Monday, 3 August 2009

Warp Knitting | Köper Stitch

All basic stitch constructions – pillar stitch, 1 x 1 stitch, 2 x 1 stitch, 3 x 1 stitch, 4 x 1 stitch and Atlas constructions can be worked so that the thread is laid over 2 needles in the overlapping motion. This produces two stitches next to each other whose foot connections are comparable to those of weft knitted fabrics.
The most well-known constructions of this kind are open and closed two-needle overlap pillar and – 1 x 1 stitches.
The production of these two-needle overlap constructions is only possible on warp knitting machines with well adjusted knitting elements. Moreover, these constructions can only be completed under low thread tension because a thread reserve which is formed via the sinkers is needed.
When knocking over, the foot connection of the loops lays over the sinkers on tricot machines or over the knock-over plate on Raschel machines. The friction thus created increases the tension and so yarn breakages or even needle damages may occur.
To avoid this, the yarn material should have appropriate elastic properties.
Out of above mentioned reasons, two-needle overlap constructions are not as popular as other stitch constructions.They are used e.g. when heavy fabrics should be produced with one guide bar. However, the yarn consumption is twice that of a normal pillar stitch. With normal threading two loops are formed on one needle.

Two-needle overlap pillar stitch, closed
 repeat in length = 1 course
yarn parts per repeat = 5.5

Two-needle overlap pillar stitch, open
repeat in length = 1 course
yarn parts per repeat = 10.5

1 x 2 stitch
The 1 x 2 or two-needle overlap tricot stitch can be worked fully threaded or threaded one in / one out // (two-needle overlap semi-tricot). This two-needle overlap semi-tricot shows alternatively one wale with straight stitches and one wale with slanting stitches.
The fully threaded two-needle overlap construction contains course-wise alternating slightly inclined stitches.It is often difficult to distinguish between the closed and the open two-needle overlap semi-tricot in the fabric. In the lapping diagram the differences in construction can clearly be recognized but in the real fabric structure (photo) it cannot be easily distinguished whether the stitches of the changing slopes of the wales are open or closed (because of the twist). Besides, both sinker loops (foot connections in the same course, and foot connections of two courses) have the same appearance.
In spite of these difficulties, the fabrics can be distinguished in such a way that the technical back of the fabric is analyzed by the position of the sinker loops and then a left or right sloping stitch has to be turned so that the stitch lying above shows the back loop according to the definition "stitch”. Afterwards the twisted stitch is examined and it can be seen if there is an open or closed stitch. The closed two-needle overlap tricot stitch has closed stitches in the sloped wales.
A further distinguishing feature is the straight wale. The stitches of the semi-closed two-needle overlap tricot stitch are distorted, whereas the same stitches in the semi-open two-needle overlap tricot are straight and rather uniformly formed.

1 x 2 stitch, closed
repeat in length = 2 courses
yarn parts per repeat = 11

1 x 2 stitch, open
repeat in length = 2 courses
yarn parts per repeat = 11