Sandblasting Process Dust Control
Dust control and filtration specialist Donaldson Australasia has been able to integrate one of its technologies into an overall solution to contain air borne particles during a sandblasting process.
A sandblasting process used to temper hard cut wire in an industrial procedure created the constant potential for that shot blasting to leave a residue in the system, potentially covering components in the workshop and calling for a regular replacement of these parts. So workshop management took an initiative to remain one step ahead and ensure this does not happen at its plant by routinely upgrading what was already a relatively new dust handling system.
Management was also aware of various cases around the world where this type of manufacturing process created a large amount of fine metal dust floating around a factory, subjecting both machine and finished product to severe rusting. With a company policy for regular, preventative upgrades, management saw it was time for an upgrade of its Donaldson DFT DownFlo dust handling technology to ensure it kept up to speed with production growth.
Ideally, it would focus on the task of gathering and containing dust from the 'shot blasting' process and allow staff to get on with the business of manufacturing without encountering and stoppages. Considering the company is processing at least 15 metres per day of sheet metal, it was seen as an imperative to maintain high levels of OH&S standards.
On any given work day the manufacturing process will create enough metal dust to fill a 205 litre drum. This is all collected and contained, unlike some operations in low labour countries where it has been found ‘floating in the air’ and creating all sorts of health and engineering problems for their workers.
The DFT DownFlo patented dust collectors utilise round shaped cartridges of the company’s patented Ultraweb filter media technology to allow large amounts of airflow through the collector without increasing the footprint size or damaging filters.
According to the Donaldson Engineer on the project, Mr Dominique Ollitrault, the operator had for three years operated with the DownFlo DFT for which it required cartridge replacement about once a year. “But since it changed its processes due to increased business the parts were now going through the shot blasting section at temperatures about 120°C,” said Mr Ollitrault.
“This was affecting the cartridges and to replace them frequently would have been expensive and impractical. With the new operation, there were now particles of a higher temperature particles travelling through our existing system and the potential for sparks was a little higher. There was microscopic oil on cartridges and an emission of fine dust so it was time for us to make routine upgrades to suit the client’s growth.“
Donaldson’s solution was a multi-stage one. The fist section uses a DownFlo pre-separator (cyclone) to take out of the filtration equation the largest particles, therefore acting as a Stage 1 screening device.
Once passing through the cyclone stage, smaller particles would transfer through the DFO system which now had two levels of filtration as a secondary filter box had been installed there. This secondary filter box provides a pre-filtration stage catches most of the remaining small dust running through the system.
Finally, the near-microscopic dust which is left as a final residue is captured by a HEPA filter, recognised by industry as capable of producing as close as physics will allow to ‘no-dust’ solution.
“The slight potential of sparks going into the dust collector was why we added the cyclone and separator,” said Mr Ollitrault. “When the dust and particles go through the cyclone it gives the system a method by which it gets rid of any sparks before they reach the dust collector. With a high efficiency cyclone, it also gives a chance to collect much more dust than the system had before. Now, only about 5% of the total amount of particles ends up in the dust collector – just the very fine particles – which means all the pre-stage work is doing most of the job.We made sure we don't have any dust coming out of the system.”