Three Real Causes of “Paper Jams” in Digital Printing Machines — How Printers Troubleshoot Three Types of Jams When Receiving Orders for Paper Stock Above 350g

In August 2026, a digital printing plant in Wuxi received an order from a baking brand—1,000 350g white cardboard gift boxes. The operator started a test run, and the machine jammed 3 times within the first 50 sheets. The jams all occurred at the feed inlet, where the paper was stuck between the feed roller and the pinch roller. The owner of the printing plant was extremely anxious as the customer was pressing for delivery. The more anxious the operator became, the more frequent the jams occurred. In the end, 80 sheets were scrapped, and the plant nearly failed to deliver the order on time.

Later, the technician calmly checked and found that the problem was caused by two factors combined: worn feed wheels and burrs on the paper edges. The feed wheels had been in use for over 1 year without replacement, and cracks had already formed on their surfaces. In addition, the knife-cut paper edges had burrs that became lodged between the feed wheels and the pressure rollers. The technician replaced the feed wheels with new ones and lightly sanded the paper edges. The remaining 900 sheets were then printed successfully.

Paper jams are a common problem when digital printing machines print on heavy stocks above 350g. How can technicians quickly identify the cause of a paper jam? This article provides troubleshooting methods for three types of paper-jam locations for digital printing plant technicians.

Cause of Type 1 Cardboard Jams: Uneven Moisture Content in Paper—the “Hidden Killer” of Jams at the Feed Inlet

Digital printing machines are highly sensitive to paper moisture content. Thick paper (over 300g) is particularly sensitive—when the paper is moved from the warehouse to the workshop and the temperature difference exceeds 5℃, moisture distribution inside the paper becomes uneven, causing the edges to curl easily. Curled paper entering the feed tray can become trapped between the feed rollers and platen rollers, resulting in a paper jam.

Real-world case: In summer, a printing plant ran 300g art paper. The paper was moved from the warehouse (temperature 18℃) to the workshop (temperature 28℃), a temperature difference of 10℃. The press operator did not allow the paper to “acclimate” and started printing immediately. The first 30 sheets all jammed, with obvious curling along the edges. After allowing the paper to “acclimate” in the workshop for 2 hours, the jamming disappeared.

Troubleshooting method:

Troubleshooting Step 1: Ask the customer/procurement, "When did the paper arrive, and how long has it been stored in the workshop?" — If the paper arrived less than 24 hours ago, it is most likely a moisture content issue.

Troubleshooting Step 2: Place the paper on a table and check whether the edges are curled. If the curling is pronounced, first allow the paper to acclimate to the workshop temperature for 24 hours.

Troubleshooting Step 3: Workshop temperature and humidity gauge inspection—the temperature should be 20-25℃, and humidity should be 50-65%. If humidity is too low (< 40%), the paper is prone to curling; if humidity is too high (> 70%), the paper is prone to absorbing ink and deforming.

Cause of Type 2 Cardboard Jams: Paper Edge Burrs—the “Physical Obstacle” Causing Jams at the Feed Inlet

If burrs are present on the die-cut edges of paper, particularly thick paper cut by hand, the burrs may become caught between the feed rollers and the hold-down rollers as the paper enters them, causing a paper jam.

Thick paper (300g and above) is prone to developing burrs when die-cut. Standard paper cutters handle paper below 250g without difficulty, but when cutting heavy paper above 300g, the blade edge tends to "tear" the paper, creating tiny burrs along the paper edges.

Real case: In 2025, a printing plant in Suzhou received an order for 800 sheets of 350g black cardstock. The first 100 sheets jammed five times. Upon inspecting the paper edges, the operator found obvious burrs approximately 0.5-1mm long. The operator gently sanded all four edges of the paper with fine sandpaper (800 grit), removing the burrs, and the remaining 700 sheets were printed successfully.

Troubleshooting methods:

Troubleshooting Step 1: Remove the jammed paper and feel along all 4 edges. If you notice any obvious burrs, first lightly sand all 4 edges with fine sandpaper.

Troubleshooting Step 2: Check whether the cutter blade is dull. The blade life for cutting paper weighing more than 300g is approximately 5000-8000 sheets. Once this lifespan is exceeded, the blade becomes dull and paper-edge burrs increase. We recommend that printing plants replace the blade after every 5000 sheets of thick paper.

Troubleshooting Step 3: If the paper provided by the customer has already been cut, the printing plant can directly ask the customer to “switch to a different paper-cutting supplier,” or the printing plant can cut the paper again.

Cause of Type 3 Cardboard Jams: Worn Feed Roller—Equipment Aging Causing Jams at the Feed Inlet

The feed roller is one of the most easily worn components of a digital printing press. Made of rubber and plastic, its surface will show wear, cracking, and gel detachment after 6-12 months of use. Worn feed rollers have reduced friction, causing paper to slip and jam.

Real-world case: In 2024, an HP Indigo 12000 digital press at a printing plant in Changzhou had been in use for 14 months. When running 300 g heavyweight paper, its jam rate rose from 0.5% to 8%. The printing plant called in an HP engineer, who found that all four feed rollers were worn out. After replacing them with new feed rollers, the jam rate returned to 0.3%.

Master troubleshooting method:

Troubleshooting Step 1: Visually inspect the feed roller—open the paper input cover and check whether the feed roller surface shows obvious wear, cracking, or separation of the rubber coating. If so, it needs to be replaced.

Troubleshooting Step 2: Test-print 10 sheets using thick paper (300g or above). If 1-2 sheets jam, the feed roller is slightly worn, so continue monitoring. If 3 or more sheets jam, the feed roller is severely worn and needs replacement.

Troubleshooting Step 3: Wipe the feed rollers with a cleaning cloth and alcohol—if ink or dust has accumulated on the roller surfaces, the reduced friction can also cause paper jams. After cleaning, conduct a test print. If the paper jam is resolved, the issue is due to contamination rather than wear.

3 Steps for Digital Printing Press Operators to Remedy Cardboard Jamming

After the cardstock jams in the printing press, reduce losses in 3 steps:

Step 1: Turn off the machine; do not pull the paper forcibly—Forcibly pulling the paper may damage the photoconductor drum/transfer belt, resulting in repair costs of 5000-20000 yuan. The correct procedure is to turn off the machine, open the cover at the paper jam location, and then remove the paper.

Step 2: Check whether the paper can continue to be printed—If the removed paper has no obvious creases, it can be returned to the paper stack for continued printing; if the creases are obvious (especially if the paper is jammed in the transfer-printing area), it must be discarded.

Step 3: Record Jam Locations—For each paper jam, record the location, paper grammage, and print run at the time of the jam to create a log. After the printing plant accumulates 20-30 jam records, recurring patterns can be identified to enable preventive action.

5 Preventive Measures for Digital Printing on Thick Paper Orders

When the printing plant receives orders for heavy paper weighing over 300g, 5 preventive measures can reduce paper jams:

The One Thing a Printing Plant Owner Should Do Most

When a printing plant receives an order for thick paper (300g or above), ask the press operators to bring the paper into the workshop 24 hours in advance and run a test print of 10 sheets before starting production. This step is almost free, but it can reduce the paper jam rate from 5-10% to 0.5-1%.

Profits on thick paper orders are already slim (unit prices are 30-50% higher than those of thin paper, but yields are lower). If several sheets of cardboard are scrapped, the printing plant will have done the work for nothing. Printing plant owners should post the following 5 preventive measures on the workshop wall.

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