Presence Sensing Device
What is a presence sensing device and how does it work?
If you’re considering improving the efficiency of your press brake or other machinery while maintaining a level of operator safety that meets regulations, you should consider installing a presence sensing device (PSD). This article will briefly explain what presence sensing devices do and how they function.
PSDs also go by a “close-proximity point-of-operation AOPD” or “active optoelectronic protective device”. A presence sensing device is an ingenious safety tool that gives a machine operator’s hands total freedom while working. The device reacts when an object, namely the operator’s fingers or hands, breaks an invisible plane or barrier.
Machine operators using presence sensing devices do not need to wear any straps or press any buttons to activate the machine’s cycle. Systems with PSDs provide fully automatic functioning. The result is faster and more efficient than any other press brake safety method. The cost of a PSD and its maintenance is relatively low. Most presence sensing devices are a custom build. The systems have custom software that fit with the machine.
What different kinds of pressure sensing devices are there on the market?
There are three basic types of press brake safety presence sensing device. The first press brake safety device is an invisible infrared “light curtain”. The second press brake safety device is a laser beam. Finally, the last press brake safety device is special type of camera creating an intangible barrier. Each function differently, but results from use of each are very similar.
Press Brake Safety Light Curtains
Safety light curtains project a ray of infrared light over a designated area. They are photoelectric presence sensors, which means they function solely from emitted light detection. They can either be set up for point of operation control protection in tight spaces or perimeter access control to protect an entire area from interference.
Press Brake Safety Laser Beam Presence Sensing Devices
Laser beam presence sensing devices or safety laser scanners function similarly to light curtains. They project a beam across an area that stops the functioning of a machine when it encounters something. They’re compact and feature a variety of simple configuration settings.
Press Brake Safety Camera Based Safety Systems
Camera based safety systems detect any foreign object that comes into the frame of the machine’s operating area. They use a linear scale to calculate the upper beam’s position, velocity, and the stopping distance, so within those parameters lies the protection zone. The image processing technology camera systems use refers to image resolution. Any change in the camera’s area of focus caused by a hand or other object entering the vicinity will cease unit operation.
Are presence sensing devices approved/permitted under OSHA guidelines?
The OSHA (Occupational Safety and Health Administration) allows the use of presence sensing devices, but approves them on a case-by-case basis. Each system must satisfy certain requirements per the OSHA website. The requirements and stipulations are as follows:
- PSDs are not permitted on full rotation clutches.
- Presence sensing systems must protect the operator’s limbs from the down stroke of the pertaining machine. The machine must interlock into a control circuit.
- Physical barriers must be in place in entry areas where the presence sensing device does not reach.
- The device may not be in use for initiation of a slide motion.
- Measures must be taken to cease machine operation immediately in the event of a system failure. The next stroke must be prevented from taking place until the system is completely fixed.
- Bypassing the device during upstroke must only be for parts removal/ejection, feeding, and circuit checking.
- Minimum safe distance between the sensing area and the point of operation must surpass that of the safety distance formula provided on OSHA’s website.
Whether the application is for a large forming press or a small assembly press, presence sensing devices are an excellent way to increase efficiently of operation while keeping all personnel safe from potential accidents.