Test to check the filling quality of heating elements

When heating elements have different lengths between each other, this may be due to a defect in the compaction of the magnesium oxide (MgO) caused by a malfunction of the filling machine. The common problems are worn-out vibration combs, clogged filling set and setting of filling speed and vibration frequency. 

The MgO compaction is a key feature for the subsequent production procceses. For this reason, the CSM filling machine has a electromechanical vibration system characterized by symmetrical oscillations which allow a uniform compaction of the magnesium oxide inside the heating elements.

Considering the importance of the MgO compaction, it is necessary to verify the filling quality of heating elements and thus the status of the machine. The test helps operators and the maintenance team troubleshoot problems with the filler and reduce downtime.

A step-by-step guide, including an Excel spreadsheet, will help you run the quality test.

To do the verification, the following tools are required: tubes, plastic plugs, MgO, tape, water and a balance.

The test is based on these simple steps:

1. Prepare as many tubes as are the stations of your filling machine, plus one tube (e.g.: with a 30-stations machine, prepare 31 tubes). Cut tubes to equal lengths and set aside the 31st tube.
2. Load 30 tubes on the filling machine and number them from 1 to 30. Without hanging coils, insert the plastic plug into the bottom end of each tube and start the filling cycle.
3. Once the cycle is completed, manually top up the tubes with the magnesium oxide.
4. Retrieve the 31st tube, seal the plug with tape and weigh it empty in order to calculate the tare.
5. Fill the 31st tube to the edge with water and weight the volume of water. Write the volume in the table.
6. Empty the filled tubes one by one and for each tube weigh the magnesium oxide. Write the weight in the table.
7. To calculate the density of the magnesium oxide, divide the weight of MgO of each tube by the volume of water.
8. To verify the accuracy of the density of the magnesium oxide, compare for each tube the resulting density with the tap density reported in the technical data sheet of the MgO used.

If the density of the MgO is too low it means that there are some anomalies in the filling machine and thanks to the initial numbering of the tubes, it is possible to identify any irregular stations.

The repeatability of the test is based on the frequency of use of the filling machine.

For a correct organization and reading of the data during the test, use the available Excel table.