Ring frame: Lower growth in modernization level, an alert to think beyond limitations

Ramakant Dubey

In spinning, ring frame is a machine that converts roving into yarn. The main component of ring frame machines are creel – drafting zone – spindle – ring – traveler; it has certain numbers of spindles per machine, and each spindle is a production center.

spinning Ring Frame machine — Courtesy: Rieter

Yarn produced in ring frame machine has to be of some structural parameters like twist per unit length (TPI or TPM) and weight per unit length (Count). These parameters along with yarn quality (imperfections, strength, evenness, hairiness and classimate faults) are spun on ring frame machine to meet the customer’s fabric requirements.

The productivity of ring frame spindle is measured as weight of yarn produced in a unit time. There are three major factors which decide the productivity of ring frame spindle.

Spindle speed (RPM)

Twist per unit length (TPI or TPM)

Yarn count.

Rest all other factors depend on these major factors directly or indirectly.

Yarn count and twist are the factors which in the yarn should be as per the requirement of the fabric construction; so the spinner is not allowed to alter these two factors subject to productivity gain. The spindle speed of ring frame is the only factor that allows a spinner to take advantage of higher productivity, with consideration of controlled performance and yarn quality.

Over the period of the last 30 years; machine manufacturers have designed ring frames components such that there is to some extent marginal improvement in productivity. During this period of 3 decades there is only 90% improvement in spindle speed, the main factor for productivity.

Therefore this growth of modernization in ring spinning can be remarked as lower growth, compared to rotor (open end) spinning; which has improved above 200% during this same time period.

Open end machine is also a yarn manufacturing machine, it has certain numbers of rotors per machine and each rotor is a production center. In the open-end machine, the main factors responsible for productivity are rotor speed, twist per unit length and yarn count; same as ring frame factors.

But in open end machine, manufacturers made developments in component and designs such that the improvement went to the noticeable stage and now in open end machine, term like meter/min instead of RPM are used for speed, it indicates that there are wide scopes for improvement in rotor speed in the near future.

In-ring frame machine, manufacturer’s keen focus on the installation of higher numbers of spindles per frame may be one of the reasons for this lower rate of growth in modernization of ring frame. They went on increase in numbers of spindles per frame above 300% during these 30 years and still their special focus on same cannot be denied.

It’s a wake-up alarm for the design development team because the spinner is concerned with the improvement in productivity, and productivity is measured per spindles; not per machine or frame.

Limitations against higher spindle speed

In-ring frame a set of spindle, ring and travelers plays an important role in producing yarn. Spindle speed is directly responsible for productivity; ring diameter depends on the count of yarn and it decides the bobbin/cop contain as well as the linear speed of traveler, so it can be understood that bigger size ring is used for coarser count worked at lower spindle speed and vies-versa.

The smallest component of ring frame machine is traveler. It is a metal loop, locked on the ring surface, which moves on the ring surface to impart twist into the yarn. Its linear speed is directly proportional to spindle speed and ring diameter.

Since the ring and traveler are metal bodies so during running it creates friction, thus heat is generated. Traveler can bear a certain amount of linear speed beyond which either it will get damaged due to overheating or will fly away from the ring due to the higher centrifugal force. So smaller diameter of ring is preferred to work higher spindle speed, preferably for finer count yarns.

From the above explanation, it can be understood that traveler, the smallest part of ring frame machine, is the biggest limitation against higher spindle speed. Moreover traveler has its life so at certain frequency of running it has to be replaced. And for different types and count of yarn it has to be selected precisely; a wrong selection can affect the quality as well as the productivity very badly.

Innovation - beyond limitations

The main objective of traveler is to impart twist into the yarn and to maintain the yarn tension. If these objectives are fulfilled by any other source then the traveler can be eliminated from ring frame machine.

The issue with traveler is that it has negative drive. If the Traveler gets positive drive there will be no friction and no heat generation; therefore the linear speed would never be the limitation.

A modified ring if given positive drive (same like the spindles) and the loop or hook is fixed on this ring; so the ring along with hook will revolve. It will full fill the purpose of imparting twist into yarn, and also yarn tension would be maintained.

Now with this concept, another limitation of ring size would be overcome and hence the bigger size ring can be installed. This bigger size ring would allow working all count range.

When this concept is applied, spindle speed would not be a hurdle for modernization of ring frame. The platform for a spindle speed of 40.....50.....60.....70 (x1000 rpm) and more would be ready. The hurdle would for yarn quality with such higher spindle speed. To achieve the quality of yarn at such higher spindle speed, few other concepts would be applied, and those concepts are also under consideration.

This concept will open a platform for the technician to perform their talents through a big series of innovations and developments. Advantages would be related to...