DISADVANTAGES OF TECHNOLOGIES TYPE 301

1. DISADVANTAGES OF EXISTING TECHNOLOGIES
FOR FORMING A LOCKSTITCH TYPE 301, WHICH
ARE ABSENT IN THE NEW ZARIF TECHNOLOGY
DOUBLE THREAD CHAIN STITCH FROM 2021.
1. Frequent changer of the bottom thread wound on the bobbin of hook (shuttle), due to the small
size of the bobbin.
2. A very large number of types of hooks (shuttles), differing in mechanical design, size, movement
and direction of the axis of oscillation or rotation.
3. All types of hooks (shuttles) have a very complex mechanical design and require high precision
manufacturing and assembly.
4. Deflection of the needle when the needle moves down while sewing through thick seams may
cause the needle to collide with the needle plate and hook (shuttle), resulting in breakage of the
needle or deformation of the needle point.
5. To obtain a high-quality seam with a lockstitch of type 301, the threads must be intertwined in the
middle of the stitched materials, the threads must tightly join the materials, it is necessary to obtain a
smooth seam on light materials and an elastic seam on elastic materials, which requires adjusting the
tension of the threads when changing the thickness, stiffness and elasticity of the materials being
stitched, while it is impossible to obtain a highly elastic seam.
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 hook point and the needle is 0.1 mm, which requires
adjusting the hook relative to the needle when switching from needle Nm. 130/21 to needle
Nm. 60/8.
8. All existing technologies of forming a lockstitch type 301 cannot guarantee sewing without skipping
a stitch and without breaking threads.
9. During sewing, the top thread loses its mechanical strength with increasing sewing speed, due to
the large number of repeated movements of the top thread through the eye of the needle, the
stitched material and thread guides, since even a standard hook consumes a sufficiently large length
of the top thread to form a stitch.
10. All types of thread take-ups unevenly shorten and tighten the loop of the top thread and it is
impossible to evenly shorten and tighten the loop of the top thread.
11. All types of hooks (shuttles) require lubrication, and non-lubricated hooks limit the sewing speed.
12. All types of hooks (shuttles) must be cleaned of dirt, and getting thread segments into the hook
slip zone can lead to jamming of the hook and sudden braking of the sewing machine.
INVENTOR: PhD. Zarif Sharifovich Tadjibaev, Director of ZARIF SEWING MACHINE CO., LTD.
Web.: ZARIF.UZ / YouTube Channel: youtube.com/@ZarifTadjibaev