GE Engineering Thermoplastics Injection Molding Processing ...

1 GE Plastics GE Engineering ThermoplasticsInjection Molding Processing GuideProcessingInjection 8/27/99 9:34 PM Page 3 Introductionii GE Plastics Processing GuideCYCOLAC resinCYC-400 CYCOLOY resinCYL-425 ENDURAN resinEND-200 GELOY resinGEG-200 LEXAN resinCDC-500 NORYL resinCDX-811 NORYL GTX resinCDX-200 SUPEC resinSUP-300 ULTEM resinULT-210 VALOX resinVAL-151 XENOY resinX-106 Custom Engineered ProductsCEP-200 Call 1-800-845-0600 for all literature requests. Copyright 1998 General Electric Company and are Registered Trademarks and Trademarks of General Electric CompanyMold DesignMold Materials ..1-3 Prototype Tooling ..1-6 Sprues and Runners ..1-7 Gating ..1-13 Tolerances ..1-18 Shrinkage ..1-18 Cavity Venting ..1-19 Mold Temperature Control.

2 1-20 Draft ..1-23 Part Ejection ..1-24 ProcessingEquipment ..2-3 Drying ..2-5 Molding Conditions ..2-9 Troubleshooting TipsProblems/Possible Solutions ..3-3 Suggested Do s and Don ts ..3-7 About This Injection Molding Processing GuideThis Injection Molding guide contains general Injection moldingparameters that apply to all GE Engineering thermoplastic on request are separate product sections with processinginformation specific to each GE resin family as listed 8/27/99 9:34 PM Page 4 IntroductionGE Processing Guide iiiInjection Molding GEThermoplasticsNew dimensions in Processing latitude, adaptability to existingequipment, economics and desirable end-product characteristicsare presented to the Injection molder of GE Plastics resins inthis Processing guide.

3 Consistent in composition and quality,dependable across a wide range of industrial conditions, GEthermoplastic materials incorporate the flexibility, feasibilityand assurance processors required to meet the sophisticationand selectivity in marketplaces resins have outstanding Processing characteristics and manywere especially designed for Injection Molding . However, theseresins like all thermoplastic materials are not indestructibleand must be processed appropriately. This is especially truewith GE Plastics flame-retardant resins which have excellentprocessing characteristics, require proper temperature controlwithin the latitudes specific for each grade. It is important thatmachinery, Processing parameters and molds be utilized underconditions which give sufficient temperature control, minimiz-ing shear heat, material hang-up and resistance to Plastics resins are converted into final parts by a meltprocess.

4 Generally this is the Injection Molding process where a plastic melt is injected at high pressures into a precisionmold. In addition to this being a high pressure process, it isalso a high temperature process. GE Plastics resins can beprocessed at temperatures ranging from 425 F (CYCOLAC resin) to 800 F (ULTEM resin). Proper Molding practices forGE Plastics resins must be employed to prevent excessive product 8/27/99 9:36 PM Page 53 Introductioniv GE Plastics Processing GuideThis Injection Molding Processing Guide is offered as an informational service to customers of GE Engineering plasticsand users of products made from these plastics. While GE hasused reasonable efforts to provide accurate information in thispublication, GE expressly disclaims any liability for damages,costs or losses resulting from reliance on the contents of thisInjection Molding Processing Guide.

5 It is the responsibility ofthe product manufacturer to determine the suitability of anydesign or product for its intended standards and specifications discussed in this InjectionMolding Processing Guide are complex and subject to general information contained in this publication is anoverview only and is not intended to substitute careful andindependent examination of applicable standards and specifications. Adequate end-use environmental testing of finished parts must always be 8/27/99 9:34 PM Page 6 GE Plastics GE Engineering ThermoplasticsInjection Molding Processing GuideMold Des ig nInjection 8/27/99 9:36 PM Page 51 Contents1-2 Mold DesignMold DesignMold Materials ..1-3P-20 Steel ..1-3H-13 and S-7 Steels ..1-4 Corrosion Protection.

6 1-4 Prototype Tooling ..1-6 Conventional Machining Practices ..1-6 Casting Process ..1-6 Liquid Plating Process ..1-6 Flame Spraying ..1-6 Mold Filling Pressure ..1-7 Computerized Mold Filling Analysis ..1-7 Sprues and Runners ..1-7 Cold Sprues ..1-7 Cold Runners ..1-8 Hot Sprues ..1-10 Hot Runners ..1-11 Hot Runner Benefits ..1-12 Hot Runner Systems ..1-12 Gating ..1-13 Direct Gating ..1-14 Tunnel Gating (Subgating) ..1-14 Pin Point Gating ..1-15 Edge Gating ..1-16 Modified Fan Gating ..1-16 Diaphragm Gating ..1-17 Flash Gating ..1-17 Tab Gating ..1-18 Tolerances ..1-18 Shrinkage ..1-18 Cavity Venting ..1-19 Mold Temperature Control ..1-20 Mold Build-Up ..1-23 Draft ..1-23 Part Ejection ..1-24 Inasmuch as General Electric Company has no control over the use to which others mayput this material, it does not guarantee that the same results as those described hereinwill be obtained.

7 Nor does General Electric Company guarantee the effectiveness orsafety of any possible or suggested design for articles of manufacture as illustrated herein by any photographs, technical drawings and the like. Each user of the materialor design or both should make his own tests to determine the suitability of the materialor any material for the design , as well as the suitability of the material or design or bothfor his own particular use. Statements concerning possible suggested uses of the materi-als or designs described herein are not to be construed as constituting a license underany General Electric patent covering such use or as recommendations for use of suchmaterials or designs in the infringement of any 8/27/99 9:34 PM Page 8 Mold MaterialsMold design 1-3 Mold MaterialsSteel selection in tooling can be as critical to the success of aplastics application as the selection of resin is to the end useperformance requirements of the molded product.

8 Just asresins are formulated to meet performance requirements inplastics applications, steels are alloyed to meet specific perfor-mance requirements in applications may require a mold steel with high hardnessand wear resistance for parting line durability, while others willrequire a mold steel with higher toughness for resistance tomechanical fatigue. In general, steels delivering higher hard-ness and wear resistance properties are those that tend to bemore brittle, and in almost all cases, a steel with greater tough-ness will deliver some reduction in resistance to steel-to-steelwear (adhesive wear) and abrasive resistance to resins contain-ing glass fibers or mineral moldmaker may select a stainless steel to mold a resin thatcould be aggressive to most other steels.

9 Listed in Table 1-1 onpage 1-5 are some of the most commonly used materials inmold line integrity will typically be greater with higher hard-ness steels (Rockwell 55 or higher), and where steel-to-steelshut-offs produce coring. One or both steel faces should be inthe hardness ranges of Rockwell 55 to Rockwell abrasion protection from glass or mineral filled resins, it issuggested that gate inserts of A-2, D-2 or M-2 steel be consid-ered with an abrasive-resistant steel be inserted in the mold coreopposite the SteelWhile there is no general purpose steel for plastic molds, P-20 steel has been regarded as the workhorse of the in the pre-hardened state at Rc 30-32, it is very tough,yet fairly easily machined. It is a good steel to consider in appli-cations where cavity sizes exceed 12 12 12 inches ( mm), since the cost and associated risks of heattreating blocks of this size may be prohibitive.

10 P-20 steel is alsochosen in smaller cavity sizes to eliminate the time and expenseof heat treatment when it is anticipated that the mold will notexceed 500,000 8/27/99 9:35 PM Page 49 Mold Design1-4 Mold DesignWhen constructing a mold of P-20 steel where slides, lifters orother cams or moving components are necessary, it is suggestedthat these moving steel components be made of steels with dif-ferent alloying and hardness to reduce galling or high adhesivewear. A common practice in large molds of P-20 steel is toemploy slides or lifters of H-13 steel that is heat treated to Rc 50-52 or to employ localized wearing surfaces of steels in the Rc 55 through Rc 58 ranges, or and S-7 SteelsThese steels offer an extremely high degree of toughness andmechanical fatigue resistance with a perceived higher toughnessin H-13 (Rc 50-52) but better durability in S-7 because of higherhardness (Rc 55-57).