Micro injection molding process

We will present the micro injection unit for low-cost standard pallets. For this type of micro injection molding we recommend using a machine with size 35 or size 45 injection units. In this plastic injection molding process the plasticizing barrel can be changed in less than 15 minutes in order to obtain a total conversion of the machine. Very important when handling low shot weights is the short injection stroke. In most of the cases it is required to have a very precise short injection with high resolution and rapid response to control the injection. Also there is the need to hold the pressure.

There are mainly two systems offered on the market at this moment. The 1st one is made from a hydraulic molding machine that features a highly dynamic smart pump with pressure and flow control. The 2nd system you could have is an electric machine that is equipped with high-torque direct drive.

Like in the case of injection molding equipment (machines) it is required that the injection mould to meet the special requirements of micro parts. That's why the standard fabrication level must be very high. In addition to having an establish injection molding machine process like micro grinding, micro-milling and micro drilling and boring there are new procedures required in order to obtain the best geometric details.

The most common methods are micro-EDM, electro discharge machining and the LIGA process that is also known as the laser machining. The usual drilled holes on the molding can sometime only be produced as blind holes. That is the main reason why mould venting becomes very important. That applies especially if you are handling cases of cold runner moulds. In this case it is necessary to allow a relative large amount of air to escape.

There is a protection of small vulnerable moulds for micro parts that need special attention. Also active and sensitive would protection is an absolute necessity. A sensor detects the force required for the champing motion and compares it with a stored master curve. If any deviations exist, the closing operation is actively broken by the drive of the clamping unit. Mould protection can be armed over the full closing movement. This will not affect the speed setting.

In injection molding, if deficient venting is filling the mold there is the change for this action to cause compression and heating of the air inside. This could cause blemishes and charring on part. It means that venting of the cavity of an injection mold of the flow path requires special attention in the case of micro parts. It is required for a remedy process of a stepped clamping force build-up and the option of evacuating the mold with the help of a vacuum pump.

In this case both of the functions are provided and supported by the control system of different machines. It is required to have a better replicate filigree surface detail in the injection mold design. This can e achieved with the use of cooling phase when the hold pressure phase is on. At this point the temperature control media is changed from hot to cold and it happens only after injection. This is a feature that is also incorporate in the control system.

There are numerous injection molding services offered by this technology. It is mainly up to the customer to decide the concept in which he wants to combine the standard machine with the injection molding process.

Also, like the conventional injection molding, there are multicavity molds that offer economical and technical advantages in micro-injection molding.
Also besides the standard injection molding at the micro scale we have discussed until now, the interest in special processes has increased greatly in the last years. Most micro parts can be provided for instance, with a sealing function by injecting flexible component.