Warp Knitting | Producing a Shoe Fabrics Using RD 6 /1-12 from Karl Mayer

Karl Mayer Kettenwirk-Praxis 1 / 2010.

Since 2007, KARL MAYER's :successful product strategy has been to offer high-tech machines for producing more upmarket products, as well as basic versions for manufacturing cheaper products, which puts this traditional company in an ideal situation to cater for all the different sectors of the market.
This twin product line strategy was  unveiled for the first time at ITMA in Munich and was applied to the company's tricot machines. The new TM series, which was developed expressly for this strategy, soon became a firm favorite among customers, and has been effectively complementing KARL MAYER's range of tricot machines ever since.

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Karl Mayer News | Comfortable children’s seats made from 3D warp-knitted textiles

A seat construction made from manufactured-to-shape, warp-knitted spacer textiles produced on the HDR 6 EL

Checking-off towns by their car licence plates, counting the number of cars, or constantly feeding them sweets are just some of the tricks used by parents to keep their children happy on long journeys, but they usually forget the glaringly obvious – the comfort and well-being of their little passengers. The build-up of heat inside the car is the main reason for children becoming fractious, especially on long journeys to holiday destinations.
Whereas dad’s driving seat is fully climate-controlled to maintain his concentration levels, the children usually end up by feeling hot and sticky - but spacer textiles are on hand to solve the problem.


Spacer textiles produce comfortable seats
The perception of heat and moisture by passengers in the car can be described by means of the thermophysiological seat comfort. Basically, this property relates to climatic perception, and includes factors such as thermal transmission during the journey, including when sitting down, as well as moisture transport and buffering. Using ventilation effects between the seat and the body to create a pleasant microclimate is the best way of achieving optimum values.
Various test methods are used at the Hohenstein Institutes to measure the extent to which these are successful. Four physiologically determined parameters are used to describe the climatic seat comfort: initial heat flow as a perception of warmth immediately after sitting down, breathability, which is expressed in terms of the resistance to water vapour transmission, thermal insulation, and water vapour buffering, which is a measure of the amount of water vapour absorbed by the seat until it feels damp. The values for the climatic comfort indicators are determined at the Hohenstein Institutes using the upholstery tester and the skin model, and enable physiological construction principles to be drawn up for car seats. One of these indicates that warp-knitted spacer textiles are better lining materials than foams. 3D warp-knitted textiles are clearly superior for moisture buffering. The textile spacers are also better for use as interior cushioning, and exhibit a 3.7 times lower resistance to water vapour transmission than moulded foam. This value cannot be achieved by a rubber-coated fibrous web either. /1/


Manufactured-to-shape, warp-knitted spacer textiles
Spacer textiles for producing comfortable seats can be produced extremely economically and flexibly on KARL MAYER’s HighDistance^® machine. This well-known manufacturer has made a breakthrough in designing 3D textile products using this high-speed, double-bar raschel machine, i.e. it is now possible to produce articles whose contours match the shape of the end product during the actual manufacturing process. This ready-to-use principle will be described in detail for the production of a children‘s car seat.
The basic principles of contouring products to match the end-use lie with the interaction between guide bars GB 4 and GB 5. These two yarn laying elements operate in the pile zone and are threaded with yarns in blocks for manufactured-to-shape production. They make up the full working width when arranged next to each other. If the distance between the two pile guide bars is reduced, the knitted width is reduced and, in the same way, increasing the distance between them increases the horizontal measurement of the textile (Fig/ download , right). The incremental width and height movements, which the guide bars execute towards and away from each other, are decisive for producing the contours. The shog movement per guide bar can be executed in the horizontal direction, i.e. along the needles – with a maximum path of 60 mm (30 needles) per stitch course – and without restriction in the production direction above the stitch courses. The gradient of the contours is produced by the specific coordinates of the shogging steps that are fixed by the lapping. If these alternate from being long in one direction and almost zero in the other direction, abrupt directional changes occur in the outline of the silhouette and the contours are flatter, i.e. staircase-shaped. Thus the outlines are worked course by course according to the structural plan to suit the intended end-use. An example of this is shown with all the details in the ‘Patterns’ section of this issue.
The pattern shown follows the shape of the child’s seat. The spacer textile is roughly 20 mm thick, has a specific resilience, and was produced professionally by an upholstery company – the result is a comfortable ride for children on long journeys.
/1/ Functional textiles for optimising climatic comfort on car seats, Paper presented by Prof. Dr. K. H. Umbach, Hohenstein Institutes, at the Annual Conference of the Forschungskuratorium Textil (Textile Research Council), 10.11.2004

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The Principles of Double Needle Bar Warp Knitting Machine

To demonstrate the working procedure of double needle bar raschel machine,a simplified version of the knitting elements
is illustrated in Fig.240 showing the two needle bars marked with the letters f (for front) and b (for back),the two guide bars marked with the number 1 and 2,two trick plates and two sinker bars.
The double needle bar machine is almost symmetrical so that the needle bars can be identified as a front and back only by the position of the batching device.The definition of front and back bars as well as the definition of the first and the second guide bars are made fro the sole purpose of establishing the knitting relationships each of guide bars and each of the needle bars in the following descriptions.






The needle bars are independently operated in an up and down movement while the guide bars are swing alternately among the needles of each bar.The simplified knitting cycles illustrated in Fig.241 1-5 can be describe as follows:

• Stage 1- The guide bars are positioned at the back of the machine,above the back needle bar.The front sinker is placed forward to secure the fabric while the front needle bar ascends to clearing position.The guide bar perform the under-lap shoging movement for the front needle bar and then swing to the hook-side.
• Stage 2- On the hook side of the front needle bar,the guide bars shog an overlap according to the pattern mechanism and then swing back.Note that not every guide bar needs to form an overlap as further explained in the following paragraphs.
• Stage 3- The swing back is completed,the yarns are wrapped within the hooks so that the front needle bar can start to descend.The front sinker bar retreats while the back one move forward.
• Stage 4- Front needle bar descent,the previously formed loops which rested on the needle stems close the latches.The front sinker bar continues to retreat,the back one is now above its needle bar.The guide bars swing for the third time,this time to the front in order to clear the way above the back needle bar.Under-lap shoging movement fro the back needle bar can start.
• Stage 5- Front needle bar is at knockover position and the needles form new loops.Back needle bar,now with its fabric secured by the sinker bar,ascends to clearing position.

The sequence describe is only one half of the knitting cycle and the movement of the back needle bar is identical to that of the front.Every knitting cycle of this machine type incorporates six swinging movements which are produced by the machine camshaft.

Drafting design for a double needle bar uses different procedure from single needle bar machines.Two rows of dots are necessary to show one knitting cycle of the machine.The first row always represents the knitting course of the front needle bar while the second represents the knitting course of the back needle bar.

The up and down movement of the needles as well as the swinging movement of the guide bars are constantly produced by the driving mechanism.
The different fabric types and effects are produced by the patterning mechanism.

When both guide bars move in the same direction in 1 and 1 lapping movement as illustrated in Fig.242,the same needle are constantly wrapped by the same yarns and unconnected chains are produced.The top view shows the movement of the guide bars between two needle bars and demonstrates this case.By observing the lapping movement one can deduce that the needles on the front needle bar are always wrapped with 2 - 0 movement,while the needle on the back are always wrapped with a 2- 4 movement.
The 1 and 1 lapping movement is not normally uses on the double bar needle machines and in fact any constan reciprocating movement will form a similar effect.

To make continuous fabric,it is customary to double each lapping movement and only then to form an underlap.A double face fabric is fromed according to lapping movement in Fig.243.Both guide bars perform overlaps on both needle bars.

The chain notations are:
Guide bar 1: 2-0-2-0/2-4-2-4
Guide bar 2: 2-4-2-4/2-0-2-0

Note :That four chain link are used for every knitting cycle,two for the first phase (front needle bar sequence) and two fro the second phase.

To produce two separated fabric,one on the front needle bar and the second on the back one,each of the guide bars is knitting on one needle bar only.The swinging movement is not altered but each of the guide bars,by not overlapping a needle bar,does not connect their yarns to these needles.

Fig.244 illustrates this procedure.The first guide bar overlaps the front needle bar during the first phase of the first knitting cycle,swings in and out of the second needle bar without overlapping it and then again overlaps the needles of the front needle bar during the first phase of the second knitting cycle.In the same way,the second guide bar overlaps only the back needle bar.Two separated fabrics,each of them with a construction of 1 - and - 1 are formed.

The chain notations for this case are:
Guide bar 1: 2-0-2-2/2-4-2-2
Guide bar 2: 2-2-2-0/2-2-2-4

If the guide bars switch their lapping movements,i.e.guide bar 1 overlaps the back needle bar while guide bar 2 overlaps the front (Fig.245),two fabrics which are locked together by the underlap are formed.

The chain notation for this fabric type are:

Guide bar 1: 2-2-2-0/2-2-2-4
Guide bar 2: 2-0-2-2/2-4-2-2

A third guide bar can be added between the previous two in order to increase the knitting possibilities.When the third guide bar is only threaded one guide finger on one side,it can be driven to connect the two separated fabrics,produce by the fully threaded guide bars as illustrated in Fig.246 a.The fabric which formed in this way can be twice as wide as the knitting machine.

By threading the middle guide bar through two guide fingers,one on each side,a tubular fabric is formed as demonstrated in Fig.246 b.

A fully threaded middle guide bar is used to produce a sandwich of two fabrics connected by the yarns.The fabric is then cut and separated into two plush fabrics by special equipment.The principle is illustrated in Fig.246 c.

The chain notations for the last three cases are:

Guide bar 1: 2-0-2-2/2-4-2-2
Guide bar 2: 2-0-2-0/2-4-2-4
Guide bar 3: 2-2-2-0/2-2-2-4

With the use of more guide bars,the fabric produced on each of the needle bars can be much more elaborate.

-Literature : Warp Knitting Production by Dr.S.Raz,Melliand Textilberichte GmbH ,1987.

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Contouring with HighDistance® textiles from Karl Mayer News

Manufactured-to-shape production on the HDR 6 EL

Components made from warp-knitted spacer textiles in the piece

Technical textiles are no longer simply materials, but are rapidly becoming ready-to-use components. The manufacturing sector is increasingly following this trend by developing tailor-made solutions for minimising costs and processing sequences during the production chain and by integrating as many functions as possible into the design of the product right from the very beginning.
The product developers at KARL MAYER are showing how warp-knitted spacer textiles can greatly reduce the distance between the machine and the end product. The company’s engineers have developed processes for manipulating the typical characteristics of 3D textiles, such as their compression elasticity and breathability, and have perfected the technology of the machine to enable pile-free zones to be produced. The zones without spacers can be arranged as channels in the transverse direction to the processing direction, or else they may alternate with zones having spacers to produce chessboard patterns in the textile.
The warp knitting specialists have now taken another successful step along the road to process-integrated production by manufacturing HighDistance^® materials having contours that match the shape of the end product.

Adjustable compressive strength and breathability
Important characteristics for using spacer textiles in their normal end-uses, i.e. in seats and beds and for lying on, are their stability under the influence of pressure and how efficiently they deal with moisture. Their breathability can be manipulated by working different patterns in the outer faces. Constructions having different opening widths can be produced, and these can be arranged all over the surface in an alternating arrangement or at the sides, depending on the drawing-in arrangement of the ground guide bars.
The monofilament yarns between the cover faces are responsible for the compression stability. In particular, the number per unit of area (which is the result of the stitch number setting), the count and the laying angle have a decisive effect on the cushioning characteristics of the spacer textiles. Furthermore, the compression stability can either be set so that it is constant over the entire textile or so that it varies from zone to zone.

Seamless integration of channels and articulating points
3D warp-knitted textiles consist of two-dimensional ground faces produced by a plain jersey construction, with a pile layer lying in-between produced by a 1 x 1 rib knitted construction. By selectively integrating the pile yarns into the ground sides, the lappings for the 2D and 3D elements are changed sequentially. The zones without spacers can be arranged in two ways, i.e. as stripes in the form of channels and specific flexing points, or as square segments alternating with full spacer zones. This variant increases the deployable radius of the 3D warp-knitted textiles considerably.

Manufactured-to-shape production
Extensive research carried out on HighDistance^® materials have led to some promising results when developing products having contours that match the final application actually on the machine itself. The technical concept of the innovative HDR 6 EL high-speed, double-bar raschel machine makes it the perfect machine for producing textiles having specific end-use characteristics. The technical features of the machine enable it to produce tailor-made products, i.e. the spacer height can be continuously adjusted centrally from 20 to 65 mm via an electro-motor, and the stitch comb is adjusted automatically when the distance between the knock-over bars is changed. The machine also features patented electronic guide bar control and electronically controlled fabric take-down. The HighDistance^® machine is therefore extremely flexible in terms of the structures it can produce and the pile yarns it can process. The pile yarns are laid by means of two guide bars, whose positions can be changed in relation to each other, enabling the laying density to be specified per unit of surface area. Reducing the distance between the pile guide bars via the lapping reduces the 3D segment width and vice versa. Consequently, warp-knitted spacer textiles having perfectly formed circular, layered, wavy or oval contours can be produced. The edges of the spacer textiles are clean and neat with firmly anchored pile yarns. The Multispeed system enables the stitch number to be adjusted so that any compression of the yarns in the pile zone can be more or less equalised.
In addition to the wide range of different contours that can be worked, circular and oval shapes without pile yarns can also be produced in the middle of the textile by varying the distance between the pile bars.
All the different design possibilities offered by the HighDistance^® machine have turned textile manufacturers into component providers and textile roll goods into piece goods.

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Warp Knitting | Spacer Fabrics

Manufacturing Methods and Applications

During recent years,spacer fabrics have become a new generation among textile fabrics.From the technology point of view,they are not quit new,they practically have existed since 15 years,however they have gained commercial importance since a few years only.
Conventional textile fabric do not meet the brilliant features of spacer fabrics or only as a compounded fabric combination.Therefore spacer fabrics were in short time successful in getting market share as substitutes for laminates,in sports and safety wear,as basic construction for composites.for filter and in the medical field.

Spacer fabric are warp knitted double face construction of which both fabric faces are interconnected by the spacer yarn.
Both fabric face can be equal or different,of dense structure,plain or patterned with small design or with a napped surface on one side.

Both faces or only can be of open structure,even with different mesh size on each side.By the choice of stitch construction,spacer fabric can be almost stable but also of controlled stretch used elastic yarn.

For connection of both fabric generally mono filament yarn is used.The thickness of the spacer yarn depends amongst other criteria on distance between the fabric space and whether the space is knitted with one guide bar or with two guide bars each one knitting in opposition to each others.

Spacer fabric are knitted on warp knitting raschel machines with two needle bars.Depending of the product and its requirement,a minimum of four guide bars normally,however five to seven guide bars are in use.The distance between the needle bars is adjustable in certain ranges and is different for the various machines types for knitting spacer fabrics.

Possibilities face structures on spacer fabrics

Type A

Dense and plain,one or both faces can be combined with type B or C.

Type B

Dense and with overall motifs,one or both faces can be combined with type A and C.

 

Type C

Small open structure,one or both faces can be combined with type A or B.

Type D

Dense structure with additional dimension for napping on one side,rear side dense or semi dense grid structure.

Type E

Honey comb open structure on both faces.

Type F

Rhomboid open structure on both face

Spacer fabrics and their way of manufacture

Spacer fabrics produced on double needle bar raschel machines.The distance between the needle bars respectively the trick plate is adjustable in certain ranges depend on the type of the machine which is used for the manufacture of spacer fabric.

For the construction type A -F two guide bars for each face are normally used,i.e. including the bar for the space,a total six guide bars are used.

For certain applications one or both faces can be knitted with one guide bar only.The spacer up to 3 mm thick could be knitted with one guide bar for the space,preference however should be given to two bars half set,both knitting in opposition to each other.

For many applications it might be possible to knit the spacer construction half set,whenever the required  shore reading and resilience do allow that.By this method the content of expensive mono filament yarn can be reduced by approx 50%.

For spacer fabric with a patterned decorative face up to three guide bars are needed,in this case two guide bars are available for the opposite face and two for the space.

Application for automotive textile

Seat covering;

spacer fabric with two dense fabric faces,height : 3mm - 8 mm,substitute for foam lamination with decorative fabric.

Produce on warp knitting raschel machine type : RD 6 N with gauge 22E - 28E.

The current car seat offered in global marketplace consist of three layers : top layer which is often plush and made of polyester ;the middle layer made of polyurethane foam;and the bottom layer a polyamide warp knitting 

 

Interior lining;

e.g. doors,columns,back seat covering,dash board,sun-shield,roof liner and similar areas

Spacer fabrics with two dense fabric faces or one side with patterns or structure with one fabric side with napped surface.Height : 3mm -6mm.

Produce on warp knitting raschel machine type : RD 6 N with gauge 22E-28E and RD 7 DPLM with 22E.

Finder splash guard for trucks and buses;

Very open structure on one side and dense on opposite side,height : 10mm-12mm,produce on warp knitting raschel machine type RD 6 DPLM/30 with gauge 16E.

Seat heating within spacer fabric;

Both side are dense structure heating wire is laid-in in the spacer area.

Bolstering material as part of the seat construction;

Both side are semi open structure totally made from mono filament yarn,height : 12mm-16mm,produce on warp knitting raschel machine type : RD 6 DPLM/30 with gauge 16E.

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Standardized Term for Discribing Warp Knitting Machines with One and Two Needle Bars

Warp knitting machines can be built with one or with two needle bars, thus, forming one
or two stitch courses per main shaft revolution. This fact often results in confusions when describing the productivity and fabric parameters of these machines.
A standardized definition of the relevant technical criteria is meant to remedy this matter.

Fig:Knitting elements of Karl Mayer
double needle bar

Rack
The only meaning of one "Rack" is : 480 main shaft revolutions. In other words: a warp knitting machine with one needle bar produces 480 stitch courses per Rack, at 480 main shaft revolutions, whereas a double-bar warp knitting machine produces 960 stitch courses during this cycle: i.e. 480 stitches on the front needle bar and 480 stitches on the rear needle bar. Thus, one guide bar can form max 960 stitches per Rack.

Yarn run-in

The yarn required during this cycle represents the "yarn run-in" value.
The unit of measure is "mm/Rack" and refers to 480 main shaft revolutions on double-bar machines.
This means: for the same lapping, the yarn run-in of a single-bar warp knitting machine can be compared to that of a double-bar machine working on one needle bar only.

Knitting line (ZLN)

The designation "knitting line" can also be used for one main shaft revolution. Thus,one knitting line for double-bar machines consists of one stitch-forming cycle, to from a course on the front and on the rear needle bar.
Nevertheless, special attention should always be paid to the type of stitch notation to be worked. If a thread should be interlaced by one needle bar only or should be kept as weft construction (inlay lap), it has to float on the opposite needle bar. Later on this float lap does not appear in the fabric, thus, not requiring any additional yarn run-in.
Connecting spacer/pile threads are always interlaced on both needle bars.
In this way,a stitch is usually formed on the front needle bar, underlap to the rear
needle bar, one stitch on the rear needle bar and the underlap back again to the front
needle bar.
In most cases, it is sufficient to use the term "knitting line" for
defining the yarn run-in value for double-bar Raschel machines. In special cases, however, this yarn run-in value has to be specified per stitch, separately for each needle bar, for which a sequential yarn feeding system is required. KARL MAYER's new computer generations will make it possible to enter an exact yarn feeding value to match the stitch courses. The input of this parameter can be done via a sub-menu on the
control panel of the MSM configuration (Multi Speed Motion) (in this context, please also
see the example given below.) This system will result in identical yarn run-in values on double-bar machines, regardless of the yarn feeding type.




Repeat-length

The description of a pattern is done by means of the term "repeat length".
For electronically controlled machines, the repeat length is defined by knitting lines. The shortest repeat length is one course, consisting of one stitch-forming cycle each on the front needle bar and on the rear needle bar (for double-bar warp knitting machines).

Number of stitches
The number of stitches is a measure for the quality of the knitted fabric, having a direct influence on the productivity of the warp knitting machine.
KARL MAYER will specify this no. of stitches also for double-bar machines in such a way that the set number of stitches per centimeter on the fabric take-up will coincide with the number of stitches per centimeter on one fabric face.

Machine speed

The machine speed will only be specified as main shaft revolutions per minute.
Based on the same number of stitches, an identical calculation of the machine performance is possible for single-bar and double-bar machines.
This standardized denomination of the technical details will surely facilitate the exchange of information,helping to avoid misunderstandings.
It will be part of KARL MAYER's new development and use for all warp knitting machines equipped with the new electronic concept starting from 01.01.2005.This definitions have been discussed and agreed upon with LIBA Maschinenfabric GmbH in Naila and with members of Standards Committee for Textile Machinery.Nevertheless,this nomenclature is not yet part of new ISO standards.

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