Let There Be Light (Curtains)

Light curtains and other safety equipment can reduce press brake operator injuries

February 1, 2010

Operating a press brake is not like working on other equipment.

Sheet metal operations with a unique danger to the fabricator are the norm in everyday press brake work. Bending, hemming, and even operations such as punching and trimming all can create dangerous situations. Light curtains and other safety systems can reduce this danger.

So how can you make your brake safer? CIM asked safety equipment manufacturer SICK’s Juergen Bukowski, program manager for safety, to explain two options.

Light Curtain

How it works: Safety light curtains safeguard personnel around press brakes and other dangerous machines. A transmitter projects an array infrared light beams to a receiver unit, and if an object interrupts one or more of these beams, a signal is sent to stop the press brake.

Moving Camera

How it works: This device, which utilizes vision-based technology for point-of-operation safeguarding, is mounted on the upper beam of the press brake. It creates a safety volume below the die that is constantly monitored for intrusion. A signal switching device provides a signal to switch off the machine as soon as an intruding object is detected.

The safety volume, configured with the bending process, is active during the downward motion of the punch. The height of this volume decreases continuously as the bar approaches the die plate.

CIM: How important is a Pre-start Health and Safety Review (PHSR)?

JB: The European style of safeguarding press brakes is slowly moving into North America. In Europe the technology is state-of-the-art, and all press brakes are equipped with some type of safety system prior to shipping. Here in North America there is much more retrofitting being done.

Now in Canada, especially in Ontario, there is a requirement on new machinery that a Pre-start Health and Safety Review be performed when introducing new equipment into the market. While there was always a requirement for safeguarding, now I think there is even more pressure on Canadians to safeguard their equipment.

Also, both ANSI and CSA are reworking the press brake standards at the moment.

CIM: How do you choose a system?

JB: There are no clear indicators for when you always must have a light curtain or always have a system that moves with the ram. It really depends on what the shop is producing on the press brake.

Choose a system based on what 90 percent of your production is like, and then for the other 10 percent you can find an alternative method.

CIM: What else influences this decision?

JB: Tooling is an important factor. If there are a lot of tool changes occurring in the shop, or if there are different sizes of tooling on the press brake, then a system that moves with the ram is not suitable. If you have multiple tool heights on one machine at the same time, some areas may not be covered.

CIM: What role does part size play?

JB: When an operator is bending smaller parts, he must have his hands very close to the bending line, and this means that a light curtain can be in the way. When there is a lot of interaction between the operator and the press brake, the systems that move with the ram are becoming more popular.

In longer press brakes, the optical parts of the equipment that move with the ram can have problems due to shop conditions affecting the alignment.

You could summarize that in small press brakes the systems that move with the ram are suitable, and larger press brakes are best-suited for light curtains. The light curtain can blank out bending assist devices on these larger press brakes too.

CIM: What role does the operator play in safety?

JB: In the camera-based system that moves with the ram, the operator must realign the system after performing a tool change. Also, if training isn’t done correctly, the operator can run into a lot of problems.

If the operator isn’t aware of how the safety system works, then he will likely simply just begin bypassing it. Operators should include the safety systems in the planning of the next setup.

CIM: How do you keep your safety systems from being intrusive and slowing down production?

JB: You really need an understanding of how the safety equipment interacts with the operation of the press brake. It doesn’t matter what type of system is being used, the operator needs to adapt. They have to be convinced that it is not there to slow down production; it’s there to protect their fingers.

Also, integrating the safety system with the press brake’s control is very important to make sure that both operate correctly and productively.

For more information, visit www.sickusa.com.