The process can be divided into two parts:
Direct cladding - high pressure cladding is used when a measurable bond is required between the ore and clad material. An illustration of this requirement is aluminium cladding steel wire.
Indirect sheathing - the sheath cannot be extruded directly onto the cores which are generally thermosensitive. The extrusion product is made as a loose sheath that is immediately cooled to ambient temperature. For some application such as CATV cables the sheath is then drawn down, in line with the extruder, tightly onto the core.

The specifications of twin-groovecontinuous cladding machine `model 350' are: Max. section area-300 sq.m. for tubing, 300 sq.m. for profile, 300 sq.m. for multi-hollow section, 132 sq.m. for sheath; Min. section area-6 sq.m. for tubing, 8 sq.m. for profile, 16 sq.m. for multi-hollow section; Min. wall thickness-0.4 mm for tubing, 0.4 mm for profile, 0.4 mm for multi-hollow section, 0.5 mm for sheath; Max circumcircle diameter-50 mm for tubing, 65 mm for profile, 30 mm for sheath; Min. outer diameter-5 mm for tubing, 5 mm for sheath; Min. diameter for core-27 mm for sheath, 8 mm for Al-clad steel wire; Nominal extrusion speed-100 m/min. for tubing, 100 m/min. for profile 50 m/min. for multi-hollow section, 100 m/min. for sheath, 100 m/min. for Al-clad steel wire; Nominal output-278 kg/h for tubing, 220 kg/h for profile, 220 kg/h for multi-hollow section.

Areas of application: Metal industry - The continuous extrusion is widely used in the processing of solid sections, hollow sections and tubes of aluminium and its alloys; solidsections and strips of copper.

Developed on the basis of continuous extrusion, continuous cladding is the latest technology for producing aluminium clad steel wire, CATV, OPGW, various aluminium sheathed electrical and fibre optical cables.

The typical products of continuous extrusion and cladding are: Internal cooled helium tight sections for magnets of particle accelerator units; cooling system for deep freezers, industrial cooling equipment, air conditioners, dehumidifiers etc.; tubes for automobile industry (radiators, tubing for fuel, fittings, etc.); strip for transformers, alternators, and starters for car engines; sections for outside protection of fibre optic cables; telecommunication and signal cables for electric railway; OPGW (composite fiber optic overhead ground wire); square hollow sections for electro-magnetic coils, Al-cladded electrical conductors (e.g.steel core conductors, cladding of super conductors); lighting protection conductors of various shapes; all types of sectorial aluminiumconductors; small and medium sized AA 6063 sections; welding wire with excellent surface, free of any lubricant; rod for steel deoxydizing which is a typical application or scrap recycling.

Advantages: Low capital cost - quick profits; high rate of using materials - no discard; energy saving - elimination of the rod heating; high productivity - no downtime; ability of using waste scrap aluminium - elimination of the remelting process; compact - less floor space required. The use of continuous cladding process has solved the problem of poor quality welding seams in the traditional process, resulting in tighter tolerances and good sealing of the sheath as well as minimum material waste.

Stage of development: Commercialised in China.

Inputs required: Manpower - total 6.

Economic data: Machinery and equipment (FOB) - US$ 500,000.

Transfer forms: Equipment.

Manufacturing process of furfuryl alcohol (FFA): A Korean organisation is offering technology forfurfuryl alcohol (FFA) manufacturing process. Furfuryl hydrogen are reacted in the presence of copper chromite catalyst at low temperature and low pressure, and furfuryl alcohol is formed as a product and 2-methyl furan as a by product.

Areas of application: Chemical industry.

Advantages: Specially designed reactor resulting in high product yield and small reactor size. Optimum reaction parameters permitting minimum operation cost. Minimum waste effluents from the process.

Stage of development: Commercialised.

Inputs required: Raw materials - furfuryl and hydrogen; water - cooling water/chilled water and brine; other utilities - steam, electricity and nitrogen gas.

Transfer forms: Turnkey plant.

For enquiries: Dr Vadim Y. Kotelnikov, Consultant, Asian and Pacific Centre for Transfer of Technology, Adjoining Technology Complex, P.O. Box 4575, Off New Mehrauli Road, New Delhi - 110 016. Phone: 6856276, 6966509, 6966521, 6966619, 6966629; Fax: 91-11-6856274;E-mail: gen@apctt.ernet.in.

Compiled by G K Pillai