Injection Molding Process Training 

(NOTE:  The generic outlines found on this website are provided solely as examples of what a particular individual course might offer.  Remember, we will work with your company to custom design each course to fit your particular situation.)

I.  Understanding the Injection Molding Process

Clamping Unit

          Types of Clamping Units (focus on differences that affect the process)

          Function of Parts and Understanding Clamp Operation

          Contrast differences between Hydraulic vs Toggle

(include All-Electric and Hydro-Mechanical systems)

          Ejectors (also discuss cores, slides etc.)

          Controls (both general controls and specific controllers)

          Setting Clamp Action, Tonnage, Core Pulls/Sets

Injection Unit

         Primary Screw Zone Functions (including non-return valve)

Barrel Temperature Settings with respect to the Screw Zones (includes feed throat, oil, and nozzle temps)

         Screw Retraction – Parameters and their Functions and Interrelationships

                    Backpressure

                    Screw Speed

                    Decompression(s)

                    Plastication Delay

Ram Forward (Injection) - Parameters and their Functions and Interrelationships

                    Relationship between Pressure and Velocity

                    Pressure Drops and the need for the Intensification Ratio

                    Fill/Boost Phase including transfer; Packing/Holding Phases

                    Velocity Profiling

                    Methods of Transfer

          Sprue Break - Parameters and Functions

          Controls (both general controls and specific controllers)

Tooling

          Major Mold Components and Parts and their Functions

          Mold Types and Options

                        2-plate and 3-plate Molds

                        Hydraulic Ejection (includes Side-Mounted Cylinders)

                        Slides/Horn Pins/Heel Blocks

                        Hot-Runner  Manifold and Hot-Tip Drop (also Start-Up Considerations)

            Part Cooling (Mold Temperature)

                        Amorphous vs Semi-crystalline

                        Differential Cooling

            Cooling Medium

                        Laminar vs Turbulent Flow

            Part Removal

                        Ejection

                        Core Sequencing

 

Calculations:  Appropriate Clamp Tonnage, Intensification Ratio, Maximum Screw Speed, Reynold’s Number for Turbulent Flow, Velocity Profiling

 

The Three Modes of Press Operation (including Mold Safety)

Timers and Time Monitors 

A Step-By-Step Method of Molding Machine Set-up (Goal Setting)

            Fill/Pack/Hold (3-stage) Machines

            Meaning of terms such as “Couple/Decouple” et al

            Determining the correct Velocity Profiles and Transfer location

Safety Considerations

          Clothing, Tool Use, Machine Safety Interlocks, Forklift/Hoist Safety Issues

II. Advanced Injection Molding

Rheology – Flow Behavior

          Temperature and Viscosity Dependence

          Non-Newtonian Flow Behavior

          Flow Rate and Viscosity Dependence

          Fountain Flow (at flow front)

          Plug Flow (in channel flow)

Molecular Orientation

          Flow Rate relationship to Orientation Development

          Temperature/Pressure relationship to Orientation Retention

          Skin Formation and Effects on Orientation

          Compression and Tension within a Molded Part

          Effects on Shrinkage

Injection Control Systems (Only Very Brief Descriptions)

          Sensors (transducers) – for temperature, pressure, position, rotation

  Basic Hydraulic Components: Direct-Acting Relief Valve, Pilot-Operated

Pressure Relief Valve, Simple Needle Valve, Pressure Compensated Flow

Control Valve, Servo-Control Valves, Proportional Valves (flow dividers)

          Recording Devices

          Process Monitoring and Process Controlling

          Open Loop vs Closed-Loop

          Basic Control Loops

          PID control

          Utilizing Cavity Pressure to Optimize, Trouble-shoot, Cycle Set-up

          Evaluating Hydraulic/Cavity Pressure Profile, Screw Position Curves

III.  Material Moisture Sensitivity and Basic Processing Characteristics

Amorphous vs Semi-Crystalline

Moisture Sensitivity (Hygroscopic)

Hydrolysis Effects (Material Degradation)

Moisture Measurements

Control of Moisture in Material

Identifying Hygroscopic Materials and Plastics that undergo Hydrolysis

Proper Storage and Drying of Hygroscopic Materials

Individual Material  Processing Characteristics (Flow Behavior, Material Specific

 Processing Procedures and Processing/Material Safety)

Processing Effects of Fillers/Reinforcements

IV.  A Logical Approach to Trouble-Shooting

Trouble-Shooting:    Sticking Sprues

                              Part Sticking

                              Drooling

                              Stringing

                              Short Shots

                              Flashing

                              Delamination/Lamination

                              Splay (Silver Streaking)

                              Flow Lines (Weld Lines)

                              Sink Marks

                              Bubbles and Voids

                              Warping

                              Gate Blush (Sun-burst, Shadowing, Orange Peel, etc)

                              Black Spots (Compression Burns)

                              Black or Brown Streaks

                              Contamination (Black Specks, etc)

                              Gloss

                              “J”-Hooks

                              Color Streaks

                              Ejector Marks

                              Stress Cracks (Micro-fracturing)

                              Record Grooves

V.  Laboratory Activities

Production Floor Activity

          Introduction to the Controllers

                    Manual Controls

                    Keypad/Screen or Console/Layout

                    Making Changes

Production Floor Activity

           Searches (supports the concept of machine generalization):

                Find important machine specifications

                Locate clamp/ejector/injection/plastication machine operating parameters

Production Floor Activity

          Obtaining the Correct Set-up of an Injection Molding Machine Processing Cycle

          (All four types of controllers)

Production Floor Activity

          Creating and Solving Specific Molding Problems 

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