Square Root of Negative One

Heat Sealing 101

Posted in EnS, inflatable by cheng on December 21, 2009

Heat sealing is a term used to define a method of attaching one or more layers of thermo-plastic synthetic material to itself. Other options exist for non-thermo-plastic materials such as sewing, adhesives, heat activated tapes and mechanical means. However, for thermo-plastic materials, heat sealing is the most cost efficient method producing the best quality seam in the least amount of time.

For most applications, heat sealing processes include two critical components – application of heat under pressure followed by a cooling cycle or no heat under pressure. Depending on the method used, heat sealing can be used to seal 2 or more layers of material, similar and/or dissimilar materials, ie. Polyethylene to polyethylene, or polypropylene to polyester; and a wide range of material thicknesses (or weights).

R.F. or High Frequency Heat Sealing
Uses high frequency energy to seal dielectric materials , i.e. vinyl. Typically high frequency sealing uses a bar of varying lengths and widths (1/4″ to 2″). The dimension of the sealing bar creates the sealing pattern — straight or curved. This process creates very nice looking seals, although high frequency sealing is relatively slow, expensive and only works with a limited range of materials, and does not work well with dissimilar materials.

Ultrasonic Heat Sealing
Uses noise energy to seal thermo-plastic materials. Noise frequencies vary from approximately 15KHz (loud noise – larger sealing area) to 40 KHz (relatively quiet –small sealing area). Typical seam widths range from 1/4″ to 1″. Ultrasonic sealing can either be accomplished with a bar sealer or a rotary sealer. Not all materials can be ultrasonically sealed, although the material range is much greater than high frequency sealing.

Wedge Welding
Uses a heated platen located between the layers to be welded. The heated platen or wedge moves between the layers with very little friction and therefore wedge welding is, perhaps, the fastest method for welding long lengths of material. Wedge welding can be used to produce straight and curved sealing patterns. Works very well with almost all thermo-plastic materials from plastics to synthetic textiles. Works better with thicker or heavier materials (over 20 mil per layer). Wedge welding used predominantly to weld vinyl or pvc coated textiles, high density materials (20-80 mil HDPE), synthetic textiles including polypropylene, polyester and nylon. For more information on wedge welding and wedge welding suppliers to the industry, go to:

Impulse Sealing
Uses a heated nichrome wire under pressure to seal a wide range of materials. Takes the form of a bar sealer and is used predominantly to produce straight sealing patterns. Works best with thin materials ranging from under 5 to 10 mil to produce a seam width ranging from 1/8″ to 1/2″ on materials such as supported or unsupported vinyl, polyethylene, and many flexible materials.

Pulse Sealing
Very similar to Impulse Sealing, however pulses the heated nichrome wire. The pulsing action emulates High Frequency and Ultrasonic heat sealing at significantly less cost. The method developed by
Novaseal is commonly used to make outdoor signs, billboards, posters and drapery systems, among other industrial uses where reduced sealing time is important. Works best with lightweight materials including polyethylene, vinyls and other thermoplastic materials ranging from 5 to 30 mil in thickness. Seam width ranges from 1/4″ to 1″, where 1″ is the most popular.

Hot Air Sealing

Uses heated air directed between the two materials followed by a pressure means to heat seal materials. Sold in various forms from heat gun (looks like a hair dryer) to large industrial systems. Relatively inexpensive method, however prone to heating coil damage (down time) and heat sealing voids (sections of material that appear to be sealed but are not sealed). Two companies are leaders in sales of Hot Air sealing systems … Leister and Miller Weldmaster. Hot Air sealing can be used with virtually all thermoplastic materials.

Heated Platen Sealing

Perhaps the oldest known form of heat sealing, this method uses one or two heated platens (also known as dies) to come into contact with one or both layers of thermoplastic materials. Most commonly used to heat seal curved or complex patterns. Drawback is that the heat is always on which may create safety and handling issues.


Posted in inflatable by cheng on December 21, 2009

Artist with Space Browsers
Space Browswers are simple airborne tele-robots. Helium-filled blimps of human proportions or smaller are propelled by lightweight motor-driven propellors with attached video camera, microphone and speaker allow for remote operation and interaction experiences.

More images are available here


Posted in inflatable by cheng on December 13, 2009


Posted in architecture, inflatable by cheng on December 13, 2009

Archigram was an avant-garde ar­chi­tec­tural group formed in the 1960s – based at the Architectural Association, London – that was fu­tur­ist, anti-heroic and pro-consumerist, draw­ing in­spi­ra­tion from tech­nol­ogy in order to cre­ate a new re­al­ity that was solely ex­pressed through hy­po­thet­i­cal projects. The main mem­bers of the group were Peter Cook, Warren Chalk, Ron Herron, Dennis Crompton, Michael Webb and David Greene.
 michael webb

Mike Webb, 1967

The Walk­ing City


Posted in architecture, inflatable by cheng on December 13, 2009

 Viennese architectural and design group founded in 1967 by Laurids (1941– ) and Manfred (1943– ) Ortner, Günter Zamp Kelp (1941– ), and Klaus Pinter (1940– ), with others representing different disciplines. The group opened offices in Düsseldorf (1970) and NYC (1971), so quickly became international. Specializing in ‘disposable architecture’, pneumatic structures, air-mattresses, and life-support systems, its projects (often featuring plastics) have included Balloon for Two (1967), the external shell around the Haus Lange Museum, Krefeld (1971), and the Oasis 5 in Kassel (1972). Among unrealized projects that have received attention are the Pneumacosm pneumatic-cell expansion of NYC (1967) and an artificial cloud with a huge ladder for access (the Big Piano—1972). Cook has identified Haus-Rucker-Co as contributing to Experimental architecture.

 On the occasion of an exhibition was in the domed hall of the Kunsthalle in Hamburg installed . In the middle of a square pool of 6 m side length of white plastic tissue a steel tower stood at the top of a glass-cube, in which there were two barrels with natural greenery. On the front sides of the cube were two attached semi-circular, divided into chambers made of transparent foil cushion the lungs, which over alternately controlled blast from the green cube and breathes. Like the wing of a human lung, lifted and pushed by them and they lowered the air is filtered and flavored with artificial additives in a tube system, which led right through the building to a customer location on the square in front of the Kunsthalle.
[google translate from here ]