What should I do if the temperature of the glue pot is not accurate? Calibrate with a thermometer and display 160 ℃, and determine the actual temperature of 100 ℃

Many people suspect that the glue on books and magazines is not good due to loose pages, weak adhesion, and loose threads. But Sunlife’s training data is very heart wrenching:About 90% of after-sales problems are rooted in equipment temperature control failure——The panel displays 160 ℃, but the actual temperature of the glue pot may only be 100 ℃. The glue hasn’t really melted, so of course it won’t stick firmly. Just take a thermometer and you’ll know. Below are how to test, judge, and handle.

1、 Why does the displayed temperature not match the actual temperature

• Sensor aging/offset/wrapped in adhesive scaleInaccurate positioning of the temperature probe and the formation of adhesive deposits on the surface will result in distorted readings; The actual temperature displayed at 160 ℃ may only be around 100 ℃.
• The temperature difference between different positions of the glue pot is largeThe temperature of the pot bottom, pot wall, and glue outlet is not uniform (see 2565 for the temperature difference between the two pots on the back glue side), and one point on the panel alone is not enough.
• lag effectThe thicker the adhesive scale, the slower the probe response, and even after a long time of startup, the panel may not have fully heated up.

2、 How to measure/calibrate with a temperature gun

• toolInfrared thermometer or contact thermocouple thermometer, used to measure the actual temperature of the glue melting area/outlet of the glue pot.
• methodAfter preheating to the set value and stabilizing during startup,Multi point measurement(Pot bottom/pot wall/glue outlet), then compare the panel display; If the difference is greater than 10-15 ℃, it is time to calibrate or repair the temperature control.
• Measure the adhesive layerYou can also measure the actual temperature of the newly glued spine to determine whether the glue is truly in place and whether the spreading is hot enough.
• Establish recordsTest and record once after preheating each time the device is turned on, and observe the trend over the long term to detect sensor drift in advance.

3、 What can inaccurate temperature cause (corresponding symptoms)

• Actual low (most common)The glue has not truly melted → the viscosity is high → the drawing, spreading, and penetration are poor → the adhesion is not firm and the page falls off (see 2692 “Adhesion Not Firm” for details); Slow curing → sticking the pages with a knife and cutting loose pages (see 2757 “Slow curing with a knife” for details).
• Actual highCarbonization becomes brittle (see 2689/2757), and the odor increases (see 2768 “What to do if the odor is strong”).
• Exclude the equipment first and then search for othersIf it is caused by paper powdering (see 2759 “Paper powdering”), it is not a temperature issue——First, use a thermometer to eliminate equipment factors, and then check the paperDon’t change the glue as soon as you come up.

4、 How to handle it

• Calibration/Maintenance: Find equipment vendors to calibrate temperature control modules and replace offset sensors; Regularly clean the probe adhesive to restore response.
• Standard operationEstablish the habit of “preheating after startup+temperature measurement recording”, Sunlife can cooperate with process training; Set the temperature according to the process card for different models (recommended 160-180 ℃ for book glue), don’t rely on the feel.
• Selection coordinationTell Sunlife your device speed, paper, and thickness, and choose the model that matches the opening time – low speed 15-20 seconds/medium speed 5-10 seconds/high speed 2-7 seconds. Only when the temperature matches the model can it be fully utilized.

Sunlife’s positioning: First help you eliminate equipment, then discuss changing glue

Sunlife has been producing hot melt adhesive for books and magazines for over a decade, and its training repeatedly emphasizes that ‘90% of after-sales service is due to temperature control failure’. So when encountering page drops and wire drawing, our first reaction is not to push new glue, but toFirst, I will help you calibrate with a thermometer and see the true temperature clearlyUse process training and selection to address equipment factors. Separate the issues with glue and equipment to avoid wasting money.

Frequently Asked Questions

Q: The panel displays 160 ℃, do we still need to test it?

A: I need it. The displayed values are often distorted, and actual measurements are the truth. If the difference is greater than 10-15 ℃, it should be calibrated.

Q: Is the temperature gun accurate in measuring the glue pot?

A: The infrared gun can measure the metal pot body/glue outlet for quick judgment; For more accurate measurement of the adhesive solution itself, a contact thermocouple can be used. The focus is on the difference between “measured vs. panel”, not on the absolute value being more precise.

Q: Is the temperature correct or can’t it stick firmly?

A: Then exclude the equipment and check the paper (see 2759 for powder loss), glue amount, and opening time matching (see 2689/2715), step by step positioning, without blindly changing the glue.

Hot melt adhesive machine, “temperature is truly in place” is more fundamental than “changing to a more expensive adhesive”. A temperature gun and a temperature record can help you avoid most of the after-sales issues that should not occur.