After bags are filled, they are sealed and put on a pallet of 40 to 60 bags for shipping. If a bag is not properly sealed, the operator must remove it before it reaches the pallet. If a badly sealed bag gets on the pallet, the operator has to unload the pallet by hand, replace the broken bag and reload the pallet.
This takes an average of 15 minutes. With three production lines, even a few poorly sealed bags a day result in a lot of lost time. If a poorly sealed bag is delivered to the customer, it adversely affects the company's quality reputation and the customer may even return the entire pallet. Nutrifeed wanted a reliable method of detecting poorly sealed bags.
The company's service engineer Willy van der Pas designed an innovative way to check bag seals. As each bag leaves the bagging machine, it passes under a plate that descends and hits the bag as it passes. If the bag is properly sealed, nothing happens.
If the bag is open, product falls onto the floor. Where the powder falls, he installed a metal plate and mounted a Sitrans AS 100 acoustic sensor on it. The acoustic sensor immediately detects powder falling onto the metal plate. This generates an alarm, signalling the operator to remove the open bag from the line.
The AS 100 detects inaudible, high frequency, structure-borne acoustic emissions generated by machinery or by the friction and impact of powders, granules and solids in motion. The sensor converts acoustic emissions into an electrical signal that can be measured by a CU 02 control unit.
Acoustic sensors are often used to warn of blockages, product absence or equipment failure. An operator can then fix the problem to prevent costly damage. Acoustic sensors mount outside the process, eliminating worries about cleaning and product contamination. They can be screwed in, bolted on or bonded in place, even in restricted spaces, in a matter of minutes without shutting down process equipment.
With no moving parts and with a stainless steel housing sealed against dust and moisture, they require virtually no maintenance.
Since the Sitrans AS 100 was installed on the three lines, poorly sealed bags never make it to the pallet anymore. Poorly sealed bags are quickly detected and operators remove them immediately. This ensures only properly sealed bags are loaded and shipped to customers.
The company claims that through improved efficiency, the acoustic sensors paid for themselves very quickly. "Not only do we save a lot of time, we can now guarantee the best quality to our customers, and this is very important to us," said Van der Pas.
Nutrifeed has also installed AS 100 acoustic sensors to detect flow on 20 switches that direct powder and materials in certain directions through tubes during the production process. The acoustic sensors verify that the material is following the correct track and alarms if there is any interruption in the flow so that corrective action can be taken. This helps protect the production process and ensure efficient, continuous operation.