Presentation on Sewing machines

Made by: Vishakha Chopra and Vrinda Gupta

Zuki Single Needle Lock Stitch machine for industrial sewing:

Basic parts of the machine:

Inner parts:

Specifications:

• Max sewing speed: 5,500 rpm• Normal sewing speed: 5000 rpm• Stitch length: 5mm• Presser foot lift: 10 mm• The stitch length can be adjusted by turning

knob

Operations of the machine:The lockstitch uses two threads, an upper and a lower. Lockstitch is so named because the two threads, upper and lower, "lock" (entwine) together in the hole in the fabric which they pass through.

The upper thread runs from a spool, through a tension mechanism, through the take-up arm, and finally through the hole in the needle. Meanwhile the lower thread is wound onto a bobbin, which is inserted into a case in the lower section of the machine below the material

Adjustments for desired output and/or better functioning

• The height of the knee lifter• Stitch length• Presser foot pressure• Thread tension• Thread take up stroke• Height of feed dog(crank)• Feed timing(eccentric cam)

Use of the machine

• Juki SNLS machines are used for mainly industrial purposes.

• It is generally used in medium- weight fabrics.

• Type of stitch produced: straight stitch, used for sewing straight seams.

About Overlock Machines

Household and industrial overlock machines are commonly used for garment seams in knit or stretchy fabrics, for garment seams where the fabric is light enough that the seam does not need to be pressed open, and for protecting edges against ravelling. Machines using two to four threads are most common, and frequently one machine can be configured for several varieties of overlock stitch. Overlock machines with five or more threads usually make both a chainstitch with one needle and one looper, and an overlock stitch with the remaining needles and loopers. This combination is known as a "safety stitch".

Pegasus

Pegasus M700 Series Overlock/Safetly Stitch Industrial Sewing Machine

Specifications:

• Max speed: 7000 rpm• Stitch length: .5mm to 5.3mm• Overedge width: 1.5mm to 6 mm• Presser foot lift: 7mm• Differential feed ratio: 1:.6 to 1:2.8• Equipped with HR device(needle/thread cooler)

for cooling of heat generated due to needle movement allowing the thread to move smoothly and producing uniform stitches

Operations:

• It contains two loopers and 2 needles

• That is 4 thread overlock machine

• An overlock stitch sews over the edge of one or two pieces of cloth for edging, hemming or seaming.

The formation of an overlock stitch

• When the needle enters the fabric, a loop is formed in the thread at the back of the needle.

• As the needle continues its downward motion into the fabric, the lower looper begins its movement from left to right. The tip of the lower looper passes behind the needle and through the loop of thread that has formed behind the needle.

• The lower looper continues along its path moving toward the right of the serger. As it moves, the lower thread is carried through the needle thread.

The formation of an overlock stitch

• While the lower looper is moving from left to right, the upper looper advances from right to left. The tip of the upper looper passes behind the lower looper and picks up the lower looper thread and needle thread.

• The lower looper now begins its move back into the far left position. As the upper looper continues to the left, it holds the lower looper thread and needle thread in place.

• The needle again begins its downward path passing behind the upper looper and securing the upper looper thread. This completes the overlock stitch formation and begins the stitch cycle all over again.

Uses of the overlock stitch

Overlock stitches are traditionally used for edging and light seaming. Other applications include:• Sewing netting• Butt-seaming is used for joining the

ends of piece goods.• Flat-locking• Edging emblems• Pearl stitching• Rolled hemming• Decorative edging• Seams of tee shirts

5 Thread Overlock Machine

5 Thread Overlock Machine

Uses 5 threads and 3 needles for functioning and has two loopers-upper looper and lower

looper.

Proper Operations

Proper operations of the machine include the following:• Threading• Adjusting movement of differential feed dog

(differential feed)• Setting differential ratio to 1:1.1 – 1.2

Threading

Needle ThreadPull thread until it reaches the front of the needles.And, cut off knots just before needle eye to re-thread.

Spreader ThreadPull Thread until knot is out.

Looper ThreadPull thread until the knot is out. Then, cut off the knot.Threading for sewing with “UT” or “UT-A”.For standard type, thread looper (5) through looper thread eyelet (left) (4)For less stretchable threads, thread looper (5) without threading looper eyelet (left) (4)

For easy threading, pull the lever (2) in the thread take-up eyelet holder (1).After threading, restore the holder (1) to the operating position with the lever(2)

Adjusting movement of differential feed dog

The differential ratio has been set from 1:0.7 to 1:1.4 at the factory.When the differential feed lever (right) (1) is aligned with the line (2), the movement of the differential feed dog is the same as that of the main feed dog (differential ratio 1:1) resulting in uniform sewing.

• Loosen the lock nut (3)• For gather sewing, turn the adjuster (4) clockwise and the movement of

the differential feed dog is increased. For stretch sewing, turn counterclockwise and the movement is decreased.

• Tighten the locknut (3) securely.

Setting differential ratio to 1:1.1 – 1:1.2

• Remove the side cover (1). (3 pieces of screws)

• Remove the screws (3) of the differential feed bar connections(2).

• Fix the differential feed bar connections(2) to the tapped hole (4) with the removed screw(3).

Note

• When the differential ratio is 1:2, the maximum stitch length of the main feed dog is 2.3mm.

• When the differential ratio is 1:5, the maximum stitch length of the feed dog is 3mm.

End Uses

By changing threading, you can obtain:• 3 thread overlock• 3 thread overlock with reinforcing tape• 4 thread overlock• 4 thread overlock with reinforcing tape• Single needle double chain stitch• 5 thread safety stitch (3 thread overlock+Single needle double chain stitch)• 5 thread safety stich with reinforcing tape (3 thread overlock with

reinforcing tape+Single needle double chain stitch)• 6 thread safety stitch (4 thread overlock+Single needle double chain stitch)• 6 thread safety stitch with reinforcing tape (4 thread overlock with

reinforcing tape+Single needle double chain stitch)