Pneumatic grinders are generally lighter and more compact than electric grinders because the power source sits outside the tool. These characteristics are important considerations: a good power-to-weight ratio, alongside comfort of handling and manoeuvrability, result in easier handling, faster operation and increased productivity. Furthermore, they are suitable for wet or dusty environments.

Power comparisons

In grinding applications, the rate of material removal is key and efficiency is affected by the tool’s ability to run the abrasive properly, whether it be a grinding wheel, sanding pad or flap disc. Abrasives are designed to run at certain speeds for optimal performance, so check what features are offered to deliver consistent, high levels of materials removal. For example, most pneumatic grinders include an air governor which increases air flow as the operator increases the load, maintaining the rotation and optimal speed of the abrasive for the best result. 

When assessing power tool performance specifications, note that a power value for an air tool has a different meaning to a power value for an electric tool. For electric tools, the value given in horsepower (hp) or Watts (W) indicates the power consumption of the motor and not the useful power. The average ratio between the power at the abrasive and the power consumption is somewhere between 0.5 and 0.6. So, an electric tool with a power consumption of 1000W will likely deliver a real useful power at the abrasive of around 600W. By contrast, the power value of pneumatic tools refers to a value measured directly at the spindle. So, a pneumatic grinder with a power of 1000W delivers that same value at the abrasive.

Safe operation

Minimising unscheduled downtime due to equipment damage or operator fatigue is a key part of optimising productivity. There are some simple steps to take when operating grinding tools to reduce risks in the workplace. 

Ensure that the grinder is assembled correctly before connecting it to the power for the first time. Before each use check that essential components like wheel guards, grinding wheels and triggers are sound and working properly. The guard should be adjusted so it provides optimum protection for the operator. Always use the safety screw and original spanner provided with the pneumatic grinder and don’t overtighten the flange or screw as this may lead to premature wear. Whether using the tool for the first time or after adjusting, test it before you begin grinding. 

To maximise productivity, operators need to find their pneumatic grinder’s 'sweet spot': the optimal force required for the best material removal rate. Start with gentle pressure and build up gradually to achieve this. When the spark stream created by the abrasive is as bright as possible, the correct force is being applied. Maintaining an angle of 30° between the grinder and the surface also gives the best results during abrasive use.

Once the job is finished, make sure the machine is switched off and has completely stopped before setting it down. Never drop or throw the tool aside: put it down carefully so that there is no risk of it starting up again.

Maintenance matters

Most pneumatic grinders are built to last and will perform reliably over long periods provided you look after them well. A bit of tender loving care can go a long way to ensuring optimum performance and avoiding unscheduled maintenance. 

*This article is based on 5 Benefits of Pneumatic Grinders, one of a series of Expert Corner Technical Guides from Chicago Pneumatic Tools available free online at: www.cp.com