The working dimensions of forming parts refer to the dimensions of the directly formed plastic components on the molded part. These dimensions primarily include the dimensions of the mold cavity and the dimensions of the moving mold core.

Every plastic component has specific geometric shapes and size requirements, with certain dimensions requiring higher precision for proper fit. The dimensions of the mold components must ensure that the dimensions of the molded plastic components meet the required specifications. Various factors can affect the dimensions and tolerances of the plastic components, making it a complex consideration.

• The manufacturing tolerances of forming parts directly impact the manufacturing tolerances of the plastic components. When determining the dimension tolerances of the forming parts, it is advisable to use one-third of the tolerances of the plastic components.
• Before determining the forming dimensions, it is necessary to classify the properties of each part's dimensions to determine the orientation of each dimension and its tolerance.

• The calculation of forming part dimensions should consider the fluctuating factors of mold shrinkage: the production process conditions of the plastic component, mold structure, operational methods, materials, etc. However, the critical requirement is to have accurate data on the molding shrinkage rate.
• Pay attention to controlling the thickness of the product walls, generally preferring thinner walls over thicker ones. Also, control the correction values: make the correction value positive for the moving mold and negative for the fixed mold to facilitate adjustments.
• Dimension labeling of forming parts should consider ease of mold trial and subsequent adjustments.
• The assembly dimensions of the moving and fixed mold inserts should be selected correctly based on the fit tolerance chart, enabling component-based production and maintenance.
• The manufacturing precision of forming parts is one of the crucial factors affecting the dimensional accuracy of plastic components. The lower the machining precision of the forming parts, the lower the dimensional accuracy of the plastic components. In practice, the manufacturing tolerances of forming parts can be set as one-third to one-sixth of the tolerances of the plastic components, further determined by standard tolerance values.