When an airborne dust issue was identified at the Placemakers Frame & Truss manufacturing plant in Wiri, Auckland, management and staff worked with experts to develop an innovative solution.

Plant engineer John Daniels helped design, and then built, a prototype plywood booth to enable more efficient extraction of sawdust sprayed from drop saws. This proved so successful the hoods were fitted to all drop saws at the plant – as well as at two other Placemakers plants.

The company has also since replaced drop saws at a number of its plants with models featuring built-in systems to enable easy extraction, and is also upgrading the overall extraction system at Wiri. 

Laurie Smith, Northern Manager for Placemakers Frame & Truss, said the factory management had always taken a rigorous approach to monitoring and managing air quality and already had a large extraction system.

There are 103 workers at the plant, which makes frames and trusses for the Auckland branches of Placemakers.

“We have independent worker exposure monitoring carried out every two years on dust, noise and levels of timber treatment to make sure we are providing a healthy working environment,” said Mr Smith.

“We had always been within the recommended limits but when the testing was carried out in 2012, the limits for airborne dust had just been reduced from 5mg per cubic metre to 2mg per cubic metre. Everything else was fine, but we found we were exceeding that limit in just one area, around the drop saws.

“We were investigating solutions when we were invited to take part in a government-funded project looking at dust levels in the pre-cut industry. We said ‘Absolutely’.

“Two thirds of the machines in the factory, including the drop saws, were already individually hooked up to our extraction system. Philippa Gibson, who is with WorkSafe, came and looked at the system and processes and accessed funding for us to work with ventilation engineers Egmont Air, which specialises in dust and fume extraction solutions in the workplace.

“They found that the extraction point of the drop saws, as manufactured, was not very efficient, with the sawdust and woodchips being sprayed into the air. Egmont and John then worked together to design a prototype hood built out of plywood.

“This encases two thirds of the saw – the back end where the sawdust and woodchips are fired out. It means they are contained in the booth and extracted from there instead.”

Philippa then brought in Kerry Cheung, a research fellow from Massey University’s Centre for Public Health Research, to assess the effectiveness of the booth.

Mr Cheung worked with staff to test the effectiveness of the hoods. People working with the drop saws wore backpacks with video cameras, which automatically began filming when the saw was activated.

“Kerry and the team monitored the dust levels around the working drop saws with and without the hood and with and without extraction,” said Laurie. “The hoods reduced the dust significantly, to a level of 0.5mg per cubic metre.”

Placemakers had plywood hoods built for all five drop saws and later modified these to make them more efficient – these are still in use at the plant.

The booths were also installed at two other Placemakers manufacturing plants using that type of saw, in Wellington and Hamilton – although drop saws at these plants have now been upgraded to models with a built-in capacity to encase particles.

“Our recent worker exposure testing found the dust levels around the saws had been further reduced to 0.47mg by the hood modification. We are also currently improving our main extraction system to make sure we are getting the best available result – hopefully the dust measurement will drop further still.

“The booths were cheap to make, simple and effective and they don’t restrict us in any way. Workers helped design, build and test the solution. We worked together to create a better, healthier working environment.”