Extrusions, aluminium

Plate evaporators (Figure 7.8) are formed by cladding a tubular coil with sheet metal, welding together two embossed plates, or from aluminium extrusions. 

Useful mono-material structural elements may be formed by bonding together a number of individual pieces of the same material. Glued laminated timber (glulam) members as described in Chapter 7 represent a development in which structural elements of large cross-section may be created. Adhesive bonding, as opposed to mechanical fastening, leads to reduced stress concentrations as well as the elimination of joint slip. The same principle may be applied to other materials where appropriate, such as aluminium extrusions and... 

As with aluminium extrusions, so with pultruded fibre reinforced composite profiles. The limit to the size and complexity of these profiles suggests that a modular approach could be adopted towards forming alternative structural configurations from the basic or standard profile shapes by bonding together individual lengths. Composite materials lend themselves to being joined with resin adhesives because they are themselves formed with vinyl ester, polyester or epoxy resins. Cursory surface treatments only, such as mild abrasion, often suffice. 

Aluminium extrusions can combine two sheets (a), three or more sheets (b), or whole complexes of interfitting parts which may be built into robust structures. 

MarhavilasP.K., KoulouriotisD.E., 2008. A risk estimation methodological framework using quantitative assessment techniques and real accidents data Application in an aluminium extrusion industry, Journal of Loss Prevention in the Process Industry, 21, 596-603. 

A1 Abbassi A.M., Basu S., Aluminium lamp posts corrosion problems and solutions. Fifth International Aluminium Extrusion Technology Seminar, Chicago, May 1992, p. 503-510. 

Fig. 3.35 Mercury porosimetry intrusion-extrusion plots of alumina gels prepared from solutions of aluminium monohydrate in A, propan-2-ol (2-5w/v%) B, propan-2-ol (4-9w/v%) C, 2-methylpropan-2-ol (4-9 w/v%) D, 2-methylpropan-2-ol (9-5 w/v%) E,butan-2-ol (9-5 w/v%). -------, ascending, intrusion curve -----, descending, extrusion curve.

Hot extrusion - Aluminium and magnesium alloys Extrusion - Tliermoplasties Extrusion - Elastomers Cold extrusion... 

EXTRUSION PROCESS CAPABILITY MAP FOR ALUMINIUM AND MAGNESIUM ALLOYS... 

Current usage is almost entirely associated with the good adhesion to aluminium. Specific applications include the bonding of aluminium foil to plastics films, as the adhesive layer between aluminium foil and polyethylene in multilayer extrusion-laminated non-lead toothpaste tubes and in coated aluminium foil pouches. Grades have more recently become available for manufacture by blown film processes designed for use in skin packaging applications. Such materials are said to comply with FDA regulations. 

The similar, older slurry process uses a less active catalyst. The monomer is dissolved in isooctane, the titanium catalyst and aluminium cocatalyst are added and this mixture is fed to the reactor which is maintained at 70°C. The inorganic corrosive (Cl) residues are removed in a washing step with alcohols. The atactic material is removed by extraction. A third process employs propene as the liquid in combination with a high activity catalyst. The Himont Spheripol process, which uses spherical catalyst particles, gives spherical polymer beads of millimetre size that need no extrusion for certain purposes. A more recent development is the gas-phase polymerization using an agitated bed. All processes are continuous processes, where the product is continuously removed from the reactor. Over the years we have seen a reduction of the number of process steps. The process costs are very low nowadays, propene feed costs amounting to more than 60% of the total cost. 

POSTER TITLE Purification of Aluminium Alloy Scrap by Backward Extrusion Process in the Semisolid Condition... 

Bhattacharya et al studied the effect of molybdenum disulphide concentration on friction in metal deformation. Their results (Figure 13.G) .iiOvv un optimum at 3 - 4 wt.% and a steady decrease at higher concentrations for unannealed aluminium alloy, and two separate optimum concentrations for annealed alloy. Nandi also reported a drop in extrusion load for lead billets at certain specif concentrations. 

Two of the substances detected, pentamethyl heptene and tetramethyloctene were considered as substances known to contribute to the odour of extrusion film coatings. The fact that these substances could transfer from the film to the gas phase supported the potential for these substances to give rise to odour problems in foodstuffs. They also impregnated a filter paper with octanal and placed it in the test cell in contact with paperboard laminated to various films including PE, PP, poly(ethylene terephthalate) (PET) and aluminium/PE (Al/PE) (with PE on the outer surface). They monitored transfer of octanal across the material held at 30 °C for 8-10 hours. Transfer was most rapid through uncoated paperboard. Octanal was shown to transfer across PE film laminated to the paperboard within ten minutes. There was no transfer of octanal through PP, Al/PE and PET over ten hours. 

Only some 15-20% of all waste plastics can be effectively recycled by conventional mechanical recycling technologies (i.e. sort/grind/wash/extrusion). Beyond this level the plastics become increasingly commingled and contaminated with extraneous materials such as soil, dirt, aluminium foils, paper labels and food remnants. 

Aluminium wire.s, 3 mm in diameter, are produced by extrusion. The wires leave the extruder at an average temperature of 350°C and at a linear rale of 10 m/min. Before leaving the extrusion room, the vire,s arc cooled to an average temperature of 50 C by transferring heal to the surrounding air at 25"C with... 

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