Certification Exam Practice Questions

Industrial Sewing Machine Operator Certification Exam Practice Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• What is the primary purpose of a feed dog on an industrial sewing

machine?

• To control thread tension
• To move the fabric under the needle
• To hold the presser foot
• To lubricate the machine

Rationale: The feed dog moves the fabric forward with each stitch,

ensuring even sewing.

• Which stitch type is commonly used for seams that require high

strength? 1 / 4

• Overlock stitch
• Lockstitch
• Chain stitch
• Zigzag stitch

Rationale: Lockstitch is strong and durable, making it ideal for high-

strength seams.

• What is the function of the presser foot?
• To guide thread through the needle
• To hold the fabric in place while sewing
• To cut excess thread
• To regulate motor speed

Rationale: The presser foot holds the fabric against the feed dog to

maintain control during stitching.

• Which industrial sewing machine is best for sewing thick materials like

leather?

• Zigzag machine
• Walking foot machine
• Overlock machine
• Coverstitch machine

Rationale: Walking foot machines have strong feed mechanisms suitable

for thick materials.

• Thread tension that is too tight can cause: 2 / 4

• Loose loops
• Uneven stitches
• Puckering of the fabric
• Machine jamming

Rationale: Excessive tension pulls the fabric too tightly, causing puckering.

• Which component prevents the needle from breaking when it hits thick

layers?

• Bobbin
• Presser foot
• Needle plate
• Feed dog

Rationale: The needle plate supports the fabric and guides the needle,

reducing breakage risk.

7. The main function of an overlock machine is to:

• Sew buttonholes
• Finish raw fabric edges
• Stitch thick leather
• Embroider designs

Rationale: Overlock machines trim and seal fabric edges to prevent

fraying.

• Which needle type is used for stretch fabrics? 3 / 4

• Ballpoint needle
• Stretch needle
• Denim needle
• Universal needle

Rationale: Stretch needles have a special tip to prevent damaging stretch

fabrics.

• What causes skipped stitches on a sewing machine?
• Loose presser foot
• Incorrect needle size or bent needle
• Incorrect thread spool placement
• Worn feed dog

Rationale: Skipped stitches often result from needle issues or

incompatibility with fabric/thread.

• What is the recommended method for cleaning lint from an industrial

sewing machine?

• Wipe with wet cloth
• Use a soft brush or compressed air
• Apply oil directly
• Submerge in water

Rationale: Using a brush or air safely removes lint without damaging

machine parts.

• Which type of stitch is commonly used for hemming knits?
• / 4