Needle with eccentric point
Stitching technique
“Invisible” seams(blind seams) can be optimally stitched for a host of different types of material using special blindstitching needles.
Product:
Curved formEcentric point on the outer curve of the needle
Blindstitching needles are characterized by :
Demand |
Schmetz blindstitching needles |
Exact,punctiform”blindstitching”
Of the woven / knitted materials
Greater stability Correct positioning of the needle Reliable guideance of the thread Loop(no skipped stitches)
|
Eccentric,slim point
Square blade cross-section Flattened shank
Narrow eye. |
Choosing the right needle size:
Material |
Needle Size NM SIZE |
|
Woven fabric
Light ( Shirt/blouse material) Medium ( Suit material) Heavy ( Coat material) |
60-90 70-100 90-110 |
8-14 10-16 14-18 |
Knitwear
Fine coarse |
60-90 |
8-14 |
Densely woven material
(microfibers,silk) |
60-80 |
8-12 |
Needles for avoiding specific sewing problems
Materials and stitching techniques with special demands
Optimum seam quality can usually be achieved by choosing the right point form and needle size to match the respective materials andstitching techniques.Some materials and stitching techniques,e.g.:
Materials:
Ø Elastic material
Ø Materials with a high man-made fibre content
Ø Densely woven material,e.g.microfibres
Ø Insufficient finishing of the material (low atmospheric humidity and extreme differences in temperature)
Stitching technique:
Cross seams
Very high sewing speeds
+/- 5,000 stitches/min
can cause sewing problems despite choosing the right needle.To deal with these sewing problems,schmetz has developed special needles whose use is determined by the sewing problem involved.
Applications:
Ø Highly elastic materials
Ø Layers of different materials
Ø Cross seams
Ø Elastic threads.
Needles for avoiding skipped stitches
Sewing problem
Occurrence of skipped stitches:
A skipped stitch occurs if the needle thread and bobbin thread(s) are not looped.
Effect:
Ø Reduction of seam strength
Ø Unravelling of the entire seam with double chain stitching
Ø Poor seam appearance
Ø Thread breakage after the skipped stitch in many cases.
Cause of skipped stitches:
Material and stitching
Highly elastic materials:
(e.g.manufacture of brass,bodies,corsetry,bathing suits): Owing to its high elasticity, the material flutters during stitching. This movement causes the loop to be pulled along with the material during the upward stroke of the needle or reduced to such a size that the hook can no longer grip the loop.
Layers of different materials:
(e.g.manufacture of waistbands) The various layers of material flutter under the presser foot.The layers of material not held by the presser foot pull the loop along with them or reduce the size of the loop during the upward stroke of the needle,meaning that the hook can no longer grip the loop.
Cross seams:
(e.g. manufacture of jeans) with this type of stitching,the fluttering is caused by the transitions from thick to thin (thin to thick) layers of material.The layers of material not held by the presser foot again pull the loop along with them or reduce its size to such an extent that the hook can no longer grip the loop.
Needle deflection:
The needle is deflected from its correct piercing path by the structure of the material
Thread
Elastic threads:
The high intrinsic elasticity of the thread often prevents optimum loop formation.
Product:
Schmetz needles of SERV 7 design
Demands: Optimum loop formation
Needle stability
Special needles with pronounced scarf(hump between eye and scarf) and reinforced blade.The hump between eye and scarf pushes the loop much further out so that the hook can reliably grasp the loop,regardless of the material and thread properties.
The reinforced blade gives the needle the necessary stability to prevent deflection
Needles for avoiding needle and eye smearing
Sewing problem:
Complete needle and eye smearing with low softening points/melting points
Effect:
Ø Thread breakage
Ø Skipped stitches
Ø Untidy seam
Cause
High sewing speed/high friction heat the needle.with materials with a low softening point/melting point,melt residues occur with stick to the needle.
Man made materials
Materials with a high man-made fibre content
Materials with special finishing (e.g.colour,modifications of textile threads or surfing as regards wear and care properties)
Products:
Schmetz Bulkold needles
Demands:
Little or no adhesion of melt residues on the needle.
Special needle with roughened, phosphorated surface & subsequent Teflon coating. Melt residues do not stick to this coating at all,or only much later than on chromium-plated needles for example. The needle remains clean for longer-skipped stitches and thread breakage are avoided.
Special Needles for button Sewing
Trouble free button sewing is determined by the following factors:
Ø Correct machine settings
Ø Correct needle point/size
Ø Correct positioning of the button
Ø Correct sewing thread.
Product:
Needles for button-sewing must meet the most stringent demands.
Demand |
Schmetz special needle for button-sewing |
|
No damage to button
No needle breakage |
|
Special point STU point |
No damage to inserted sewing thread |
|
Special point STU point |
No damage to end product
No needle breakage |
|
Special point STU point |
Centring of the needle in the button holes
Is of decisive importance for the quality of the end product
|
|
Particularly straight needles |
Choosing the right needle:
Ø Type of machine
Ø Material
Ø Thickness of sewing thread
Ø Diameter of button holes
Determine the choice of the right needle system and the right needle size,
Choosing the right point form:
Material |
Point |
Woven
Fabric
Knitwear Fine Medium Coarse |
STU
STU SUK SUK |
Choosing the right needle type:
Machine |
Needle type |
Button-sewing machine
For single-thread chain stitch Double lockstitch |
Needle with round shank ; Needles with special point for button sewing.
|
Button-sewing machine
For Imitation handstitching
Needle with two special points and an eye in the middle(central-eye needles).The needles and the measured thread length pass through the entire material during each stitching and form the imitation handstitch |
Double point needle
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