Welding metalwork pieces such as those made from aluminum is relatively easy as it melts at a much lower temperature and does not crack after solidifying. Aluminum welding is done according to the type of aluminum used such as commercial grade aluminum having 99 percent purity, non-heat treatable alloys containing small amounts of manganese (Mn) or magnesium (Mg), and heat treatable alloys containing copper, silicon, zinc, or magnesium.

Work pieces made from these types of aluminum are easier to weld whereas aluminum work pieces containing copper or lead additives are difficult to weld and often lead to cracking while welding.

Aluminum welding methods include MIG and TIG welding, apart from conventional techniques such as gas, plasma, resistance welding, and welding with covered electrodes. The TIG technique is used when there is a need for good surface finishes and when welding from one side is not accessible, such as when welding pipes, and when repairing castings. The MIG technique is better suited for welding thicker aluminum work pieces at a faster rate and for achieving long, continuous welds. This technique has a lower heat input, which results in less distortion in the welding zone.

The latest aluminum welding technique involves the use of pulse arc welding combined with MIG that give much better results as compared to conventional methods. This technique gives better control of the molten pool in the case of thin material, makes the arc more stable, reduces spatters, and mitigates the risk of welding imperfections.

Welders need to take a few precautions while welding aluminum work pieces as the higher melting point of oxide that forms on its surface, when mixed into the molten pool, can cause welding defects. The surface of work pieces that are to be welded need to be scraped or brushed clean using stainless steel wire brush immediately before welding.

Porch Railings – First And Lasting Impression

The porch railing is the first thing your visitors sees and in order that it makes a lasting impression, this article gives you tips for porch railings. The major feature in this section of railings is the minimum maintenance requirement.

The Form And Look – Essence Of Porch Railing

Since the porch is the first thing, a visitor observes after getting down from the car it always makes a lasting impression on the visitor. Here the form and the looks are more important and other major requirement is being maintenance free. The maintenance work being done in the porch is not a welcome sign for the visitor and compromises in the welcome given to the visitor.

Materials Used In Porch Railings

Materials have to be carefully selected for porch railings, workability is more important since the form, and looks are more important here. Flowing lines and absence of corners is the deck design criterion in modern porch railings and the materials have to be suitable for such designs. Most common materials are,

1. Stainless Steel: Because of high workability and the fact that it maintains shine for a long time and that too in adverse conditions, stainless steel is the preferred material in porch railings. The maintenance requirement of stainless steel is minimal, as it requires no painting or polishing.
2. PVC coated steel: The steel can be coated with PVC in multiple colors. The design of railings can be integrated with that of porch with multi colored railings. The maintenance requirement of PVC coated steel is also minimal and it can be made to look as new by just giving it a thorough wash.
3. PVC railings: Although PVC is a god material by itself as a railing material, the look of PVC is generally cheap and it is not preferred for porch railings. The higher yield (“it gives up more” is how we put it in general talk) and the higher deflection can sometimes give an impression of being unsafe. Therefore, it is not used as material for porch railing.
4. Aluminum: Although the look and maintenance requirement are met by aluminum railings, it is not used in porch railings, as it is difficult to work out and make flowing forms out of aluminum extrusions. Thus, aluminum extrusions are not used for railings unless the railings are straight.

Make your choice of material porch railings and make a good first impression on your visitor and it sure will last for a long time.

The European Commission has approved the acquisition of VAW Aluminium by Norway's Norsk Hydro. "The acquisition, does not give rise to any competition concerns in Europe due to only minor overlaps of the companies' activities and limited market shares," the EC said. While the commission noted that Norsk Hydro and VAW had overlapping activities in primary aluminum and semifinished products (flat-rolled products and extrusions), said "the combined entity's market positions would be relatively small in these markets and would not lead to any competitive concerns." The EC said its' investigation concluded that "there are a number of significant competitors who are internationally active in these markets. Therefore, the proposed transaction will not give rise to any creation or strengthening of a dominant position as a result of which effective competition would be significantly impeded in the European economic area."

LUXFER HOLDINGS PLC and PECHINEY (NYSE:PY) announced today that they had reached an agreement under which Pechiney will acquire the British Aluminium Speciality Extrusions business from Luxfer. The business is located in Workington, Cumbria in England where it manufactures hard alloy aluminium extrusions used for transportation (land and air) and general engineering applications.

The business generated approximately (pound) 28 million in revenue in 2000 (44 million euros) and employs about 280 people. The business operates three extrusion presses (5,000, 2,750 and 1,600 metric tons) with a production capacity of approximately 10,000 tonnes per year.

Philippe Darmayan, Pechiney's Senior Vice President of Aerospace, Transport & Industry, commented "The Workington plant is an excellent acquisition for Pechiney. It will nicely complement our existing hard alloy operations at Montreuil-Juigne and Issoire in France. Both the Pechiney and the Workington operations will benefit from sharing metallurgy and technical expertise. It will also allow us to improve our offer to our customers."
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Ian McKinnon, Chief Executive of Luxfer, commented, "The sale of British Aluminium Speciality Extrusions to Pechiney is the next step in focusing Luxfer on its core activities. It is a logical step following the sale of the bulk of our British Aluminium operations to Alcoa in 2000. The Workington business will benefit from being part of one of the largest aluminium groups in the world."

The completion of the transaction remains subject to the clearance by the competent regulatory authorities.

Pechiney is an international group that is listed on the Paris and New York stock exchanges. Its two main sectors are aluminum and packaging. With a presence in 45 countries, Pechiney achieved sales of approximately 10.7 billion euros in 2000 with 31,272 employees.

The Luxfer Group is an international group of businesses that specialize in the design, manufacture and supply of high performance engineering materials, alloys and semi-fabricated components to manufacturing industry worldwide. With turnover of (pound)250 million (394 million euros) it employs 2,350 people in 20 manufacturing plants in the USA, UK, Germany and Australia.

Corus Aluminium Extrusions, Vogt, Germany, will invest more than $19 million in a joint venture with Tianjin Non Ferrous Metal Group to design, produce and sell large extruded aluminum sections in China.

Executives said the joint venture would be based in Tianjin, southeast of Beijing, where the municipality owns the nonferrous metal group. It will make products aimed at transport, mechanical and electrical engineering industries.

Corus Aluminium Extrusions, a unit of Corus Group Plc, initially will invest 80 million renminbi ($9.6 million) for a 61-percent share in the venture, while Tianjin Non Ferrous will provide a 55-meganewton extrusion press for a 39-percent stake. An additional 80 million renminbi will be invested during the next two years to upgrade the press and provide new finishing equipment, executives said.

Tianjin Non Ferrous currently produces 6,000 tonnes of aluminum profiles a year; the joint venture has targeted a production growth to 8,000 tonnes of extrusions per year. "We consider China a strategic and promising market and have therefore built up an extensive sales network in China over the past few years," said Werner Graf, managing director of Corus Aluminium Extrusions.
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He said a government policy of investing in infrastructure and residential housing, along with railway and highway development, was expected to provide opportunities.

GA Pan-L-Trim is an alloy framing system for wall lining systems. Quick to apply with no visible fixings, these elegant high quality aluminium alloy extrusions will fit a wide variety of board types with widths of 20, 16, 13 and 6mm. GA offers the total aluminium solution, so why not apply for The Really Useful GA Handbook, the 160 page selector and design guide, visit www.goodingolum.com or fax 020 8694 2004.

Pechiney Aluminium has agreed to purchase British Aluminium's specialty extrusions operations from Luxfer Groups Luxfer Holdings Plc unit. Terms were not disclosed.

The Paris-based Pechiney interests said that the extrusions unit is a $40-million-a-year business producing hard alloy extrusions for the transportation industries and general engineering applications.

Situated in Workington in northern England, the unit has a workforce of 280 producing about 10,000 tonnes of extrusions a year on three presses.

Luxfer, which sold the bulk of its British Aluminium holdings to Alcoa Inc. of Pittsburgh last year, said that completion of the transaction awaited clearance by regulatory authorities.

Hydro Aluminium AS is reviewing the future of three of its Norwegian smelters after announcing it will phase out its Soderberg technology because of new environmental emissions laws.

The aluminum producer said it planned to phase out Soderberg production at its 205,000-tonne-per-year Ardal and 80,000-tonne-per-year Hoyanger plants by 2006 and at its 270,000-tonne-per-year Karmoy smelter by 2009. Production already has been cut by 8,500 tonnes at Karmoy because of soaring electricity prices and a weak market for extrusion products.

"We are presently faced with the challenge that in the medium term some of our Soderberg plants will have to close because of the introduction of environmental regulations that limit emissions from the plants," a Hydro spokesman said. The company has commissioned an internal report that will explore replacements for the redundant capacity at the three plants.

"We are presently examining the options available to us when the plants' capacity is phased out in relation to investment opportunities, metal supply and manpower," the spokesman said, adding "We have invested 6 billion kroner ($867,500) in developing Sunndal to become our largest aluminum smelter and have already phased out its older Soderberg units in December 2002, two months ahead of schedule." Sunndal's new potlines, expected to reach full capacity of 330,000 tonnes per year in 2004, currently are around 60 percent complete.

Last week, Hydro Aluminium announced it was seeking 85 million kroner ($12.3 million) in cost savings from its Holmestrand rolling mill and Alucoat coating plant in Norway in response to high aluminum scrap prices and an 8-per-cent increase in the value of the kroner against the euro. The company also said it was cutting 60 jobs from its 40,000-tonne-per-year Grevenbroich rolling mill in Germany in an efficiency drive.

Holland Shielding Systems has developed the latest extrusion system for manufacturing EMI shielding gaskets. The gaskets consist of a foam core covered with the copper-nickel plated fabric.

The conductive gaskets are compatible with the most commonly used materials such as stainless steel, copper, nickel, chromed aluminium and zinc-plated steel.

The gaskets come on rolls, cut in lengths, as well as in the shape of ready-made gaskets with bolt holes. Combinations with additional water seal, temperature or chemical-resistant and flame-retardant versions are also available.

Norsk Hydro ASA plans has reached an agreement to buy Indian Aluminium Co. Ltd.'s share in Indal Hydro Extrusions Ltd. (IHEL).

Currently, Norsk holds a 50.5-percent stake in the extrusion venture, which will increase to 100 percent when the deal is completed.

An Indian Aluminium (Indal) spokesman-said that papers were being filed with India's Foreign Investment Promotion Board to seek clearance from the government authority. Under the rules, a board resolution will have to be submitted along, with a "no objection" certificate from the Indian partner--in this case, Indal.

The current paid-up capital of IHEL is $500,000 and Norsk will have to bring in $1.25 million. IHEL, which started operations in early 1997, manufactures and distributes aluminum extruded products, primarily for the building and construction industry.

Norsk also has a stake in Utkal Aluminium International, the Orissa-based 100-percent-export-oriented unit, which is engaged in upstream aluminum mining and refining. The Utkal project, a $1.075-billion alumina refinery project, is expected to go on stream by 2005. Norsk holds a 45-percent stake in the project.

Hydro Aluminium will construct its first wholly owned automotive components plant in China to better serve customers in the country's growing automotive market.

Hydro will build the plant in Suzhou, north of Shanghai, to satisfy its automotive customers and further raise its own profile as the leading global supplier of lightweight precision tubing components. Global market leaders in heat and fluid transfer like Behr, Calsonic, Delphi, Denso, Valeo and Visteon are each located in the regions close to the Suzhou Industrial Park site, where the plant will be based.

At the new site, Hydro will produce precision drawn tubing, multi- port extrusions (MPEs) and extruded tubular profiles used in automotive heat transfer applications. The company will also deliver other high-value components from the plant.

Hydro will break ground in the first quarter of 2004 and install the plant's extrusion press by July. Production is scheduled to start in the third quarter of next year. The plant will create about 140 new jobs in Suzhou in first phase (2004).

We present a retrospective series of 170 cemented titanium straight-stem femoral components combined with two types of femoral head: cobalt-chromium (CoCr) alloy (114 heads) and alumina ceramic (50 heads). Of the study group, 55 patients (55 stems) had died and six (six stems) were lost to follow-up. At a mean of 13.1 years (3 to 15.3) 26 stems had been revised for aseptic loosening. The mean follow-up time for stable stems was 15.1 years (12.1 to 16.6).

Survival of the stem at 15 years was 75.4% (95% confidence interval (CI) 67.3 to 83.5) with aseptic failure (including radiological failure) as the end-point, irrespective of the nature of the head and the quality of the cement mantle. Survival of the stem at 15 years was 79.1% (95% CI 69.8 to 88.4) and 67.1% (95% CI 51.3 to 82.9) with the CoCr alloy and ceramic heads, respectively. The quality of the cement mantle was graded as a function of stem coverage: stems with complete tip coverage (type 1) had an 84.9% (95% CI 77.6 to 92.2) survival at 15 years, compared with those with a poor tip coverage (type 2) which had a survival of only 22.4% (95% CI 2.4 to 42.4). The poor quality of the cement mantle and the implantation of an alumina head substantially lowered the survival of the stem.

In our opinion, further use of the cemented titanium alloy straight-stem femoral components used in our series is undesirable. Titanium alloys are widely used for the manufacture of orthopaedic implants in total hip replacement (THR), for both cemented and cementless prostheses. The properties of titanium alloys include good biocompatability, low modulus of elasticity and resistance to fatigue and corrosion. The ability to accept bone on-growth makes titanium alloy favourable for cementless fixation. According to the literature, cementless stems produce less osteolysis and suffer fewer mechanical failures than similar cemented stems.2-4 However, the use of titanium for articulating surfaces is not recommended because of their low wear resistance.5

Cemented titanium alloy monoblock stems were introduced in the 1970s6 and initial results proved encouraging. Sarmiento and Gruen7 reported good short-term radiological results for cemented titanium alloy straight stems. Additional reports for other cemented titanium alloy stems with cobalt-chromium (CoCr) heads quote survival rates of 97% at 7.5 years8 and ten years.9

Straight Müller stems (Proteck, Freiburg, Germany) made of titanium-aluminium-niobium (TiA1Nb) with a ceramic head had a revision rate of 2.5% at a mean of six years' follow-up.10 The patient's weight was considered to he a factor affecting loosening. Good long-term results with 87.3% survival at 20 years were reported with 89 Ceraver Osteal (Ceraver Osteal, Roissy, France) polished titanium-aluminium-vanadium (TiAl^sub 6^V^sub 4^) cemented stems when combined with an alumina-on-aluniina coupling.11

Manner et al12 reported increased loosening of cemented straight Millier stems made of titanium alloy compared with cobalt-nickelchromium (CoNiCr) alloy stems at a median follow-up of 7.7 years, and noted that smaller titanium stem sizes, male gender and increased physical activity were associated with an increased risk of failure. Failure rates of 4.5%,13 and 9%14 at five years and 11.5% at 5.5 years,15 have been reported for titanium alloy cemented stems. The report from Jacohsson et al14 found that most failures occurred with smaller stems, especially in heavier patients, implicating the influence of the modulus of elasticity. The results of the Capital modular titanium alloy stems (3M, Loughborough, United Kingdom) with either CoCr or nitride-coated titanium heads were poor, with loosening of 16% of the femoral components at a mean follow-up of 26 months.16

The cemented modular Müller self-locking titanium alloy straight stem was introduced in 1984.12 We have retrospectively examined the outcome of 164 self-locking titanium alloy straight stems combined with either a CoCr alloy or an alumina head, implanted in patients between June 1986 and June 1988.

Patients and Methods

During the study period 386 THRs were performed in our hospital, of which 170 consecutive cemented titanium alloy straight Millier-style stems were implanted. Although 62 patients had bilateral THRs during this period, none had self-locking stems bilaterally. Six patients were lost to follow-up, leaving a final study group of 164 patients (164 hips).

The mean age of the patients was 64.9 years (48 to 80), with three less than 50 vears old at the time of operation, There were 114 women and 50 men. The pre-operative diagnosis was primary osteoarthritis in 139 hips, rheumatoid arthritis in six, avascular necrosis in eight, osteoarthritis secondary to dysplasia in four, and post-traumatic osteoarthritis in seven. There were 80 left and 84 right THRs.

The self-locking stem (Lima-Lto, Udine, Italy) is a Müller-style cemented straight stem made of a titanium alloy (TiA1^sub 6^V^sub 4^) which relies on a biomechanical self-locking mechanism. The surface of the stem is roughened by grit-Blasting. The surface roughness of retrieved components was measured at rhrec sites on the surface with a diamond stylus profilometer using a 2 mm evaluation length and a 0.25 mm cut-off length (Taylor-Hobson Form Talysurf Series 2; Leicester, United Kingdom). The mean surface roughness (Ra) was 1.72 µm (1.30 to 2.5). The tapered stem is flattened anteropusteriorly and primary stability is achieved by impaction into the broached femoral canal. Introduction of the stem and the extrusion of excess cement is facilitated by a groove on the anterior and posterior surfaces (Fig. 1). The stem is available in seven different sizes, with a 14/16 morse taper and can he coupled with a 32 mm diameter cobalt-based alloy (CoCr) or an alumina (Al^sub 2^O^sub 3^) ceramic head. The polyethylene cemented acetahular components obtained from the same manufacturer were sterilised in ethyleneoxide.