charateristics that make Zamak an excellent raw material for the production of components for the textile sector, let’s now examine some products that allow us to shed further light on the applications of zinc alloy die casting useful in this sector.
The adapter is part of the spinning unit of rotating frames. In detail, it is installed on the machines that produce the type of cotton thread called “open end”: a thread intended for thick fabrics such as those of jeans or some shirts and which is opposed to the finer thread that is obtained in two phases, a first phase in which short pieces are made and a second in which the pieces are spliced generating an endless thread.
The component is placed in series on machines with 300/500 units, each independent in the production of cotton thread starting from cotton that is washed and centrifugated in order to make it homogeneous.
All the properties illustrated above are fundamental for this component: the anti-vibration property allows to dampen vibrations and it prevents the thread from slipping, the wear resistance allows the surface not to deteriorate, the fluidity of Zamak allows to obtain, directly during the casting phase, the details that are visible in the image of the post while the surface quality proves to be fundamental for keeping the yarn intact.
Feed Tray Bracket
Feed tray brackets are component derived from the assembly of two articles: feed table and holder.
Both the feed table and the holder have holes inside which magnets are installed, the assembly is therefore possible by magnetic force. The feed tray bracket, differently from the adapter, does not come in direct contact with the yarn and for this reason no particular surface qualities or resistance to wear are required. Zamak, in this case, was chosen for two fundamental reasons: the anti-vibration property and the possibility of obtaining a high degree of detail directly during the production phase.
The anti-vibration property is essential because the component is inserted in a jack rotating at 180K revolutions per minute and, if not able to dampen vibrations, it would risk hitting the other components with which it is in contact causing damage and breakage. The possibility of obtaining a high degree of detail results important for the making of the features of the object, such as, for example, the housing of the magnets that allow the assembly of the article.
In this post we analyzed some Zamak components that can be made for textile machineries, solutions that allow to illustrate the properties of zinc alloys and that result as a winning choice for this kind of mechanical applications.
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