As with many modern devices, computer numeric control (CNC) machines are very safe when correctly used. They should be installed behind a protective barrier that protects the user from sparks, dust and any dislodged components that could cause a serious injury. However, it’s wise to follow a few steps to minimise the possibility of unforeseen accidents.

Operator

Anyone using the CNC should be properly trained. If someone with little experience is using it, he or she should be helped by an experienced supervisor. The correct apparel is extremely important. Operators should not wear loose clothing, gloves or bracelets and rings that may become trapped in moving parts. All long hair should be tied back and held in place with a cap or other tight headgear. Protective goggles, not just spectacles, are crucial as dust and flying fragments can cause serious eye injuries. Hearing protection and steel-tipped non-slip shoes are important.

Machine

The CNC machine should be attached firmly to a workbench or any rigid surface or frame and clamped securely into place. All of the manufacturer’s recommended accessories, including the protective guards and other shielding and dust-collection systems, should be attached and operational. The floor around the machine should be kept clean and dust-free. There should be a taped or painted safety zone clearly marked out on the floor at least one metre around the machine. All tools should be inspected before work to ensure they are sharp and correctly set and the emergency shut-off button should be identified and accessible.

When Operational

Allow the machine to warm up before starting work. Conduct a dry run to ensure that the programming is correct for the job in hand. While the machine is running, avoid any touching of operational controls. Ensure that the operator does not lean over the machine beyond the zone marked on the floor. Other people in the machine room should not stand closer than three metres from the device. The operator should not stand on tools or try to use the machine bench as a work surface. Further CNC safety information found here will help.

The operator should not carry on a conversation with another person while the machine is running and requires supervision. He or she should remain focussed on the task in hand. All visitors, especially children, should be kept away from the work room when the machine is running. It is also extremely important not to machine wood and metal in one work piece. Sparks from the metal can ignite the wood dust and create an explosion. Never leave the machine running unattended.

Adjustment and Maintenance

Always turn the power off before making any adjustments to the machine. Give the machine time to cool off before removing any components, especially if milling metals. Clean all debris from the inside of the machine before working on another piece and sweep away all the debris around the machine. Store the CNC machine in a safe, dry and dust-free environment so that its electrical components remain undamaged.

Source: http://www.hse.gov.uk/pubns/wis22.htm

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