Q: What are the main causes of frequent yarn breaks after doffing when restarting the machine?

A: The causes are mainly as follows:

  • Wire traveller is too light, resulting in a large balloon when starting, causing yarn breaks.
  • Improper doffing operation: If the tail yarn left after inserting the tube is too long, it can get entangled with the normal yarn balloon when starting, causing breaks.
  • Incorrect stop time: If the tail yarn is too long, it forms a small braid and breaks when restarted; if too short, the ring rail pulls and breaks the yarn.
  • Incorrect stop position during doffing, causing the ring rail not to properly straighten the yarn balloon during restart.
  • Related to start-up speed: If the initial speed is too low, the balloon cannot be thrown out; if too high, the yarn breaks directly.
  • Improper setting of the traveller clearer distance, or mismatched traveller shape, which may cause collision or snagging.
  • Ring rail too low, causing tail yarn to wrap around the spindle.
  • Low yarn strength, although this is less likely.

Q: Our ring spinning frames use inverters, but several touch screens at the end of the machine are unresponsive. What could be the cause?

A:  A touch screen is essentially a type of sensor, comprising two main components: the touch detection device and the touch screen controller.

The detection device senses the touch location and transmits the data to the controller. The controller interprets this into coordinates and corresponding commands, which are sent to the PLC, and receives PLC commands in return.

If the touch screen becomes unresponsive, the issue could lie in either or both components.

Possible issues and solutions with the detection device:

  • Dirty screen surface, affecting touch sensitivity – clean the screen regularly.
  • Position drift – recalibrate the screen using the “center calibration” function.
  • Static interference – eliminate static electricity.
  • Aged touch glass – replace if necessary.

Possible issues and solutions with the controller:

  • Poor signal cable contact or damaged communication port – check and repair.
  • Faulty circuit board – repair or replace.
  • Touch screen system address error – reset the address.

Q: Some spindles on the ring frame are producing thick roving yarn and hard yarn heads, with a roving twist multiplier of 110. What’s the reason?

A:  First, identify if the problematic spindles are fixed or random positions.

If fixed positions, issues may include: low pressure from the drafting arm, improper position of rollers or top apron, incorrect or misplaced spacer blocks.

If random spindles, the reasons might be:

  1. Process parameters are on a critical edge.
  2. Poor roving evenness, such as thin and thick spots.

You can optimize the process or adjust the roving draft accordingly.

In general, shorter back roller spacing, lower arm pressure, and smaller spacer blocks can all cause thick roving yarn. If you’re spinning 100% cotton, a roving twist multiplier of 110 is acceptable.

Q: For 40s cotton yarn, some spindles have fiber accumulation in the yarn clearer. What can be done?

Ring spinning machine

Ring spinning machine

A: Suggestions include:

  • Too small floating zone leads to short fibers accumulating. Increase the floating zone slightly.
  • Static electricity – sprinkle a small amount of talcum powder and enlarge the floating zone.
  • Check if certain spindles have poor roller conditions, such as uneven coating or surface damage.
  • Misalignment of top apron or yarn clearer can cause reduced floating zone spacing.
  • Contact between clearer and top apron due to small floating zone or improper installation.
  • Uneven or unclean pressure bar may affect the floating zone.
  • Inspect top aprons and rollers’ condition.
  • Ensure drafting zone cleanliness.
  • Roller surfaces should be anti-static.
  • Yarn clearer should be made of or structured with anti-static materials.
  • Check workshop temperature and humidity.

Q200: For 100% cotton 40s yarn, with a 18x38mm draft spacing, back draft multiple ~1.25, roving hank 6.5g, CV ~16.5, how can we reduce the CV value?

A: Here’s how to reduce CV from a process perspective:

  • Optimize blowroom and carding to protect fibers, reduce fiber damage and short fiber content.
  • Proper drawing and roving settings to increase fiber parallelization.

In spinning：

  1. new-type top aprons or pressure bars and spacers.
  2. Choose high-elasticity, low-hardness, self-cleaning rubber rollers.
  3. Optimize draft settings.

Regarding your fiber length, based on your setup:

  • Try reducing back draft ratio to 1.14–1.18.
  • Slightly increase roving twist multiplier.
  • Reduce front draft spacing to 17.2–17.5mm, depending on fiber length, strength, and roller diameter.

Although not guaranteed, these are worth trying as experiments.