Are your interlocks this rugged?

One of our customers approached us with an extremely challenging machine guarding application in a dirty, wet and sticky environment. After reviewing the project with the customer, we decided that a Fortress Interlocks mGard Key Exchange System would be the perfect solution, here’s why;


Customer needs regular access to six hatches on a machine that slices sugar beats, but only when the motor running the slicer blades is at a complete stop and de-energized. This is a very wet and sticky environment and downtime is very costly.


A solenoid controlled key switch (SS1-MLIS-A02022DO24F) is used to make sure the machine is stopped before any access to the hatches is allowed. The key cannot be removed until the VFD running the motor signals the switch that the motor is stopped and de-energized.

After the motor is stopped and de-energized, the solenoid switch key can be removed where it is inserted into a key exchange module (XM6-MLIS). This releases the hatch keys. When one or more hatch keys are taken from the key exchange module the solenoid switch key is trapped, so it cannot be removed and taken back to the solenoid controlled key switch. This ensures the machine cannot be restarted.

The hatch keys can now be used to open hatches. When a key is put into a DM1 interlock located on the hatches and the hatch opened, the key is trapped and cannot be removed until the hatch is closed and secured. In this way, we ensure that all hatches are closed and secured before the machine can be restarted.

Except for the solenoid controlled key switch, this is a totally mechanical system. There is no expensive cables or wiring that needs to be done on the machine. This made installation and maintenance very quick, easy and less expensive than many other options.

Below are some pictures of the actual machine application:

As you can see, it is a very tough environment for most any safety devices. mGard is up for the challenge though and the customer is very happy with the solution.