Every grinding machine has an optimal method of operation.

The variations in technique between different machines will depend on a range of factors, such as:

• the size and type of machine it is, including the number of heads and the manufacturer's design
  
  
• the tooling that's been fitted and the CSP you're aiming to achieve
  
  
• the loose material or contaminants that you're removing
  
  
• the presence of high spots or ridges in the floor, especially if you are planning to install a floor covering directly on top.

Some machines are designed to be moved in a circular motion as they are pushed up and down the floor in parallel lines. Others may have different processes.

If you haven't been instructed by an experienced operator on how to use a particular machine, make sure you read the manufacturer's manual before you start.

This will tell you what pattern to follow, how much overlap to incorporate, and what to do if you strike unusual features in the floor.

Below is a general procedure that applies to most grinding machines.

General procedure

1. Assemble all the tools and equipment required, so that everything is to hand when you need it.
   
   
2. Clean the floor and prepare the area. This may include isolating smoke detectors if there's a risk that the level of dust might set them off.
   
   
3. Inspect the equipment and complete all pre-start checks. Look out for damaged or excessively worn parts, misalignments and binding of moving parts.

4. Set up the tooling, depending on the hardness of the concrete and the type of material that needs to be removed from the surface.
   
   
5. Connect the dust extraction hose and power lead. Position them so that they will stay out of the way while you're working.
   
   
6. Turn on the extraction system and then start up the machine.

7. Grind in manageable sections of the floor, working up and down in parallel lines, or as instructed by the manufacturer.
   
   
8. Inspect the tooling regularly, and change the grit size and bond hardness to match the conditions and wear rate that's appropriate.

9. Shut down the machine when you've finished. Sweep up or vacuum any remaining dust on the floor. Empty out the bag or bin in the dust extractor and dispose of the bag in the designated area.
   
   
10. Clean down the machine, extraction system and surrounding work area and pack the equipment away.

Working to Australian Standards

If you're planning to lay a floor covering directly on top of the concrete subfloor, you'll need to carefully check the planeness and smoothness of the surface before you finish the grinding task.

The tolerances for both of these characteristics are set by the Australian Standard that applies to the floor covering you'll be laying.

We discussed methods for measuring planeness and smoothness in 'Inspecting concrete subfloors' in the unit: Inspecting and testing subfloors.