Designing with Celcon Acetal Copolymer

1 Designing with Celcon Acetal copolymerCE-10 Celcon Acetal copolymerTiconaA business of Celanese AGForewordThe Celcon Acetal Copolymer Design Manual (CE-10) is written for parts designers, materials engineers,mold designers and others wishing to take advantage of the unique and desirable features of this versatile line ofthermoplastic materials. This manual covers the basic structure and product characteristics of the broad classes of the Celcon acetalcopolymer product line and its physical, thermal, mechanical, and electrical properties. Dimensional stability, creepand other long term properties, and resistance to the environment (including chemical resistance) are alsodiscussed. An introduction to gear and bearing design is included. Mold design criteria, methods of assembly, andsecondary operations including machining, part bonding and surface decoration complete the the manual, the design information is presented primarily for product classes rather than forindividual grades, using a descriptive rather than a detailed mathematical treatment.

2 Some simple calculationexamples are included to illustrate a specific property (such as creep deflection) where appropriate. Ticona provides additional technical literature to compliment this brochure. Readers will find information ongeneral design principles of engineering thermoplastics in Designing with Plastics: The Fundamentals (TDM-1).Additional specific information on Celcon Acetal Copolymer can be found in Celcon Acetal Copolymer Short-termProperties Brochure (CE-4), Celcon Acetal Copolymer Processing and Troubleshooting Guide (CE-6) andCelcon Acetal Copolymer Ultraviolet Resistant Grades Extend Part Life in Harsh Environment (CE-UV).These brochures are available from our Internet site, , or can be requested through TechnicalInformation at and suggestions for improvement of this and other Ticona technical literature are always welcome, andshould be sent to us by phone at 1-800-833-4882, or by writing to us at the address shown on the back Acetal copolymer21 Overview2 Physical and ThermalProperties3 Mechanical Properties4 Dimensional Stability5 EnvironmentalResistance6 Electrical Properties7 Part Design Criteria8 Gear Design9 Bearing Design10 Mold Design11 Assembly12 Machining andSurface OperationsCelcon Acetal copolymer3 Introduction1.

3 Of Acetal Codes and Agency and Health Information132. Physical and Thermal of Linear Thermal Mechanical Test Term Mechanical and s Line Abrasion/Wear Temperature Stress-Strain Dynamic Mechanical Deflection Temperature Under Load (DTUL) Underwriters Laboratories (UL) Thermal24 Index Term Mechanical of Contents4. Dimensional of Linear Thermal Caused by Processing31(Injection Molding) Annealing is Absorption345. Environmental Use Permeability416. Electrical of of Thickness437. Part Design and and Radii478. Gear Gear Dimensions and of Metal and Plastic Gear Calculations for Celcon 57 Acetal Copolymer Spur Tooth Long-Short Addendum Fillets a Plastic Gear to a Types Application Quality Number65 Celcon Acetal copolymer41 Overview2 Physical and ThermalProperties3 Mechanical Properties4 Dimensional Stability5 EnvironmentalResistance6 Electrical Properties7 Part Design Criteria8 Gear Design9 Bearing Design10 Mold Design11 Assembly12 Machining andSurface OperationsCelcon Acetal copolymer59.

4 Bearing of Celcon Acetal Copolymer Acetal Copolymer Bearing Wear Factors Wall Design Tips7210. Mold Cavities and Surface - Standard Injection Machine Barrels and with Metal Metal Bonding8612. Machining and Surface General Threading and Blanking and Screw Rotary Power Barrel Deburring and Surface Hot Stamping and Colorability90 Celcon Acetal copolymer61 Overview2 Physical and ThermalProperties3 Mechanical Properties4 Dimensional Stability5 EnvironmentalResistance6 Electrical Properties7 Part Design Criteria8 Gear Design9 Bearing Design10 Mold Design11 Assembly12 Machining andSurface OperationsCelcon Acetal copolymer7 List of FiguresFigure Acetal Copolymer stress-strain properties (ISO 527)18 Figure Acetal Copolymer tensile strength range (ISO 527)18 Figure Acetal Copolymer flex modulus range (ISO 178)18 Figure Acetal Copolymer secant modulus range (ISO 527) 18 Figure plot for 25% glass-reinforced21grade of Celcon Acetal Copolymer (ISO 527)Figure plot for unfilled melt flow grade21of Celcon Acetal Copolymer (ISO 527)

5 Figure plot for toughened grade of Celcon 21acetal (ISO 527)Figure modulus-strain plot for 25% Glass-reinforced22grade of Celcon Acetal copolymerFigure modulus-strain plot for unfilled melt22flow grade of Celcon Acetal copolymerFigure modulus-strain plot for toughened grade22of Celcon Acetal copolymerFigure normalized Celcon Acetal Copolymer DMA plot23 Figure creep modulus plots for Celcon 25acetal Copolymer gradesFigure cross section26 Figure rupture, Celcon Acetal Copolymer unfilled 27melt flow gradeFigure recovery for Celcon Acetal copolymer27 Figure fatigue plot for Celcon Acetal copolymer29(ASTM D 671)Figure of molding conditions and wall thickness on32mold shrinkage for Celcon Acetal Copolymer M90 Figure due to heat aging for standard melt flow33grade of Celcon Acetal copolymerFigure absorption of unfilled Celcon Acetal copolymer34under various conditionsFigure change due to water absorption of34unfilled Celcon Acetal copolymerFigure strength at yield for Celcon Acetal copolymer38M90 after exposure to various fuels at 65 CFigure strength at yield for Celcon Acetal copolymer38TX90 Plus after exposure to various fuels at 65 CFigure strength at yield for Celcon Acetal copolymer39EC90 Plus after exposure to various fuels at 65 CFigure strength at break for Celcon Acetal copolymer39GC25TF after exposure to various fuels at 65 CFigure in linear dimensions at 23 C (73 F) and 3950% relative humidityFigure in tensile strength after exposure to 82 C water39and tested at 23 C (73 F)

6 And 50% relative humidityFigure in tensile modulus after hot water exposure40at 82 C and 100 CFigure in tensile strength after boiling water exposure40at 100 CFigure in notched Izod impact after hot water40exposure at 82 CFigure in melt flow rate after hot water exposure at 82 C40 Celcon Acetal copolymer8 List of Figures (continued)Figure weathering resistance for Celcon 41acetal Copolymer (black)Figure weathering resistance for Celcon acetal42copolymer (colored grades)Figure strength of unfilled Celcon Acetal Copolymer 44vs. thickness @23 CFigure constant of unfilled Celcon Acetal copolymer44vs. frequency @23 CFigure factor of unfilled Celcon Acetal Copolymer 44vs. frequency @ 23 CFigure of uniform and non-uniform (poor)45wall thicknessFigure rib proportions46 Figure and good rib design46 Figure draft angle for bosses47 Figure of ribs with bosses47 Figure (left) and good (right) bosses47 Figure ejector system for bosses47 Figure curve generation51 Figure gear nomenclature51 Figure bearing characteristics for grades of Celcon57acetal vs.

7 Load cyclesFigure center distance measuring device58 Figure chart of measuring device radial displacements58 Figure in a gear pair59 Figure relief61 Figure typical gear types and arrangements63 Figure coefficient of friction vs. speed67 Figure coefficient of friction vs. pressure67 Figure values for unlubricated grades of Celcon Acetal Copolymer 69 Figure wear of unlubricated Celcon Acetal copolymer70journal bearingFigure bearing clearances71 Figure for interference fit bearings71 Figure basic gate designs suitable for Celcon Acetal Copolymer 76 Figure leg snap-fit79 Figure snap-fit79 Figure and socket snap-fit80 Figure fits80 Figure plastic internal and external threads81 Figure press-fit designs for a metal pin in a81plastic hubFigure ultrasonic welding equipment82 Figure design for ultrasonic welding83 Figure staking, swaging and spot welding84 Figure assembly, stress problems and solutions84 Figure type threaded inserts85 Figure Push-on style fasteners86 Figure lathe tool bits for turning Celcon Acetal copolymer88 Celcon Acetal copolymer91 Overview2 Physical and ThermalProperties3 Mechanical Properties4 Dimensional Stability5 EnvironmentalResistance6 Electrical Properties7 Part Design Criteria8 Gear Design9 Bearing Design10 Mold Design11 Assembly12 Machining andSurface OperationsList of TablesTable listings12 Table and physical properties of Celcon acetal15copolymer gradesTable and burning rate of Celcon Acetal copolymer16 Table typical properties comparison17 Table stress-modulus values per ISO 7524test methodTable DTUL table for Celcon Acetal Copolymer per24 ISO 75 test methodTable of UL relative thermal index ratings for25 Celcon Acetal copolymerTable creep (flexural) modulus values for grades of26 Celcon Acetal copolymerTable of linear thermal expansion (CLTE)

8 For31various grades of Celcon Acetal Copolymer , 23-80 CTable of processing conditions on part shrinkage33 Table before and after annealing different34part thicknessesTable resistance of Celcon Acetal Copolymer 36standard unfilled gradesTable fuels composition38 Table Acetal Copolymer grades for weathering resistance 41 Table permeability of Celcon M25, M90 and M270 41 Table properties of Celcon Acetal Copolymer 43(at 23 C and 50% relative humidity)Table tooth nomenclature and definitions52 Table symbol terminology54 Table gear dimensions54 Table used in defining single spur gear geometry55 Table factors for terms used in defining single55gear geometryTable relationships between a spur gear 55and pinionTable of load characteristic c57 Table quality number ranges for gear applications59 Table values of addendum for balanced strength60 Table coefficient of friction for unlubricated67standard Celcon Acetal Copolymer against other materialsTable ranges for Celcon Acetal Copolymer systems69 Table size recommendations for Celcon acetal75copolymerTable gate dimensions for rectangular75edge gates, mm (in.)

9 Table guidelines for shear joints with84 Celcon Acetal copolymerTable and stripping torques of self-tapping85screws in Celcon M90 Acetal copolymerCelcon Acetal copolymer10 List of Tables (continued)Table of push-on style fasteners using86 Celcon Acetal Copolymer M90 studsTable bonding of Celcon Acetal Copolymer to itself86and other substratesTable drilling speeds for Celcon acetal87copolymerCelcon Acetal copolymer1111. Chemistry of Acetal Polymers Acetal polymers are chemically known aspolyoxymethylenes (POM). Two types of acetalpolymers are commercially available: Homopolymer is prepared by polymerizinganhydrous formaldehyde to form a polymer composed of oxymethylene repeating units (-CH2O). Acetal homopolymer products havesomewhat better short-term mechanical properties than Copolymer . Copolymers, including Celcon Acetal Copolymer ,are prepared by copolymerizing trioxane (cyclictrimer of formaldehyde) with a cyclic ether (usually containing an ethoxy group) to form apolymeric chain composed of oxymethylene (-CH2O) and oxyethylene (-CH2-CH2-O-)repeating units.

10 Copolymers have a wider pro-cessing window than homopolymers, and areinherently more stable and resistant to thermaldegradation during service life. This is because the repeating Copolymer units block polymer unzipping under thermal the homopolymer and Copolymer are end-capped, and also contain specific additives to preventirreversible thermal depolymerization of the polymerbackbone during General Characteristics Celcon Acetal Copolymer is a high strength, crystallineengineering thermoplastic material having a desirablebalance of excellent properties and easy Acetal Copolymer is a candidate to replacemetals and thermosets because of its predictable long-term performance over a wide range of in-servicetemperatures and harsh environments. Celcon acetalcopolymer retains properties such as creep resistance,fatigue endurance, wear resistance and solventresistance under demanding service Acetal Copolymer can be converted easilyfrom pellet form into parts of different shapes using avariety of processes such as injection molding, blowmolding, extrusion, rotational casting andcompression molding.