mold flow checklist 解释说明

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Good
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Enter flow front temperature variation at end of fill for each scenario 前端温差
Enter flow front temperature variation.
The variation should be less than 30 degrees F. Consequences: Large variations in temperature can lead to residual stresses, which can lead to warpage.
20 – 5 = 15 sec
Enter second stage (pack + hold) time.
11
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Enter maximum clamp tonnage required for each scenario 最大锁模力
Enter clamp tonnage peak.
This value should not exceed the press tonnage of the machine being used for production. Consequences: Planning for a machine that is smaller than the required tonnage can result in parts that are flashed.
1600
ton
12
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Review and enter volumetric shrinkage at ejection for each scenario 顶出时的体积收缩量
Enter volumetric shrinkage at ejection.
The target value is 3 times the tool shrinkage rate. For example, for tool that has 0.8% shrinkage, volumetric shrinkage is 0.8% * 3 = 2.4%. Consequences: If the value is greater than 3 times it could lead to undesirable part warpage, and it should be evaluated in greater detail with warpage analysis.
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Vent
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Review air traps for each scenario 气泡
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Avoid
GUIDELINES: Force all air traps to edges of part. Air traps located at the edges of the part should be vented. Air traps that are on the surface of the part should be avoided. 将所有气泡赶到产品边缘。位于产品边缘的 气泡可以排气。避免产品表面气泡。 8
8675.6
psi
2
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Avoid • Review pressure distribution and balance at end of fill for each scenario 压力分布及填充平衡
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Part is poorly balanced and has large distribution of pressure 产品填充不平衡且压力 差较大 Consequences: Uneven pressure distribution can • result in less consistent material shrink, higher residual stresses, and areas of overpack or underpack conditions. • 压力分布不均会导致材料收缩不一致， 残余应力高并且有些地方可能出现断层 情况。 Part is very well balanced and has small distribution of pressure 产品填充平衡且压力 分布均匀 3
The shear rate in the gate should not exceed resin material maximum limit (TPO - 100,000; ASA, ABS - 50,000). Consequences: Exceeding the shear rate of the material can cause it to degrade and therefore not perform as anticipated.
~25
psi
6
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Review weld lines and include temperature at flow front for each scenario 熔界线位置和长度包括 熔接线位置的前端温度
GUIDELINES: Minimize the length of all knit lines. Where possible, horizontal lines are preferred to vertical knit lines. Also, review the flow front temperature at the weld lines.使熔接线 长度最小化。 可能的话，水平的熔接线比 垂直的好。同时要审核熔接线处的前端温度 。 7
551.5 - 548.9 = 2.6
Deg. F
4
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Enter bulk shear rate in gate for each scenario 浇口处剪切率
流体的流动速相对圆流道 半径的变化速率—剪切速 半径的变化速率 剪切速 率(shear rate)
Enter the bulk shear rate in gate.
CONSEQUENCES: Air traps that are not properly vented can cause gas burns in those locations. 不能排气的气泡可能导致该区域气体灼伤。
8,000 6,400
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Enter pack and hold pressure for each scenario 第二阶段压力
CONSEQUENCES: Lower temperatures may indicate that it will be difficult to control the appearance of the weld line. The strength of the cooler weld lines may also be less than higher temperature weld lines.温度低会使得熔接线外观难于 控制。温度低的熔接线处强度比温度高的差 。
Enter first stage injection pressure.
In general, the value should be a maximum of 10,000 psi. Consequences: If the required pressure is more than 10,000 psi, the part may flash, have undesirable residual stresses, or may not fill.
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Leabharlann Baidu
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Enter fill/pack switchover percentage for each scenario 填充/保压转换时填 充百分率
Enter fill/pack switchover percentage.
Value generally should be between 95% and 99%. Consequences: If the switchover is less than 95%, the part may not fill with packing. If the switchover is more than 99%, the part may flash.
~60,000
1/sec
5
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Enter shear stress in the part for each scenario 填充末端（95%时）壁上剪 切力
Enter the 95th percentile shear stress at the wall at the end of filling in the part.
The shear stress in the part should not exceed the resin material maximum limit (TPO - 73psi; ASA, ABS - 43psi). Consequences: Excessive shear stresses in the part can lead to surface quality issues.
As a starting point, this should be greater than or equal to 80% of injection pressure. Enter second stage pressure. Consequences: Not meeting the minimum value can result in underpacked parts which can result in poor appearance.
97% %
1
This plot shows the pressure distribution at 97% switchover by volume. Pressure to fill – 8,675 psi.
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Enter maximum pressure at end of fill for each scenario 第一阶段注射压力
JES3.2—Analyze Mold Flow and Select Optimal Scenario通过模流分析选择最佳方案
This plot shows the pressure distribution at 97% switchover by volume. Pressure to fill – 8,675 psi.
10
CONSEQUENCES: Uneven spikes are an indication of unbalanced parts, which can lead to residual stresses.若不然 会导致产品不平衡，产生残余应力。
Gate Freeze • at ~20 sec. •
Enter pack and hold time for each scenario 第二阶段（保压）时 间
5
20 This time should be greater than or equal to the 100% gate freeze time. Consequences: If time is less than the gate freeze time, part may be underpacked resulting in poor surface quality. If time is more than the gate freeze time, part cannot be further packed so extra time is not required.
6,400 (80% of 8,000)
psi
9
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Review injection pressure at nozzle versus time for each scenario 喷嘴处压力/时间图
GUIDELINES: Optimal designs have nearly equal spikes at filling and switchover points. 最好是尖点位于转换点。