Root Causes for Broken Stitch at Sewing line in Garments Industry

Identifying the key root causes of broken stitches — from machine settings to operator handling — is essential to ensure seam strength, production efficiency, and consistent garment quality.

Broken stitch is a common and critical quality issue found in the garment sewing process. It directly affects the appearance, strength, and durability of the garment. Identifying and controlling the root causes of broken stitch is essential to maintain consistent quality and reduce rework or rejection. The main root causes can be classified into several categories:

1. Machine-Related Causes

Sewing machine condition and settings have a direct and significant impact on stitch formation. Even with good-quality thread, fabric, and trained operators, an improperly adjusted or poorly maintained machine can lead to frequent broken stitches. Understanding and controlling these machine-related causes is essential for ensuring consistent seam quality and production efficiency.

• Improper machine timing (needle, hook, and feed not synchronized)
• Damaged or blunt needle
• Wrong needle size or type for the fabric or thread
• Incorrect thread tension (too tight or too loose)
• Improper presser foot pressure causing fabric slippage or excessive tension
• Burrs or rough edges on needle plate, hook, or presser foot damaging thread
• Feed dog misalignment leading to uneven feeding and thread breakage
• Poor machine maintenance (dirty, dry, or unlubricated parts)

Preventive Measures

• Conduct daily machine checklists before production (needle, tension, presser foot, feed dog).

• Follow regular maintenance and lubrication schedules.

• Use correct needle size, type, and point based on fabric and thread.

• Ensure proper timing between needle bar and hook movement.

• Replace worn or damaged parts immediately.

• Check tension balance and bobbin setting before bulk sewing.

• Provide mechanic and operator training on machine setup and adjustment.

2. Thread-Related Causes

Thread quality and compatibility play a critical role in sewing performance and seam strength. Even when machines and operators function correctly, unsuitable or poor-quality thread can cause frequent stitch breakage, rework, and production delays. Understanding the thread-related causes is essential to prevent such quality issues.

• Low-quality or uneven thread strength
• Incompatible needle-thread combination
• Thread too thick or too thin for the machine setup
• Old or dry thread losing elasticity
• Incorrect threading path or skipped thread guide
• Thread cone placed improperly causing irregular feeding

Preventive Measures

• Use good-quality, lubricated sewing thread from reliable suppliers.

• Select the correct thread size and type for each fabric and operation.

• Follow proper thread storage practices (cool, dry, and dust-free).

• Check thread tension balance before starting each line.

• Ensure correct threading through all guides and tension discs.

• Match the needle size with the thread size as per the standard chart.

• Position thread cones and stands correctly to maintain smooth feeding.

3. Fabric-Related Causes

Fabric type, structure, and behavior have a major impact on stitch performance and seam strength. Even with correct machine settings and quality thread, the nature of the fabric can cause frequent broken stitches if not properly considered during production. Below are the key fabric-related causes and their detailed explanations:

• Too thick or too dense fabric for current needle/thread setup
• Fabric stretch or slippage during sewing
• Improper fabric handling by operator
• Hard spots or seams overlapping causing excessive resistance

Preventive Measures

• Select the correct needle type and size based on fabric construction (e.g., ballpoint for knits, sharp point for woven).

• Adjust thread tension and presser foot pressure according to fabric thickness.

• Conduct fabric test sewing before starting bulk production.

• Use Teflon or roller presser feet for coated or sticky fabrics.

• Ensure fabrics are relaxed and conditioned before cutting and sewing.

• Train operators to handle stretch and slippery fabrics properly.

4. Operator-Related Causes

The sewing operator plays a vital role in maintaining stitch quality during garment production. Even if the machine and materials are in perfect condition, improper handling or incorrect operating methods by the operator can cause frequent broken stitches. Below are the key operator-related causes and their explanations:

• Incorrect handling technique (pulling or pushing fabric while sewing)
• Inconsistent sewing speed (starting too fast or stopping abruptly)
• Not changing damaged needles on time
• Skipping machine cleaning or threading checks

Preventive Measures

• Train operators regularly on correct fabric handling and machine threading.

• Implement operator checklists before starting each shift (needle, tension, threading, and presser foot).

• Encourage operators to report machine issues immediately to mechanics.

• Monitor sewing performance through in-line quality checks and provide on-the-spot feedback.

• Maintain a standard needle and thread chart at each workstation to ensure compatibility.

5. Environmental & Process Causes

Broken stitch is not only caused by machine, thread, or operator factors — it can also result from environmental conditions and poor process control. In many garment factories, environmental and process-related issues often go unnoticed but have a significant impact on sewing performance and stitch quality.

• Improper machine setting change after style switch
• Untrained or newly assigned operator
• Lack of regular preventive maintenance
• No in-line quality check or poor supervision