科学化射出成型_1.ppt

1、Symbol Technologies,Scientific Injection Molding 科学化射出成型 (Process Optimization) (过程最优化),Johnny Singh,2,CONTENTS内容,Introduction简介 Plastic Flow Rate塑料的流动率 Plastic Pressurel 塑料的压力 Cooling Rate and Time冷却的速率和时间 Plastic Temperature塑料的温度 Characteristics to Monitor塑料特性之监控 Molding Window optimizationl 成型窗口最

2、优化 Appendix附注,3,1. Introduction,Scientific Injection Molding Ensures that identical parts are produced consistently independent of the normal machine to machine, day to day and lot to lot variations 保证相同部件生产的一致性, 不受一般的不同机器,生产批号,日期之变异所影响 Scientific approach to establish all molding variables 以科学的方法来建

3、立所有成型的变异数 Provides ability to detect and document problems based on data - not personal opinions 能够用数据化的方式来侦测和纪录问题点,而不是靠个人观点 Can increase profit margin by 20 to 50% 能够提高利润20%到50%,4,1. Introduction,Profit percentage(利潤百分比),5,Effect of Cycle Time on Profit (成型周期对利润的影响),1. Introduction,6,1. Introductio

4、n,Four Critical components to make a good part 做出好成品的四大重要成分 Part Design(成品设计) Material selection and handling(材料选择和处理方式) Tool design and construction(模具设计和结构) Processing(加工制程) In Processing, the four main plastic variables (加工中的四大塑料变异因素) Plastic Flow Rate(塑料流动率) Plastic Pressure塑料压力 Cooling Rate 注射循

5、环之组成:,19,4. Cooling Rate like through cooling lines- 能量通过接触转移; 如通过冷却管路 - The most effective and the one we can control 是最有效的和我们能控制的- - Its a science but often done poorly -是科学但经常很少有效的去执行,20,4. Cooling Rate Reynolds # -乱流;雷诺号码 - Cooling Line Location冷却管路的位置 - Clean Channels -干净的管道 - Time -时间 - Temper

6、ature difference -温度区别 Reynolds Equation (Nr): Reynolds公式(雷诺号码) Nr =3160 x Q Q = GPM of coolant冷却剂的GPM D x n D = Channel Diameter (in)管道直(吋) n = Kinematic Viscosity动态黏度(cs),21,4. Cooling Rate insulated 一致溫度,需作绝缘 Clean it with vacuum以真空清洗 Material Drying using dehumidifier at -40F. 物料使用除湿乾燥机在-40F干燥。,

7、25,5. Plastic Temperature,Injection Screw should deliver melted plastic uniformly.螺杆必须均匀的把熔融射出 L/D ratio:L/D比率 - 16:1 is short, poor melt quality! - 16:1是很短的,很差的熔融质量! - 24:1 is long, better melt quality.Critical 24:1是长的, 更好的熔融质量.非常重要 - 20:1 minimum 20:1最少值 Compression ratio:压缩比 - Flight depth ratio;

8、 feed to metering section进入深度比;进料到测量部分 - Range: 1.5:1 to 8:1范围: 1.5:1 到 8:1 - High ratios tend to work the plastic more; higher temp 高比率会使塑料工作更快;更高的温度,26,5. Plastic Temperature,Temperature profile温度特征 Target mid range of mfg. recommendations目标为使用原料商推荐范围之中间值 Use 800 1200 psi to turn screw用800 1200 ps

9、i转动螺杆 Most energy to melt plastic comes from screw rotation (shearing effect)多数熔化塑料的能量来自螺杆的转动(剪切热作用) Front zone should not attempt to change melt temperature前面区域不应该试图用来改变熔融温度 Watch Temperature controller during molding:成型时要时常观察温度控制器 If zone overrides set points如果区域超过设定点 - raise rear or center zone提高

10、后方或中心区域 - slow screw rpm减慢螺杆rpm - lower back pressure减低背压 - remove barrel blanket - 移除料桶的毯子?,27,6. Characteristics to Monitor,Factors to Monitor:主要监控因素: Pressure at transfer (V-P)切换时的压力 Cushion缓冲 Fill Time充填时间 Recovery time恢复时间,28,7. Molding Window Optimization,Process Window Study加工窗口研究 Traditional

11、ly Hold Pressure and Melt Temperature (and Mold Temp for SC Materials)传统上保压和熔融温度(和sc物料的模具温度) As discussed Melt temp has very little effect on processability (shear rate is the main controller)如讨论所说,熔融温度对加工能力很少有影响,剪切率是主要控制因素 Drop melt temp from study?放弃熔融温度的研究? Add high and low fill rate?增加高和低的填充率?,2

12、9,8. Appendix,Appendix附錄,30,Shear Rate Formula,For a circular orifice:對於圓形的管口 Where Q is the volumetric flow rate And r is the radius of the orifice Q是容量流速, r 是管口的半徑 So, during the first stage, shear rate is affected by the geometry of the tool and the volume of melt entering the cavity during the i

13、njection time.因此, 在第一階段, 剪切率是受在射出期間,模具的幾何形狀和熔融進入模穴的容量所影響的,31,Shear Rate for Machine,For simplicity, imagine measuring the shear rate at the nozzle of an old fashioned plunger type molding machine:,衝程Stroke = L,灌咀半徑Nozzle Radius = r,射出時間Injection Time = t,料管半徑Barrel Radius = R,簡單來說, 想像在一種老的柱塞類型的成型機器的

14、噴管上測量剪率,32,Shear Rate for Machine (cont.),Then the volumetric flow rate is: 容量流速是: Q = (面積X長度)/時間 Substituting into the shear rate formula, we get: 代入剪切率公式, 我們得到:,33,Effect of Stroke on Shear Rate,So, if the tool and machine arent varied : 所以, 如果工具和機器不變化: Where k is a constant equal to 4R2/r3 k 是恆定的等於4R2