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Why does the parison slow down when passing through the shaping die during extrusion? How can this problem be solved?
Why does the parison slow down when passing through the shaping die during extrusion? How can this problem be solved?
① Insufficient lubricant dosage: When the lubricant dosage is insufficient, the friction coefficient on the surface of the parison increases, leading to an increase in the sliding resistance.
② Insufficient traction force: The traction force should be slightly greater than the sliding resistance of the profile in the shaping die.
③ Insufficient cooling of the parison: This may increase the friction coefficient on the surface of the parison, thereby increasing the sliding resistance of the parison.
④ Vacuum fluctuation: Vacuum fluctuation is manifested as unstable vacuum, with sudden highs and lows, causing unstable contact between the parison and the shaping die wall, resulting in unstable movement. Especially when producing single-wall open profiles, the single wall of the profile is sometimes adsorbed and sometimes detached, generating a rustling sound during the traction process, and the single wall of the profile develops waves.
The main solutions are as follows:
① Under the premise of not affecting the mechanical properties of the profile, the lubricant dosage can be appropriately adjusted to reduce the friction coefficient and thereby decrease the sliding resistance.
② Observe whether there is any slippage between the belt and the profile. If slippage occurs, the clamping force of the belt should be adjusted. The clamping force should be such that no plastic deformation occurs in the profile in the clamping direction.
③ Lower the temperature of the cooling water or increase the flow rate of the cooling water. Generally, a water temperature between 10 and 18°C is ideal, and the water pressure should be greater than 294 kPa (3 kg/cm²).
④ Check if the shaping die modules are deformed or assembled unstably, and if there is any air leakage.
⑤ Increase the vacuum adsorption force during shaping to maintain a stable vacuum.
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Shanghai Omega Machinery Co., Ltd.
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Contact: Nina
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