What are safety edges?

In this article we will discuss the HSC safety edges from Haake. These safety components are used for machine safety, generally in access technology such as industrial gates.

The use of machines and systems in a company entails risks. Well-known examples of safety risks are moving parts of machines where getting trapped can occur. If these moving or sliding parts are not properly secured, they can cause injuries. For example, if an employee's hand gets trapped. Haake has developed so-called safety edges to prevent such injuries.

Safety edges are touch-sensitive sensors that can detect contact with a person or body part. When the rubber of the safety edge comes into contact with an obstacle or person, a contact is witched instantly.

We come across these safety edges more often in daily life than you might initially think. Consider, for example, a large roller door with a rubber bumper underneath. If this safety edge makes contact with an obstacle or person, the drive of the door is switched off immediately, before the door can cause trapping and injuries. Another example is the revolving door or tourniquet door at an airport. Haake safety edges often ensure that our arms or legs do not get stuck between the frame and the wing of the revolving door.

Different types of safety edges can be found in machine and acces safety. In addition to electrical systems that work according to the "normally open" principle, there are also opto-electronic safety edges. This type of safety edge requires a special signal processing module to process the signals. The Haake safety edges, however, work according to the very effectively and reliable in terms of safety technology with the 'normally closed' principle. This is a fail-safe method, which also does not require a separate safety module.


Functionality and set-up of our HSC® safety edges

The core element of our HSC® safety edges is the Haake patented contact chain. It consists of electrically conductive contact rollers connected in series and containing insulating intermediate elements. So-called wool rolls. These are arranged alternately on an expansion cord. The contact rollers are compressed by pre-pressurization; the circuit is closed in normal mode. When actuated, at least one of the contact roller pairs is separated via the wedge-shaped intermediate elements. This interrupts the closed circuit. A conversion of the output signal is therefore not necessary, as a break signal is generated immediately. This signal can be sent directly to the existing emergency stop module of the machine to be protected.


The patented switch chain of the HSC® safety edge

The response capabilities of the HSC®

The link chain mounted in the rubber profile

The Haake contact chain is located on the front of the rubber bumper profile, which is available in various heights. The separation of the contact points in the chain is not based on a bending of the contact chain itself, but on the deflection of the outer radial from the inner axial force. Touching the rubber profile thus leads to a switch-off function, even if the safety edge is pressed gently or briefly. Due to the rotation-symmetrical construction of the switching elements, the contact chain is interrupted independently of the operating direction.


Due to the safety edge switching off at the start of pressing the rubber, the remaining height of the rubber profile is used for the so-called "braking distance". This is the time it takes for the machine to come to a stop after receiving the shutdown signal. In order to avoid injuries, this "braking distance" is a very important factor in determining the necessary height of the rubber profile. 


Example operation of a safety edge

In the example on the right, we use an HSC safety edge with a (rubber) profile height of 95 mm (HSC-95-350x). We approach the object with 100 mm/s and press with a force of 104 N on the safety edge. After 16.1 mm (activation distance SB) we reach switching point A and the circuit is interrupted. In this example, it takes another 33 mm (braking distance SN) before the machine comes to a stop. The total embossed height of the rubber profile is 49.1 mm (deformation distance SB + SN).


Application examples

  • In (height adjustable) extractor hoods for machines
  • Automatically operated doors and gates
  • Lifting tables
  • Packaging machines
  • Industrial trucks
  • Automated Guided Vehicles (AGV)
  • (Railbound) transport systems
Haake HSC® safety edges on an AGV
Haake HSC® safety edges on an AGV


The simple but very effective and safe operating mechanism of our safety edges allows for a wide range of application possibilities. Some examples of machines and systems in which our HSC® safety edges are used are:

Because the link chain has a modular structure and the rubber profiles are available in various heights and lengths, the HSC® safety edge is completely tailor-made for your application. Our product specialists are happy to advise you!


The advantages of our safety edges

  • High level of safety: our safety edges conform to Category 3 and Performance Level d according to DIN ISO EN 13849-1.
  • Favorable switching properties: switch-off function even with low operating forces and short response time. Signaling of the contact chain regardless of the operating direction.
  • Cost-saving: A special signal processing module is unnecessary because the Haake contact chain consists of "normally closed" contacts whose signal can be further processed immediately.
  • Simplicity: No complicated connection and cabling efforts necessary.
  • Conformity: Our safety edges are manufactured according to harmonized standards and therefore meet all requirements of the Machinery Directive 2006/42/EC.
  • Custom-made: wide range of safety edges, completely according to your individual safety requirements and depending on the application.
  • Plug-and-play set to customer specs: The safety edge is directly connected to the existing emergency stop module of the machine or installation.

Contact product specialist

Our employees are ready to provide you with the best advice. Fill in the contact form and describe your desired application with as much detail as possible! Our experts get to work immediately.