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NCK Technology Co.,Ltd

Process Of Injection Molding For Optical Product Components

In the process of injection molded optical components, the measurement of cavity pressure is limited because it cannot be labeled on its surface. But in order to use this important process parameter for quality control, a non-contact measurement method using a special measuring pin is used to measure the cavity pressure. The flow path is coupled to the Pvt diagram to develop new processing monitoring techniques.

This does not include the quality of high-end optical components, on the contrary, just at the highest level of quality to produce the actual application of optical components. As far as the prism is concerned, not only its geometrical shape and surface structure play an important role, Optical Products Component Injection Molding but also the repeatability of production can greatly affect the internal performance of products such as internal stress or molecular orientation. Therefore, in the case of the production process to assess the optical performance of the product, Optical Products Component Injection Molding only by checking the geometrical shape of the parts or to the naked eye to check the surface of the parts is not enough. The measurement of optical properties is more important.

For continuous production processes, such as injection molding, it is difficult to use the above method for optical testing. There is no doubt that the need to place sensitive test devices from the outside is a time-consuming process. And we need to wait a long time in this process until we get the test results. Optical Products Component Injection Molding This delays the entire production order, especially at the beginning. Generally speaking, the machine must stop working in the above time period. Considering the long production cycle and machine cost, it is unacceptable to produce waste products.

Machining variants for manufacturing optical components

During the injection molding process of optical product components, the molding process not only has an effect on its geometrical shape, but also has an important influence on the internal performance of the components. Research on the quality of components has shown that, for example, plastic injection molding-compression molding can only slightly increase the accuracy of the geometrical dimensions of the parts. However, Optical Products Component Injection Molding its optical properties can be improved by about 7 factors, so it is not enough to evaluate the optical properties of a component only by measuring geometrical parameters. Therefore, it is proved that injection molding-compression molding is a suitable method for the injection molding of optical product components. In the compression process, Optical Products Component Injection Molding the pressure phase is directly after the compressing phase. Pressure is applied to the surface of the component by a homogeneous distribution of pressure. As an example of the different variants associated with the conventional injection molding-compression molding, the injection-compression and expansion-compressive moulding is described below.

Conventional injection molding-compression moulding

Compared with the standard injection molding molding, the injection-compression molding allows the mold to flow/wall thickness ratio up to 500:1. It is important to have no conversion flow marks on the surface of the optical components. Therefore, each independent process and movement in a cycle must be continuously connected.

In the fill phase, the stencil opens only a little. Optical Products Component Injection Molding The gap size corresponds to the value of the compression stroke. After the plastic melt is injected into the mold, the compression process begins with a function of the screw position. Because the mold is open, Optical Products Component Injection Molding the internal pressure in the injection process decreases or even disappears completely. The compression phase begins with a position-adjustable screw. Before the mold cavity is fully filled, the plastic melt flows along the end of the flow path and is compressed by the subsequent compression phase, which also compensates for the shrinkage of the plastic.

Expansion-Compression Molding

The expansion-compression moulding using the Clamping unit is more suitable for the production of parts with constant wall thickness at cross-section. The advantage of the processing method is that the stress is not introduced into the production parts after the molding, because the pressure is not exerted by the screw, but by the locking mode. Thus, the pressure in the cavity is homogeneous, and the plastic melts can be cooled almost without stress, thus obtaining a homogeneous microstructure component.

As with the standard injection molding method, the plastic melt filling process of the method is also done in a closed mold. In the expansion phase, the mold may gradually reduce the clamping force through the screw is opened to a limited and accurate repeat position. The accuracy of the position control is a key factor that can produce a reproducible part of the output wall thickness. The compression process moves the compression core of the stencil to the compressed position.

When the position is reached (measured directly on the stencil), the compression process begins, and the fill process stops immediately. The compression and holding stages are composed of a multi-stage clamping force/compression force distribution.

Expansion compression molding and injection-compression molding can change the compression ratio by compressing the mold core rather than the clamping unit of the machine. However, Optical Products Component Injection Molding this only makes sense in cases where parts need to be partially compressed. Depending on the concept of the injection molded mechanical clamping unit, the compression process may be done only through the core. The complete hydraulic lever clamping module provides the most flexible choice for the user.

Process Control with three-dimensional problem field

In the process of injection molding of optical components, three-dimensional problem areas must be managed: the geometrical, surface and optical properties of the components must be included in the quality assessment of the required products. This requires precise process control, Optical Products Component Injection Molding which is to speculate on the melt state and the existing process within the known mold. These conjectures require knowledge of cavity pressure. Because the cavity pressure accurately reflects the filling, compression and holding stages during injection molding, this information can be helpful during process optimization and during processing and quality monitoring.

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