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AX Molding Co., Ltd.
Specialized manufacturer of T-dies and feed blocks
We can handle a variety of applications, including high-precision thin film dies, sheet dies, and multi-layered products.
Tanzawa Techno Center (design, development, and manufacturing base)
0463-68-8223
FAX: 0463-57-8276
553-1 Soya, Hadano City, Kanagawa Prefecture, 257-0031
03-6424-7570
Head Office (Administrative and Accounting)
FAX 03-6424-4676
CINZA101, 2-8-2 Minami-Kamata, Ota-ku, Tokyo 144-0035
Reception hours: 8:30-17:30 (excluding weekends and holidays)
Multi-Manifold Die
Multi-layer T-die (multi-manifold die)
There are roughly two methods for producing multilayer sheets and films: the feedblock method and the multi-manifold method.
Here we will explain about T-dies that have many manifolds (flow paths) inside them.
This method spreads each layer in each manifold and makes them meet near the lip outlet in the T-die.
Because the time after merging is short, there is little variation in the thickness of each layer, which makes it possible to improve the accuracy of the layer ratio.
- Feed block method: The resin that meets in the manifold inside the T-die is spread out, which inevitably results in variations in the thickness of each layer. - Multi-manifold method: It is possible to create temperature differences in the resin of each layer. The thickness of each layer can be adjusted by the extrusion volume or choke bar.
Multi-layered multi-manifold dies are difficult to manufacture and require greater machining precision to align each layer at an angle.
<Reference diagram>
3 types, 3 layers, with outer layer chalk bar
3 types, 3 layers, no outer chalk bar
Actual photo (for reference)
Resin supply to a multi-manifold die for multi-layer film can be achieved by directly supplying resin to each manifold from extruders of different diameters, so the extrusion volume can be changed for each extruded layer according to the user's target layer ratio, thereby controlling the layer ratio.Different extrusion volumes mean that the pressure, flow rate, and flow velocity applied to each manifold inside the T-die must be taken into consideration, along with the manifold gap and feed pipe diameter.
Multi-manifold die features
The characteristic of a multi-manifold die is that it has a structure in which several T-dies are stacked, the films are ejected, and the films are joined near the lip to overlap each other.
Advantages of the multi-manifold die system
・The film is laminated inside the die, making it easy to control the thickness ratio.
・Can be used with resins with different viscosities
・Can be used inside a multi-manifold die even with resins with different temperatures (approximately 20 to 50°C)
・Choke bars can be attached to each layer to adjust the flow.
Disadvantages of the multi-manifold die system
・It is expensive
- Difficult to handle due to its large size
・There are many heaters and zones, and wiring is cumbersome.
・The T-die body has many diagonal parts, making it difficult to hang upright and disassembling
・The angle of the tip of the T-die is obtuse, so it may be difficult to obtain an air gap.
・It may be difficult to find space for the lip adjustment bolt.
The figure on the left is a cross-sectional view of a typical 3-type 3-layer multi-hold die.
The three-layer multi-manifold die is made up of four die bodies joined together.
A manifold is engraved on one side of the outside of the die body, and manifolds are engraved on both sides of the inside of the die body.
The outer flow path passes through the diagonal gap at the joint, and this diagonal gap also becomes a flow path.
The polished surface is plated.
The tip of the inside of the die body is an acute angle because it is where the resin meets.
The inside of the die body must be protected on both sides, so it cannot be left as is when disassembled for cleaning.
The tip must also not be damaged.
The outside of the die body cannot be hung parallel to the surface, so it must be disassembled carefully with the lip side facing up and the underside moved on the surface plate.
Another drawback is that the outer layer's resin flow path is long, which can cause the die lip to open due to resin pressure. The outer body of the die has a rear mounting surface and a long resin flow path. Because the flow path is long, the area subjected to resin pressure and the moment of force are large, which can cause the die body to bend and the lip to open.
We use analysis to design a multi-manifold die that balances the flow path gaps based on the resin being used and the planned discharge volume, so that the pressure of the three resin layers is uniform, and also takes into account the nozzle opening.
Although this method is difficult to handle and requires an expensive die, it is possible to control the layer ratio of each resin with higher precision (0.2% deviation) compared to the feedblock method.
For films that require high quality, many customers consider using a multi-manifold.
We can handle a wide range of products, from small to large multi-manifold dies.
We have a wealth of knowledge, so please feel free to contact us even if it's just a small matter!
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