20kHz 1500W Ultrasonic Lace Machine for Nonwoven Cutting and Sealing

An Overview
It is amazing to see what ultrasonic energy can achieve in joining, cutting, patterning, and quilting on synthetic fabrics. These and more operations are done without the use of thread or adhesives and at speeds much greater than can be reached with sewing machines - as much as four times the speed!
How does it work? As the fabric passes under the machine's horn, ultrasonic vibration causes the materials to heat up and fuse together. Without any additional glue or heat, the seam is finished. When used with cutting edge tooling, the vibration cuts through the fabric and seals the edges of the cut to eliminate any fraying at the edges.
Sewing machine operators quickly adjust to this threadless sewing technique. Modular systems are available for integration into automated textile manufacturing equipment and web handling equipment.
Plunge welding or cutting is accomplished by placing the material over a fixed anvil and having the horn or tool descend to the fabric. This approach is used to punch holes, such as buttonholes, to cut fabric strips to preset lengths, or to join pieces together.

Principles of Operation

Every ultrasonic unit contains the following five elements:
1. A POWER SUPPLY which takes line power at 50 or 60 cycles and changes it to high ultrasonic frequency at 20,000 cycles per second or even higher.
2. A CONVERTER which contains piezoelectric crystals which change the incoming high frequency electrical signal to mechanical vibration.
3. A BOOSTER which transmits the vibration energy and serves to increase its amplitude in much the same way as volume control on a radio.
4. A HORN which delivers the vibration energy to the plastic film or fabric to be worked on.
5. AN ANVIL or backup part which supports the work piece and, in the case of textiles, takes the form of a pattern wheel or non-rotating cutter wheel depending on the application.
The ultrasonic vibration is transmitted from the horn to the material. developing frictional heat where they touch. This momentary heat fuses the edges of the fabric. If double plies are present, the plies join together. Where a cutting edge is used on the anvil, the fabric is cut through and the edges sealed at the same time.

Materials
Materials may be 100 % synthetic or blends with up to 40 % natural fibers. Nonwovens, woven, stretch woven or knit materials can be bonded and cut or slit. Acrylics, acetates, polyester, nylon, polyethylene, polypropylene, spandex and PVC are all suitable for bonding or cutting. In general, the higher the synthetic content, the easier it is to cut and seal with ultrasonic energy.
Some fabrics may be directional; that is, the fibers in one direction have a different composition than the fibers in the other direction. This may lead to different results depending on the direction of the cut and seal.

Making seams
One of the most common applications is to make seams or hems in medical disposable products. These include medical garments, drapes, wipes, face masks, among others. The most commonly used machine is the Seamstar. Pattern wheels can be changed to simulate a single row, double row or triple row of stitches.
Extra sealing and neater appearance is seen when an edge cutter on the same pattern wheel is used to trim the edge as it is stitched. This feature also guarantees that the edge of the seam and the seam itself are perfectly parallel… a bonus quality feature at no extra labor cost. Sealing the seam edge also provides the benefits of overcasting without the cost.
With an air-driven edge guide, the Seamstar can be operated with minimum supervision. Just manually feed the materials and straight lines or slight curves can be joined with no operator adjusting or guiding.
Most of the familiar attachments can be used with the Seamstar; folders of almost every type can be used with this stitchless sewing technique.
Stitch patterns available include solid lines, dots, single stitch, double stitch, zigzag, knurl, slant, rope, serpentine, flower and leaf patterns. The patterns are machined or etched into the rotating anvil.

Sleeves and Cuffs
Cylinder machines, both off-the-arm and around-the-arm styles, are available. These machines use a cylindrical arm with a rotary stitch wheel and an ultrasonic system above me wheel. The fabric is fed between the pattern wheel and the ultrasonic system. The off-the-arm model is used for making tubular pans, such as sleeves, pant legs or continuous tubes. The fabric can be fed through a folder to give a lapped seam or a double felled seam, for instance. The ultrasonic pattern wheel then determines the stitch pattern.
The around-the-arm configuration can be used to seam collars and cuffs, or to set elastic in pant legs, cuffs and similar shapes. Again, a variety of patterns is available, from single row up to three rows of stitches or solid lines.
On the around-the-arm machine an edge cutter can be used to trim the edges for a neater appearance and to prevent fraying.

Special Seams
The effect of special seams, such as top stitching or zigzag stitch, can be achieved by the pattern wheel design. Let your imagination be your guide.

Slitting/Sealing
Ultrasonic slitters cleanly cut and seal the edges of synthetic or blended fabrics, eliminating the disadvantages of hot wire or rotating knives. Fraying, unraveling, or beading along the cut edge are eliminated.
Slitters may be mounted on a loom to cut the non-selvedge edge of woven fabric. Equipment is available to operate at the slow speed of weaving looms without burning or beading me fabrics. With special framework and motor drive, crosscuts can be made on the loom.

Web Handling Equipment
Many designers and manufacturers of web handling equipment are able to coordinate the requirements for adding ultrasonic slitters and cutters to their equipment.
Slitters may be installed on a loom to trim and seal the edge of fabric or to slit wide fabric into thinner strips. A single system with a bar horn and multiple cutting modules can cover about 20 to 25 cm wide fabric. Multiple systems can be used to cover wider widths of fabric. This technique is used frequently for slitting garment labels; it provides an attractive sealed edge with a soft feel to the skin. Fine fabrics with a high percentage of synthetics can be slit at high speeds up to 100 m per minute or more. Heavier fabrics require a slower speed.
With appropriate framework and motor drive, cross-cuts can be made on the loom for cutting to a selected length. Special high-power rotary system modules are available to cut and seal heavier weight materials, such as automotive carpeting.
If a particularly broad sealed seam is required it is sometimes preferred to pre-compress the material using one ultrasonic head, and then slit me center of the sealed area using either a second ultrasonic head or a mechanical cutter. This technique has been used to produce lint-free wipes.

Nonloom Applications
An extra fine filter fabric used in the medical industry is made in a long thin tubular form. A very high frequency. low power ultrasonic cutter is used to slit the tube into shorter sections by placing the ultrasonically vibrating cutter against a circular mandrel which rotates the long regular part.
Ultrasonic systems can be used to slit computer ribbon, plastic films, filters, fabrics, nonwovens, pads, and quilted fabrics.
When a double layer of fabric is ultrasonically slit, the materials fuse together along the cut line. This is a perfect way of joining fabrics and sealing the edges together where a high strength bond is nor needed or where later finishing work is needed. A quilt maker uses this technique to compress and seal the edges of quilts and mattress pads which later have piping or skirting attached.

Hand Cutting
A hand-held cutter is available for cutting straight lines or gentle curves by hand or using a simple guiding mechanism. One application is for a small flag and pennant manufacturer. Cutting the edge of the flags ultrasonically eliminates the former requirement of folding and stitching a seam along the edges, producing an attractive flag without excessive labor cost.
A modular version of the hand cutter has been used with a robot arm to perform fairly high-speed cutting of a circular part Iying on a steel table.

Plunge Cutting
A plunge Cut operator can be used to cut-to-length ribbons, belts, etc. Widths up to about nine inches can be considered. A plunge approach is used together with a commercially available strip measuring device to preselect the length of ribbon and ultrasonically cut a diamond shape at the preselected length, forming two ribbon ends with an inverted "V" shaped end. Straight cuts are made on tubular-shaped padded material used for patient restraints, This tubular part is folded and ultrasonically seamed before being ultrasonically cut to length. When cutting the double layer, the seam is also made, an advantage over a mechanical cut.
The waistband of men's slacks is cut and seamed ultrasonically to give a pleasing finish to the cut edge without sewing.
Belts are edge-seamed and then automatically cut to length ultrasonically by using a triple cutter wheel on the Seamstar sewing machine and plunge cutting to length. This permits two belts to be made at a time using two layers of fabric, cutting each edge and the center and then cutting to length.

Plunge Sealing and Cutting
Ultrasonic plunge sealing and cutting are accomplished by single or multiple horns advancing onto the materials which are placed on a fixed anvil. The horns are generally flat faced titanium with a carbide coating and a maximum width of about 25 cm. The desired pattern is usually machined or embossed on the anvil which is made of heat treated steel. Production rates of 20 pieces per minute are possible with manual feed. Automatic feeding may be used to increase or sustain higher rates.
Applications include buttonholes, eyelets or grommet-like patterns cut and sealed from single or multiple plies. For instance, pet collars have several spaced holes punched in them using a flat horn and a series of spaced punchlike tools in the anvil. Other practical uses include fabric and vinyl belts and collar stays.
Splicing or sealing applications include the joining of hook and loop such as Velcro® to itself or to other fabrics permitting the attachment of loops, traps or buckles. Splices can be made straight or on the bias. A stitch pattern can be achieved, if desired. A plastic stiffener is inserted into a folded nonwoven fabric and the edges sealed using a plunge welder for a first aid splint; tapes are attached and eye shields attached to a surgical face mask; ties are attached to a nonwoven medical gown, all using the plunge welding technique.
A special machine is available for adding a plastic collar to a filter bag. The machine uses multiple heads (up to six) to weld through the fabric to the collar. Production rates up to 180 pieces per hour are achievable.
Equipment includes 20 kHz units at power levels up to 3000 watts, 35 kHz equipment at power levels co 900 watts and a small 70 kHz, 90 watt unit for very light work. Units are available with microprocessor controls for control and monitoring of the welds by time, energy or distance.

Adhesive Bonding
Heat-activated materials are placed between two fabrics that are nor thermoplastic. such as cotton or wool or blends with little synthetic content. The ultrasonic vibrations cause the heat-activated material to flow into the fibers of the fabric, joining them together.