K 42 achieving top speeds with good yarn quality also in China
by Yun Wu, Product Management Ring Spinning and Combing,
Machines & Systems.
Customers in China requested for the Rieter compact-spinning
machine K 42 to run at slower speeds than it does in other
countries. They expressed concerns that high spinning speeds
would lead to higher ends down rates, and subsequently trigger a
rise in wage costs. Rieter conducted trials at a Chinese
customer to prove that the K 42 is a master at balancing high
speeds and low ends down rates.
Spinning mills can successfully sell their yarn only when the
quality is right and the production costs are low. With this in
mind, Rieter sees its task as developing machinery that will
allow spinning mills to cut their costs. Production speed plays
a key role in this regard. Increasing the speed boosts overall
production, which results in a reduction in yarn production
costs. Using high-performance machines is, therefore, key to any
spinning mill being profitable.
Fig. 1: The compact-spinning machine K 42 can
achieve better results than
those currently being achieved in China.
Ruling out all risks
The compact-spinning machine K 42 (Fig. 1) runs at lower
speeds in China than in other countries. In India, for example,
weaving yarns of pure cotton in Ne 60 and Ne 80 yarn counts are
run at speeds of up to 25,000 rpm (for Ne 60) or 23 000 rpm (for
Ne 80). The same yarn counts are run at a maximum speed of just
18 500 rpm in China.
Chinese customers do not operate their machines at higher
speeds because this could lead to higher ends down rates. If the
accepted maximum of 15 ends down per 1000 spindle hours were to
be exceeded, it would bring about an increased risk of higher
wage costs. There is also an assumption that higher speeds will
result in lower yarn quality, in terms of hairiness in
particular. Chinese customers, therefore, want to ensure that
their machines work soundly and deliver good quality, which is a
perfectly normal requirement. However, this does mean that they
are missing out on the chance of high productivity. Trials
conducted at a Chinese customer are set to disprove the
widespread concerns of spinning speeds being too high.
30% more yarn with the same quality
In a joint project with a Chinese customer, Rieter took the
opportunity to increase the speed of the current compact -
spinning machines K 42. Additional parameters such as yarn count
and elongation, as well as technology components, remained
unchanged. For instance, the original spinning speed of 16,500
rpm was increased incrementally to 21,500 rpm for a weaving yarn
of Ne 60. The result was a rise in productivity by 30.3% and a
consistently good yarn quality (Fig. 2). For weaving yarn of
count Ne 80, the speed was increased from 18,500 rpm to 20,500
rpm, resulting in a 10% rise in production. Although the yarn
quality was slightly worse, it still met the customer's
Fig. 2: With 30% higher production, the Ne 60 yarn
quality is of virtually the same standard.
Ends down and hairiness also at a
When increases are made to the spinning speed, Chinese
customers focus, in particular, on the ends down and hairiness
of the yarn. Both aspects were tested with every incremental
increase. Even when run at higher speeds, the ends down rate
fell below the maximum permitted ends down of 15 per 1000
spindle hours, while the hairiness remained virtually unchanged,
as shown in Fig. 3.
The trial results therefore clearly showed the concerns of
Chinese customers regarding maximum production with the K 42 to
be unfounded. Key requirements included the precise centering of
components such as the yarn guide, balloon control ring and
spinning ring as well as an incremental increase in speed.
A 30% increase in speeds provides a 14% decrease in yarn
production costs. For example, in a project involving
compact-spinning machines K 42 with a total of 50 000 spindles,
the customer could achieve an annual increase in profits of CHF
750,000, based on running 350 days, 24 hours a day.
Fig. 3: The number of ends down per 1000 spindle
hours and the hairiness
reached a very good level, even at high speeds.
Spinning mills that use Rieter compact spinning machines can,
therefore, run at high speeds, and with good yarn quality. This
is made possible by the unique spinning geometry. A systematic
approach is required to fully utilize the potential of the K42.
In doing so, factors such as raw material and technology
components must be considered, as well as machine settings and
climate control. In comparison to competitor machines, the K 42
can spin affordable yarns at a good level of quality, enabling
all Rieter customers to assert themselves strongly in a