Do all components reach the prescribed temperature?
A loaded furnace can have cold spots. Air temperature alone is not proof.
- Use a thermocouple and record the temperature on the component.
- Check different positions in a normally loaded oven.
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1. Component temperature 2 · Holding time 3 · Storage 1 · Heat generation 2. Material compatibility 1 · Storage 2 · Temperature changes 1 · Surface 2 · Order & Fixing 3 · Load
Heat curing
1K epoxides
The actual component temperature is crucial – not just the oven display.
Product and application
Select the system so that only relevant test steps appear. If no system is specified, the test will remain general.
01
What are you observing?
02
Identify the cause
03
For reference
All test steps in this guide can be used even without the guided process.
Terms briefly explained
- Hand strength
- The parts should be handled carefully. The connection is not yet fully load-bearing.
- Complete curing
- The curing conditions and times prescribed for the product were adhered to.
- Adhesive gap
- Distance between the two joining surfaces, not the length of the adhesive seam.
- Pot life and nozzle life
- Test the processability of a mixed quantity and the processability in the mixing nozzle separately.
Does not fully harden; 3 test steps
Monitor the temperature profile under actual oven load.
Does the holding time only begin once the component has reached the target temperature?
Heating time and prescribed curing time must not be confused.
- Use the temperature and holding time from the specific TDS.
- A temperature that is too low cannot simply be replaced by a longer time.
Has the material been stored within its shelf life and according to the data sheet?
Aging, humidity, separation of components or unsuitable temperatures can alter processing and hardening.
- Record batch number, expiry date and inventory history.
- Check for segregation, thickening, and contamination. Do not correct conspicuous material with unauthorized additives.
- If the material quality is unclear, check a fresh, correctly stored batch for comparison.
Foam, bubbles or charring: 2 test steps
With large quantities of adhesive, the reaction can generate too much heat.
Does the temperature remain within the approved curing schedule?
Overheating can damage adhesives and components.
- Examine quantity, geometry, and temperature profile.
- Coordinate a gentler curing plan or a less reactive type with the manufacturer; do not unilaterally lower the minimum temperature.
Can all components withstand the intended hardening process?
Plastics can discolor, deform, or react with the material.
- Check materials and temperature resistance.
- If necessary, select a type suitable for lower curing temperatures.
Material becomes too viscous. 2 test steps.
1K epoxides can thicken with age.
Has the material been stored within its shelf life and according to the data sheet?
Aging, humidity, separation of components or unsuitable temperatures can alter processing and hardening.
- Record batch number, expiry date and inventory history.
- Check for segregation, thickening, and contamination. Do not correct conspicuous material with unauthorized additives.
- If the material quality is unclear, check a fresh, correctly stored batch for comparison.
Are repeated heating and cooling cycles avoided?
Frequent temperature changes can shorten the usable shelf life.
- Provide only the required quantity according to the manufacturer's specifications.
- Replace material that can no longer be processed.
Insufficient strength: 3 test steps
First, define the fracture pattern and then examine the surface, application, and load.
Are the actual materials clean, dry, and properly prepared?
Oil, release agents, varnishes, and weak oxide layers can impair adhesion. Changing suppliers can also alter the surface.
- Determine the material and alloy or plastic mixture. Ask the supplier about any changes to release agents, plasticizers, and coatings.
- Adjust the cleaning process to the material and allow the cleaning agent to evaporate completely. Check the blasting media for cleanliness and condition.
- Apply adhesive promptly after pretreatment and avoid further contact or oxidation. If necessary, test wettability using suitable testing methods.
Is sufficient adhesive applied to the correct area and is the joint held still during the curing process?
Gaps in the order, incorrect contact points, and movements during curing can explain local failures.
- Check the dosage and actual wetting of the contact surface.
- Maintain fixation until the required strength is achieved; pay attention to air gaps and torn structures.
- Document the error rate and distribution. Individual failures may indicate fluctuating process conditions.
Is the bond only subjected to stress within its operating conditions after sufficient curing?
Premature stress, peeling forces, media, or differing thermal expansion can weaken a connection that initially appears to be good.
- Compare the waiting time before loading with the product data sheet.
- Capture joint geometry, temperature, chemicals and humidity in real-world use.
- For peeling loads or different materials, test tougher or more flexible systems with the application engineer.
Additional information from the source
- When working with different materials, thermal expansion and cooling stresses must be taken into account. The curing plan must still remain within the limits specified by the product.
German version prepared according to the archived Permabond guide troubleshooting-1-part-epoxyes.md. Always compare product-specific values and procedures with the corresponding technical data sheet.