SEAL HEAD AIR MANIFOLDS WITH AIR GAUGES AND PRESSURE SWITCHES

By Larry Bush

Due to excessive maintenance problems with the snack cup production line seal head air manifolds, management decided to replace each double set of eight seal head air pressure regulating and supply manifolds with new air manifolds.

The seal heads are arranged in two rows of eight cylinders. The head of each cylinder is heated and when the entire seal head assembly of sixteen seal heads presses down on the snack cups, the individual seal heads are fired down onto the snack cup sealing film on top of the cup lip at a set pressure, time and temperature.

This operation seals the film to the cup lip. The variables can be adjusted up or down individually in order to get an optimum seal on the cups. The cups are tested before and after the sterilization process in order to ensure there are no leakers.

The cups are also tested to ensure that they are sealed to a preset burst pressure and a preset range of force required to peel back the film from the lip of the cup. Testing the peel force ensures that the film is not sealed on too tightly so that the customer has no problems opening the product.

The air manifolds are crucial to the correct sealing process. The maintenance mechanics learn to adjust the air pressure up or down to correct for changes in the other variables. The pressure switches are each set to operate to shut down the machine if the pressure differs from the set point by a preset range and period of time.

The new manifolds came from the distributor partially assembled. The production supervisor responsible for ordering the parts also ordered the remainder of the parts required to finish two complete manifolds.

The manifolds were assembled with the parts ordered and the ordering supervisor was informed that the air gauges, pressure switches, and 120 VAC plugs supplying power to the solenoids were different than the old ones. The air gauges, in particular, were not heavy duty and oil filled as were the original air gauges.

The pressure switch replacements were much more robust than the original switches and less likely to fault or vibrate out of range. The 120 VAC plugs were equivalent to the originals and standard.

The air gauges installed on production line 1 seal head air manifolds lasted less than a year and were all going bad. Six have been replaced already and four of the ten left were not reading correctly. When the air gauges fail to read correctly, someone may try to adjust the air pressure on the particular seal head and wind up with a problem because the air gauge does not indicate the actual air pressure.

More than one of the regulators was damaged just this way and had to be replaced. When the air gauge on the A-3 seal head of #1 production line was changed, the pressure had been raised to 95# psi. It was lowered to 55# where it should have been. The old gauge was reading 28# and the actual pressure was at 95#.

The production supervisor was apparently trying to save money by purchasing the cheap gauges. The conditions of heat, vibration and pressure changes are too much for the cheap gauges. No money was saved.

Ten more cheap air gauges on production line Seal Head Air Manifolds need to be replaced with good, oil filled air gauges. The good air gauges installed on the replacement air manifolds are being removed to replace the defective air gauges on the various installed air manifolds.

Quality replacement parts should be used in equipment repairs which reduces down time and repetitive repairs.

Larry Bush

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About the Author: Larry Bush has been an electrician for 47 years, and in maintenance management for 22 years. Download his e-Book "Emergency Diesel Electric Generators" and the "Maintenance Policy and Procedures Manual" !!