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1、Design Guidelines Injection Moulding,Engineering Design,Presenter:Laszlo PatakiSABIC-Innovative Plastics,2,Design Guidelines Injection Moulding,Design can be split into 2 main activities:Industrial Design(concepts,styling)Engineering Design(mould ability,functionality)This presentation is about Engi
2、neering Design.,Design Guidelines Injection Moulding,3,Design Guidelines Injection Moulding,Successful injection moulding depends on the good interaction between:Part DesignMould Design Processing Equipment and process controlMaterial selection.,Design Guidelines Injection Moulding,4,Design Guidelin
3、es Injection Moulding,Part Design Aspects Mould Design aspects(general,Hot runner)Flow Simulation examples.,5,Design Guidelines Injection Moulding,1,Part Design Aspects Firstly,part requirements have to be defined.Mechanical behavior(stiffness,impact)Thermal behavior(stiffness,Creep)Chemical resista
4、nce(material selection)Cosmetics(surface finish,color,gate location,ribs,weld line)Mould ability(wall thickness,flow length,gating)Assembly(screws,welding,bonding)Painting,Design Guidelines Injection Moulding,6,Design Guidelines Injection Moulding,Part Design aspects Design for mould ability Design
5、for stiffness Design for impact Design for appearance Design for precision.,7,Design Guidelines Injection Moulding,1,Design for Mould ability Constant wall thickness recommended If not possible,transitions should be smooth.,Design Guidelines Injection Moulding,8,Design Guidelines Injection Moulding,
6、Design for Mould ability Ribs-if needed-max.0.6 x nominal wall at root,min.0.5 degree draft on each side.Filling thin ribs can be problematic,Design Guidelines Injection Moulding,9,Design Guidelines Injection Moulding,Design for Mould ability Bosses for screws same rule as ribs,to increase stiffness
7、 boss can be supported with gussets.Sharp corners rounded off,better release,better strength.,Design Guidelines Injection Moulding,10,Design Guidelines Injection Moulding,Design for Mould ability Undercuts should be avoided where possible.If needed,use undercuts without sliding cores.,Design Guideli
8、nes Injection Moulding,11,Design Guidelines Injection Moulding,Design for Mould ability Draft angles,12,Design Guidelines Injection Moulding,Design for Mould ability Ejection Allow for sufficient ejection locations,specially complex shapes with many ribs and pockets can be critical with higher visco
9、us materials.Ribs are best ejected on the rib itself with blade ejectors.Use as large as possible ejector pins,lowest deformations will occur.,13,Design Guidelines Injection Moulding,Gating Flow should be from thick to thin,if not constant wall thickness.Gate location(s)to be considered to prevent f
10、illing issues.Flow curves can be used for first check.,14,Design Guidelines Injection Moulding,Design for Mould ability Gate shapesGate size is importantfor shear rate controlFlow simulation usefulfor predicting shear and pressure drop.,15,Design Guidelines Injection Moulding,VentingImportant for pa
11、rt quality.Good venting is always needed where air traps and weld linesare expected,also at the end of flow.Dynamic vents(using ejectors with facets)are suitable for local air traps,mould parting line should always be vented.Size of venting depending on material viscosity.,16,Design for stiffnessPar
12、t stiffness determined by:Material E moduleShape of the partStiffness increase Higher E moduleRibsCorrugationsHollow parts,Design Guidelines Injection Moulding,17,Design Guidelines Injection Moulding,Design for stiffnessStiffness to weight ratio.Most efficient material use in corrugated design.Struc
13、tural analysis can help to check mechanicalbehavior in advance.,18,Design Guidelines Injection Moulding,Design for impact Avoid stress concentrators(sharp corners,transitions,notches)Avoid impact load near gates and weld lines Avoid poor processing conditions(moulded in stress)Choose the right mater
14、ial(ductile/brittle transition)In critical cases perform structural analysis.,19,Design Guidelines Injection Moulding,Design for AppearancePossible surface defects gate marks sink marks due to ribbing or thick sections weld lines air traps.voids jetting,20,Design Guidelines Injection Moulding,Design
15、 for AppearanceSink mark reduction,Gas assist can reduce sink marksUnder ribs,Design feature appliedTo eliminate visible sink mark,21,Design Guidelines Injection Moulding,Design for Appearance,Sudden changes in thickness should be avoided,22,Design Guidelines Injection Moulding,Design for Appearance
16、,Try to avoid jetting when choosingthe gate location,23,Design Guidelines Injection Moulding,Design for PrecisionImportant factors:material choice(GF,GB,CF,Amorphous,Crystalline),shrinkage behavior gating(type and size of gate)mould design(cooling,gating)processing(temperatures,pressures,orientation
17、),24,Design Guidelines Injection Moulding,Design for Precision Volumetric Shrinkage Amorphous,25,Design Guidelines Injection Moulding,Design for Precision Volumetric Shrinkage Crystalline,26,Design Guidelines Injection Moulding,Design for Precision(shrinkage control)Design related aspects for precis
18、ion Wall thickness distribution gate location,gate size,gate typeProcessing related aspects melt-mould temperature,injection profilePost moulding effects Expansion,post shrinkage,moisture absorption,Design Guidelines Injection Moulding,27,Design Guidelines Injection Moulding,Design for Precision Gat
19、ing type and size important for orientation shrinkage differences between flow and cross flow for Crystalline and glass filled materials.,28,Design Guidelines Injection Moulding,Design for PrecisionThin long ribs shrink different compared to nominal wallthis can cause warpage.,29,Thank you for your attention,Design Guidelines Injection Moulding,
