by Glass molds help form the molten glass into the desired shape through the precise mold cavities. This process allows for mass production of consistent glass items.
Types
Blow Molding
In blow molding, parison or gob of molten glass is first blown into a blank or perform shape using air pressure. This semi-molten glass perform is then placed inside a multipart cavity mold where final shaping takes place using air or water pressure to force the glass to conform to the mold cavity. This creates hollow glass objects like bottles and jars.
Press and Blow Molding
Press and blow involves using blow molding along with pressing. In this process, a pre-formed parison of glass is first shaped using mechanical pressing and then final shaping takes place inside the blow mold using air pressure. This helps produce complex shaped glass articles.
Cast Glass Molding
Cast glass molding or casting involves pouring molten glass into molds with complex shapes and patterns. The molds are made of refractory materials that can withstand high heat. As the glass cools and solidifies inside the mold, it takes the shape defined by the mold cavity. Fine glassware, decorative glass items, and scientific glass apparatus are commonly made using cast glass molding.
Materials Used
Glass Molds need to withstand intense heat ranging from 1100°C to 1600°C during the melting and forming process. Therefore, the mold materials must have good heat resistance, strength, and dimensional stability at high temperatures.
Ceramic Molds
Ceramic molds are commonly used for shaping glass using processes like cast glass molding. Ceramics like silicon carbide, zirconium silicate (ZBS), and alumina possess high heat resistance making them suitable mold materials. Ceramic molds can withstand 10,000 molding cycles but have lower thermal conductivity.
Metallic Molds
Metals like steel, nickel, copper provide good thermal conductivity which aids in uniform heat dissipation from molten glass. However, metals have lower heat resistance compared to ceramics and require water or air cooling mechanisms during use. Metals are used for short production cycles in processes like blow molding.
Factors Considered while Designing
Glass molds are precisely engineered to obtain quality glass products. Some important factors considered during its design include:
Mold Cavity Design
The mold cavity design defines the final geometry and dimensions of the glass part. Cavities are designed to facilitate smooth filling and shaping of molten glass without defects. Draft angles are provided on vertical surfaces for easy part removal.
Runner and Gating System Design
A well-designed runner system ensures uniform filling of molten glass into the mold cavity. Gates help control filling speed and pattern. This is crucial to prevent air entrapment and shape imperfections.
Thermal Analysis of Molds
Heat distribution analysis using simulation or testing aids in determining optimal mold material, thickness based on heating/cooling rates and temperatures for uniform heat transfer. This helps minimize heat stresses on molds.
Parting Line Placement
Proper parting line placement of two-piece molds is important for easy opening-closing of molds and minimizing damage to fragile glass parts during ejection. Parting lines are often placed in low stress areas or hidden features.
Lubrication and Refractory Coatings
Lubrication of molds with graphite or molybdenum disulphide reduces friction for smooth glass removal without sticking. Thermal barrier coatings increase mold life by insulating molds from extreme heat.
In conclusion, glass mold plays a vital role in mass production of consistent glass products across industries. Careful design of molds, gates, parting lines along with use of suitable materials helps manufacture high-quality molded glass parts economically on a large scale.
*Note:
1.Source: Coherent Market Insights, Public sources, Desk research
2.We have leveraged AI tools to mine information and compile it
Money Singh
Money Singh is a seasoned content writer with over four years of experience in the market research sector. Her expertise spans various industries, including food and beverages, biotechnology, chemical and materials, defense and aerospace, consumer goods, etc. LinkedIn
