The advantages of the latest extraction systems when grinding include cost-savings through increased coolant life, improved surface finish and reduced production downtime. Most importantly of all though, are the benefits it can bring to employee health.
CoSHH (Control of Substances Hazardous to Health) regulations require all employers to use and maintain effective control measures to protect employees from exposure to hazardous substances – a subject oil mist extraction specialist Filtermist has extensive experience in.
The extraction specialist has set out some tips on the best way to ensure operatives are working in a safe and productive environment.
Wet grinding
With flatbed filter media, swarf and sludge produced in grinding will contain metal fragments from the material being machined, as well as particles from the grinding wheel, and general dirt and debris.
Coolant containing swarf can easily pool on the surface of the filter media if the flatbed system isn’t loaded with a suitable media for that particular coolant. This can result in bypass and tearing, meaning the machine tool will need to be stopped and cleaned more regularly, which can be time-consuming for the machine operator.
Grant Tyrer, product manager at Filtermist division direct filtration, explains: “Viscose media is widely used for filtering coolant used in grinding machines, but it’s not always the most effective. The type of coolant varies in viscosity meaning that some of our stronger/coarser grade materials can often be more suitable as they have greater fluid penetration characteristics letting the coolant through more easily than finer grade media.
“A number of our customers who have switched to a non-woven filter roll with a higher tensile strength have reported far less production downtime, and increased coolant life meaning they’ve saved money by reducing the frequency of waste disposal and coolant purchase.”
Whilst tearing can be a frustrating issue, a more harmful occurrence is filter bypass. This happens when the contaminated coolant cannot penetrate the filter media. Fluid will always take the path of least resistance and can at times simply pass over the sides of the filter media and into the coolant tank. This unfiltered coolant is then re-used in the machine tool which can impair the quality of both the tool and the components being produced and impact on the surface finish.
“Even the smaller particles can cause an issue,” explains Mr Tyrer. “Quite often a flatbed filter media isn’t enough to remove particles invisible to the naked eye. In this instance, adding a downstream polishing filter to the filtration system may be all that’s needed. We come across this problem quite frequently, but find that customers don’t always realise that we can offer a solution to this issue.”
Fluid management
The importance of responsible fluid management is well recognised, for both environmental and safety reasons, as well as from an operations and financial perspective.
A number of lubricant specialists offer fluid management as a value-added service for customers. This can include identifying the best type of coolant for specific applications to reduce usage and waste, as well as recommending equipment which will deliver efficient coolant efficiently and help to extend coolant life.
Filtermist works with a number of fluid suppliers, including Houghton International and Fluid Solutions, to ensure effective extraction and filtration is a key offering of its wider fluid management programmes.
Tramp oil skimmers are designed to remove the tramp oil from the surface of the coolant sump. If left to accumulate on the surface of the coolant, tramp oil can lead to a build-up of bacteria which affects the quality of the coolant and poses a health risk to machine operators.
Regarding coolant mist extraction, Filtermist director of sales Stuart Plimmer, comments: “Filtermist offers a number of options to ensure coolant mist is effectively removed from the atmosphere in workshops that use both enclosed and open grinding machines. These include Filtermist oil mist collectors and filters from our sister company Absolent AB. The recommended system will depend on the nature of the application. We approach every requirement on an individual basis to ensure we provide the most effective solution for each customer.”
Pre-filters and after-filters offer additional filtration stages to ensure as much particulate as possible is removed from the air. The cyclone pre-filter is specifically designed to collect swarf before it enters the centrifugal filter. The system is attached to the inlet of the Filtermist unit and the contaminated air passes through it. The low-pressure area within the separator encourages the heavier particles to fall to its base where they can be easily removed.
Filtermist also offers the CSX low level stand which includes an inbuilt pre-separator for more demanding grinding applications. In some applications, a single filter fitted to the grinding machine will be more than adequate, but others may require multiple filters connected to machines in cell-based production areas.
Dry grinding
Dust and fume that arises from using grinding wheels in dry applications also needs to be effectively removed from the work area to ensure it doesn’t pose a hazard to health.
Kevin Hood, sales director at Filtermist-owned Multi Fan Systems, explains: “As with wet grinding, the nature of specific applications will dictate the best extraction system. Sometimes individual filters offer the best solution, alternatively the dust and fume from grinding operations can be captured as part of a centralised extraction system designed to remove a range of contaminants from workshop air.
“If a central system is installed, extraction points should be fitted as near to the operation as possible and operators should be trained on the importance of ensuring the extraction hood position is maintained.”
As well as extraction equipment from sister company Absolent AB, Filtermist also supplies UK manufactured industrial dust collectors from subsidiary company Dustcheck. The company was founded in 1978 and has since established a reputation as a provider of effective dust extraction equipment used in a wide range of applications including grinding, shot-blasting and powder coating.
Once an LEV (local exhaust ventilation) system has been installed, it is a legal requirement that it is tested by a competent person at least once every 14 months.
“Despite widespread communication campaigns about the importance of regular LEV testing, we still encounter customers who don’t realise their legal obligations,” says Matt Wall, one of Filtermist’s LEV engineers. “Installing an LEV system is all very well, but if it is not tested regularly then any performance issues may not be flagged up until it’s too late. Employers are responsible for ensuring the air in their facility is safe to breathe at all times so regular testing is vital.”
Conclusion
“Dealing with a supplier that offers all permutations of system and supporting services will ensure that the customer’s needs are dealt with most effectively,” Mr Plimmer states. “We work with a wide range of customers that use grinding machines to ensure they are benefitting from cleaner, safer, more productive workshops.”
Filtermist www.filtermist.co.uk
