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Designing With Plastic
The Fundamentals
TDM-1

Designing With Plastic
The Fundamentals

Designing With Plastic
The Fundamentals

Table of Contents
Introduction 1. 1.1 1.1.1 1.1.2 1.1.3 1.1.4 1.1.5 1.1.6 1.1.7 2. 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 Plastics Materials – An Overview Classification Thermoplastics Thermosets Crystalline, Amorphous,and Liquid Crystalline Polymers Copolymers Alloys Elastomers Additives, Reinforcements, and Fillers Physical Properties and Terminology Density Specific Gravity Water Absorption Mold Shrinkage Opacity/Transparency Elasticity Plasticity Ductility Toughness Brittleness Notch Sensitivity Lubricity Homogeneity Heterogeneity Isotropy Anistropy Significance of Elasticity, Homogeneity, and IsotropyMechanical Properties Basic Definitions Stress Normal Stress Normal Strain Modulus of Elasticity Proportional Limit Yield Point Ultimate Strength Elastic Limit Secant Modulus Yield Strength Poisson’s Ratio 10 11 12 12 13 13 14 14 14 14 15 15 15 15 15 16 16 16 16 16 17 17 17 17 17 17 17 18

3. 3.1 3.1.1 3.1.2 3.1.3 3.1.4 3.1.4.1 3.1.4.2 3.1.4.3 3.1.4.4 3.1.4.5 3.1.4.6 3.1.5

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Designing With Plastic
The Fundamentals

3.1.6 3.1.7 3.2 3.2.1 3.2.2 3.3 3.3.1 3.3.2 3.4 3.5 3.5.1 3.5.2 3.5.3 3.5.4 3.5.5 3.5.6 3.5.7 3.5.8 3.5.9 3.5.10 3.5.11 4. 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10 4.10.1 4.10.2 4.10.3 4.10.4 5. 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8

Shear Stress Shear Modulus Relating Material Constants Direct Shear True Stress Other Measures ofStrength and Modulus Compression Strength and Modulus Bending Strength and Modulus Rate Dependence of Mechanical Properties Time-Related Mechanical Properties Creep Apparent or Creep Modulus Creep Rupture Stress Relaxation Extrapolating Creep and Relaxation Data Impact Loading Izod Impact Charpy Impact Tensile Impact Falling Dart Impact Test Fatigue Endurance Thermal Properties Melting Point GlassTransition Temperature Vicat Softening Point Deflection Temperature Under Load Coefficient of Linear Thermal Expansion Thermal Conductivity Aging at Elevated Temperatures Temperature Index (UL) Flammability Effect of Temperature on Mechanical Properties Strength, Modulus, and Elongation Creep Impact Fatigue Electrical Properties Conductivity in Solids Volume Resistivity Surface Resistivity DielectricStrength Dielectric Constant (Permittivity) Dissipation Factor Arc Resistance Comparative Tracking Index (CTI)

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Plastics Materials – An Overview

1

Physical Properties and Terminology

2

Mechanical Properties

3

Thermal Properties

4Electrical Properties

5

Environmental Considerations

6

Structural Analysis

7

Design Considerations for Injection-Molded Parts

8

Assembly

9

Machining, Finishing And Decorating

10

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Designing With Plastic
The Fundamentals

6. 6.1 6.1.1 6.1.2 6.1.3 6.2 6.2.1 6.2.2 6.2.3 6.2.4 6.3 7. 7.1 7.2 7.2.1 7.2.1.1 7.2.1.2 7.2.2 7.2.2.1 7.2.2.2 7.2.2.3 7.2.2.4 7.2.2.5 7.2.37.3 7.3.1 7.3.2 7.3.3 7.3.4 7.4 7.5 7.6 7.7 7.8 7.9 8.

Environmental Considerations Factors Affecting Environmental Resistance Stress Level Temperature Exposure Chemical Compatibility Reaction Solvation Plasticization Environmental Stress Cracking Weathering Resistance Structural Analysis Introduction Defining the Structure Loads Directly Applied Loads Strain-Induced Loads Support ConditionsFree (Unsupported) Guided Simply Supported Held (Pinned) Fixed (also Clamped or Built-In) Simplifications and Assumptions Safety Factors Failure Criteria Beam Bending Stress Shear Stress, Torsion Shear Stress, Direct Shear Pressure Vessels Press-Fits Thread Strength Pipe Threads Impact Loads Thermal Stress Design Considerations for Injection-Molded Parts Injection Molding Process Design Strategy...