Injection Mold Ejector System Design Standard

1. Injection mold ejector pin design standard

*No ejector pins smaller than .093" (3/32") diameter are to be used. 3/32" DIA. EJECTOR PINS MUST BE THE 2" SHOULDER TYPE.

*Use the largest size ejector pin possible.

*Ejector pins should be cleared to within 3/4" of molding surface.

*Ejector pins should be designed to "PUSH" the part, not "PULL" the part.

*Ejector pin "bosses" can be used only with customer approved with size and locations. Normally these "bosses" will cause part sink distortion, therefore use with caution.

*Ejector pins and pin plate must be like-numbered for ease of assembly.

*All contoured ejector pins must be keyed to prevent rotation by a pocket in a pin plate (refer to drawing S6-1). NO DOWELS WILL BE USED FOR KEYS.

*All ejector pins must be DME "EX" type or equivalent.

*There can be no ejection under a slider or lifter detail without written customer approval. If the customer accepts ejector under a slider or lifter detail, limit swithes must register both forward and back movement of ejector system. DME standard "Thin Swith" limit swithes are acceptable.

*National standard Ejector Blades and Ejector Blade shanks (two piece design) or equivalent are to be used. Other standard single piece Ejector Blade types can be used if necessary.

*Rectangular ejectors and bush bars can be used. In cases where the rectangular ejectors and bush bars contact the parting line, the return pins must be pre-loaded with a spring behind the head with a minimum of .100" preload (refer to drawing S6-2).

2. Injection mold guided ejector design standard

*Ejector plates must be guided with two ejector guide pins and ejector guide bushings minimum. For guide pins and guide bushings are considered standard, and normal pratice. The amount and size will be determined based on mold size and number of ejector plate activated actions.

*Guide pins will be DME Standard Guided Ejection Leader Pins (DME "PF" or "GL" type).

*Guide bushings will be DME Standard Bronze Plated Guided Ejection Bushing (DME "GEB" type).

3. Injection mold spring return design standard

*Spring return will only be designed  when specified by customers.

*Use DME standard medium duty (blue) mold and die springs or equivalent. Total spring compression should not exceed 35% of the free length. Spring pre-load should be designed to provide twice the weight of ejector bar/pin plate assembly if possible. 

*If external springs are used, provide spring cages securely installed on the pin plate with S.H.C.S. (refer to drawing S6-3).

*In case where the rectangular ejectors and bush bars contact parting line, the return pins must be pre-loaded with a spring behind the head with a minimum of .100" preload (refer to drawing S6-2).

4. Injection mold hydraulic ejector design standard

*The selection of cylinder bore size and cylinder mount type will be determined by mold size and amount of ejector plate activated actions. Aoxu normally uses "JJ" mount.

*"T" style coupling will be used to secure  the cylinder rod end to the back clamping plate.

*Hydraulic cylinders used to activate the ejector system will be plumbed into a common port for "push" and "pull" sequence. The mold rails or sub-plates can be used as a hydraulic manifold.

Posted by Shine