Laser and other cleaning procedures for aerospace moulds and a study of mould release agents
A selection of cleaning procedures are discussed which may be used to remove epoxide resin flash contamination bonded on metal and carbon fibre reinforced composite mould tooling that is used in the aerospace industry. Laser ablation, dry ice blasting and chemical cleaning using sodium hydride are three cleaning procedures studied in depth and have been used to treat a range of industrially sourced and model substrates, and contaminants. The effectiveness of the different cleaning regimes have been evaluated using Scanning Electron Microscopy, Atomic Force Microscopy, Auger Electron Spectroscopy, X-ray Photoelectron Spectroscopy and other analytical characterisation techniques. The necessity to clean aerospace tooling arises when moulded parts cannot be easily released from mould tooling and this is associated with mould release residues that have built up over a number of moulding cycles and eventually cause the moulding to stick. A comprehensive literature review of non-stick coatings is given and alternative mould non-silicone based release coatings are evaluated using the above analytical techniques. Coatings investigated include; fluoroalkylsilane, fluoropolymers and metal-fluoropolymer composites and the problems and merits associated with each are discussed.