INFRASTRUCTURE: Aerial lift bucket
Published in: Advanced Composites Bulletin
Date: 10/1/1998
An aerial lift bucket made from a polymer composite using resin transfer moulding (RTM) is said to be 30% stronger than its sprayed-up counterparts, according to Amoco Chemicals, a supplier of some of the materials used. The vast majority of lift buckets are glass fibre-reinforced plastic and these are typically made using spray-up of chopped glass and resin. However, Contemporary Products of Texas Inc (CPI), USA, makes its bucket using an isopolyester resin and continuous glass fibres. These materials combined with the RTM process give the final product its improved strength: the bucket sustained loads exceeding 2700 kg without failure in tests conducted by Trinity Engineering Testing Corp of Austin, Texas, Amoco Chemicals reports. To protect the glass fibres from degradation, they are embedded in an isopolyester resin matrix that is custom-blended by Reichhold Chemicals Inc of Research Triangle Park, North Carolina, USA. For extra protection, the composite uses a tough layer of isophthalic-neopentyl glycol (ISO-NPG) gelcoat produced by Neste Polyester of Fort Smith, Arkansas, USA; the isopolyester resin is made using purified isophthalic acid (PIA) from Amoco Chemicals. The one-piece bucket is made in a closed mould which produces a strong, monolithic structure with a seamless surface. Both the inside and outside of the bucket have gelcoat surfaces, produced by spraying the gelcoat on the mould before the part is moulded. After the gelcoat hardens, continuous strand glass mat is laid down. For added strength in critical areas, heavier woven glass fibre is placed in the corners, top lip and floor of the part. The two mould halves are then fitted together and resin is pumped into the cavity. After the resin has cured, a process which takes 4555 minutes, the glass fibres are encapsulated in the protective isopolyester matrix. Applications for the lift bucket are mainly found in the utility sector, such as installing and repairing power lines and other types of electrical contractor work. Although the composite is itself non- conductive, a low density polyethylene liner that is safety rated for electrical work is also installed to protect against electrical shock.
For further information, contact: Dalton Jones, Chief Executive Officer, Contemporary Products of Texas Inc, FM 1105, PO Box 510, Walburg, TX 78673, USA; tel: +1-512-868-0346; fax: +1-512-868-0351; or: Reichhold Chemicals Inc, PO Box 13582, Research Triangle Park, NC 27709, USA; tel: +1-919-990-7500; fax: +1-919-990-7711; E-mail: question.box@reichhold.com; Internet: https://www.reichhold.com; or: Tina DeCanter, Customer and Sales Support, Neste Polyester Inc, 5106 Wheeler Avenue, Fort Smith, AK 72901, USA; tel: +501-643-7865/800-643-6693; fax: +1-501-646-4279; Greg Cook, Purchasing Manager, Time Manufacturing Co, Versalift Division, PO Box 20368, Waco, TX 76702, USA; tel: +1-817-399-2124; fax: +1-254-399-2655; or: Fred Hartman, Professional Engineer, Trinity Engineering Testing Corp, 3601 Manor Road, Austin, TX 78723, USA; tel: +1-512-926-6650; fax: 512-926-3312; or: Dorothy Kuechl, Amoco Chemicals, Mail Code 7802, 200 East Randolph Drive, Chicago, IL 60601-7125, USA; tel: +1-312-856-3092; fax: +1-312-856-4151.
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