精密射出成形は、必要なサイズに応じて金型を作成できるという前提に基づいている必要があります. しかしながら, 金型サイズが固定されていても, 製品の実際のサイズは、実際の収縮によって異なります. したがって、, 精密射出成形では収縮率の制御が非常に重要です.
金型設計の良し悪しで収縮率が決まる, また、異なる樹脂バッチによって異なります. 顔料が変われば, the shrinkage rate will also be different. Because of the different molding machines, the setting of molding conditions, reproducibility and the action of each molding cycle fluctuate, and the actual shrinkage rate fluctuates, so it is difficult to control the shrinkage.
1. The main factors affecting the shrinkage
The mold size can be obtained by the product size plus the shrinkage rate, so the main factors of shrinkage rate should be considered in mold design
Resin pressure
Resin temperature
金型温度
Gate sectional area
射出時間
冷却時間
Wall thickness of products
Reinforcing material
Directionality
射出速度
Resin pressure
The resin pressure has a great influence on the shrinkage rate. If the resin pressure is large, the shrinkage rate will be smaller and the product size will be larger. Even in the first mock exam, resin pressure varies with the shape of the product, resulting in shrinkage. In the case of multi cavity mold, the resin pressure in each mold cavity is easy to be different, and the shrinkage rate of each mold cavity is also different.
金型温度
Whether it is amorphous resin or crystalline resin, if the mold temperature is high, the shrinkage rate will increase. Precision molding should maintain the mold temperature at a specific temperature. 金型設計で, attention must be paid to the design of cooling circuit.
Gate sectional area
一般的に言えば, the shrinkage rate also changes when the gate cross-section area is changed. The shrinkage rate decreases with the increase of gate size, which is related to the fluidity of resin.
Wall thickness of products
The wall thickness of the product also affects the yield. For the amorphous resin, the shrinkage rate increases with the increase of the wall thickness due to the different influence tendency of the resin on the wall thickness. For crystalline resin, it is necessary to avoid large wall thickness variation. In the case of multi cavity mode, if the cavity wall thickness is different, the shrinkage will also be different
Reinforcement content
When the resin is reinforced with glass fiber, the more glass fiber is added, the smaller the shrinkage rate is. The shrinkage rate in the flow direction is smaller than that in the transverse direction. According to the resin, the difference is large. In order to prevent the distortion and warpage, the shape of gate, the location of fly away gate and the number of gate must be considered.
Directionality
Although there is a great difference in the orientation, it exists for all resins. Due to the special difference in crystallinity and wall thickness of the resin.
加えて, there is shrinkage after molding, the main factors are:
Internal stress relief
crystal
温度
湿度
2. Possible measures
ランナー, gate balance
上記のように, shrinkage varies with resin pressure. In the case of single cavity mold with multiple gate and multi cavity mold,
To do the same, gate balancing is required. The resin flow is related to the flow resistance in the runner, so it is better to take the runner balance before taking the gate balance.
Cavity arrangement
In order to make the setting of forming conditions easy, it is necessary to pay attention to the arrangement of mold cavities. Because the molten resin will be hot into the mold, the mold temperature distribution takes the gate as the center in the case of general mold cavity arrangement. したがって、, when selecting the cavity arrangement of the multi cavity die, it is necessary to take the balance of the runner and the concentric circular arrangement centered on the gate
3. Prevent forming deformation
The reason of forming deformation is that there is internal stress under uneven shrinkage, so it is necessary to prevent uneven shrinkage. In the case of circular products with holes in the center of the gear, a gate must be set in the center. しかしながら, when there is a big difference in the shrinkage rate between the flow direction and the vertical direction of the resin, there is a defect of ellipse. When a higher precision roundness is needed, a 3-point or 6-point gate should be set.
しかしながら, it is necessary to pay attention to the balance of each gate. When using side gate, 3-point gate will increase the inner diameter of cylindrical products. In the case of no gate mark on the surface and end face, less use of inner multi-point uniform gate can get good results.
JasonMould Industrial CompanyLimitedについて
ジェイソンモールドは 中国の金型メーカー プラスチック金型の- 射出成形金型, ダイカスト金型, プラスチックブロー成形, 回転成形, 医療 プラスチック射出成形, ツーショット プラスチック射出成形, インサート成形, オーバーモールド, 金属射出成形, マイクロ射出成形, 粉末射出成形, セラミック射出成形, 液体射出成形, ハスキーインジェクションモールディング, 家庭用カビ, 鋳造金型, ダイモールドツール, カスタムモールド, 中国のカビ, ラピッドプロトタイピングツール, プラスチックプロトタイピングツーリング, パンチプレス工具, 携帯電話/携帯電話部品用の金型と工具, 自動車部品, 掃除機, 充電式ツール, 電話, コピー機, コンピューター, マルチメディアスピーカー, および他の多くの電子製品および家電製品. また、プラスチック製品メーカー, 金型メーカー中国- プラスチックの部品, プラスチック製の水タンク, プラスチックボール, プラスチック容器, プラスチックバックル, プラスチックアンカー, プラスチックハンガー, プラスチックスプーン, プラスチックパイプフィッティング, プラスチックタンブル, プラスチック製食器, プラスチックのコップ, ペットボトル, プラスチックトレイ, プラスチック化粧品容器, プラスチックケース, プラスチック製の食品容器, プラスチック製の椅子, プラスチックキャップ, プラスチックキャップクロージャー, プラスチックチューブ, プラスチック製の水道管, プラスチック製のノブ, プラスチックチューブ, プラスチック製ユーティリティボックス, プラスチックラックなど.
連絡先:
人: ジェームズ・ユアン
会社: JasonMould Industrial Company Limited
追加: 竜崗村,Long西町,博羅県,恵州市,広東省, 中国
電話: 86-752-6682869
Eメール: [email protected]
