Many customers have raised concerns about silicone molds breaking easily, particularly during the demolding process for small parts or due to a short service life. This issue is often more noticeable with large, complex products, where the cost of producing the mold is relatively high. Given that customers expect silicone molds to have a longer lifespan and higher reproduction capabilities, it’s important to understand why silicone molds are prone to breaking.
Several factors can contribute to this problem:
- Improper Hardness of Silicone Rubber
One of the main reasons silicone molds break easily is due to using silicone rubber with improper hardness. If the hardness exceeds 50 Shore A, the mold’s tensile and tear strength can be significantly reduced, making it more prone to breakage after curing. Molds made from high-hardness silicone rubber are often too brittle, particularly when casting small or intricate parts. It’s crucial to select silicone rubber with the right hardness for the mold’s intended use. - Incorrect Catalyst Mixing Ratio
Another factor is the incorrect mixing ratio of the curing agent. The amount of curing agent used directly affects the mold’s durability. If too much curing agent is added (above 2% at room temperature of 25°C), the mold becomes harder and more brittle, increasing the likelihood of breakage. It’s essential to adjust the catalyst ratio based on the ambient temperature to maintain proper curing properties. - Frequent Use and Fatigue
Silicone molds can also break more easily when used too frequently. Prolonged exposure to repeated stress and strain can lead to fatigue fractures. The mold’s susceptibility to fatigue depends on the properties of the silicone rubber, such as strength, toughness, hardness, and the presence of any fillers or additives in the material. Over time, the repeated stresses can weaken the mold, making it more prone to breaking.
In conclusion, to prevent silicone molds from breaking easily, it’s essential to choose high-quality silicone rubber that offers the right balance of hardness, wear resistance, toughness, and temperature stability. Additionally, paying attention to the correct mixing ratios for curing agents and practicing proper mold handling and maintenance can help extend the life of silicone molds.