Pengacuan suntikan ketepatan mestilah berdasarkan premis bahawa acuan boleh dibuat mengikut saiz yang diperlukan. Walau bagaimanapun, walaupun saiz acuan tetap, saiz sebenar produk berbeza dengan pengecutan sebenar. Oleh itu, the control of shrinkage rate is very important in precision injection molding.
Whether the mold design is appropriate or not determines the shrinkage rate, which also varies with different resin batches. If the pigment is changed, 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
Suhu acuan
Gate sectional area
Tekanan suntikan dibekalkan oleh sistem hidraulik sistem suntikan
Masa penyejukan
Wall thickness of products
Reinforcing material
Directionality
Kelajuan suntikan
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.
Suhu acuan
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. Dalam reka bentuk acuan, attention must be paid to the design of cooling circuit.
Gate sectional area
Secara amnya, 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. Untuk resin kristal, 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.
Sebagai tambahan, there is shrinkage after molding, the main factors are:
Internal stress relief
crystal
suhu
kelembapan
2. Possible measures
Pelari, gate balance
Seperti yang dinyatakan di atas, 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. Oleh itu, 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. Walau bagaimanapun, 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.
Walau bagaimanapun, 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.
Mengenai JasonMould Industrial Company Limited
Jasonmould adalah Pembuat acuan China dari acuan plastik- acuan suntikan, acuan pemutus mati, acuan plastik, acuan putaran, perubatan pengacuan suntikan plastik, dua pukulan pengacuan suntikan plastik, masukkan acuan, terlalu banyak, pengacuan suntikan logam, pengacuan suntikan mikro, pengacuan suntikan serbuk, pengacuan suntikan seramik, pengacuan suntikan cecair, acuan suntikan husky, acuan isi rumah, acuan pemutus, alat acuan mati, acuan khas, acuan cina, perkakas prototaip pantas, perkakas prototaip plastik, perkakas penebuk, mati dan perkakas untuk bahagian telefon bimbit / telefon bimbit, bahagian automotif, pembersih vakum, alat yang boleh dicas semula, telefon, mesin penyalin, komputer, pembesar suara multimedia, dan banyak produk elektronik dan perkakas rumah yang lain. Dan juga pengeluar produk plastik, pengeluar acuan China- bahagian plastik, tangki air plastik, bola plastik, bekas plastik, gesper plastik, sauh plastik, penyangkut plastik, sudu plastik, pemasangan paip plastik, plastik jatuh, pinggan mangkuk plastik, cawan plastik, botol plastik, dulang plastik, bekas kosmetik plastik, sarung plastik, bekas makanan plastik, kerusi plastik, penutup plastik, penutup penutup plastik, tiub plastik, paip air plastik, tombol plastik, tiub plastik, kotak utiliti plastik, rak plastik dan sebagainya.
Hubungi:
Orang: James Yuan
Syarikat: JasonMould Industrial Company Limited
Tambah: Kampung LongGang,Bandar LongXi,Daerah BoLuo,Bandar HuiZhou,Wilayah GuangDong, China
Tel: 86-752-6682869
E-mel: [email protected]
Tapak: https://www.jasonmolding.com/custom-injection-molding/
