Keeping it Clean
Argweld® Flexible Weld Purging Enclosures® make it possible to weld stainless steels, titanium and other reactive alloys effectively without oxidation & discolouration.
There's not much that's new about Flexible Weld Purging Enclosures®. For more than a generation flexible welding enclosures have been a cost-effective way for welders to maintain an atmosphere that's entirely inert, which is necessary for fabricating products from sensitive materials that are used in many high-tech, high quality or safety-critical applications.
Metal enclosures have been the most common choice for fabricators, even though such equipment has always been very expensive to produce and operate. Now, as the demand for products fabricated from sensitive or reactive materials increases, the demand is rising for new designs to enclose welding processes.
An increasing number of companies that fabricate products in such metals are recognizing the benefits of the Flexible Weld Purging Enclosures™.
To begin, welding titanium demands more care than usual. It's not impossible, but it's a particular skill.
Titanium is highly reactive. It will form compounds with undesirable elements. If the metal is heated in air, the surface of the part will gain carbides, nitrides, and oxides that may reduce the weld's fatique resistance and notch toughness, as well as that of the heated zone.
According to titanium manufacturer Timet Corp., the techniques and equipment used to weld titanium are similar to those required for other high-performance materials (e.g., stainless steels or Ni-base alloys).
By contrast, titanium demands greater attention to cleanliness and to the use of auxiliary inert
gas shielding than those materials.
"Molten titanium weld metal must be totally protected from contamination by air," according to Timet, and 'hot heat-affected zones and root sides of titanium welds must be shielded until temperatures drop below 800O F (427O C)."
Timet recommends welding of titanium be done in a separate, specifically designated area.
This area should be kept clean and isolated from dirt producing operations like grinding, torch cutting, and painting that may produce dust or other particulates. It should also be draught-free and humidity should be controlled.
Leading British weld purging ancillaries manufacturer Huntingdon Fusion Techniques (HFT®) reports significant sales of its flexible enclosures to global aerospace manufacturers involved in helicopter, bellows, spacecraft and fluid handling systems production, as well as top sports car and surgical product manufacturers and to Airlines for repair and maintenance applications.
CEO, Georgia Gascoyne notes, 'We have been taken by surprise at the sudden surge in demand from these highly demanding fabricators although we have promoted our enclosures for these very applications for many years.
The HFT® enclosures are manufactured from UV resistant PVC and have proved to be extremely successful for welding with oxygen levels down to 10 parts per million. Aerospace companies are now placing orders for batches of six at a time so that they can meet production demands'.
The Flexible Weld Purging Enclosures® are manufactured as standard with two sets of glove ports but extra sets can be specified. The upper half of the enclosure is optically clear and provides excellent welding vision. An entry lock is fitted for small parts to be taken in and out without loss of purge quality. An exhaust valve allows continuous purging so that impurities can be expelled during welding.
Although welding stainless steel components inside Flexible Welding Enclosures® is not a pre-requisite, the cost and time savings might be considered a justifiable reason to begin welding in totally inert atmospheres rather than pouring away expensive Argon gas by welding in ambient conditions and trying to shield from the front and purging the backside simultaneously.
Having examined the staggering cost differences of Argon from enclosure welding to ambient welding, by adding the savings of time in cleaning and/or pickling, there is another significant sum of money to to be saved.
The purchase and disposal costs of pickling fluids needs to be taken into consideration as well as the costs of abrasives and polishing materials.
A Return on Investment chart is available showing the extent of these enormous savings.
A production enclosure for manufacturing sports vehicle chassis with many joints welded in the same purging cycle.
A specially designed welding enclosure for research purposes studiyng mechanised welding techniques for Titanium.
To read the published article in Tube First, click this image
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