What is Insert Injection Molding?
Insert injection moulding is the manufacturing process of installing inserts into the plastic mold before injecting the molten material, in order to form part of the final product. First inserts are placed in the mold, then molten resin is injected into it and allowed to harden. After the plastic is cooled, the part is ejected out with the inserts and plastics forming one piece.
Plastic insert molding is ideal for improving the strength and reliability of a component and can help save on cost and production time. It replaces metal and plastic secondary operation assemblies, and components made solely of plastic or metal. This unique manufacturing process combines metal and plastic, ceramics, or multiple combinations of materials, components, and plastic into a single unit.
Insert Mold Manufacturing
Insert Injection Molding
Vertical Injection Molding
Insert Molding Design Considerations:
Insert molding design rules are similar to standard injection molding.
- Maintain proper draft angles to let the part released from the mold.
- Uniform wall thicknesses. Uniform wall thicknesses. A wall section that is too thin can lead to structural failure or poor insulation characteristics. A wall section that is too thick, even locally, can result in appearance defects and an overweight component.
- Good design of ribs and support ribs and bosses,
- Hollow out thick sections,
- Add smooth transitions,
- Round all edges,
- Undercut. Undercuts of part geometry in the mold should be avoided if possible through redesign.
- Avoid unneeded component features
- Proper use of radii, corners and fillets to keep uniform wall thickness and reduce stress concentrations in a part.
- Part surface, textures or polish. Textures and lettering can often be molded into the surface of a part. It can also help to hide surface imperfections such as weld lines.
These are all good advice and applies equally to insert molding. However, there are many factors for mold design engineers to consider when designing or constructing insert molding tooling. Some of the main considerations include:
- Evaluating Material Bonding and Adhesion.
- Plastic components and metal inserts are designed for mechanical bonding.
- Avoid sealing off plastic with R angel as much as possible or enlarge R angel as much as possible to reduce the risk of plastic overflow.
- Putting the inserts into the mold by Robot or manual.
- Holding the inserts during the molding process and so on.
The inserts used for plastic insert molding
- Brass, blinded threaded, threaded inserts, threaded steel parts,
- Steel, stainless steel, screw machine parts, metal stampings,
- Photo chemical etched parts, cold headed parts, die-cut plastic parts,
- Insulated wires, flexible circuits, lead frames, ceramic, composite insulators
Insert Injection Molding Manufacturing Services
Stebro Mold is a professional insert mold manufacturer and insert molding specialist. We offer extensive engineering and design support to aid customers with insert design and material selection. Our integrated consultation, design and manufacturing process delivers a complete insert-molded assembly.
We use advanced Engel Vertical Injection molding machines with a rotatable plate for the insert injection molding production. First, The vertical injection molding press can use gravity to keep the insert in place as the mold is closed. As the molten plastic resin is slowly poured into mold, it helps hold the insrt in a fixed position. With the rotatable plate, we can upload one cavity side and two core sides on the vertical injection molding machine. While one core side is in the injection molding process with the cavity side, the other core side is available to be loaded with the inserts, cycle time is reduced.
As a full service insert molded parts specialist, our Insert Injection Molding Services include:
- Procurement or manufacture of Inserts
- Mold Design and Mold Manufacturing for the Insert Injection Mold
- Insert Molding include low volume and high volume Mass Production
- Part Design Assistant on the insert-molded plastic parts
- Plastic Materials Selection for Plastic Insert Molding
Benefits of Insert Molding Process
- Reduced assembly Time and labor costs
- Reduction of component size and weight
- Enhanced product design flexibility
- Increased flexibility for more complex shapes and components
- Increased reliability by removing adhesives and fasteners
- Higher strength and durability, Improved strength and structure
- Product consistency
- Accurate, repeatable high tolerance
Insert Molding VS OverMolding
One of the most common plastic injection molding processes application are overmolding and insert molding.
Insert Molding is insert a separate part into the mold prior to the molten plastic is injected into the mold cavity. By doing this, the two parts are fused together, becoming one piece. Normally we put the metal parts into the mold for the inserting mold.
Overmolding is another way to combine multiple parts into one single piece. The base layer is molded first and the additional plastic layer is molded over and around the original part – resulting in a single and finished product. Overmolding is often used to add a soft material to an existing product. It is also used to create two-color part.
Both Insert Injection molding and over molding can be done through manual or automation.