Circular Knitting Machine Troubleshooting: 12 Common Problems & Solutions

A circular knitting machine running 30-35 RPM produces over 50,000 stitches per second across 100-plus feeds. At that speed, a single misaligned needle or inconsistent tension value becomes a visible defect within meters of fabric. The cost isn’t just the defective fabric — it’s the downtime to diagnose and fix the problem, which compounds fast when you’re running 24/7 production.

This guide covers the 12 most common circular knitting machine problems, what causes them, and how to fix them quickly. It’s written for operators and production managers who need to get machines back running, not for engineers designing new equipment. For a complete breakdown of needle types and their applications, see our circular knitting machine needle types guide.

How to Use This Guide

Each problem follows the same structure:

• Symptoms: What you’ll see in the fabric or hear from the machine
• Root Cause: The most likely mechanical or process issue
• Fix: Specific steps to resolve it

For complex issues that require machine-level disassembly, note the relevant component sections in our circular knitting machine maintenance guide.

Problem 1: Holes in Fabric

Symptoms: Small, randomly distributed holes in the knitted fabric. Often appear suddenly and persist until the cause is found.

Root Causes:

• Broken or bent needle hook
• Needle latch stuck open
• Groove on needle cylinder wall damaged
• Yarn tension too high, causing yarn to snap and leave a gap

Fix:

1. Stop the machine and inspect the needle cylinder. Look for needles with visibly bent hooks or latches that don’t close fully.
2. Check the needle groove walls for scoring or burrs — even a small burr can catch yarn and create holes.
3. Verify yarn tension with a tension gauge. Compare against the yarn manufacturer’s recommended tension range.
4. Replace any damaged needles immediately. Keep spare needle strips on hand for the gauges you run most often.

Problem 2: Uneven Horizontal Stripes

Symptoms: Visible horizontal lines or bands across the fabric width, often repeating at regular intervals.

Root Causes:

• Inconsistent yarn tension across feeds
• Needle cylinder not level (concentricity issue)
• Yarn feeder height or angle incorrect
• Uneven yarn package tension (some packages feeding tighter than others)

Fix:

1. Measure yarn tension at every feed position using a tension gauge. Variation should be within ±10% of target.
2. Check needle cylinder concentricity with a dial indicator. Runout should be under 0.05mm for fine-gauge machines.
3. Verify all yarn feeders are at the same height and angle. Even a 2mm difference visible at production speed.
4. If the problem appears after changing yarn packages, check that all packages are the same lot and have similar residual tension.

Problem 3: Yarn Breakage

Symptoms: Frequent yarn breaks, especially at specific feeds. Machine stops repeatedly, killing productivity.

Root Causes:

• Tension set too high for the yarn count
• Rough surfaces on yarn guide ceramic eyes
• Yarn quality issues (weak spots, excessive knots)
• Incorrect yarn path through the feeder

Fix:

1. Reduce tension incrementally — try 10-15% lower than current setting and monitor break rate.
2. Inspect yarn guide ceramic eyes for cracks or roughness. Replace any that feel rough when you pull yarn through by hand.
3. Check yarn quality: pull-test several packages for consistent strength. Reject packages with visible weak spots.
4. Verify the yarn path matches the diagram for your specific feeder type. Lycra feeders in particular are sensitive to path geometry.

Problem 4: Dropped Stitches (Laddering)

Symptoms: Vertical lines of dropped stitches running down the fabric, creating a ladder-like appearance.

Root Causes:

• Needle latch not closing properly (wear or damage)
• Insufficient yarn feed — needle doesn’t catch enough yarn to form a loop
• Cam timing off — needle rises at wrong point in the cycle
• Yarn too slippery for the needle hook profile

Fix:

1. Inspect needle latches on the affected feeds. A latch with too much play won’t close consistently.
2. Increase yarn feed slightly — the yarn loop needs to be large enough for the hook to catch reliably.
3. Check cam timing if the problem appeared after maintenance. The needle rise point relative to the yarn feed angle is critical.
4. For slippery yarns (silicone-coated, some synthetics), consider needles with deeper hook profiles or serrated hooks.

Problem 5: Oil Stains on Fabric

Symptoms: Oil spots or streaks on the fabric, usually near the needle cylinder area.

Root Causes:

• Over-lubrication of needle cylinder or cams
• Oil leaking from the central lubrication system
• Condensation mixing with oil in humid environments

Fix:

1. Reduce oil flow rate. More oil doesn’t mean better lubrication — excess oil drips onto fabric.
2. Check the lubrication system for leaks, especially around the cylinder oil ring.
3. In humid environments, use oil with better water separation properties.
4. Clean the needle cylinder thoroughly to remove accumulated oil, then restart with proper lubrication levels.

Problem 6: Fabric Slippage (Off-Cylinder)

Symptoms: Fabric not pulling down evenly from the cylinder, bunching or riding up on one side.

Root Causes:

• Take-down tension too low
• Cloth roll not aligned with the cylinder
• Uneven stitch height around the cylinder circumference
• Knife or fabric cutter not engaging properly

Fix:

1. Increase take-down tension evenly on both sides.
2. Realign the cloth roll so it’s perfectly centered under the cylinder.
3. Check stitch height consistency — if some feeds are knitting tighter than others, the fabric won’t pull down evenly.
4. Inspect the fabric cutter blade for wear or misalignment.

Problem 7: Needle Breakage

Symptoms: Sudden increase in broken needles. Machine may make a clicking or grinding noise before a needle snaps.

Root Causes:

• Incorrect needle gauge for the yarn being run
• Cam profiles worn, causing excessive needle acceleration
• Needle butt hitting cam edges due to timing issues
• Poor-quality needle steel (brittle, not enough flexibility)

Fix:

1. Verify needle gauge matches yarn count. Running thick yarn on fine-gauge needles will snap them.
2. Inspect cam surfaces for wear scallops. Worn cams accelerate needles too aggressively at the bottom of the stroke.
3. Check cam-to-needle butt clearance. Too tight causes impact loading; too loose causes erratic motion.
4. When replacing needles, buy from reputable manufacturers. Cheap needles snap more often and damage cams with fragments. For a full range of compatible needles and sinkers, check our circular knitting machine factory price guide.

Problem 8: Sinker-Related Defects

Symptoms: Yarn not properly looped, fabric with inconsistent loop structure, or visible vertical lines.

Root Causes:

• Worn sinker tips (they control loop length)
• Sinker cam timing off
• Sinker bed not parallel to needle cylinder
• Accumulated lint in sinker slots

Fix:

1. Measure sinker tip thickness — worn sinkers produce longer, inconsistent loops.
2. Verify sinker cam timing relative to needle timing. Sinkers must retract at the right moment for clean loop formation.
3. Check sinker bed parallelism with a dial indicator.
4. Clean sinker slots thoroughly. Lint accumulation prevents sinkers from moving freely, causing irregular loops.

Problem 9: Lycra/Elastane Feeding Problems

Symptoms: Lycra yarn not feeding into the fabric, appearing on the surface instead of being buried in the knit structure. Or lycra breaks frequently.

Root Causes:

• Lycra feeder angle or height incorrect
• Lycra tension too high (it stretches and snaps)
• Covering yarn (cotton or polyester) not wrapping the lycra cleanly
• Wrong needle type for lycra-covered yarn

Fix:

1. Adjust the lycra feeder so the yarn feeds at a shallow angle — too steep causes the yarn to ride on top.
2. Lycra tension should be very low. The covering yarn provides the main tension; lycra should feed almost freely.
3. Verify the covering yarn wraps the lycra with sufficient overlap. At least 360° coverage is needed for a clean bury.
4. Use needles with a slightly deeper hook to catch both the lycra and covering yarn reliably.

Problem 10: Bird’s Nests (Yarn Accumulation)

Symptoms: Clumps of tangled yarn accumulating under the needle cylinder or around yarn feeders. Machine may jam.

Root Causes:

• Yarn feeding too freely (too little tension)
• Yarn packages damaged or deformed, causing uneven unwinding
• Static electricity causing yarn to cling to machine parts
• Wrong yarn path causing loops to catch on machine components

Fix:

1. Increase yarn package brake tension slightly — yarn should feed smoothly without surging.
2. Inspect yarn packages for damage. Deformed packages don’t unwind evenly.
3. In dry environments, consider anti-static bars near the yarn feed zone.
4. Verify yarn path from package to feeder to needle — no loops should be able to catch on guides or brackets.

Problem 11: Clicking or Grinding Noise

Symptoms: Unusual sounds from the needle cylinder area. May be intermittent at first, then worsen.

Root Causes:

• Worn cam surfaces causing needle butts to jump instead of glide
• Needle butt broken or chipped
• Insufficient oil on cam tracks
• Foreign object (broken needle fragment, screw) in the needle bed

Fix:

1. Stop the machine immediately. Running with metal-on-metal contact causes cascading damage.
2. Inspect the needle bed under good lighting. Look for broken fragments or foreign objects.
3. Check cam surfaces for bright wear marks or scoring.
4. If the noise came on suddenly, the most likely cause is a broken needle fragment lodged somewhere in the mechanism.

Problem 12: Inconsistent Fabric Weight (GSM)

Symptoms: Fabric GSM varies across the roll or between production batches, exceeding acceptable tolerances.

Root Causes:

• Needle cylinder eccentricity (wobble)
• Inconsistent yarn lot-to-lot count variation
• Take-down tension varying during production
• Feeders not all set to the same stitch length

Fix:

1. Check needle cylinder runout with a dial indicator. More than 0.05mm eccentricity causes visible GSM variation.
2. Verify yarn count consistency across packages being used simultaneously. Mixing lots with different counts creates variation.
3. Monitor take-down tension throughout the roll — tension drift over time is a common cause of GSM change.
4. Calibrate all feeders to the same stitch length setting, then verify by measuring loop length directly from the fabric.

For a detailed breakdown of pricing and specifications that affect machine consistency, see our circular knitting machine price guide 2026.

When to Call for Professional Service

Most of the problems above can be resolved by trained operators. These situations require the machine manufacturer or a qualified technician:

• Cam replacement or re-timing after major wear
• Needle cylinder reboring or replacement
• Main drive bearing replacement
• Electronic pattern system calibration issues
• Recurring problems that persist after standard troubleshooting

Keep a log of all defects and fixes. Patterns in the data — for example, the same feed position always having issues, or defects appearing at specific intervals — point to systematic problems that need engineering attention, not just operator-level fixes.

For maintenance schedules and preventive procedures that reduce the likelihood of these problems, refer to our circular knitting machine maintenance guide. For replacement parts, see our circular knitting machine spare parts guide.

References

1. Yuanda — Troubleshooting Common Issues with Circular Knitting Machines

Comprehensive guide covering tension issues, yarn breakage, fabric holes, and slippage diagnostics.

1. Leadsfon — Circular Knitting Machine Troubleshooting Guide

Reference for needle/sinker-related defects and yarn tension adjustment procedures.

1. Qattex — 5 Common Circular Knitting Machine Problems That Cause Downtime

Maintenance-focused guide covering lubrication issues, needle wear, and downtime prevention.

1. iFactory — Knitting Machine Maintenance: Circular and Warp Knit Guide

Preventive maintenance protocols and needle replacement tracking for circular knitting machines.

1. Yuanda — Understanding the Crucial Role of Cams in Circular Knitting Machines

Technical reference on cam function, timing, and its impact on needle/sinker motion and fabric quality.

1. ACM Digital Library — Sound-based Fault Detection in Knitting Machines

Research on detecting needle, sinker, and cam faults through acoustic analysis of knitting machines.

1. ResearchGate — On-line Fabric Defect Detection in Circular Knitting

Research on machine vision and AI-based defect detection systems for real-time fabric quality control.

1. KnittingMachine.com.tw — Common Problems in Flat and Circular Knitting Machines

Broad reference covering stitch formation defects, needle issues, and tension problems across machine types.