A high duty cycle and a need for low maintenance in a highly dusty environment were the challenging performance demands from Griffith Textile Machine Ltd (GTM) looking for a linear guide for their Griffith Projectile Carpet Weaving Machine. Having worked with linear motion expert HepcoMotion for a number of years, GTM were quick to turn to Hepco to specify the linear motion component.
Griffith is a leading innovator of technical textile machinery. With over 30 years of experience, Griffith design and manufacture carpet machinery and accessories, Rapier Hand Looms, as well as special machine builds for 3D weaving, composites and non-woven’s. Griffith also manufacture Axminster carpets for prestigious environments, from hotels, museums and golf courses, to restaurants and public houses. Using their in-house machinery, Griffith produce in excess of 250,000 square metres of bespoke carpet per annum.
It is in one of these machines, the Griffith Fast Ax 2 high speed carpet weaving machine, that Hepco’s GV3 linear guides are used. This 4 metre wide machine produces high quality, high value Axminster carpet. The machine is fully computer controlled and can use up to twelve colours of wool in the surface of the carpet, with an endless pattern repeat. This loom produces carpet at three times the rate of previously available machines. The Fast Ax 2 can produce 700m² of carpet in 24 hours and Griffith have two of these machines in their factory, producing carpet 24 hours a day, 5 days a week.
The Fast Ax2 is fitted with a jacquard patterning mechanism which enables the individual selection and lifting of the different coloured wool threads to produce a wide variety of patterns and designs. The jacquard that selects the colours runs horizontally on the GV3 slides. 8 x double edge spacer slides are equally spaced out along the 4 metre machine. 16 x 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 colour yarn, continually repeating the cycle every 0.5 seconds, selecting the colours according to the pattern.
Hepco’s core product, GV3, is a superior V-based linear motion range that is designed to serve a diverse range of automation and linear applications. Ideally suited to this application, GV3 is durable, reliable and low maintenance and confidently able to work in harsh environments.
Harsh and dusty environment
Griffith was faced with a number of challenges when specifying for this machine. A pertinent consideration was the environmental conditions of carpet manufacturing. Carpet weaving produces a significant amount of dust and fibres from the materials, which can cause mechanical damage. If particles of dirt and debris find their way beyond the seals, or if they become damaged, the system will become jammed and motion will be impeded. This can result in catastrophic failure – meaning excessive downtime, and a complete system change. GV3 is ideally suited to this harsh environment thanks to its V guide system that functions on the basis of tight geometrical control over matching slide and bearing V’s. In turn this provides a wiping action that expels debris, keeping machines running and reliable. This self-cleaning action eliminates contamination of the slide – a key benefit for Griffith working with extensive carpet fibres and debris.
Testament to GV3’s rugged construction, the Fast Ax2 has been in operation for 10 years and the bearings have never been changed. Moreover, even in the demanding environment, they have not required any maintenance, saving Griffith costly and inconvenient downtime.
Accurate and constant – key requirements
A 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 bearings 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 ideally suited to providing smooth indexing of the jacquard.
The 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 colour to be woven into the carpet. Hepco’s V guide system has a high level of built-in compliance that enables consistent running along the whole length, ensuring accurate selection.
Lubrication
One key point with V 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 fibres sticking together and building-up on the slide. Cap seals with felt wipers are used which provide effective sealing and protection, plus wiping of debris from the slide profile.
Challenging cycle requirements
The Fast AX2 works 24 hours a day, five days a week which equates to approximately 250,000 cycles every week. Over a 10 year period, the machine has woven over 20 million cycles with the same GV3 bearings. These high duty cycles are demanding for a clean environment, let alone a harsh environment such as this.
The Fast Ax 2 has now been in operation at Griffith for over 10 years, and Griffith has also sold these machines to carpet manufacturers worldwide including China, South Africa and Abu Dhabi to name but a few. GV3 has once again proven to be a reliable, low maintenance product eminently capable of working in harsh environments.
