1. DISADVANTAGES OF EXISTING TECHNOLOGIES
FOR FORMING A DOUBLE THREAD CHAIN
STITCH TYPE 401, WHICH ARE ABSENT IN THE
NEW ZARIF TECHNOLOGY DOUBLE THREAD
CHAIN STITCH FROM 2021.
1. All existing technologies for the formation of a double thread chain stitch type 401, where the
looper carries the bottom thread, are not able to tightly join materials, as well as qualitatively sew
combinations of various materials, such as textile-leather, textile-plastic, knitwear-leather and
knitwear-plastic.
2. For high-quality sewing of various materials, it is necessary to adjust the tension of the threads, i.e.
it is impossible to sew various materials qualitatively under normal tension of threads.
3. To form a double thread chain stitch, it is necessary to use a special needle with two long grooves,
which is less durable for longitudinal bending than a conventional needle with one long groove.
4. To increase the reliability of stitch formation, it is necessary to use movable and fixed needle
guards.
5. Deflection of the needle when the needle moves downwards, during sewing through thickened
seams, can lead to a collision of the needle with the body of the looper and the needle guards, which
can lead to needle breakage or deformation of the needle point.
6. With a small stroke length of the needle bar equal to 32 mm, it is impossible to sew materials up to
8 mm thick.
7. The maximum allowable gap between the looper point and the needle is 0.1 mm, which requires
adjusting the looper relative to the needle when switching from needle Nm. 130/21 to needle
Nm. 60/8.
8. All existing technologies for the formation of a double thread chain stitch type 401 cannot
guarantee sewing without skipping a stitch and without breaking threads.
9. Loopers have rather complex mechanisms.
10. All existing technologies for forming a double thread chain stitch of type 401 do not allow
reducing the stitch length to 0.5 mm in order to securely tack the end of the chain seam.
INVENTOR: PhD. Zarif Sharifovich Tadjibaev, Director of ZARIF SEWING MACHINE CO., LTD.
Web.: ZARIF.UZ / YouTube Channel: youtube.com/@ZarifTadjibaev