In the production of tempered glass, hot spots are a critical issue that directly affects product appearance quality and yield rate. They not only damage the transparency of the glass but also become a core pain point restricting product quality in high-standard applications such as architectural curtain walls and high-end home appliances. Based on extensive industry practice and technical expertise, Landglass has traced the root causes of hot spots to oversights in three key control areas: insufficient cleanliness, poor equipment condition, and inappropriate process parameters. Landglass will analyze these three issues one by one, explain the characteristics and specific causes of the resulting hot spots, and provide systematic prevention and control solutions.
Full-Process Cleanliness Management
Cleanliness control runs throughout the entire glass tempering process, and negligence in this regard is the most direct cause of hot spots. Hot spots caused by such problems are mostly distributed irregularly, either scattered or locally concentrated, and are often accompanied by traces characteristic of contaminants.
The primary root cause is inadequate glass pretreatment. Caked anti-mold powder on the raw glass surface, glass powder residue after edge grinding, as well as mildew or water stains formed during storage will firmly adhere to the glass surface at high temperatures if not thoroughly cleaned before entering the furnace. Second, contamination on equipment contact surfaces cannot be ignored. Dust, oil, or glass powder accumulated on the loading table and roller surfaces can be directly pressed onto the glass during conveyance. A more hidden source is contamination inside the furnace. For example, if the insulation cotton on the top of the heating furnace ages or breaks, falling debris onto the ceramic rollers will form stubborn hot spots. In addition, failure to thoroughly clean the furnace rollers after power outages or glass explosions during production will leave residual glass fragments as a pollution source for subsequent mass production. To address this, a full-process cleanliness standard from raw materials to finished products must be established. In the raw glass cleaning stage, high-efficiency washing and drying equipment shall be equipped, and cleaning agents matched to the type of contaminants shall be used to ensure that glass entering the furnace is clean, dry, and residue-free. For equipment cleaning, strict daily and in-depth cleaning plans must be formulated and implemented, including wiping the loading table per shift, regularly cleaning the rollers with special cleaning agents or grinding tools, and performing thorough furnace cleaning after any abnormal shutdown. Meanwhile, regular maintenance and inspection of the heating furnace chamber should be conducted, and aged or loose insulation materials replaced in a timely manner to eliminate the risk of material fallout at the source.
