Extending cutting fluid life

Extending cutting fluid life Economic pressures have focussed attention on ways of cutting manufacturing costs. One short term method of saving money, which has been adopted by many companies, is to continue using cutting fluids long after they have lost their effectiveness. In the long term, this is probably an uneconomic practice. PERA believe that it is possible to increase the period between fluid changes and maintain machining performance by using suitable treatments. They are setting up a project to evaluate methods of extending the life of metal cutting fluids. Project objectives are: to survey and identify materials, equipment and techniques for controlling the condition of cutting fluids using biocides, sterilisation processes, and filtration processes; and to evaluate on a practiCal basis a representative selection of the materials, equipment and techniques suitable for use in the machine shop. The proposed programme of work consists of a survey and a practical evaluation. The survey will start with a critical evaluation of published literature covering the whole range of treatments of cutting fluids. This will be followed by discussions with companies supplying bacteriocides, filtration, and other equipment to determine the most appropriate ways of using their products in a range of production engineering environments. The performance of the treatment procedures under production conditions will be discussed with selected user companies. During the course of this work, appropriate materials, equipment and techniques will be selected for practical evaluation. Cutting fluids treated with biocides will be used in metal cutting machines in a PERA workshop and the effectiveness of the biocides will be determined at intervals. In order to obtain further information as quickly as possible, laboratory trials will be undertaken using a simulated coolant system to determine the effectiveness of biocides against both aerobic and anaerobic bacteria.

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Arrangements will be made for other procedures for improving the life of cutting fluids, such as filtration and heat sterilisation, to be carried out by companies supplying or using the appropriate equipment, and culture fluids so treated will be evaluated at PERA. Tool wear measurements will be undertaken at PERA together with other measurements required to meet the criteria for the evaluation. The criteria will be: extent of contamination by bacteria; corrosive breakdown products; cutting fluid stability; cutting fluid performance in terms of tool wear; monitoring and control requirements; economic considerations; environmental and health aspects; and disposal requirements. This project will be multi-client sponsored. The findings will be reported to participating companies in confidence, including the results of the survey, the subsequent practical evaluation trials, and the economic evaluation of the application of selected conditioning systems in specific cases.

Operation of the control valve is entirely automatic. The setting of the needle valve detivers the desired oil flow rate. The oil then enters the valve and passes through an orifice creating a pressure drop, and moving a piston, thus compressing a spring until a balance is restored. The location of the piston, and specifically its relation to the outlet port in the cylinder, depends on the inlet pressure. The movement of the piston increases or decreases the area of the outlet port of the cylinder, keeping the flow rate constant under varying pressure. Flow control valves are supplied with inlets of '~, NPT pipe thread. The outlets can be either '/,, 3/8, '/2, or 3/, NPT pipe threads. Needle valves can be furnished with a T-handle or in a tamperproof construction. Oil-Rite Corporation, 2318 Waldo Boulevard, Manitowoc, Wi 54220, USA

PERA, R & D Division, Melton Mowbray, Leicestershire, LE13 0BE, UK

Oil flow control valves Oil flows of 30-450cmsa/min in low pressure lubricating systems can be kept constant using a recently announced control valve. Oil-Rite claim that their Type A-4472 valve will maintain an accuracy of-+ 10% with oil pressures of 15-250psi and viscosities of 400750SUS. Lubricant enters under pressure through the pipe thread inlet, flows through the constant flow control valve into the sight chamber, and is usually discharged by gravity. The bulls-eye sight allows a visual check of the oil flow from a distance, assuring proper functioning. The flow control valves are intended for use in low pressure lubricating systems for large fans, bearings, gear boxes, etc. It is claimed that they do not need the frequent adjustments that ordinary needle valves require and are, therefore, suitable for use in automated plants or in remote locations.

TRIBOLOGY international June 1977

Exceptional versatility is the major advantage claimed the Metavar microscope recently introduced by Reichert-Jung of Slough. This metallurgical microscope, with three design options, is said to enable all known examination techniques in the field to be undertaken. Reichert-Jung UK, 820 Yeovill Road, Slough, Berkshire, UK