jammed inserter

5 Common Causes of Mail Inserter Jams

By Tim Plunk

While not ideal, you may find yourself in a situation where your inserting equipment suffers downtime. In the event an envelope is the cause of the problem, there are some troubleshooting techniques that can prove helpful.  

First, keep a detailed record of each problem that occurs. Most issues involving envelopes on inserting equipment occur intermittently, so it’s important to establish history and identify a theme if one presents. 

Secondly, discuss any problems with your envelope manufacturer. Together, you can investigate the issue to determine its severity and work to discover the root cause of the inserter jam. 

Lastly, be aware of these five common causes of inserter jams: 

1. Adhesives are improperly applied or not working.  

  • Side seams that aren’t glued to the top of the back panel can cause the envelope to separate and create an opening for the inserted materials to catch on and stop the machine. 
  • Side seam glue that sticks to the inside or outside of the envelope can respectively cause envelopes to be stuck together in the shipping carton or cause the envelopes to stick together on the inserter and not allow insertions to be placed inside the envelope. 
  • Not enough side seam glue can deter the envelope from staying folded so nothing can be inserted. 
  • Bad seal flap glue that won’t allow the envelope to seal can cause documents to fall out after the envelope has been inserted.  

2. Windows are not accurately sealed. 

A tiny amount of space can make a big difference on your envelope. When a window patch is not sealed close enough to the window opening, it can cause snagging when inserted materials come in contact with it. When a window is not sealed solidly enough across the top of the window opening, it can also cause snagging and will consistently jam the inserting equipment.  

3. The envelope is not well-folded. 

An envelope that is over- or under-folded during production can negatively impact your inserting equipment. 

  • Under-folded envelopes produce a larger envelope than intended. This can cause several issues with inserting equipment, as inserted materials are likely to catch on side seams that aren’t sized to specifications due to the folding errors. 
  • Over-folded envelopes produce a smaller envelope than intended and will not allow materials to be inserted. 

4. The envelope is warped. 

Envelope bond-grade paper, such as wove, is specifically designed to minimize warp. For envelope production, paper with a basis weight between 20# (i.e. 20 pounds) and 24# is ideal for inserting projects, although different projects may call for different types of paper. If you come across a scenario where warped envelopes cause inserter issues, be sure to check the consistency of paper quality in terms of weight, as well as burst strength and stiffness. 

How envelopes are packed can also impact productivity on inserting equipment. It is critical for an envelope to arrive and remain flat as it runs through the inserter. In general, tightly packed cartons that do not allow for movement can help keep the envelopes flat throughout shipping and delivery. 

5. The paper grain direction does not run vertically. 

The wrong paper grain direction can cause significant issues. It is imperative for the paper grain direction to run vertically, from north to south (i.e. seal flap to the throat) on an envelope. It can be the difference between an inserter running at top speed or not running at all. When grain direction runs any other direction than north to south, the insert can create friction against the grains and feed differently into the envelopes. Additionally, when grain direction lies horizontally it can cause envelope warping and related issues. 

The Industry Leader 

Understanding exactly why a problem occurs can help establish a path to a lasting resolution and lend experience to mitigate the problem from occurring again. Contact a Tension Sales expert and see how our more than 130 years of leadership in the envelope industry can help keep your inserter running.  

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