How do Cracking and Blistering form during Thermal Debinding? How can this be resolved?

Date：2025-07-29   Views：0

(Background: The defects that arise after thermal debinding of green parts are not necessarily related to the thermal debinding process itself, but may originate from previous processes such as mixing and granulation, injection molding, or solvent debinding, and are amplified and made more visible during the thermal debinding process. During thermal debinding heating, the temperature should be controlled to ensure a slow temperature rise, as defects in thermal debinding can occur when the heating rate is too fast, due to the rapid decomposition of binder components.)

Mechanism:

During the heating process of parts in thermal debinding, the moisture adsorbed by the material is converted into steam. When the decomposed gas molecules cannot escape to the environment through the interconnected pore channels quickly enough:

• Good plasticity of the green part → Blistering

• Hard green body or low interparticle friction → Cracking

Causes:

• Too rapid heating rate

• Raw material moisture absorption

• Insufficient binder removal during solvent debinding

• Uneven binder distribution, insufficient mixing of feedstock

• Excessively high binder ratio, low metal powder content

Solutions:  

• Extend heating time to prevent excessive heating rates  

• Extend solvent debinding time to ensure complete removal of the binder during solvent debinding  

• Extend mixing and granulation time to ensure complete fusion of metal powder and binder in the feedstock  

• Adjust binder composition  

• Keep raw materials dry and reduce humidity in plant  

• Increase gas purging rate  

• Shorten gas flow path