StableSewing.com - Guide to Schmetz Needles for stitching textiles

Optimum stitching of a wide variety of textile materials requires needles which avoid damage to the material by having a displacement point (round point). SCHMETZ has carefully developed needles with round points for a host of materials and applications, e.g.:

Woven fabrics
Knitwear
Elastic materials
Composite materials
Laminated materials
Films
Material combinations

Manufacture of ready-to-wear-clothing
Accessories / Bags / Belts
Upholstery industry
Home furnishing textiles
Interior design
Shoe manufacture
Manufacturer of vehicle interiors (cars, aeroplanes, trains, etc.)
Leisure industry (e.g. parachutes, paragliders, tents)

The advantages of round points

Widen the needle hole in the material by means of displacement.

Choosing the right round point form (acute round points or ball points) is guaranteed to avoid damage to the material.

Choosing the right needle

Timely consideration of the right needle ensures optimum manufacturing and the desired quality of the end product.

Material, material properties, stitching technique (stitch type, number of layers of material, seam structure) and thread are the criteria which already decide the right point form and needle size at the design stage.

Choosing the point form and needle size

Every material places different demands on the needle. The different point forms permit damage-free stitching of the various materials by different displacement of the individual fibres during piercing.

The finishing of the material and the climate (low atmospheric humidity and extreme temperature differences) can have a considerable impact on the sewability of the material!

The material and material properties determine the right point form and needle size.

Thin needle sizes require a more rounded needle point than thick needle sizes
(cf. knitwear).

Woven fabric

Light (Shirt/blouse material) 65-75 9-11 R

Medium (Suit material) 80-90 12-14 SES

Heavy
(Coat material, covering material) 100-110 16-18 SES

Denim

Light 70 - 90 10-14 SES

Medium 100-110 16-18 SUK

Heavy 110-140 18-22 SES

Very densely woven material

Light
e.g. microfibres, silk, artificial silk 65-70 9-10 SES
to prevent
material damage

65-70 9-10 SPI
to prevent
seam puckering

Medium
e.g. tarpaulins 100-180 16-24 SPI

Heavy 200-330 25-30 SPI

Knitwear

Fine 60 8 SUK

Medium 65-75 9-11 SES

Coarse 75-90 11-14 SUK

Very coarse 75-90 11-14 SKF

Elastic materials
e.g. highly elastic knitted fabrics
and knitted fabrics with
covered elastomeric threads
(Elastan, Lycra, etc.)

Fine 65-70 9-10 SKF

Medium
(particularly bandages) 80-90 12-14 SKL

Coarse 80-90 12-14 SKL

Non-covered elastomeric threads,
e.g. elastic for waistbands 65-90 9-14 SPI
to prevent the elastomeric
threads being pushed out

Composite materials

Woven fabrics/knitwear
combined with an inlay,
e.g. shirt manufacture
(seams for cuffs, collars) 65-80 9-12 SPI

Coated materials
combined with
woven fabrics/knitwear,
e.g. Goretex, Sympatex, Helsapor

Fine 65-70 9-10 SPI

Medium 80-90 12-14 SPI

Coarse 80-90 12-14 SPI

Laminated materials

Textile/textile
e.g. car seat covers,
wetsuits and
diving suits 80-110 12-18 SES

Textile/cardboard,
textile/plastic,
very rigid plastic/plastic 100-140 16-22 R

100-140 16-22 SD1
for safety and reliable locking

80-130 12-21 DH
for an attractive seam

Coated materials
e.g. tarpaulins

Medium 100-180 16-24 SPI

Heavy 200-330 25-30 SPI

200-330 25-30 SD1

Films 65-90 9-14 R

Material combinations

Leather with textile 80-100 12-16 R

Manufacture of
furs and skins 80-100 12-16 R

Choosing the right needle size

In addition to material and material properties, the choice of thread also determines the right needle size:

Continuous filament
Coarse 13 231 160-200 23-25 13 231 130-160 21-23

14 214 130-140 21-22

15 200 160-180 23-24 15 200 120-140 19-22
18 167 120-130 19-21
20 150 120-160 19-23 20 150 110-130 18-21
24/25 125/120 110-130 18-21
30 100 100-140 16-22 30 100 110-120 18-19
35/36 86/83 100-110 16-18

Medium 40 75 90-120 14-19 40 75 90-100 14-16
50 60 80-90 12-14
60/70 50/43 80-100 12-16 60/70 50/43 70-80 10-12
80 38 70-90 10-14 80 38 60-80 10-12
90 33 65-90 9-14 90 33 60-80 8-12

Fine 100 30 60-80 8-12
120 25 70-80 10-12 120 25 65-70 9-10
180 17 70-80 10-12 180 17 60-65 8-9
200 15 55-60 6-9
250 12 50-55 5-6
360 8

* No = Label number
tex = Unit of size 1g/1000m (e.g. 75 tex = 1000m yarn weights 75g)

These tables only include the most common threads. Cotton threads, sewing silk and embroidery yarn have been omitted for the sake of clarity. If you have specific questions concerning these threads, please ask your thread manufacturer.

Core-spun
Coarse 15 200 140-160 22-23

20 150 130-160 21-23 20 150 120-140 19-22

24 125 130-160 21-23 25 120 110-130 18-21
25 120 130-160 21-23
28 107 130-160 21-23
30 100 120-140 19-22 30 100 110-130 18-21
35/36 86/83 110-130 18-21 35/36 86/83 110-120 18-19

Medium 40 75 100-120 16-19 40 75 90-110 14-18
50 60 100-120 16-19 50 60 90-100 14-16
60 50 100-110 16-18 60 50 90-100 14-16
75 40 90-100 14-16 75 40 70-90 10-14
80/90 38/33 80-90 12-14 80 38/33 65-80 9-12

Fine 100 30 70-90 10-14 100 30 70-80 10-12
120 25 70-80 10-12 120 25 70-80 10-12
140 21 60-70 8-10
150/160 20/19 65-70 9-10 150/160 20/19 50-60 5-8
180 17 50-65 5-9 180 17 50-60 5-8

* No = Label number
tex = Unit of size 1g/1000m (e.g. 75 tex = 1000m yarn weights 75g)

The coordination of material and needle described particularly applies to the following stitch types: Double lockstitch including bartack, double chain stitch, zigzag, overlock and flatlock stitch.

Double lockstitch (Basic stitch type 301):

Advantages:

Lower thread consumption than double chain stitch
Same seam strength on the upper and lower sides
Good seam strength owing to interlocking in the middle of the material (but not as strong as with the chain stitch)
Easy tying of the seam end by reverse sewing
No seam impressions on thin woven fabrics

Disadvantages:

Considerable mechanical stress on the sewing thread when forming the stitch
Lower productivity owing to bobbin changing (standstill and handling times)

Bartack:

Double lock stitch for separate tying of the start and the end of seams.
Double lock stitch for tying belt loops, for example.
Double lock stitch bar tacks for stregthening jeans pockets, for example

Double chain stitch (Basic stitch type 401):

Advantages:

High seam stretching and high seam strength
Little mechanical stress on the sewing thread when forming the stitch
The chain can safely run out without material - even at high sewing speeds
Only marginal displacement puckering owing to interlocking of the needle thread and bobbin thread on the underside of the material being sewn
High productivity owing to large thread supply (no spooling necessary)

Disadvantages:

Twice the sewing thread consumption compared with double lockstitch
Thick underside of seam - impressions possible on thin woven fabrics
Seam opening in the event of skipped stitches

Zig-zag stitch (Stitch types 304 and 404):

Exists as both double lockstitch and double chain stitch
Primarily used in the corsetry sector
Optimum stitch for decorative seams

Overlock stitch (Basic stitch type 501):

Advantages:

High seam stretching for edge trimming seams
Excellent stretching properties
Saving of working steps if a safety stitch type is used
Needle thread determines the strength of the seam, while looper threads ensure good seam appearance and softness
Little mechanical stress on the sewing thread when forming the stitch
High sewing speeds possible
High productivity thanks to large thread supply (no spooling necessary)

Disadvantages:

Very high sewing thread consumption

Flatlock stitch (Basic stitch type 601):

Advantages:

High stretching properties
Flat seams with no marks through the material on knitwear
Decorative seams if a textured thread is used

Disadvantages:

Very high sewing thread consumption (example: 4 needle threads, 4 looper threads, 1 face thread)