Introduction

Injection molding is one of the most commonly used manufacturing processes for producing plastic parts. It is widely used in various industries due to its versatility, high production rates, and low cost. However, designing an injection mold can be a complex process, and a key consideration is the incorporation of draft angles. This blog will discuss why draft angle design is essential for injection molding and provide guidelines for incorporating draft angles into injection mold design.

What is a draft angle?

A draft angle, also known as a taper angle, is the angle that is incorporated into a mold design to allow for the easy removal of a molded part from the mold. The draft angle is a slight angle that is added to the vertical walls of a mold, which allows the part to be easily released from the mold after it has been formed. Without a draft angle, the part would stick to the mold, resulting in damage to the part and the mold itself.

Benefits of a draft angle

The incorporation of a draft angle into an injection mold design offers several benefits, including:

Easy part release: The draft angle allows for the easy removal of a molded part from the mold, reducing the likelihood of damage to the part or the mold.

Improved part quality: A draft angle can help to prevent part deformation or warpage, resulting in a higher quality finished product.

Reduced cycle time: The incorporation of a draft angle can help to reduce cycle time, as it allows for faster and easier part ejection.

Lower production costs: The use of a draft angle can help to reduce production costs by improving the efficiency of the injection molding process.

How Draft angle injection molding?

The incorporation of a draft angle into an injection mold design can be achieved through various methods, including:

Tapered mold design: A tapered mold design is the most common method of incorporating a draft angle into a mold. This involves adding a slight taper to the vertical walls of the mold cavity, which allows for the easy removal of the molded part.

Slider or lifter mechanism: A slider or lifter mechanism can also be used to incorporate a draft angle into an injection mold design. This involves adding a separate mechanism to the mold, which can move to create a tapered surface on the molded part, allowing for easy release from the mold.

Cam action mechanism: A cam action mechanism is another method of incorporating a draft angle into an injection mold design. This involves using a cam-shaped surface to create a tapered surface on the molded part, allowing for easy release from the mold.

Draft angle and feature depth in injection molding

When incorporating a draft angle into an injection mold design, it is important to consider the feature depth of the molded part. A feature is any detail or feature of the part that protrudes into the mold cavity. If the feature depth is too great, it can make it difficult to incorporate a draft angle without compromising the part's design or functionality. In such cases, it may be necessary to consider alternative molding processes or design modifications to ensure that the part can be produced successfully.

No draft angle (Zero Draft mold) in the injection molding

In some cases, a draft angle may not be necessary, and a zero draft mold design can be used. A zero draft mold design does not include any draft angle, and the mold cavity is designed to match the exact shape of the finished part. Zero draft molds are used in applications where the part geometry or material properties make it impossible or impractical to incorporate a draft angle.

When draft angle injection molding?

Draft angles are required for injection molding for several reasons. Firstly, they ensure that the molded part releases smoothly from the mold cavity, reducing the chances of damage to the part or mold. Secondly, draft angles are essential for ensuring that the molded part is consistent in size and shape and meets the required dimensional tolerances. Without draft angles, the part may become warped or distorted during the ejection process, leading to product failure.

The amount of draft angle required for injection molding varies depending on the part's design, material, and the specific requirements of the application. A general rule of thumb is that a draft angle of at least 1 degree is required for every inch of the part's depth. However, this can vary depending on the complexity of the part's design and the material used.

Draft angles are also necessary for parts that require overmolding or insert molding. These processes involve molding one part onto another or molding an insert into a part. The draft angle allows for the easy ejection of the finished part and ensures that the overmolded or inserted part is securely held in place.

Conclusion

Draft angles are a critical design element for successful injection molding. They ensure that the molded part releases smoothly from the mold cavity, reducing the likelihood of damage to the part or mold. Draft angles also ensure that the molded part is consistent in size and shape and meets the required dimensional tolerances.

When designing parts for injection molding, it is essential to consider the draft angle requirements carefully. The amount of draft angle required will depend on the part's design, material, and the specific requirements of the application. Working closely with an experienced injection molding company can help ensure that the correct draft angles are incorporated into the part's design, leading to a successful and cost-effective molding process.