Why do automatic sealing machines need to be individually tuned to the type of film?

Why do automatic sealing machines need to be tuned to film?

Sealing machines are at the heart of many production lines - from food packaging to pharmaceuticals to the engineering industry. Although they may look versatile, in practice they require precise tuning to the type of film being used. Incorrect settings can result in a poor seal, damage to the material and even stop production. Why does this happen and what to look out for?

The films differ in construction and properties

• Chemical composition

  Polyethylene (PE), polypropylene (PP), polyamide (PA), PVC or laminates - each of these films behaves differently when exposed to temperature. Some soften quickly, others need higher temperatures to start the sealing process.

• Material thickness

  Thin films can melt or stretch if sealed for too long. Thick film or multilayer laminates need longer contact with the hot jaw and higher pressure.

• Coatings and functional layers

  Some films have a non-stick layer, others are printed or contain metallization. These layers affect heat conductivity, adhesion and seal quality.

Why does this affect the performance of the machine?

• Welding temperature

  Each type of film has its own 'sealing window temperature' - the range within which the plastic adheres optimally. Too low a temperature results in a leaky seal. Too high a temperature will result in burning of the film.

• Contact time (welding)

  Some films require a quick, short seal, others need extended time to achieve a permanent bond.

• Welding pressure

  The jaw pressure should be adapted to the type of film and its elasticity. Too little pressure results in inaccurate contact. Too high can deform the film or damage the seal.

• Post-weld cooling

  Some plastics need a cooling phase in the form of pressure to maintain the shape and strength of the weld. Ignoring this phase leads to deformation.

What can happen without tuning in?

• Leaky or unstable seals

  The seal may look good but tear at the slightest pressure after cooling. This is a problem in vacuum packaging or sealing liquids.

• Burns, melting and contamination

  Too high a temperature or the wrong time can burn the film, causing smoke, sticking to the jaws and downtime.

• Damage to the device

  Inadequate pressure and the wrong type of film can lead to wear on the sealing jaws or overheating of the heating elements over time.

How do you tune a vending machine to a specific film?

• Perform weld tests

  Each new film should be tested for temperature, time, pressure and seal quality (e.g. by a tensile test).

• Consult the film manufacturer

  A good manufacturer provides technical data and recommended welding parameters - these can be used as a starting point.

• Use automatic control systems

  Modern sealing machines provide parameter recording for different film types, automatic error detection and calibration systems.

Summary

There is no universal sealing machine setting "for every film". Different plastics require an individual approach to sealing parameters - only then will the machine work efficiently and the seals will be durable and aesthetically pleasing. Adjusting the temperature, time and pressure to suit a particular film is an investment in quality, less waste and trouble-free production.