Using the Physics of Acoustics to Reduce Weight in Cars


As automotive manufacturers continue to push for improved fuel consumption and lower carbon emissions, they are squeezing every single gram of weight out of every single part that goes into a car.  Meanwhile, however, the pressure to save money and create a smoother, quieter driver experience is also increasing. Greensboro, North Carolina headquartered Precision Fabrics Group, has commercialized a unique nonwoven fabric called Nexus AFR which helps solve the car makers need to improve acoustics and reduce weight without breaking the bank. Physics of acoustics The Precision Fabrics solution is based on the ‘physics of acoustics’ and the science focuses on two dominant properties in part design – thickness and resistance to airflow.  Because sound moves through air in waves of minute pressure variations, the solution has to work for long wavelengths (low frequency) and for short wavelengths (high frequency). The frequency of sound, the wavelength of sound, and the speed of sound are related The thickness of the existing insulation layer is important and determines what low frequency wavelengths can be absorbed.  The new Nexus AFR nonwoven material replaces the traditional black scrim on the surface and controls the mid and high frequency wavelength by managing the sound pressure level variations and ‘trapping’ the energy in the insulation layer of the part.  This makes the composite more efficient than just the Homogeneous insulation material by itself.

Advantages over traditional homogeneous insulation

According to Precision Fabrics’ Richard Bliton, this two material approach has many advantages over the traditional homogeneous insulation, one material approach. “Traditional black scrim – the commodity black scrim used in the auto industry is a descendent of the fabric interlining and lining materials.  The typical nonwoven manufacturing technology is a chembond or thermalbond technology,” explains Bliton. Low cost fibres are carded and oriented primarily in the machine direction and a chemical spray or waterfall coats the web and it is compressed and dried.  The web then has a hot melt adhesive powder sprinkled on the face which is to be reactivated during on processing.  Properties such as FR or repellency can be added to the waterfall treatment. “The strength of this type of web is low compared to other nonwoven structures, but the prime advantage is that it is low cost.   Most of the purchasing specifications for this type of material only specify- fabric basis weight, colour, width, and amount of adhesive.  Acoustic characteristics such as Rayls are not controlled, tested or reported,” Bliton continues. An example, Bliton says, is an automotive hood liner.  A traditional design would have a 30 gsm black nonwoven scrim on the back (B) side, 1600gsm resonated fibreglass about 10mm thick as the insulation layer and a 50 gsm black scrim on the front (A) side. A recently launched next generation hood liner with Nexus AFR was made up of 30 gsm B side, 600 gsm Fiberglass insulation 10mm thick and 100 gsm Nexus AFR on the face.  The weight reduction is 950  grams/m² which is more than 2 lbs/m². In this particular case, the acoustics stayed the same and there was cost reductions generated in the raw material line, and additional improvements in manufacturing related to shorter cycle times required to mould a 600 gsm fibre glass part as compared to a 1600 gsm part. Alpha Cabin Random Incidence Sound Absorption

Automotive industry quick to adopt solution

According to Precision Fabrics Group, the automotive industry is moving quickly to implement this new approach. Parts using the AFR nonwoven are commercial in 10 platforms within 5 OEMs and one major OEM has adopted the low density fibreglass with AFR facing design approach as a worldwide corporate best practice. The focus on reducing weight and cost is one of the drivers for the adoption of the new material, but in some cases a vehicle may have a sound problem that has to be solved.  In these cases, the company says, a properly selected AFR facing can significantly improve that acoustic absorption of the part. The physics based solution offers the acoustic engineer some flexibility to tailor the part to focus the acoustic absorption on mid to high frequency ranges. “Some of the commercial parts on the road are last minute ‘fixes’ to acoustic problems found during pre-launch road tests.   The switch to an AFR facing is an easy change for a part manufacturer and an OEM to make,” Rich Bliton adds. The new fabric meets or exceeds all of the fabric specifications that are in place, the modified part can be made on the same tooling and the improved part will have the same fit as before. “The design approach to build a part with low density material for thickness and an acoustically tuned fabric facing for impedance as opposed to the traditional parts where performance was defined by the weight/thickness of the insulation is a new paradigm.  The science can be applied all types of insulation materials. Each situation will have to be tuned and validated, but early feedback is generating 30-40% weight reductions without loss of acoustic absorption performance,” Bliton concludes.

About Precision Fabrics Group

Precision Fabrics manufactures, markets and sells value-added products and services to selected, highly specified markets. The company’s high-performance products play a key role in several diverse markets, which demand engineered, finished fabrics, the common thread amongst which is  the technical nature of their requirements. Precision Fabrics was the first ISO-qualified textile supplier in the USA. – and ISO continues to provide the discipline and framework for effective and efficient product development, customer service, and manufacturing. Precision Fabrics has been ISO-registered to 9001 since 1993 and upgraded to 9001-2008 in October 2009. Precision Fabrics was created in 1988 via a leveraged buyout from Burlington Industries and continues as a privately-held company today. The company has evolved from a traditional textile company into an engineered materials business, focused on highly technical, high-quality woven and nonwoven fabrics. Today, Precision Fabrics employs approximately 600 people and operates plants in North Carolina, Virginia and Tennessee. Corporate headquarters are located in Greensboro, North Carolina and sales offices are maintained in Greensboro and in Bamberg, Germany. Precision’s Vinton, VA, Plant specializes in weaving some of the most technically challenging continuous-filament fabrics in the world. The Greensboro and Madison facilities are world-class in the range of nonwoven products that they produce.   Ref: http://www.innovationintextiles.com/using-the-physics-of-acoustics-to-reduce-weight-in-cars/

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Ultrasonic Technology in Nonwoven and Textile Industry


Flexible technology for a flexible market

Today’s textile and nonwoven market is so complex that fields of application, production techniques and technologies for further processing as well as the variety of new products are difficult to grasp, even for specialists.The variety of new composite materials of fleece, paper, films and fabric as well as the numerous possibilities in terms of combinations have one requirement in common: a safe and reliable process.

Ultrasonics is also the method of choice for these materials, for example for parting fabrics so that there is no thickening of the material along the cut edges.

No consumables such as glue, staples or sewing thread are needed. The fabric remains intact, because no external thermal energy is directed into the fleece. Position, shape and displacement of the welding points can even support the desired properties of the composite.

Textiles is thus a field where ultrasonic technology can prove its uniqueness.

The Functioning Principle of Ultrasonic Welding

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Low frequency mains voltage is transformed into high frequency electrical energy. A converter connected in line converts these electrical oscillations into mechanical vibrations. This is done using a piezoelectric transducer having an efficiency above 95 %.

The mechanical vibrations are transferred to a transformer element coupied to the converter, the so-called booster. This booster optimises the amplitude for the horn.

The horn is individually manufactured for each application and transfers the ultrasonic energy to the material to be processed. To build up a mechanical clamping force, a so-called anvil is required enabling the energy to effect melting on account of physical processes (internal and external absorption).

The Optimum Process for any Application

Cycle-controlled process

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The actuator applies a defined pressure onto the anvil and hence onto the part to be welded between the two components. Usually, the ultrasonic irnpulse applied  simultaneously is time-controlled. Using the weld depth or the amount of energy applied as criteria for deactivation is also possible.

Main fields of application for cyclecontrolled welding:

  • Overlapping welding of belts and tapes
  • Linear welding of fabric and nonwoven
  • Welding textile materials with thermoplastic contents
  • Joining the end of a material strip to the start of a roll to prevent costintensive drawing in of material into the production equipment.

Seal and cut edges can also be manufactured to excellent quality. This only requires a special design of horn and anvil which is important for the following particular applications:

  • Cut belt strips to length and/or punching
  • Parting of edge binding for blankets
  • Manufacturing buttonholes and eyes applying a certain structure to the rim in order to leave the impression of a sewn edge
  • Parting colour ribbons in bureau machine industry

Continuous Process

Two or more overlapping material strips are fed between horn and anvil which, if required, is rotating. Again, different systern combinations are possible:

Fixed Horn/Rotating Anvil

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This is the most commonly applied combination. Material strips (e. 9. fleece for use in agriculture) are joined at very high speeds using special profile wheels. Using profile wheels, sandwich structures can be generated. Combinations of different materials such as paper, films and textiles are particularly interesting applications. This combination can also be used for cutting processes. This usually involves cutting without sealing or with only slight edge sealling. The extension of the service life as well as the reduction of the cutting force and hence an increased cutting speed are strong arguments for the application of ultrasonic technology. Non-thermoplastic materials can also be cut. In this case ultrasonic energy supports breaking of the materials. Maximum precision is of course a prerequisite in such applications.

Rotating Horn/Rotating Anvil

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In this combination horn and anvil serve both to weld and to transport the welded product. In most cases both horn and anvil are driven synchronously. As in this system only a limited amplitude can be generated. This method is usually used for thin materials having a low mass per unit area.

Fixed HornlFixed Anvil

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This combination is usually used for cutting/ parting applications with simultancous sealing. However, it can also be used for continuous welding of paper, films, or textiles.

 

 

 

Refrance: BRANSON BROUCHER

CARPET CONSTRUCTION


It is important to understand carpet construction in order to apply the variables that affect performance of a specific installation. Tufted carpet consists of the following components: the face yarn, which can be cut pile, loop pile, or a combination of cut and loop pile; primary backing fabric; a bonding compound, usually SB latex, but may be polyurethane, PVC, or fabric; and (often) a secondary backing fabric.

The development of the broadloom tufting machine and the introduction of synthetic carpet yarns in the early 1950s transformed the American carpet industry from low-volume production of woven luxury products to mass production of high quality and comfortable, yet popularly priced, goods. The explosive growth of carpet sales in the United States in the ensuing years paralleled the continual development of tufting technology, the proliferation of high-speed tufting machines, and the development of synthetic carpet fibers and alternative backing systems. As a result, today’s carpet is both better and less expensive.

Figures 1.1 and 1.2 illustrate how these elements are combined to form carpet.

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The primary carpet fabric construction methods include tufting, weaving, knitting, needle punching, and bonding.

TUFTING

Over 90% of carpet produced is tufted, the most prevalent carpet construction method. Tufting machines are similar to giant sewing machines, using hundreds of threaded needles in a row across the width of the machine. Today’s machines are increasingly complex and sophisticated, providing a wide variety of styles and constructions.

The creel, located in front of the tufter, may be racks of many yarn cones or multiple large spools, referred to as beams, and containing many individual strands of yarn. From the creel, the yarns are passed
overhead through guide tubes to puller rolls. The speed of the puller rolls controls the amount of yarn supplied to the tufter and, along with other factors, determines the carpet’s pile height.

The eyed needles, which number up to 2,000 for very fine gauge machines, insert the yarn into a primary backing fabric supplied from a roll of  material located in front of the machine. Spiked rolls on the front and back of the tufting machines feed the backing through the machine.

Below the needle plate are loopers, devices shaped like inverted hockey sticks, timed with the needles to catch the yarn and hold it to form loops. If a cut pile is called for, a looper and knife combination is used to cut the loops. For cut-loop combinations, a special looper and conventional cutting knife are used.

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Tufting has reached a high degree of specialization, utilizing a variety of patterning devices, many of which are computer-controlled. Stepping, or zigzag moving, needle bars, and individually controlled needles greatly expand patterning possibilities. Such patterned carpet is frequently referred to as a graphics pattern. Other advanced tufting techniques are loop over loop and loop over cut (LOC) machines

After completion of tufting, the unbacked tufted carpet is dyed (if precolored yarns were not used) then followed by a finishing step to add an adhesive compound backing and, usually, a secondary backing material.

Tufted carpet styles range from loop, cut pile, and combinations of both in solids, tweeds, stripes, and patterns from the most simple to the exotic and complex. The designer has an endless variety of carpet choices due to advances in tufting–technology, coloration options, and finishing techniques.

WEAVING

While there are several methods of weaving and several types of looms, there are basic similarities to all. In general, woven carpet is formed by the interweaving of warp and weft yarns. The warp yarns are wound from parallel or heavy beams that unwind slowly as weaving progresses. Two main types of warp yarns form the carpet back: chain and stuffer. Chain yarns provide structure and stability while stuffer warp yarns increase bulk and stiffness of the fabric. The face yarns of woven carpet are also pre-dyed warp yarns that are normally fed into the loom from a yarn creel.

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The warp yarns run through a heddle, a series of vertical wires, each having an eye in the center through which the yarn is threaded. The heddle controls the action of the warp yarns. The wires are  mounted on two frames that rise alternately to form a space or shed.

The face of the carpet is formed with warp yarns moving into the loom from yarn creels. These pile yarns are looped over wires that lie at right angles to the warp yarns that are then bound with a yarn known as the weft, which is shot through the shed with a shuttle or other means. When a cut pile carpet is desired, wires with a knife blade at one end are used.

KNITTING

A carpet knitting machine, known as a double needle bar knitter, has a row arrangement of hundreds of latch needles that move in an up-and-down motion in conjunction with yarn guide bars. Yarn guide tubes are attached to a guide bar that passes the yarns between and about the needles, thus laying down the pile face yarns and weft backing yarns. Separate sets of guide bars control each of the yarns–knitting, backing and face yarns. Additional bars may be used for color and design variety.

Knitted carpet is used mainly for commercial loop construction and is sometimes referred to as woven interlock. It often is used in school applications.

NEEDLEPUNCHING

In the needle punching process, several webs of staple fibers are superimposed to create a thick, loose batting. The batting is then tacked, or lightly needled, to reduce its thickness before it is fed into the  machine. As the batting is fed into the machine, it passes between two plates. The stationary lower plate contains many holes, while the upper plate, or headboard, contains several rows of barbed needles. The batting passes between the plates and the headboard moves up and down, passing the barbed needles through the fibers. As the needles pass through the fibers, they carry fiber ends from the top of the batting to the bottom, and when they are withdrawn, vice versa. The needles are passed repeatedly through the batting as it moves through the machine to form the carpet.

Needlepunch carpet is used mainly for outdoor applications and may include uses like entrance mats, marine uses, wall coverings and automotive applications. Surface patterning creates a large number of design possibilities.

BONDING

Fusion bonded carpet is produced by implanting the pile yarn directly into a liquid polymer, usually PVC, which fastens it directly to the backing. This results in very little buried yarn compared to other processes. The yarns can be closely packed, producing very high densities suitable for high-use areas. This process is used most frequently to produce carpet to be cut into carpet tiles or modules. Fusion bonded carpet may be loop construction, but most often is a cut pile product, made by a two-back process, slicing apart two simultaneously made carpets that are mirror images.

What is real choice for HEALTH AND HYGIENE TEXTILES? – REUSABLES or DISPOSABLES


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ABSTRACT

A number of crucial issue regarding medical products in general and health care and hygiene products in particular have been identified and debated amongst clinical, environmentalists, drug companies, etc. for a long time now. The issues such as natural against chemical or manufactured fibres; disposables against reusable or durable fabrics; antibacterial or anti-microbial fibres against such finishes or coatings for infection control; and method of disposal of clinical waste i.e. landfill against incineration and other forms of medical and clinical waste disposal, are constantly being discussed in most relevant forums and conferences across the globe.

There are pros and cons to using disposable nonwovens and reusable textiles infection control products. The decision-making process often becomes more difficult for healthcare facilities that are trying to reduce both disposal costs and high labour costs related to reprocessing. And when it comes to evaluating the safety and infection control abilities of disposable and reusable products, particularly surgical textiles, there is little consensus on which is better, other than the importance of balancing cost considerations relating to infection prevention issues and the environmental effects.

From the discussion we would be able to say that the argument between disposables and durables for healthcare products will continue and one obvious solution of this argument is the increased and universal usage of biodegradable natural and manufactured fibres and products across the whole spectrum of the products. The recycling or disposal of clinical or medical waste materials poses problems of health and safety and availability and cost of landfill sites and incineration. This problem can be also controlled by using the reusable barrier fabrics with an improved laundry facilities and standards. But at last, “The Choice Depends On Customer”.

 

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REUSABLE vs DISPOSABLE

Needle Punching Technology


Abstract:

Needle punching is the oldest method of producing nonwoven products. The first needle punching loom in U.S. was made by James Hunter machine co. in 1948. Then in 1957, James Hunter produced the first high speed needle loom, the Hunter model 8 which is still used today.

The needle punching system is used to bond dry laid and spun laid webs. The needle punched fabrics are produced when barbed needles are pushed through a fibrous web forcing some fibers through the web, where they remain when the needles are withdrawn.If sufficient fibers are suitably displaced the web is converted into a fabric by the consolidating effect of these fibers plugs or tufts. This action occurs in needle punching occurs around 2000 times a minute.

Needle punched fabrics finds its applications as blankets, shoe linings, paper makers felts, coverings, heat and sound insulation, medical fabrics, filters and geotextiles.

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Nonwoven Technology- for unconventional fabrics


INTRODUCTION TO NONWOVENS

We know that nonwoven fabrics are one of the oldest and simplest textile fabrics. Its classic example is felt. The first well documented discovery of felt dates back 3500-3000 BC. It was made from hairs of various animals. The term “Nonwoven fabrics” was applied to new modern techniques, which were totally based on new principles, by U.S.A. in 1965. “Non woven fabrics” is being defined into different ways by different literatures; the term defined by “Textile oregano” in 1965 is as follows:

“Nonwoven fabrics are products made of parallel laid, cross laid or randomly laid webs bonded with application of adhesive or thermoplastic fibres under application of heat and pressure.”

In other words nonwoven fabric can be simply defined as a fabric those can be produced by a variety of processes other than weaving and knitting.
The nonwoven fabric properties depends on following particulars to an great extent,

1. The choice of fibres.
2. Technology which determines how the fibres are to be arranged.
3. The bonding process and the bonding agent.

Fabric properties of nonwovens range from crisp to that soft-to-the –touch to harsh, impossible-to-tear to extremely weak. This leads to a wide range of end products such as nappies, filters, teabags, geotextiles, etc. some of which are durable and others are disposable.

The first stage in the manufacturing process of nonwoven fabrics is “production of web” and another is “bonding of web by using several methods”. Some of those (binding methods) are felting, adhesive bonding, thermal bonding, stitch bonding, needle punching, hydro-entanglement and spin laying.

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NEEDLE PUNCHING TECHNOLOGY


Abstract:
Needle punching is the oldest method of producing nonwoven products. The first needle punching loom in U.S. was made by James Hunter machine co. in 1948. Then in 1957, James Hunter produced the first high speed needle loom, the Hunter model 8 which is still used today.

The needle punching system is used to bond dry laid and spun laid webs. The needle punched fabrics are produced when barbed needles are pushed through a fibrous web forcing some fibres through the web, where they remain when the needles are withdrawn. If sufficient fibers are suitably displaced the web is converted into a fabric by the consolidating effect of these fibres plugs or tufts. This action occurs in needle punching occurs around 2000 times a minute.

Needle punched fabrics finds its applications as blankets, shoe linings, paper makers felts, coverings, heat and sound insulation, medical fabrics, filters and geotextiles.

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