By Alex Marques, Associate Product Manager
Griffith Textile Machine Ltd is a manufacturer of luxury carpets. The company uses its in-house machinery to produce over 250,000 square meters of carpet per year for hotels, museums, golf courses, restaurants, and public houses. Built for high duty cycles in a dusty operating environment, the company’s Griffith Projectile Carpet Weaving Machine faced challenging performance demands. The machine’s linear guidance systems needed to deliver reliable motion with low maintenance — which is why the OEM turned to vee guide technology.
In one of these in-house machines, the Griffith Fast Ax2 carpet weaving machine, engineers chose the HepcoMotion GV3 linear guides. This 4-meter-wide machine produces carpet with up to twelve colors of wool woven in an endless pattern repeat. The Fast Ax2 is fully computer-controlled and produces carpet at three times the rate of previously available machines — 700m² of carpet in 24 hours. Griffith has two of these machines in their factory.
The Fast Ax2 is fitted with a jacquard patterning mechanism that enables the individual selection and lifting of the different colored wool threads to produce various patterns and designs. The jacquard that selects the colors runs horizontally on the GV3 slides. 8 double-edged spacer slides are equally spaced out along the 4-meter machine. 16 carriage plates with cap seals (2 carriages for each slide) are mounted directly to the machine. Connected to a motor-driven shaft, GV3 slides are used to guide the jacquard back and forth 130mm to select the required color yarn, continually repeating the cycle every 0.5 seconds, selecting the colors according to the pattern.
Hepco GV3, from Bishop-Wisecarver, is a vee-based linear motion offering that is designed to serve a diverse range of automation and linear applications.
Griffith was faced with several challenges when specifying linear guidance for this machine. A primary consideration was the harsh environmental conditions of carpet manufacturing. Carpet weaving produces a significant amount of dust and fibers from the materials, which can cause mechanical damage. If particles of dirt and debris breach the seals, or the seals become damaged, the system will jam, and motion will be impeded. This can result in catastrophic failure. The GV3 is suited to this harsh environment because its vee guide system operates using matching angled profiles on the track and guide wheels. This geometry provides a wiping action that expels debris, keeping machines running and reliable. This self-cleaning action eliminates contamination of the guide track.
Another fundamental requirement for this application is the need for accurate and repeatable guidance. The jacquard must move freely and repeatedly to the correct position, with as little variation in height as possible. Any vertical or rotational play in the guide wheels would cause a variation in height which directly causes quality problems to the carpet. With its precision ground running surface, GV3 provides a low-friction and highly accurate system for providing smooth indexing of the jacquard.
Speed is also an important consideration. The jacquard moves 130mm in 0.5 seconds, but it must move at a very constant speed. If the bearing is not running smoothly, for example, this would result in a change in speed, which would cause the wrong color to be woven into the carpet. Hepco GV3 system has a high level of built-in compliance that enables consistent running along the whole length, ensuring proper selection.
Another critical point with vee guide technology is that only a small amount of lubrication is required to prevent wear of the slide, and in some instances, it can also run dry. This was important for Griffith, not only to avoid any contamination with the fabric but also to avoid the debris and fibers sticking together and building up on the slide. Cap seals with felt wipers are used to provide sealing and protection, and to aid in wiping off debris from the slide profile. The vee guide wheels themselves are lubricated for their expected life.
With the Fast AX2 working 24 hours a day, five days a week — that equates to approximately 250,000 cycles every week. For over 10 years, the machine has woven over 20 million cycles with the same GV3 guide wheels.
Filed Under: Linear motion • slides