Variothermal process

The principle of the variotherm process (Figure 1.263) is based on the fact that the mold, at a high mold temperature (in the range of the melt temperature), is filled and the molded part is removed from the mold after cooling of the mold. 

A dynamic temperature control is a variothermal process control. Here, two independent temperature cycles with different temperatures (Figure 2.101) are used in the mold. 

Inductive heating is thus another possibility of temperature control in injection molds. It can always be considered for special requirements or when conventional options are not available or only in combination with significant increases in cycle time, such as in the variothermal process, which is frequently used for the manufacturing of micro components or microstructures. 

Microinjection Moiding for Microfiuidics Appiications, Fig. 6 Comparison of variotherm molding process and conventional molding process (Reprinting with permission) [17]... 

Development of auxiliary equipment and technologies to improve the microinjection molding process, such as variotherm mold heating systems, vacuum venting, alignment techniques, etc. 

To preserve the miao-feature as complete as possible, variotherm technique is often introduced into the molding process. With the technique, the mold surface with the micro-feature is allowed to be heated up to a tempaature higher than general recommended mold tempaature to keep the polymer from solidification in miao-features during injection. The extra benefit of the technology is that molders can heat up the mold surface efficiently and accurately to achieve the required temperature [3-6]. 

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