科学化射出成型_1

Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,Click to edit Master title style,*,Click to edit Master title style,Click to edit Master text styles,*,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 Pressure,l,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 optimization,l,成型窗口最优化,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,),Part Weight (gm)(,部件重量),Material(,材料),Approx Cost per lb( 1b,的大约成本,),Material Cost Cents (,物料成本分),Cycle Time(,周期,),Machine Rate $/hr(,机械速率,),Cycle Time Cost Cents (,周期成本,分,),Actual Plastic Cost(,实际塑料成本,),Overheads and Labor(,管销和人力,),Profit at 5% - Cents(,利润,5%),分,Percent of Quoted Price Profit(,报价利润率,),50,PC/ABS,$ 3.00,33.3,20.0,$ 30.00,16.7,50.0,60.5,5.52,100,50,PC/ABS,$ 3.00,33.3,22.5,$ 30.00,18.8,52.1,63.0,3.44,62.3,50,PC/ABS,$ 3.00,33.3,25.0,$ 30.00,20.8,54.2,65.5,1.36,24.6,1. Introduction,6,1. Introduction,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 & Time,冷却速率和时间,Plastic Temperature,塑料温度,7,2. 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 & freeze to wall, thus forming frozen layers.,流体末端会附着、凝固在侧壁,形成凝固层,Directly proportional to shear rate; higher the shear, faster the flow,与剪切率比例成正比,:,剪切率越高,流动率越快,Inversely proportional to viscosity; 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 does,NOT,correlate to processability,对,MFR,的误解,它与加工能力无关,What,does,it affect?,它的影响,8,2. Plastic Flow Rate,Typical 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 Effect MFR,效應,Stiff,Easy,Slow,Fast,11.5 MFR,6 MFR,MFR 10 gm/10 minutes. Shear Rate 1/10/60 = .007,Machine 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 speed,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 have,constant fill time (same fill time on any press).,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 to,use abundant pressure difference between pressure at,transfer 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 to 95-99% on 1,st,stage,第一步注料95%-99%,Pack and hold on 2,nd,Stage,第二步 射饱和保压,Velocity control, delta P,速度控制,delta P,Switch 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,充填时间和,delta P,Packing 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 Delta 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 of 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 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 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 & 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-cavity,-,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. Cooling 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,GPM,Delta T should be maximum 4 F,最大,DeltaT,应该是,4F,Larger 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 between plastic and mold steel,在塑料和模金属之间的,Delta T,Stiffness & 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 vacuum,以真空清洗,Material Drying using dehumidifier at -40F.,物料使用除湿乾燥机在-40,F,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.,Critica,l 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; 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 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 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 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 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 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,4Q,p,r,3,剪切率,Shear Rate =,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:,t,p,R,2,L,Q =,4Q,p,r,3,Shear Rate =,4(,p,R,2,L/t),p,r,3,=,4R,2,L,r,3,t,=,Area x Length,Time,(,),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 4R,2,/r,3,k,是恆定的等於4,R2/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,L,t,剪切率,Shear Rate =,k.,