When designing plastic parts for mass production, building a mold is an integral part of the process. The mold is the master tool for producing the final product, so it's critical to ensure that the mold is built with precision and accuracy. This is where the importance of a plastic part drawing comes in. A complete plastic part drawing should contain the following information at a minimum:
1. Dimensions
The most important component of a plastic part drawing, is dimensions. These dimensions define the size and shape of the final product. It's important that these are as accurate as possible, as variations in dimensions can lead to defects in the final product.
2. Wall Thickness
It refers to the thickness of the plastic material in different parts of the product. Uneven wall thickness can lead to warping or sagging in the final product, so it's important to carefully define the wall thickness in different areas.
3. Gate Location
The gate is where the molten plastic material enters the mold during the injection process. The location and size of the gate play a critical role in ensuring that the plastic material fills the mold completely and evenly. It's important to consider aspects such as gate size, location, and orientation when designing the plastic part drawing.
4. Ejector Pin Locations
Ejector pins are used to remove the plastic part from the mold once it's been formed. It's important to consider the location and orientation of these pins, as well as the shape and depth of the ejector pin relief, to ensure that they don't leave marks or damage on the final product.
5. Draft Angle
Draft angle refers to the angle of the sides of the plastic part and plays a crucial role in the mold release process. Without proper draft angles, the plastic part may stick to the mold or be difficult to remove. The draft angle should be designed to ensure that the plastic part will easily release from the mold.
6. Surface Finish
A detail showing any fits to other components;
Engraving, artwork and cavity numbering;
Mold label information (if in-mold labeled);
Any stacking details (if appropriate);
Part weight (using an assumed plastic density);
Part volume (if filled and weighed);
Center of gravity (if appropriate);
Identification of plastic or steel sizing;
Identify all split lines and parting lines, including any intentional mismatches.
Once the part drawing is completed, it must be reviewed with the customer and internally at the moldmaker's facility. After Checked all above items,designers can ensure that the final product is manufactured accurately and efficiently.
