07723 grb

Glossary Amorphous: A condition where the long chains of a plastic are disordered, much like a pot of boiled spaghetti Angstrom (Å): A unit of length One angstrom is equal to 1/10,000,000,000 meter Anisotropic: Nonuniform shrinkage of a polymer, usually related to molecular orientation (especially in semicrystalline polymers) or fiber orientation in fiber-reinforced materials Atom: The smallest basic particle that can be identified with an element name Any smaller particles are common to many different elements Barrel Capacity: The amount of plastic that the molding machine can inject each cycle It may be expressed in weight or volume, but most often in weight of a common material such as polystyrene or polyethylene Boss: Protuberance on a plastic part designed to add strength, facilitate alignment, provide fastenings, etc Bubbler: A cooling system where coolent is introduced to the bottom of a drilled cooling hole via a central tube The coolant then flows around the tube and back to a return passage Cavity: A depression in a mold created by casting, machining, or hobbing Clamping Plate: A plate fitted to the top or bottom of the mold that is then attached or clamped to the molding machine platens to secure and position the mold Clamping Pressure: The pressure applied to the mold to keep it closed during a cycle Cooling Channels: Channels located within the body of a mold through which a cooling medium is circulated to control the mold surface temperature Cooling Fixture: A jig or block to hold the shape of a molded part after it is removed from the mold until it is cool Crystalline: A condition or area in a plastic mass where the molecular chains are neatly packed together much © Plastics Design Library like a pack of cigarettes or a new box of spaghetti Refer to Fig 1.1 Crystallites: Smallest crystalline structure, generally a few hundred angstroms (approximately 0.00005 mm) across Polymer molecular chain lengths can be many times the size of crystallites Cycle: The complete sequence of operations in a process to complete one set or parts The cycle is taken at a point in the operation and ends when this point arrives again Density: A measure of the compaction or crystallinity of a resin For example, high-density polyethylene weighs from 0.941 to 0.960 grams per cubic centimeter Low-density polyethylene weighs from 0.910 to 0.925 grams per cubic centimeter Medium density falls between these ranges Diaphragm Gate: A disk-like runner system on the end of a symmetrical cavity allowing material to flow evenly in all directions into a part from the runner See Ch 5.2.5 Draft: The difference in dimension between the top of a core or cavity and the bottom of the same core or cavity It is usually expressed as an angle, usually from to degrees The mold cores are smaller at the end than they are at the mounting surface The cavities are smaller at the closed end than they are at the parting line Family Mold: A multicavity mold in which each cavity makes a different part of a larger assembly or group of parts Fan Gate: A type of gate that starts full depth of a runner with a relatively narrow width that widens and becomes shallower as it approaches the cavity This type of gate often minimizes warpage See Ch 5.2.4 Flash: Extra undesired plastic attached to the part along the parting line It is usually quite thin Gate: An orifice through which the molten resin enters the mold cavity Refer to Fig 5.2 Glossary 234 Hob: A master model of the part made of hardened steel, which can be pressed into soft steel to form a cavity Hot Runner Mold: A mold in which the runners are insulated from the cavities so that the plastic remains molten Injection Molding: A process whereby a plastic is forced from a reservoir by a ram through a heated cylinder to soften it, and into a cavity where the plastic is cooled or cured Refer to Fig 1.4 Injection Pressure: The pressure on the face of the ram when it is used to force plastic into the mold Injection Ram: A shaft or heavy screw that forces the plastic through the heating cylinder into the injection mold Melt Index: A measure of how far a plastic resin will flow before setting up under certain conditions Melt Index and Molecular Weight are generally inversely proportional Specifically, the grams of plastic material that can be forced through an orifice of 2.1 mm when subjected to a force of 2160 grams for 10 minutes at 190°C Mold: The complete assembly that fits into the platen area of an injection-molding machine that provides the void space to contain, cool, and shape the molten plastic into the desired part or parts Molecular Weight: The sum of the weight of all the atoms in a given molecule Polyethylene, for example, may vary from 1000 to several thousand molecules of ethylene in a single chain The average molecular weight and the molecular weight distribution are important measures of the quality and applications appropriate for a resin Molecular Weight Distribution: The range of molecular weight variation within a given resin In other words, does the resin have mostly small or mostly large molecular chains, or some weighted distribution toward large or small? Is the “bell curve” of weight distribution narrow or wide? Does the curve “lean” in one direction or the other? Molecule: The smallest particle of a chemical compound It is made up of two or more atoms Multicavity Mold: A mold having two or more voids for forming two or more finished parts each machine cycle Glossary Nozzle: The hollow cored metal tip attached to the end of the cylinder in which the plastic is melted and pressurized The nozzle is held tightly against the sprue bushing of the mold to direct the molten plastic into the mold Nomogram: Also called nomograph, this is a graph containing several parallel scales graduated for different variables so that when a straight line connects values of any two, the related value may be read directly from the third at a point intersected by the line It assists in estimating data that normally would require intricate calculations developed long-hand or via computer Refer to Figs 11.62 and 11.63 Nucleation Agent: Any one of a number of substances that when added to a plastic causes crystals to start to form Often dyes and colorants provide just such a substance Orientation: Alignment of molecules, generally in the direction of flow or stretch Flexing or coining a hinge (especially with polypropylene) causes additional orientation and crystalline structures to form in the hinge, resulting in increased strength and life Parting Line: The primary separation plane for a mold Molded parts are usually removed from the mold at the parting line Pin Point Gate: A restrictive gate with an orifice diameter of 0.030 inch or less Typically used with hot runner molds but may be used with conventional runners See Ch 5.2.2 Plastic: A synthetic resin similar in many ways to natural resins found in trees and plants For it to be useful, it must have a high molecular weight Natural “plastics” exist: slime or bitumen, with which the fiber-reinforced boat was built in which Moses was placed as a baby Amber is a form of natural plastic Lac, or shellac, is yet another natural plastic Gutta-percha was used for years as an insulating coating on electrical cables until the mid 1900s Platens: The mounting plates in a molding press upon which the mold is fastened They transfer the clamping pressure from the machine to the mold Retainer Plate: The mold plate upon which, or within which, the mold cavities or cores and guide pins are mounted © Plastics Design Library 235 Runner: The distribution channels that carry the molten plastic from the mold entry to the cavities Shot or Shot Weight: The weight of everything that is removed from the mold each time the mold opens This includes all the parts, runners, and sprue Shrinkage: The difference between the size of a mold cavity and the size of the finished part divided by the size of the finished part Usually expressed as shrinkage in inches of change per inch of length, or in/in Sink Marks: A shallow depression on the surface of the molded part due to internal mold shrinkage Spherulites: Larger crystalline structures, which can be as large as 0.1 mm (0.004 in) Sprue or Sprue Bushing: The contact surface and tube that directs the molten plastic from the molding machine nozzle to the parting line or runner level of a mold Stereolithography: SLA is the process of defining a solid in a computer with a multitude of triangular elements in such a manner that an SLA “printing machine” can create a solid model from the computer model thus created Submarine Gate (Tunnel Gate): A type of gate where the opening from the runner into the cavity is displaced from the parting plane of the mold This type of gate is sheared as the mold is opened or as the part is ejected See Ch 5.2.2 Tab Gate: A small removable tab about the same thickness as the molded part but usually perpendicular to it for easy removal See Ch 5.2.6 Thermoplastic: A type of plastic that can be melted and recast into a different shape A thermoplastic always softens when heat is applied Thermoset: These plastics soften only once upon application of heat The continued application of heat causes them to react or cross-link, forming a rigid substance that will not soften upon application of heat, although if enough heat is applied the thermoset will decompose into ash or granules Vent: A shallow depression or opening cut in the cavity to allow air or gases to escape as the material fills the cavity Warpage: Twisting or distortion of the part Nearly always caused by differential shrinkage © Plastics Design Library Glossary References and Bibliography References (cited in text) Polyolefin Injection Molding: An Operating Manual, USI (supplier brochure) McCrum, N., Buckley, C., and Bucknall, C., Principles of Polymer Engineering, Oxford Science Publ (1988) Injection Molding Lids from Tenite Polyethylene, Eastman (supplier brochure) Zöllner, O., Process Variables as Production Cost Factors in the Injection Moulding of Thermoplastics, ATI 916e, Bayer Application Technology Information Standard Test Method of Measuring Shrinkage From Mold Dimensions of Molded Plastics, standard specification, designation D955-89, ASTM Malloy, R., Plastic Part Design for Injection Molding, Hanser Gardner Publ (1994) Techniques: Guidelines for Plastic Design, technical publication SR-408, Borg-Warner Chemicals Shi, L., and Gupta, M., Prediction of Sink Marks in Injection-Molded Plastic Parts Using a Localized Shrinkage Analysis Near a Rib, SPE (CD:Antec 98) Moulding Manual for DuPont Minlon and Zytel Resins, DuPont (web document, Moulding manual TRZ 30 - Part I) 10 Rosato, D., Di Mattia, D., Rosato, D., Designing With Plastics and Composites: A Handbook, Van Nostrand Reinhold, (1991) 11 Hostalen Polyethylene, Hoechst (supplier brochure) 12 Mulholland, B., Colored Engineering Resins for High Strain/Thin Walled Applications, SPE (CD: Antec 98) 13 Sensan Technical Note: Factors That Influence Dimensional Accuracy, Tolerances and Stability, Rapra Technology (CD: Rapra KBS v3) 14 Delrin Handbook: Ch - Dimensional Considerations, pp 31–35, DuPont (technical paper) 15 Zenite Product and Properties Guide, DuPont (web document) 16 Shay, R., Poslinski, A., and Fakhreddine, Y., Estimating Linear Shrinkage of Semicrystalline Resins from PVT Data, SPE (CD: Antec 98) 17 Delrin Molding Guide, DuPont, supplier brochure, 180176 (10-92) 18 Hostalen GUR UHMW Polymer Injection Molding Guide, Hoechst Celanese (supplier brochure) 19 Andreassen, E., Larsen, A., and Hinrichsen, E., Computer Modelling of Polymer Processing, Rapra Review Report no 55, Rapra Technology (1992) 20 Crastin PBT Moulding Manual, technical report TRC 30, DuPont (web document) 21 Wilkinson, R., Poppe, E., Leidig, K., and Schirmer, K., Engineering Polymers: the “Top Ten” Moulding Problems, Rapra Technology (CD: Rapra KBS v3) 22 Chang, R Y., Hsieh, Y C., and Hsu, C H., On the PVT and Thermal Shrinkage for the Injection Molding of a Plastic Lens, SPE (CD: Antec 98) 23 Polypropylene Technical Tips: Mold Shrinkage, Equistar Chemical (web document) 24 Whelan, A., and Goff, J., Injection Moulding of Thermoplastics: 1, Whelan and Goff (1988) 25 Xia, Z., and Mallick, P., Control of Dimensional Variability in Injection Molded Plastic Parts, SPE (CD: Antec 97) 26 Moulding Manual for Rynite PET Glass-Reinforced Thermoplastic Polyester, Moulding manual TRR 30, DuPont (web document) 27 Bearmont, J P., Revolutionizing Runner Designs in Hot and Cold Runner Molds, Proceedings, Antec, Tech Paper # 3680SPE (CD:Antec 2001); Beaumont Runner Technologies, Inc., 5091 Station Rd., Erie, PA 16563, www.meltflipper.com 28 Sensan Notes: Cooling Time in Injection Moulding, Rapra Technology (CD: Rapra KBS v3) 29 C-Mold Shrinkage and Warpage User’s Guide, C-Mold (software documentation) © Plastics Design Library References and Bibliography 238 30 Damle, M., Mehta, S., Malloy, R., and McCarthy, S., Effect of Fiber Orientation on the Mechanical Properties of an Injection Molded Part and a Stereolithography-Insert Molded Part, SPE (CD: Antec 98) 31 Rosato, D., Rosato’s Plastics Encyclopedia and Dictionary, Hanser Publishers (1993) 32 Patel, P., Effect of Processing Conditions on the Shrinkage and Crystallinity of Injection-Molded Parts, SPE (CD: Antec 97) 33 Delrin Moulding Manual, Moulding manual TRD 30 - Part I, DuPont (web document) 34 Hytrel Injection Moulding Guide, Technical bulletin TRH 30, DuPont (web document) 35 Design Information on Minlon - Zytel Resins, Module II, DuPont (web document) 36 Thermofil Reinforced Plastics Engineering Manual, Thermofil (supplier brochure) 37 Barrett, J., Reducing Costs and Adding Value: A Gas-Assist Molding Case Study, SPE (conference paper) 38 Grelle, P., Kallman, M., and Kerouac, K., Solid vs Gas vs Foam: Who Has the Best Ribs in Town? SPE (conference paper, originally presented at Structural Plastics 96) 39 Murphy, J., New Horizons in Plastics: A Handbook for Design Engineers, WEKA (1991) 40 Processing Fortron Polyphenylene Sulfide, Processing and Troubleshooting guide FN-6, Hoechst Celanese (technical paper) 41 Finapro Polypropylene for Injection Moulding, Fina Chemicals (supplier brochure) 42 Min, B H., A Study of Quality Monitoring of Injection Molded Parts, SPE (CD: Antec 98) 43 Lee, S C., Huh, Y J., Kim, C Y., and Kwon, O K., Unified Design Method of the Cavity for Injection Molded Spur Gears, SPE (CD: Antec 98) 44 Kleiss, R., and Kleiss, J., A Practical Guide for Molding Better Plastic Geared Transmissions, SPE (CD: Antec 98) 45 Bur, A., and Thomas, C., In-Situ Monitoring of Product Shrinkage During Injection Molding Using An Optical Sensor, SPE (CD: Antec 99) 46 McIlvaine, J., Effects Of Filler, Wall Thickness and Geometry on Shrinkage and Warpage of Engineering Plastics, SPE (conference paper, originally presented at Structural Plastics 96) 47 Progelhof, R., and Throne, J., Polymer Engineering Principles, Hanser Publishers (1993) 48 Warpage Design Principles, Moldflow Pty Ltd (software documentation) (1991) 49 Zenite Moulding Guide, Moulding guide TR ZE 30, DuPont (web document) 50 Novolen Polypropylene: Product Range, Properties, Processing, BASF (supplier brochure) 51 Injection Moulding Faults and Their Causes: Poor Dimensional Tolerances, Rapra Technology (CD: Rapra KBS v3) 52 Crastin PBT and Rynite PET: Design Information, Module IV, DuPont (web document) 53 Supplement to Standards and Practices of Plastic Molders, The Society of Plastics Industry (SPI) 54 Gipson, P., Grelle, P., and Salamon, B., The Effects of Process Conditions, Nominal Wall Thickness and Flow Length on the Shrinkage Characteristics of Injection Molded Polypropylene, SPE (CD: Antec 99) 55 Belofsky, H., Plastics: Product Design and Process Engineering, Hanser-Gardner (1995) 56 Guide to the faHold Package™, TMconcept®, AdvFEA-GuideFH011, Plastics & Computer (software documentation) 57 Injection Molding Tenite Cellulosic Plastics, Publ # PC-2a (11-73) ECP 2549, Eastman Chemical Products, Inc (supplier brochure) 58 Private conversation with Sam Miller, of GE, who collaborated on Ch of this book 59 Modern Plastics Encyclopedia, The McGraw-Hill Companies 60 Plastar Plastic Injection Molding Machine, Toyo Machinery and Metal Co., LTD (advertising brochure) 61 Advanced FEA Analyses to Model Filling, Holding, Cooling and Warpage, TMconcept®, AdvFEA-GuideFH011, Plastics & Computer (software documentation) 62 Injection Molding Polypropylene, Basell, basell.com/our products/brochures (web document) 63 Maier, C., and Calafut, T., Polypropylene: The Definitive User’s Guide and Databook, Plastics Design Library, William Andrew Inc., Norwich, NY (1998) References and Bibliography © Plastics Design Library 239 64 Computer-aided analysis progams: TMconcept ®, Plastics & Computer, Milan, Italy, www.plastics-computer.it; Cadmould®, Simcon Kunststofftechnische Software, Aachen, Germany, www.simcon-worldwide.com; REM3D®, Transvalor, Mougins, France, www.transvalor.com; Sigmasoft ®, Sigma Engineering, Aachen, Germany, www.sigmasoft.net; Moldex®, CoreTech, Hsin-Chu City, Taiwan, www.moldex.com.tw; Timon®, Toray Industries, Tokyo, Japan, wwwe.3dtimon.com; Planets®, Plamedia Corporation, Tokyo, Japan, www.plamedia.co.jp Bibliography Beall, G., Plastic Part Design for Economical Injection Molding, Glenn Beall Plastics Berins, M., Plastics Engineering Handbook of the SPI, Chapman and Hall, 5th Ed (1991) Brydson, J., Plastics Materials, Butterworth-Heinemann, th Ed (1995) Buckleitner, E., Dubois and Pribble’s Plastics Mold Engineering Handbook, Chapman and Hall, 5th Ed., (1995) Dominghaus, H., Plastics for Engineers, Hanser (1993) Ehrenstein, G., and Erhard, G., Designing with Plastics: A Report on the State of the Art, Hanser (1984) Hough, M., and Dolbey, R., The Plastics Compendium: Volume - Key Properties and Sources, Rapra Technology (1995) Kennedy, P., Flow Analysis of Injection Molds, Hanser (1995) Malloy, R., Why You Should Worry About Mold Shrinkage, Plastics World, pp 23–24 (Jan 1996) McRoskey, J., Co-Injection Molding: Current Applications, originally presented to the Plastics Product Design and Development Forum Noller, R., Understanding Tight-Tolerance Design, Plastics Design Forum, pp 61–73 (Mar./Apr 1990) White, J., Residual Stresses in Injection Mouldings - A Review, Rapra Technology General References Society of Plastics Engineers (SPE), CD: Antec 97; CD: Antec 98; CD: Antec 99 Rapra Technology, CD: Rapra Abstracts; CD: Rapra KBS v3 © Plastics Design Library References and Bibliography