The electronics sector is booming, as are all the sectors that supply it. The production and processing of fine glass filaments is one of the sectors that is profiting from the growing demand for electronic components.
These yarns, with their high elastic modulus, are used in the reinforcement layers of circuit boards.
Demand for them is particularly high in Asia, where they are being processed in increasing volumes. A new yarn tensioner has been developed by KARL MAYER to ensure that the best possible warps are produced for the subsequent manufacturing processes.
This new yarn tensioner in the AccuTense range is known as the AccuTense 0º Type C. It operates smoothly, handles the yarn gently, and is ideal for processing warp beams made up of non-stretch glass yarns. It can operate from a yarn tension of 2 cN up to a tension of 45 cN. The lower value defines the minimum tension for removing the yarn from the package.
The AccuTense 0º Type C can be used in all the current types of creels for processing filament yarns. This innovative device is mounted horizontally and can be fitted with a non-contact yarn monitoring system, without needing any modification.
The results of an internal customer survey of market requirements, together with the extensive expertise of KARL MAYER in the field of yarn tensioners, played a key role in the development of the AccuTense 0º Type C.
Design modifications
Like all the models in the AccuTense series, the AccuTense 0º Type C is a hysteresis yarn tensioner, which operates along the principles of eddy-current braking. The advantage of this is that the yarn is handled gently, since the thread is tensioned by an induction-dependent, rotating wheel and not by frictional points directly at the yarn itself. The wheel is the key element in this new tension control system.
It consists of a flat cylinder with tapering sides in the middle, and the conventional version is equipped with the AccuGrip surface on which the yarns run. The yarn is tensioned by being clamped at a 270º wrapping angle. With the AccuTense 0º Type C, the polyurethane AccuGrip yarn wheel is replaced with a version made from aluminium plated with hard chromium, and the design is also different. The new rotating ring is wrapped 2.5 to 3.5 times and produces the tension by adhesive force, rather than by the clamping effect as used to be the case.
This seemingly simple process is the result of extensive development work carried out at KARL MAYER. When wrapping is carried out several times, it is imperative that there is no clamping or superimposition between the ingoing or outgoing yarns and the wrapping yarns.
The side surfaces have been specially designed to ensure that the yarn layers are separated cleanly, i.e. there is a defined angle between the conical taper and the parallel holes. This means that the yarn runs into the yarn tensioner, moves by one layer thickness upwards for each revolution, and exits again without being damaged – and this principle offers many advantages.
Advantages for the yarn and the handling procedures
This new principle of multiple wrapping means that the filaments are not damaged and there is no abrasion. The yarn is also handled gently by the change in the entry and exit direction of the yarn. With the conventional versions, the entry and exit sides are opposite to each other.
The yarns are deflected by an additional guide to avoid adjacent devices from colliding when they are arranged parallel to each other. This additional friction point puts stress on the yarn. The handling processes are also increased compared to the new system with entry and exit from the same side.
Another advantage of the AccuTense 0º Type C in terms of user friendliness is that the pre-tension can be adjusted easily. This can be done simply by adding or removing weights, without having to use a screwdriver. It is also easier to adjust the new yarn tensioners in relation to each other, which is an advantage in terms of maintaining the accuracy of the yarn tension throughout the entire creel.
