injectionblow

Injectionblow, more commonly written as injection blow molding or IBM, is a plastic forming process used to manufacture hollow, bottle-like parts. The process combines elements of injection molding and blow molding to achieve precise preforms and uniform final shapes, especially for small to medium-sized containers with consistent wall thickness and clear finishes.

In the typical IBM or ISBM setup, a molten polymer is first injected into a hollow preform mold with the required neck finish. The preform is cooled, ejected, and then transferred to a second station or machine where it is reheated and inflated inside a blow mold by pressurized air, forming the final bottle or container. In the classic IBM variant, the blow step occurs in an integrated line; in two-stage ISBM, the preforms are produced in separate injection molds and later moved to dedicated blow molds. A stretching rod may be used in PET applications to improve height and strength.

Materials commonly used include PET, HDPE, and PP, with PET being especially prevalent for transparent bottles. The process yields high dimensional accuracy, good surface finish, and efficient material usage, making it popular for beverages, cosmetics, pharmaceuticals, and household products. Limitations include higher equipment costs, longer cycle times for larger containers, and less flexibility compared with single-stage blow molding for simple shapes.

Overall, injection blow molding provides a favorable balance of precision and efficiency for constrained sizes and requirements, bridging the capabilities of injection molding and blow molding.