◼︎ VENTLESS TWIN SHELL ® MOLD
Tire molds play a key role in cost and performance of tire manufacturing. Mainstream developments are driven by maintenance cost reduction and the aesthetical appearance of the tire. In an effort to address both, puzzle molds were introduced in the 1990's. This special mold type however, involves an increase in manufacturing cost and is only applicable to simple tread designs. The proprietary Ventless Twin Shell ® Mold technology enables uniting the best of both worlds while applying the proven concept of the puzzle mold, yet with strongly increased design freedom and at reduced cost.
Our Laser Solution enables:
✔︎ Cutting of surface connection slots as narrow as 0.04mm
✔︎ Virtual Puzzling
➤ Substitution of Puzzle Molds
➤ Twin Shell Molds
➤ Tire Tread Mold Inserts made by 3D metal printing
Ventless Twin Shell ® Mold: ⎸ Laser processing of surface connection slots ⎸ Ready Tread Shell ⎸
Twin Shell technology enables adoption of 3D printed tire molds
Additive manufacturing technology in the tire industry
Additive manufacturing technology is already applied in the tire industry today. Complex multi-dimensional sipes for tire molds are generated in significant volumes by 3D metal printing. Within the tire industry there is also a growing desire to utilise in particular very complex tire tread molds produced by 3D metal printing. To achieve this, 3D printed tire mold segments must be produced time-efficient and with a good surface quality. The Twin Shell mold is a particularly favourable design to achieve exactly that.
Tire Technology International’s October 2017 issue features an interesting article about additive manufacturing for tire molds.
3D printed tire molds in Twin Shell design
The idea behind the Twin Shell mold design in general, is to split the value added part of the mold - which is the tread - from the heat capacitance part of the mold. By designing the tread part of the mold as a thin yet stable shell, it becomes economically viable for production by 3D metal printing. The bulky backside body of the mold can be conveniently manufactured by conventional casting or direct milling technology. 3D metal printing of tire mold tread shells enables adoption of highly complex tread designs while maintaining cost efficient printing strategies.
By applying surface connection slots analog to the gaps of a puzzle mold, essentially a virtual puzzle is created. To achieve the required through flow as well as cleanability, these surface connection slots are best applied by a Laser Micro Milling post process.
The Puzzle Mold compared to Ventless Twin Shell ®
Tires from puzzle molds are characterised by their clean surface appearance. Typically only simple treads can be puzzled.
✔︎ Clean surface appearance
✘ Only for simple treads
Puzzle Mold (old)
Over the life cycle of the mold, cleaning, disassembly and re-assembly can impact the gap size between tread pitches.
✘ Pitch gaps change over life cycle
✘ Surface appearance degrades
Ventless Twin Shell ® Mold
The puzzle effect is created by surface connection slots in a solid tread shell. Gap size does not change over the mold life cycle.
✔︎ Constant gaps over life cycle
✔︎ No tread limitations
Air removal from tire molds
The very first issue of 4JET’s technology magazine 4SURfaces from 2006, features an interesting article about various tire mold venting concepts and the strong efforts that are made to produces tires by utilising ventless tire molds.
With Avonisys Laser Micro Milling technology for machining of tire molds, in particular machining of Ventless Twin Shell ® molds, the addressed micro-venting features can now by produced in a practical and cost-effective way.