Insert Molding Presented by Joshua Bush Michael Goetz

Insert Molding Presented by: Joshua Bush Michael Goetz Michel Mc. Cluskey

Introduction ® Inserts Provide: ® Anchorage / Reinforcement ® Bearing Surfaces / Shafts ® Internal / External Threaded Sections ® Thermal or Electrical Conductivity ® Positioning ® Nameplates / Lettering ® Hinging

Background and Theory ® An insert is an integral part of a plastic molding consisting of metal or other material which may be molded into position or may be pressed into the part after it is molded

Basic Operation ® Types ® Two of Inserts general types: Molded-In inserts ® Post Molded inserts ®

Basic Operation (cont. ) ® Molded-In ® Typically Inserts for internal threads / studs ® Metal Inserts ® Usually Undercut or knurled so they stay in the part

Basic Operation (cont. ) ® Post Molded Inserts ® Uses Molded-in Hole ® Press Fit / Ultrasonically Fit / Self- Tapping ® Used for Internal Threads usually

Basic Operation (cont. ) ® Other Types of Inserts ® Blind-Hole Inserts ® Through-Hole Threaded Inserts ® Protruding Thread Inserts ® Shoulder-Type Inserts

Basic Operation (cont. ) ® Other Types of Inserts (cont. ) ® Pressed-in Inserts ® Expansion Inserts ® Self-Tapping Screws ® Flat-type

Equipment ® Injection molding machine ® Hand/Pneumatic press (for post molded inserts) ® Specialized Molds ® Pockets to place the insert ® Magnetic Insert Holders ® Robots / other mechanical ways of putting inserts into molds.

Advantages ® Provide metal threading in a plastic part ® Provide for bearing surfaces ® Good for anchoring parts in an assembly ® Electrical Contacts in a plastic part

Disadvantages ® Floating ® Crushing ® Flow of Material Into an Open Hole Through The Inserts ® Flow of Material Into Blind-hole Inserts ® Protruding Inserts

Plastic Part Design Standards ® Dimensions/Tolerances: Thread dimensions critical. ® Exterior Dimensions/Knurling not as Critical. ® Tolerances: ® l l l Length +/- 0. 010 in. Diameters +/- 0. 002 in. Angular +/- 1 degree max.

Minimum Wall Thickness Around Inserts ® Dependant Upon Shrinkage of Plastic ® Coefficient of Expansion (plastic and inserts) ® Temperature Range of Inserts ® Moisture Sensitivity of Plastic Resin ® Design of Insert ®

Minimum Wall Thickness Around Inserts (cont. ) ® Try To Keep Wall Thickness Around Inserts Nominal ® Put Inserts in Bosses or Gussets

Mold Design Suggestions ® Ejectors on the Inserts ® Post Inside the Mold to Hold Inserts ® Magnetic Insert Holders

Selection of Metal For Inserts ® Refer to Data Sheets from Material Supplier ® Essential Due To Coefficient of Expansion ® Must Be The Same

Materials Used For Inserts ® Aluminum ® Brass ® Copper ® Carbon Steel ® Alloy Steel ® Stainless Steel ® Silver and Other Precious Metals

Insert Illustrations

Conclusions ® Through the use of inserts, a plastic part can be used in applications where once only metal could be used. Good thread, pin, and bushing properties can now be obtained in plastic parts through the use of inserts.

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