Injection molding is use to prepare the materials like plastics or rubbers particles.
Here injecting of plastics articles into mold with high Temperature.
- Mold closes :As the screw begins to forward for injecting.
- Cavity fills: Screw moves forwards.
- Cavity is packed :As the screw moves continuously forward.
- Cavity,s cools : AS to screw begins to retract.
- Mold open’s : for ejection.
- Mold closes : Next cycle begins.
- Feed section : Transports material from hopper to heated portion of barrel.
- Compression section : Plastic granules are compressed to Homogeneous melts.
- Metering section :The final mix and heating of material into homogeneous melt carried out in metering section.
Parts of mold:
Two cavity injection mold:
- CAVITY INSERTS : External form of component is made on the cavity
- CORE INSERT : Internal form of component made on the core.
- GUIDE BUSH AND PILLAR:Used for Align two halves and guide pillar are fitted on cavity plate.
- Guide bush are fitted on the core plate.
- Used as a 4 sets in a mold.
- CAVITY PLATE : Stationary part of mold .
- Holds cavity inserts guide pillar and Sprue bush.
- CORE PLATE :
- Part of movable part of mold.
- Holds core insert,Guide bush and supports ejector pins sprue puller and return pins.
- SPRUE BUSH :
- Transports the material form machine nozzle to cavity through runner and Gate.
- Has a tapered conical shaped hole.
- REGISTER RING:
- Fitted on the top plate and its purpose is to align machine nozzle and spur bush.
- TOP PLATE :
- Plate holds all stationary parts of mold to the fixed pattern of machine.
- It holds directly or In directly cavity plate,Register ring,Guide pillar and Cavity insert.
- BOTTOM PLATE :
- It holds a movable parts of mold to the movable patten of the machine.
- Holds directly or in directly all the movable part of the mold.
- SUPPORT PLATE :
- Mounted behind the core plate to keep this plate from bending under high pressure during injection.
- SUPPORT BLOCK:
- Sandwiched between support plate and bottom plate to form a space.
- Which allows ejection system to function for the ejection of molded.
Few more parts of mold:
- EJECTOR RETAINER PLATE :
- Holds the return pins,ejector pins and Sprue puller.
- Clamped together with ejector back plate to form a unit.
- EJECTOR BACK PLATE:
- Clamped together with ejector retainer plate to form a unit.
- To act as a backup plate for the pins mounted in ejector retainer plate.
- EJECTOR ROD :
- Mounted with Threads on the ejector back plate and is guided in ejector rod bush.
- Trans’mitts the knockout of the ejector assembly to function.
- ROD BUSH :
- Mounted on bottom plate and act’s guide to ejector rod.
- PUSH BACK PINS :
- Push the ejector assembly to its rear position as the mold is closed.
- mold used in injection molding.
- Machine having Hydraulic actuating system do no require this.
- SPRUE PULLER :
- When the molds open its positively pulls the sprue from sprue bush.
- Common pulling method is an a undercut recess situated directly opposite to bush.