| Walmark Corporation phone: (847)546-0400 fax: (847)546-1777 |
| Poor Adhesion | |
| Problem | Suggested Solution |
| 1. Adhesive mostly on one surface due to insufficient amount of adhesive or low running temperature. | Apply heavier glue film thickness and/or raise temperature. |
| 2. Adhesives on both surfaces but shows "legs". Caused by disturbing the bond while still in semi-molten state. | Check compression, apply cooler, or use faster setting adhesive. |
| 3. Glossy surface appearance of hot melt. Caused by poor or non-contact of surfaces being adhered. | Adjust pressure to keep glued surfaces together while hot melt cools. |
| 4. Easy Separation of bond. Usually a result of improper selection of adhesive. | Try a more suitable product. |
| Charring of adhesive | |
| Problem | Suggested Solution |
| 1. Temperature too high in tank. | Lower temperature in tank. |
| 2. Hot melt charring on side walls of tank. | Keep tank filled. |
| 3. Air oxidizing hot melt. | Keep tank covered. |
| Gelling of Adhesive | |
| Problem | Suggested Solution |
| 1. Overheating. | Drain and flush system and lower temperature. |
| 2. Mixing of incompatible adhesives. | Check with your Walmark representitive. |
| 3. Unstable hot melt (if repeated). | Check with your Walmark representitive. |
| Stringing | |
| Problem | Suggested Solution |
| 1. Running temperature too low. | Raise temperature... however, too high a tempperature can affect heat stability. |
| 2. Stock temperature too low. | Prewarm stock. |
| 3. Poor timing or misalignment of carton flap to applicator roll. | Machine adjustment. |
| 4. Poor shutoff of nozzle. | Clean and repair nozzle shutoff. |
| Adhesive Not Flowing Evenly From All Nozzles | |
| Problem | Suggested Solution |
| 1. Nozzles colgged. | Clean or repair nozzle. |
| 2. Remote nozzle in multitude nozzle set-up may be affected by pressure drop. | Increase temperature or pressure slightly. Put larger orifice openings on remote nozzles. Melt down capacity of unit may be inadequate for demand. Raise temperature or add auxiliary pre-melter. |
| Fuming or Smoking | |
| Problem | Suggested Solution |
| 1. Poor heat control. | Use calibrated thermometer, reset thermostat. |
| 2. Hot melt has poor heat stability. | Reduce temperature to minimum needed for a good bond. Cover reservoirs or premelters whenever possible. Open pots almost always smoke. Use suction fan over pre-melter or reservoir and exhaust fumes to outside. |