Heat sealers are essential tools in industrial packaging, foodservice operations, and many other sectors that require secure and consistent sealing of plastic bags and pouches.
Whether you’re working with impulse sealers, continuous band sealers, or direct heat sealers, proper care and troubleshooting knowledge are crucial to maintaining performance, extending equipment lifespan, and ensuring package integrity.
In this article, we’ll cover:
- A detailed breakdown of common heat sealer problems
- Step-by-step troubleshooting tips
- When to call in professional support
- Daily, weekly, and monthly maintenance tasks
- Why heat sealer maintenance matters
Let’s get started!
Common Heat Sealer Issues and How to Troubleshoot Them
Even well-maintained machines can encounter problems. The key is to recognize symptoms early and apply the right solution before small issues escalate.
Here are common heat sealer problems. In the section below, we’ll dive into their causes, and recommended fixes as well:
- Weak or Incomplete Seal
- Burned or Melted Bag
- Seal Not Holding (Peels Open Easily)
- Machine Won’t Heat
- Seal Sticks to the Bar
- Intermittent Heating or Inconsistent Sealing
Weak or Incomplete Seal
One of the most frequent problems operators encounter is a weak or incomplete seal. This occurs when the sealing bar fails to fully bond the packaging material, leaving gaps or flimsy seams. Thicker or multi-layered films require more heat and longer contact time to fuse properly.
The 3 most common causes of a weak or incomplete seal include:
- Temperature Too Low
- Dwell Time Too Short
- Not Enough Pressure
Temperature Too Low
One of the most common reasons for a weak or incomplete seal is insufficient heat. If the temperature isn’t high enough to fully melt and bond the layers of packaging material, the seal may appear partial or fail under pressure. This issue is especially frequent when sealing thicker, multi-layered, or foil-lined films.
The Solution:
Increase the sealing temperature gradually in small increments. Make small adjustments (typically in 10–20°F intervals) until the seal fully forms without burning the material.
Dwell Time Too Short
Another contributing factor is short dwell time, or the length of time the sealing jaws are held closed. If this time is too brief, even adequate heat might not be able to complete the bond.
The Solution:
Extend the dwell time slightly and test again. Most heat sealers allow dwell time to be adjusted through a dial or digital control panel.
Not Enough Pressure
Inadequate pressure between the sealing bars can cause a seal to form unevenly or not at all. Uneven contact may result from misaligned jaws, worn springs, or low pneumatic pressure.
The Solution:
Check the pressure settings. On impulse or jaw-type sealers, this may involve adjusting spring tension or the clamping mechanism. Adjust the jaw pressure or spring tension until full contact is made.
Pro Tip: If the material is multi-layered or foil-lined, it may require higher heat or longer dwell time compared to single-layer films.
Burned or Melted Bag
On the other end of the spectrum, bags that come out scorched or melted are usually exposed to excessive heat or dwell time. This problem is particularly common when switching to thinner films without adjusting the sealer settings accordingly. Bags that are too thin or made from low-melting-point materials are especially prone to damage if the sealing temperature is too high.
The 4 most common causes of a burned or melted bag include:
- Temperature Too High
- Sealing Time Too Long
- Incompatible Bag Material
- Worn Teflon Tape Cover
Temperature Too High
If your bags come out scorched, melted, or deformed, the culprit is usually excessive heat. When the temperature is set too high for the bag material, it can easily cause deformation or create holes.
The Solution:
To fix this, lower the sealing temperature gradually and test the result with each adjustment. You want a clean seal without discoloration or distortion.
Dwell Time Too Long
Another cause could be prolonged dwell time, which increases the duration of heat exposure and may result in overheating even if the temperature setting is within the normal range.
The Solution:
If your machine allows it, reduce the dwell time slightly to lessen the exposure to heat.
Incompatible Bag Material
Using the wrong type of packaging material, such as bags not rated for high-heat sealing, can cause a burned or melted bag. Lower-grade or thinner films have lower melting points and are more sensitive to heat.
The Solution:
Examine the type of bag you’re using. Make sure the film is compatible with your heat sealer and can withstand the required temperature range.
Pro Tip: Excessive heat not only weakens the material but may leave carbon residue on the jaws, requiring immediate cleaning.
Worn Teflon Tape Cover
A worn or damaged Teflon tape cover can allow direct heat contact with the bag and worsen the burning issue.
The Solution:
Inspect the Teflon tape covering the heating element. If it’s thin, blistered, or missing altogether, replace it.
Seal Not Holding (Peels Open Easily)
Sometimes, a heat sealer may appear to complete a seal, but the packaging later fails during handling or shipping. A seal that peels apart easily is often due to contamination on the sealing surface or misalignment between the jaws. Even small amounts of powder, oil, grease, or dust on the sealing area can prevent the plastic layers from bonding properly. Similarly, if the sealing bars are not aligned, the pressure may be uneven, resulting in partial or weak seals.
The 3 most common causes of a seal not holding or peeling open easily are:
- Dirty Sealing Bar
- Jaw Misalignment
- Inadequate Sealing Pressure
Dirty Sealing Bar
A seal that doesn’t hold under pressure or peels open easily is usually the result of contamination on the sealing surface. Even a light layer of dust, powder, oil, or moisture can interfere with proper bonding.
The Solution:
Start by cleaning the sealing surface thoroughly. Use a lint-free cloth with isopropyl alcohol to remove residue from the sealing bar. Also make sure the bags themselves are clean and dry; this is especially important in food and industrial environments where contaminants are common.
Jaw Misalignment
Misalignment of the sealing jaws is another common factor. If the jaws or bars are not making uniform contact, some areas of the seal may not bond at all.
The Solution:
Check the alignment of the jaws by slowly closing the sealer and visually confirming that both jaws meet evenly across their entire length. If alignment is off, consult the user manual for calibration instructions or contact support for mechanical adjustments.
Inadequate Sealing Pressure
Inadequate sealing pressure, usually due to mechanical wear or incorrect settings, can lead to seals that look intact but fail under even light stress.
The Solution:
If necessary, adjust the sealing pressure. This may involve tightening springs or adjusting pneumatic pressure in air-powered machines. Always re-test the seal afterward to ensure the fix is effective.
For vacuum sealers, ensure that air is fully removed before sealing.
Machine Won’t Heat
A machine that fails to heat up at all is typically experiencing an electrical issue. The most common culprit is a faulty heating element, such as a broken wire or damaged heating bar. Other possible issues include a tripped breaker, a blown fuse, or a malfunctioning thermostat or temperature controller.
Common causes include:
- Faulty Heating Element or Wire
- Broken Fuse or Tripped Breaker
- Faulty Thermostat or Control Board
Faulty Heating Element or Wire
When a heat sealer fails to heat at all, it’s most often due to a faulty heating element or sealing wire. Over time, these components can wear out, break, or become disconnected internally.
The Solution:
Begin by unplugging the machine and inspecting the heating element. If you see visible damage, such as broken wires, corrosion, or discoloration, the heating element will need to be replaced. Use a multimeter to check for continuity in the heating circuit.
Broken Fuse or Tripped Breaker
Other possible causes include a blown fuse or tripped circuit breaker, which interrupts the power supply.
The Solution:
If the heating element appears intact, check the fuse and circuit breaker for continuity and functionality. Replace any blown fuses and reset tripped breakers as needed.
Faulty Thermostat or Control Board
A malfunctioning temperature controller, relay, or thermostat may prevent the machine from initiating a heat cycle.
The Solution:
For digital models, check for any error messages on the display panel. If none are present but heating still doesn’t occur, the issue may be internal.
In that case, contact the manufacturer or a qualified technician for help diagnosing and replacing faulty control components.
Pro Tip: Always unplug the machine before inspecting electrical components. Consult the manual or a certified technician if unsure.
Wrinkled Seal
A seal that appears wavy or wrinkled may still hold, but it is often a sign of an underlying mechanical or material issue. Wrinkled seals are typically caused by uneven pressure, misalignment between the sealing jaws, or the use of low-quality or overly soft bag materials that deform under pressure.
The most common issues include:
- Uneven Pressure Across Sealing Bar
- Jaw Misalignment
- Soft or Low-Quality Bag Material
Uneven Pressure Across Sealing Bar
A wrinkled or distorted seal is often caused by uneven pressure between the sealing bars. When pressure is applied inconsistently, the material can shift or buckle during the sealing process.
The Solution:
Check the sealing bar alignment by slowly closing the machine and looking for uniform contact. Adjust as needed using the machine’s alignment controls or screws. On pneumatic models, ensure the air cylinders are operating in sync.
Jaw Misalignment
Another likely cause is misaligned sealing jaws, which fail to close evenly. Over time, usage can knock bars out of position or cause small shifts that impact the quality of the seal.
The Solution:
Test the pressure output to ensure the jaws are clamping evenly. Realign the sealing jaws if needed to ensure uniform pressure.
On older machines, worn springs or tired pneumatic components may need to be replaced or recalibrated.
Soft or Low-Quality Bag Material
Using soft or low-grade film materials that deform easily under heat and pressure can also lead to wrinkled seals, even if the machine settings are correct.
The Solution:
If the equipment is functioning properly, try switching to a higher-quality or thicker film. Some materials simply don’t hold their shape well during sealing and are more prone to wrinkling.
A small upgrade in packaging material can drastically improve seal appearance and integrity.
Pro Tip: Wrinkled seals may look secure but often fail under stress. Always test seal integrity before packaging large quantities.
Seal Sticks to the Bar
If bags are sticking to the sealing bar after sealing, this is usually a sign of worn Teflon tape, excessive heat, or incompatible materials. The Teflon coating on the sealing bar acts as a barrier between the hot wire and the plastic. When this coating becomes damaged, the bag can melt slightly and adhere to the metal surface, making it difficult to remove without tearing.
Look for these potential issues:
- Worn or Missing Teflon Tape
- Excessive Heat or Dwell Time
- Low-Melting-Point Bag Material
Worn or Missing Teflon Tape
When bags stick to the sealing bar, it’s usually due to worn or missing Teflon tape. The Teflon layer acts as a non-stick barrier between the sealing wire and the packaging material. Without it, bags can melt onto the hot metal surface.
The Solution:
Replace the Teflon tape as soon as it shows signs of wear, such as bubbling, peeling, or thinning. Teflon covers are inexpensive and should be changed regularly to maintain sealing performance.
Excessive Heat or Dwell Time
Excessive heat or dwell time set too long can also increase the likelihood of sticking, especially when sealing thinner materials.
The Solution:
Lower the temperature or reduce dwell time slightly and test for improvement. This reduces the chance of overheating the film.
Low-Melting-Point Bag Material
Using bags made of soft, low-melt films without adjusting the machine settings can result in adhesion to the bar.
The Solution:
Evaluate the bag material to ensure it’s rated for heat sealing. If you’re working with low-grade plastic, upgrading to a more durable film may be necessary.
Pro Tip: Sticking often results in residue buildup, which can impact the next several seals. Cleaning and replacing the tape can prevent costly rework.
Intermittent Heating or Inconsistent Sealing
In some cases, the heat sealer may appear to work sporadically—producing strong seals on one bag and weak or incomplete seals on the next. This inconsistency is often the result of loose internal wiring, a failing temperature controller, or mechanical wear in components responsible for pressure and timing.
Common causes include:
- Loose Internal Wiring
- Faulty Temperature Controller
- Worn Mechanical Pressure System
Loose Internal Wiring
If your heat sealer produces strong seals one minute and weak or faulty seals the next, it’s likely a result of loose or damaged internal wiring. Over time, vibrations and repeated use can cause connectors to loosen or wires to wear down.
The Solution:
Start by unplugging the machine and carefully inspecting the internal wiring. Tighten any loose connectors and replace any wires that are frayed, pinched, or heat-damaged.
Faulty Temperature Controller
Another possible issue is a malfunctioning temperature controller or thermostat that causes temperature fluctuations during use.
The Solution:
If the wiring appears intact but issues persist, calibrate or replace the temperature controller. Fluctuating heat levels can be tested with a digital thermometer or infrared sensor while the machine is operating.
Worn Mechanical Pressure System
Worn-out mechanical components responsible for applying pressure, including springs, rollers, or pneumatic cylinders, can also lead to inconsistent seals across the same batch.
The Solution:
Examine the mechanical pressure system. Weak springs or uneven roller pressure can cause the jaws to seal improperly. Replace or service worn components as needed, and always recalibrate the machine after making mechanical adjustments.
Pro Tip: Machines that are used in high-volume settings may develop wear on moving parts faster, so prioritize inspections in those environments.
Proactive Troubleshooting Best Practices
In addition to fixing immediate issues, follow these best practices to minimize future problems:
- Log every issue. Keep a maintenance log including problems, fixes, dates, and replacement parts. This can help identify recurring issues and predict future maintenance needs.
- Train operators. Many sealing issues stem from improper use. Make sure every operator understands basic settings, maintenance tasks, and warning signs of trouble.
- Use genuine replacement parts. Heating wires, Teflon strips, and electrical components should match the original specs. Off-brand replacements can reduce efficiency or void warranties.
- Run seal tests. Periodically test the strength and integrity of your seals using peel tests or immersion tests, especially when changing bag materials or sealing settings.
When to Call a Professional
While many issues can be solved in-house, certain repairs and diagnostics are best left to trained professionals. Consider calling technical support or a service technician when:
- Electrical components fail repeatedly
- You detect a burning smell or signs of short-circuiting
- The sealing results vary drastically with no clear pattern
- You’re unsure how to safely replace internal parts
- You’re operating in a regulated industry that requires certified repairs
Routine Maintenance Schedule for Heat Sealers
To keep your machine running smoothly, use this general maintenance checklist based on how often your sealer is in use. Always follow the manufacturer’s guidelines for your specific model.
Daily Maintenance
- Clean the sealing jaws or bars. After each use, wipe down the sealing surface with a lint-free cloth. Avoid abrasive materials. For stuck-on residue, use a plastic scraper and approved cleaning solution.
- Inspect the Teflon cover or tape. Teflon protects the sealing wire from residue buildup and prevents sticking. If it looks worn, blistered, or torn, replace it immediately.
- Clear debris from vents and fans. Some sealers, especially continuous ones, have fans to regulate temperature. Keep them clean to prevent overheating.
Weekly Maintenance
- Check wire and heating elements. Look for visible damage, discoloration, or corrosion. Loose wires or cracked heating bars should be replaced to prevent uneven heat distribution.
- Inspect pressure and alignment. Ensure the sealing jaws or bars close evenly across the full width. Misalignment can result in incomplete or wrinkled seals.
Monthly Maintenance
- Test temperature calibration. Use a digital thermometer or test seals with standard materials. Make sure the actual sealing temperature matches the set point.
- Lubricate moving parts (if applicable). Some machines have mechanical components that benefit from periodic lubrication. Use food-safe lubricants when working in food packaging environments.
- Audit seal quality. Run a seal integrity test. Check for leaks, wrinkles, or weak seals across different materials and bag thicknesses.
Why Heat Sealer Maintenance Matters
A heat sealer is a precision tool. It relies on consistent temperature, pressure, and timing to create airtight, tamper-proof seals.
When maintenance is neglected, these variables can drift, resulting in:
- Inconsistent seals that compromise product safety
- Reduced machine efficiency and lifespan
- Costly downtime during busy production runs
- Waste due to resealing or discarded materials
Routine maintenance is a proactive way to minimize these risks. It also helps you spot worn components before they fail, reducing the likelihood of unexpected repairs.
Final Thoughts
Heat sealers are indispensable in industrial, foodservice, and commercial packaging settings, but like any equipment, they require consistent care to function at their best.
By implementing a regular maintenance routine and knowing how to troubleshoot common issues, you’ll ensure your heat sealer delivers strong, reliable seals every time.
Investing time in understanding your heat sealer’s needs can help you reduce downtime, prevent product loss, and extend the lifespan of your equipment.
Need help choosing the right heat sealer for your business? Reach out to Imperial Dade with details about your packaging materials and daily output, and we’ll help you find the perfect fit.
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