Plastic Molding Machinery Primer
Molding Machinery—Plastics Processing Machinery Includes
- Blow Molding Machinery
- Extrusion Molding Machinery
- Horizontal Injection Machinery
- Vertical Injection Machinery
Molding Machinery—How a Plastic Injection Molding Machine Works
- Resin is vacuum fed from the hopper into the injection barrel. Dryers are used to eliminate any excess moisture in the materials.
- Plastic resin is moved forward toward the barrel. Hydraulic power pushes the materials forward.
- Drag flow is the process when resin melts as it’s heated through he chamber on its way to the nozzle.
Plastic Processing Machinery —3 Main Types of Blow Molding Machinery
- Extrusion blow molding machinery
- Injection blow molding machinery
- Stretch blow molding machinery
Plastic Processing Machinery—Blow Molding Machinery Process
- Melting the materials is the first step in the process.
- A parison or hollow tube is then formed.
- The parison is clamped into a mold.
- Air is pumped into the mold.
- Air pressure moves the plastic forward to match the mold.
- After the cooling process, the plastic hardens and the mold opens.
- The process ends when the component is ejected.
— There are 5 elements of Extruder Machines and 3 Types of Extruders
- Spherical barrel
- Heated Electrically
- Turing screw
- Barrel with Internal Ram
Extrusion Molding Machinery—3 types of Extruders
- Single Screw
- Multiple Screw or Twin Screw
Plastic Processing Machinery —What do Injection Molds Produce?
Injection molds are used for creating surgical tools, hearing aids, orthodontics, corrective eye surgery, and high-end electrical devices.
How do they make them?
Raw material is pulled by the extrusion machine into guides that create typical components. A hopper is at one end of the molding machinery where the resin is fed to the ram. The resin is pushed toward the other end where the die that will shape the resin.
Molding Machinery—Injection Molding Machines Utilize 3 Methods of Operation
- Manual Operation—Manual Operation or Manual mode is controlled by the operator. The operator controls each separate function when utilizing manual mode. During maintenance and when opening and closing the mold, for resin adjustments, and during startup and shutdown is when this when the manual method is used.
- Semi-automatic Operation—Semi-automatic mode is used when components are needed to be removed during startup or troubleshooting. The semi-automatic process comes to a stop after one cycle and the operator then starts a new cycle.
- Automatic Operation—This operation is used when minimal participation from an operator is needed. Used instead are robotics. The ejection of the molds happen automatically while components are continuously molded.
Molding Machinery—Blow Molding Machinery
- The most common type of extruder head and die assemblies is the Crosshead. The Crosshead type redirects resin flow from horizontal rotation to 90 degrees vertical orientation.
Plastic Processing Machinery—2 Primary Types of Die Tooling
- Converging—Converging is when the die tooling flares inward.
- Diverging—Diverging is when the die tooling flows outward.