A plastic bag making machine is the workhorse of the packaging industry, a powerful piece of equipment designed to perform two fundamental tasks with precision and speed: sealing plastic film and cutting it. When this machine is running smoothly, it can produce thousands of bags per hour. But when a problem arises, it can lead to costly downtime, wasted materials, and a great deal of frustration. Effective troubleshooting is a systematic process of elimination. It requires an understanding of the machine’s core functions and a logical approach to diagnosing the root cause of common failures, from weak seals to inconsistent cuts.

The quality of the seal is the most critical aspect of the bag. Most sealing problems can be traced back to one of three key variables: temperature, pressure, or time.

• Inconsistent or Weak Seals: This is often a temperature issue. If the sealing bar is not hot enough, it won’t properly melt the plastic film to create a strong bond. The solution is to incrementally increase the temperature setting. However, if the seal is weak but also looks melted or deformed, the problem could be a lack of pressure. Ensure that the sealing bar is making firm and even contact across the entire width of the film. Worn-out rubber pads on the sealing jaw are a common cause of uneven pressure.
• Melted or Burnt Seals: This is the opposite problem—too much heat. If the seal is burnt, brittle, or has holes, the sealing bar temperature is too high. Reduce the temperature in small increments until you achieve a clean, strong seal. If the plastic film is sticking to the sealing bar, it’s a sign of excessive heat or a worn-out non-stick coating on the bar itself.
• Incomplete Seals (Gaps): If the seal is strong in some places but unsealed in others, the cause is almost always uneven pressure or a problem with the sealing bar itself. Check for any debris or foreign matter on the sealing bar or its rubber counterpart. Inspect the non-stick cover for wrinkles or tears. In some cases, the heating element within the bar may be failing, leading to cold spots.