Safe use of machinery factsheets : Press Brake Machine Guarding
Press brakes are an unforgiving piece of machinery, and a frequent cause of workplace amputations.
Press brakes, also known as brake presses or just brakes, are a mechanical or hydraulic machine for bending sheet metal and plate material. It is a common machine in engineering workshops.
Employers have a legal responsibility under the Health and Safety in Employment Act 1992 to provide a safe working environment and this includes the safe use of machinery. Under Regulation 17 of the HSE Act’s 1995 Regulations, provision must be made for the safe cleaning, maintenance and repair of machinery. This includes guarding, lockout mechanisms, and a training programme for safe work procedures.
Hazards
The main hazards are trapping by the long tool and die of the machine, and trapping between the press frame and the work piece. The most frequent causes of accidents are:
- The foot pedal being activated while the operator’s hand is in the danger area
- Safety controls are by-passed while the controls are activated to align stock or undertake repairs
- The operator being caught by the pinch points created between the work piece and the press brake frame during the bending process
- Failure to lock-out the machine during cleaning, maintenance, installing or aligning dies
- Small work pieces that increase the closeness of the operator’s hands to the danger area
- Turning off the light beam safety device
- Inadequate training and supervision.
Hazard Controls
Fixed guards and interlock guard
For simple and repetitive work, fixed guards with a safe gap and distance for feeding metal sheets into the machine may be used. If this is not practicable, an interlock frontal and rear guard, with fixed guards on the sides may be used to prevent access by the worker during operation.
Presence-sensing devices
Along with fixed and interlock guards, a certified light curtain can be used. The light curtain is activated when the tool descends up to the 6mm safe gap. Never turn the light curtain protection off during operation.
An alternative is a light curtain with floating light beams that allow movement of the work piece. Reaching in through the light curtain immediately will stop the press brake.
An unguarded brake press means workers’ hands are too close to the hazardous trapping space.
A light curtain guard can prevent workers from accessing the brake press.
Light beam/safety laser device
If a light curtain is not feasible, guard the front of the press brake by using a light beam/safety laser. This device consists of three infra-red light beams mounted on the press brake blade. If the operator interrupts a light beam during the tool’s descent, the machine will immediately stop.
Press brake guarding has to accommodate work pieces of all shapes and sizes, therefore its operations come under Category 4, the most stringent category of AS4024.1-2006 Safety of Machinery should apply to safety controls. Press Brake guarding is in category 4 because of the severity of injury – the likelihood of amputation, the high frequency of access to the dangerous area, and the high speed of the tool.
Camera-based protection system
An LED-based solution is installed on the upper die of the press brake. If the system detects something in the protected field between the transmitter and the receiver, the machine will stop immediately or reduce power and speed.
A certificate is required from the installer/supplier to confirm that the installation complies with the appropriate standard such as IEC 61496, Safety of Machinery- Electro-Sensitive Protective Equipment, or equivalent.
Automated feeding and robot usage
A robot can be used to feed and handle the work piece, eliminating the need for a person to access the dangerous area at the tool and die of the machine. The press brake and robot can be guarded by fixed guards and interlock guards or light beams that conform to the requirement of an appropriate standard such as AS4024.1-2006 Safety of Machinery, AS 4024.3301 Safety of machinery: Robots for industrial environments — Safety requirements, or ANSI/RIA R15.06, Robot Safety Standards.
Maintenance and lockout
Machinery maintenance is very important, and an effective isolation and lock-out procedure must be implemented to protect people working with the machines. Staff must be trained in these procedures.
Long Metal Folders
Long metal folders operate similarly to Press Brakes for folding thin sheet metal, but the tool and die are usually 5 to 6 metres long, or longer. They are generally operated by two people handing the long work piece.
Protect operators from the long tool and die and the moving parts by a presence-sensing device, a single light beam/laser safety device, or a camera-based protection system.
Relevant standards – Available at www.standards.com.au
AS4024.1-2006 Safety of Machinery
AS 4024.3001 Safety of Machinery – Material Forming and Shearing – Mechanical Power Presses
AS 4024.3002 Safety of Machinery –Material Forming and Shearing – Hydraulic Power Presses
IEC 61496 Safety of Machinery- Electro-sensitive protective equipment
AS 1219 - -1994 Power Presses Safety requirements
Practical examples of best practice guarding using various options for Press Brakes and Folder
Safeguard with light curtain
Safeguard with light curtain
Safeguard with camera based protection system
Rear of press brake guarded by interlocked guards
Light curtains for safeguard of long metal folder
The Department of Labour would like to acknowledge the Victorian WorkCover Authority (WorkSafe Victoria) for allowing the reproduction of their material in this Guidance Sheet. Further information can be obtained at www.worksafe.vic.gov.au.
Note: This material is also only intended to provide general advice and does not constitute legal advice. You should make your own judgement about action you may need to take to ensure you have complied with your workplace health and safety obligations under the law.
