Weaving without harness - Lubrication-free plastic bearings in innovative weaving machine

The UniShed 2 developed by Gitec GmbH is the world's first harnessless Jacquard weaving machine.

With the UniShed2, Gitec GmbH has developed a completely new type of weaving machine and therefore a real innovation. This is because the machines work without the electromechanical "harness" and instead utilise vibrating axles, which are supported in plain bearings from igus®. Bearing bushes made from the high-performance polymer iglidur® J3 are used.

The textile industry is closely associated with the name Jacquard: Around 1800, Joseph-Marie Jacquard invented the loom named after him in Lyon, which scans the individual weaving pattern via punched cards. He thus made an important contribution to factory automation and also to the development of computer technology: almost a hundred years later, pioneers such as Herman Hollerith used punched cards as data carriers for the first machines for automated data acquisition.

Problem

Permanent movements in 24/7 operation. The machines should have as much downtime as possible, because every standstill is associated with a lot of repair and maintenance work and costs.

Solution

With the iglidur® J3 material, a significant improvement in service life was achieved. The freedom from maintenance and lubrication ensures that no dust or dirt from the environment is bound to the bearing points.

"We initially used plain bearings from another manufacturer, which worked perfectly technically but were quite expensive. As the textile industry is very price-sensitive and each individual axis is stored many times, we switched to igus® bearings."

Roland Micheln, Head of Development at Gitec GmbH

The world's first harnessless jacquard machine

It was not until the 1980s that the punched card technology of the looms was replaced by electronic control systems. The basic mechanical principle has lasted even longer. The individual warp threads are moved by the so-called "harness system": this is a mechanical connection that raises or lowers each heald according to the desired pattern using hooks and pulleys or return springs. The individual harnesses are usually operated by magnets.

There is now a much more flexible alternative to this very complex principle. Gitec GmbH in Neu-Ulm has developed the UniShed 2, the world's first harnessless jacquard weaving machine. Each warp thread is individually controlled by a piezo actuator. A mechanical oscillation system replaces the traditional harness system with hooks and return springs.

Major advantages for new web principle

igus sales consultant Joachim Mayr and head of development at Gitec Roland Michel

This innovation offers numerous advantages. Head of Development Roland Michel "The machines allow absolute freedom in patterning because the process can be better controlled. They work extremely reliably because every single thread is monitored optically. The machines are also very compact and consume around 20 per cent less energy."

A first prototype of the UniShed 2 is already being field-tested by a user and others are being trialled at Gitec. The development is attracting a great deal of attention in the textile industry and Gitec expects sustainable market success: "We are convinced that the new principle will replace the old technology by 80 per cent."

Wanted: Highly stressable and lubrication-free plain bearings

One of the design challenges that had to be overcome when building the first prototype machines was the bearing support for the oscillating shafts, which have a diameter of 50 millimetres and are moved by servomotors via an electronic cardan drive. Roland Michel: "These bearings are subject to heavy loads, as the shafts oscillate and the systems work as endurance runners in 24/7 operation. At the same time, they have to manage without external lubrication because the mesh is generated underneath the shafts. We initially used plain bearings from another manufacturer, which ran technically flawlessly but were quite expensive. As the textile industry is very price-sensitive and each individual axis is stored many times, we switched to igus® bearings."

Newly developed polymer material in use

Originally, the standard material iglidur® J was planned, which as a genuine endurance runner material is very wear-resistant and has low moisture absorption. But according to the motto "the better is the enemy of the good", igus® developed the new material iglidur® J3, which is characterised by even better wear resistance. Depending on the application conditions, up to three times longer downtime is achieved compared to iglidur® J.

In addition, the moisture absorption of this material, which has been included in the standard programme along with 15 other high-performance polymers since the beginning of the year, is lower. This specification is also very important for Gitec, as Roland Michel explains: "Our machines are often used in countries where the humidity is very high. There, the plastic can swell during storage, which affects the bearing clearance."

New ways of airbag production

The machine, which is currently working in the technical centre in Neu-Ulm, is equipped with eleven modules, each with 128 piezo actuators. As each module is supported by two bearing bushes, there are 22 iglidur® J3 bushes with a diameter of 50 millimetres on each axis.

With the UniShed2 machines, Gitec is targeting the classic applications of Jacquard weaving machines such as clothing, home textiles and - in particular - technical fabrics made of polyester and polyamide as well as glass-fibre reinforced plastic/CFRP materials. New methods of airbag production are currently being tested in Neu-Ulm. Roland Michel: "Until now, the airbag bags have been sewn together from two parts that were previously cut to size and coated. With the UniShed2, we are now trialling the weaving of hollow bags from a single piece. This significantly simplifies the process."

As a subsidiary of a Chinese group that specialises in the textile production process chain, Gitec GmbH, which emerged from the long-established textile machinery manufacturer Grosse, also has direct access to the practice of industrial weaving: the parent company operates its own weaving mills near Shanghai, which produce sophisticated jacquard fabrics for technical applications.