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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 成型窗口最优化Ap
2、pendix附注,3,1.Introduction,Scientific Injection MoldingEnsures 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以科学的方法来建立所有成型的变异数Pro
3、vides 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.Introduction,Four Critical compon
4、ents 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&Time冷却速率和时间Plastic Temperature塑料温度,7
5、,2.Plastic Flow Rate,Fundamentals基本性Its flow pattern is like fountain flow塑料流动模式类似于喷泉流动模式Chain ends sticks lower the viscosity,faster the flow与黏度比例成反比:黏度越低,流动率越快Big misunderstanding about MFR,it doesNOT correlate to processability 对MFR的误解,它与加工能力无关Whatdoes it affect?它的影响,8,2.Plastic Flow Rate,Typical
6、 Plastic Flow 典型的塑膠流動率,Stiff,Easy,Slow,Fast,9,2.Plastic Flow Rate,Typical Plastic Flow 典型的塑膠流動,Stiff,Easy,Slow,Fast,Non Newtonian,Mixed,Newtonian,10,2.Plastic Flow Rate,Newtonian fluids can be defined as those for which viscosity is a constant regardless of shear stress or rate of shear.牛顿流体可被定义为黏度是
7、一个常数,不随着剪切应力或剪切率变化的流体。Non-Newtonian fluids are those for which viscosity is not a constant,but varies based upon the rate of shear or the shear stress.非牛顿流体是那些黏度不是一个常数,而是随着剪切应力或剪切率变化的流体,11,2.Plastic Flow Rate,Momentum Effect 慣性作用,Stiff,Easy,Slow,Fast,Electric電力,Hydraulic水力,12,2.Plastic Flow Rate,MFR
8、 Effect MFR 效應,Stiff,Easy,Slow,Fast,11.5 MFR,6 MFR,MFR 10 gm/10 minutes.Shear Rate 1/10/60=.007Machine flow rate 30 gm in.5 sec=3/.05=60,13,2.Plastic Flow Rate,Melt Temp Effect 融熔溫度效應,Stiff,Easy,Slow,Fast,525 deg F,425 deg F,14,2.Plastic Flow Rate,Plastic Viscosity Varies塑料黏度的变化与以下有关With injection s
9、peed与射出速度Lot changes,temperature生产批号变化,温度%regrind,colorants再生料%,抽料制程Screw rotate time螺杆旋转速度-But these can be minimized by velocity control但这些可经速度控制减到最小What else changes the viscosity?其他改变黏度的因素:In order to have cruise control on velocity,we need to haveconstant fill time(same fill time on any press).
10、为了在速度上的稳定性,我们需要有稳定的注料时间(在任何射出循环有稳定的注料时间)In order to have control on constant fill time,we need touse abundant pressure difference between pressure attransfer and available machine pressure-Delta P.为了对稳定的注料时间进行控制,我们需要在 移转的压力和可利用的机器压力之间使用大量的压力差-Delta P,15,2.Plastic Flow Rate,Two Stage Molding成型二阶段Fill
11、 to 95-99%on 1st stage第一步注料95%-99%Pack and hold on 2nd Stage第二步 射饱和保压Velocity control,delta P速度控制,delta PSwitch over by position位置交换(V-P切换位置)We will determine the following perimeters:我们将决定以下参数Cutoff position,cushion,velocity and plastic pressure at transfer.切换位置,缓冲,速度和切换时之塑料压力Fill time and delta P充
12、填时间和delta PPacking pressure and time(Gate sealed&unsealed)保压压力和时间(浇口被密封或未封)Back pressure and screw delay背压和螺杆延迟时间Cooling and cycle time.冷却时间和成型周期,16,2.Plastic Flow Rate,Two Stage Molding成型二阶段,17,3.Plastic Pressure,Fundamentals基本原理It is very important to determine plastic pressure at transfer and Del
13、ta P.在转换和Delta P时决定正确的塑料压力是很重要的Also determine the pressure loss of the flow path(Nozzle-Sprue-Runner-Gate-Part)也要决定流道的压力流失(喷嘴,注道-流道-浇口-成品)Machine controllers must use plastic pressure机器控制器必须使用塑料压力Intensification Ratio:强化比率:-Ratio of effective hydraulic ram area to screw area-有效的液压缸区域与螺杆区域的比率-Ratio o
14、f max.injection pressure to max.hyd.Pressure-最大的射入压力与最大液压比。-Use machine graph-使用机器图表,18,4.Cooling Rate&Time,Cooling Time is the profit killing giant冷却时间-是利润的最大杀手Injection cycle components;注射循环之组成:,19,4.Cooling Rate&Time,Basics of Cooling冷却的基本知识Radiation辐射-Mold radiates energy in all direction模具在所有方向
15、放热能量-Not usually visible-通常不可视-Infrared waves can be monitored-红外线可被监测Convection对流-Energy is emitted through air currents-能量通过气流散发-Hot air rises,less dense-热空气上升,较轻-Mold faces sees an updraft-模具正面有上升气流Conduction传导-Energy is transferred through contact;like through cooling lines-能量通过接触转移;如通过冷却管路-The
16、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&Time,Conduction Cooling传导冷却:Depends on:依靠-Turbulent flow;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-Temperature difference-温度区别Reynolds Equatio
17、n(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&Time,Reynolds#for 1/8”&5/16”ID,Minimum Nr,32 F,50 F,80 F,100 F,140 F,22,4.Cooling Rate&Time,Cooling Line Connection冷却管路连接Parallel Flow平行流动-Blockage in multi-cav
18、ity-多洞穴之阻塞-Uneven flow thru Channels-通过管路时流量不均-Maximum Cooling-最大值冷却-Largest GPM demand最大的GPM需求-Least deltas:T&P-最少变数:时间&压力Series Flow串联流动-Blockage found quickly-阻塞可迅速找到-Even flow thru Channels-通过流道流量均匀-Average Cooling?Delta T-平均冷却值-Minimum GPM demand 最小值GPM需求-Maximum deltas:T&P-最大变数:时间&压力,23,4.Cool
19、ing Rate&Time,Cooling Issues有关冷却的议题Uniform for each cavity每穴位需均匀Same GPM for each line各管路同样的GPMDelta T should be maximum 4 F最大DeltaT应该是 4FLarger Hoses than mold channels水喉要比模子管路更大Use parallel/series combo使用并联与串联组合方式Cooling Time is affected by:冷却时间受影响于:How thick is the thickest section最厚部分的厚度Delta T
20、between plastic and mold steel在塑料和模金属之间的Delta TStiffness&Thermal properties of the plastic塑料之硬度和热力特性Release Characteristics&Draft angles脱模特性和脱模角度Amount of ejection surface area顶出面积的大小Coolant flow rate冷却剂的流动率,24,5.Plastic Temperature,Hopper料斗Mass flow 大流量Uniform temp;insulated 一致溫度,需作绝缘Clean it with
21、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。,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 m
22、inimum 20:1最少值Compression ratio:压缩比-Flight depth ratio;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
23、Use 800 1200 psi to turn screw用800 1200 psi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
24、区域超过设定点-raise rear or center zone提高后方或中心区域-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
25、Study加工窗口研究Traditionally 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
26、 rate?增加高和低的填充率?,29,8.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 rateAnd 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 d
27、uring the injection 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噴
28、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/r3k 是恆定的等於4R2/r3 In other words:Shear Rate is directly proportional to the stroke and inversely proportional to the injection time;change either in isolation and the Shear Rate changes.換句話說:剪切率與衝程是成正比與射入時間成反比;單獨改變任何一方都會帶來剪切率變動,k.,
