Mold Design: Pin Gate Frustration
The part that caught my attention this month represents two problems that have plagued molders for as long as I have been in plastics: poorly designed pin gates and an unbalanced runner system.
A Poor Flow Path for Crystalline and Amorphous Plastic Materials
A review of design requirements for crystalline and amorphous plastic materials sets the stage for healing a troubled hot runner part.
Mold Part Design: FREE STANDING BOSS WITH TWO GUSSETS
Bosses are used in parts that will be assembled. Connect the boss to a wall or rib with a connecting rib as shown in Figure 1. If the distance of the boss from the wall makes a connecting rib impractical, design the boss with gussets as shown in Figure 2.
Molding Part Design: Free Standing Boss With Four Gussets
Bosses are used in parts that will be assembled. Connect the boss to a wall or rib with a connecting rib as shown in Figure 1. If the distance of the boss from the wall makes a connecting rib impractical, design the boss with gussets as shown in Figure 2.
Injeciton Molding Guidelines: Support Ribs
Sometimes we use support ribs when design a plastic part.
Ribs should follow the proportional thickness guidelines shown below. If the rib is too thick in relation to the part wall, you may experience sinks, voids, warpage, weld lines, and longer cycle times. Position ribs in the line of flow to improve filling and prevent air entrapment.
Injection Molding Guidelines: Boss or Rib
A reinforced or protrusion on a mold part for strength or alignment during assembly or fastening.
Ribs should follow the proportional thickness guidelines shown below. If the rib is too thick in relation to the part wall, you may experience sinks, voids, warpage, weld lines, and longer cycle times. Position ribs in the line of flow to improve filling and prevent air entrapment.
Injection Molding Guidelines: Rib Details
Ribs should follow the proportional thickness guidelines shown below. If the rib is too thick in relation to the part wall, you may experience sinks, voids, warpage, weld lines, and longer cycle times. Position ribs in the line of flow to improve filling and prevent air entrapment.
Plastic Injection Mold Design: Adjoining Walls
The connection point between two molded surfaces are called adjoining walls
Injection Molding Guidelines: Thick to thin Wall Gating
Avoid sudden changes in wall thickness by using transition zones to eliminate stress concentrations and reduce sinks, voids, and warping in the molded part.
Plastic Injection Mold Gate Design: Internal Ring Gate
Internal Ring Gate is a system used with large circular parts when concntriciy and smooth outer surface are required. Can only be used with single-cavity molds.
The gate serves as the entrance to the cavity and should be designed to permit the mold to fill easily. A cavity can have more than one gate. Gates should be small enough to ensure easy separation of the runner and the part but large enough to prevent early freeze-off of polymer flow, which can adversely affect the consistency of part dimensions.