Mold Design for Electric Injection Molding Machines

Electric injection molding machines are coming into wide use in the case of injection molding machines with mold clamping forces of 1800t or less. In order to bring out to the maximum extent the excellent features possessed by fully electric injection molding machines, it is very important to carry out mold design giving attention to the following factors.

(1) Accurate positioning

In a fully electric driven injection molding machine, although it is possible to carry out at high speeds the opening and closing of molds, in order to prevent breakage or abnormal wear at the time of contact between core pins while carrying out accurate positioning of the cavities on the movable side and on the fixed side, it is recommended to install precision positioning guides.
The recommended Misumi standard components are:

	-	Tapered tweezers TPN, etc.
	-	Tapered block sets TBS, etc.
	-	Side straight block set TSSB, etc.

(2) Smooth operation of the ejector plate

In a fully electric motor driven injection molding machine, although it is possible to carry out operations of ejector plates such as high speed operation and multiple stage ejection, if the construction is not designed so that the operation of the ejector plate is smooth, biting of the ejector pin or biting of the return pin are likely to occur.
Therefore, it is recommended to use an ejector guide system.
The following Misumi standard components are being used widely:

	-	Precision ejector guide pin EGH, etc.
	-	Ejector guide bush EGBH (Plain type) 　　　　　　　　　　　　EGBZS (Copper alloy non-lubricated type) 　　　　　　　　　　　　EGBL (Linear type) 　　　　　　　　　　　　EMBS (Ball slider), etc.

Further, it is recommended to install a switch for confirming the returning of the ejector plate.
For this purpose, the following are recommended:

	-	V-156-1A5-T (Micro switch)
	-	MGXL-8F (Contactless type)

(3) Smooth operation of the slide core

Smooth operation of the slide core is also important. In order to prevent biting, it is recommended to provide a lubricating groove in the guide rail, or to use a non-lubricating type material (oil free metal).
The following Misumi standard components are recommended:

	-	GR5SCM (Guide rail with groove)
	-	SRTL (Non-lubricating guide rail)
	-	CGZ (Non-lubricating center rail)
	-	STW (Non-lubricating slide plate).

(4) Stabilization of the cavity surface temperature

In order to stabilize the molding conditions, it is very important to stabilize the mold cavity surface temperature. In order to achieve this, it is recommended to use the following standard components:

	-	HIP (Thermal insulation plate), etc.
	-	M-HTM3021 (For cartridge heaters)
	-	Mold temperature controller: PID control type