Using High-Speed Industrial Lockstitch Sewing Machines

 

1. Needle Size Selection of Industrial Lockstitch Sewing Machines

For sewing thin, brittle, dense fabrics, a smaller needle should be chosen. For sewing thick, soft, loose fabrics, a larger needle is more suitable.

Needle sizes	Thread sizes	Fabric types
9	80-100 tex	Extremely thin fabrics like chiffon
11	60-80 tex	thin fabrics like silk,
14	50-60 tex	ordinary fabrics like cotton and wool,
16	30-50 tex	medium to thick fabrics, thin leathers.

 

2. Needle Cooling

At high sewing speeds, the severe friction between the needle and fabric can cause the needle temperature to rise excessively. This can create holes or melting in synthetic fabrics, increase needle thread resistance, worsen looping conditions leading to skipped or broken stitches. Therefore, cooling is necessary.

Double-grooved needles, high-speed needles, or applying silicone oil to the thread and air cooling can be employed.

 

3. Needle Installation

The needle should be inserted until it bottoms out in the needle bar clamp with the long groove facing directly to the left of the industrial lockstitch sewing machines.

The upper thread should be a left-twist thread with a moderate twist level. Either a left or right can be used for the bobbin thread.

 

1. Feed Dog Height: The height the feed dog rises above the needle plate at its highest position.

For general fabrics, the feed dog height is typically 0.7-0.9mm. It can be increased to 1mm for thick fabrics or decreased to 0.5mm for thin fabrics.

Adjustment: Loosen the feed bar crank set screw, adjust the feed bar crank height, and re-tighten.

 

2. Presser Foot Pressure

Usually less pressure for thin fabrics, and more for thick fabrics.

Adjustment: Loosen the locknut on the adjustment screw on top of the machine head. Turning the screw in increases pressure out and decreases it. Re-tighten the locknut after adjusting.

 

1. Adjusting Needle Bar Height

There are two marking lines on the needle bar to indicate its highest and lowest positions.

Adjustment: With the needle bar at its lowest position, loosen the set screw, align the upper marking line with the bottom edge of the needle bar bush, and tighten the screw.

2. Adjusting the Rotary Hook Position

The lower marking line is used to set the rotary hook position.

Adjustment: Ensuring the needle position is correct, loosen the hook shaft set screw. As the needle rises from its lowest point, align the lower marking line with the bottom of the needle bar bush. Position the shuttle point on the needle centerline, leaving a ~0.05mm gap between point and needle, then tighten the set screw.

 

3. Synchronizing Needle and Feed Dog

The needle and feed dog must be synchronized so that when the needle point descends to the needle plate surface, the feed dog also drops until its teeth are level with the needle plate.

 

If you need to purchase Lockstitch sewing machines, you can choose DAPSEW. The brand we cooperate with is the Singer and Juki brand.

you can contact:

Email: sales@dapsew.com

WhatsApp: +8613186027908