Key Words to Know Better about Adhesive (3)

Mold shrinkage refers to the reduction in size or dimensions that occurs when a molten plastic material solidifies and cools inside a mold during the injection molding process. It is an important factor to consider in the design and production of plastic parts, as it can affect the final dimensions and tolerances of the molded product.

Measuring mold shrinkage typically involves comparing the dimensions of the molded part with the dimensions of the mold cavity that it was formed in. Here is a general outline of how mold shrinkage is measured:

1. Mold Design: A mold is designed and fabricated with a specific cavity size and shape, taking into account the expected shrinkage of the plastic material being used.

2. Mold Preparation: The mold is prepared by cleaning and ensuring its temperature is stabilized according to the processing conditions.

3. Injection Molding: The plastic material is melted and injected into the mold cavity under specific conditions, such as temperature, pressure, and cooling time.

4. Cooling and Solidification: The plastic material solidifies and cools within the mold cavity, undergoing shrinkage as it transitions from a molten state to a solid state.

5. Ejection of the Part: Once the plastic has fully cooled and solidified, the molded part is ejected from the mold.

6. Dimensional Measurement: The dimensions of the molded part are measured using specialized metrology equipment, such as calipers, coordinate measuring machines (CMMs), or optical measurement systems. Multiple points on the part, including critical dimensions, are typically measured to get an accurate assessment of the shrinkage.

7. Comparison: The measured dimensions of the molded part are compared with the dimensions of the mold cavity to determine the shrinkage. The shrinkage is calculated as the percentage reduction in size or as the absolute dimensional change.

The measurement of mold shrinkage allows for adjustments in the mold design, processing parameters, or part dimensions if necessary to achieve the desired final product specifications. It helps ensure that the molded parts meet the required functional and dimensional requirements.