What is Overmolding | Insert Molding vs Overmolding

In today's Post, We are Going to learn about What is Overmolding | Insert Molding vs Overmolding. Read this post to the last and you will get Useful pieces of information from this post.

What is Overmolding?

Overmolding is a process used to combine at least two materials into one object. 

These days, 2 technologies can be used to create over-molded objects-

• Injection molding

• 3D printing

Overmolded parts typically consist of a substrate and the over-molding material. Substrate materials include metal, plastic, glass, and more.

Overmolding material includes rubber or thermoplastics. 

With 3D printing technology, jetting deposits different materials to create objects with different characteristics in different areas of the object.

Benefits of over-molding:

• Eliminates secondary
• operations. Which reduces
• manufacturing costs; and gives a product a specific feature, such as a comfortable and firm grip.

With injection molding technology, a substrate is molded first. 

Then, either a different mold is used to combine the first material with the over-molding material. Or, the part is put back into the mold and the overmolding material is added.

Overmolded objects include

• Tool handgrips like drills
• Scissors and screwdrivers
• Personal care products 
• Cell phones

Type of Inserts

• Female Threads
• Male Threads
• Dowel Pins
• Electrical Contacts
• Spring-Loaded Clips

Manually placing insert

The operator used to press insert, heat staked, or ultrasonically to place the insert into the part.

The disadvantage of a Manual insert

• Increase the cost of equipment and fixture 
•  Labor is require
• Not as strong and consistent as insert molding

We can place insert manually or automatically with the help of robots

Points need to be considered.

• To withstand high pressure and high temperatures

• Insert location

• Placing insert automatically or manually

• Cost of product

Over-molding (One kind of injection molding process)

• Used for creating features like grips, bump stops, and aesthetic feature

• Overlapping plastic over another plastic or metal.

• Creating a single part by using two or more different materials

Applications of Over-molding

1. Plastic Over Plastic Color option for aesthetics -

2. Rubber Over Plastic - Soft grip area to a rigid part

3. Plastic is Metal - Fastening

4. Rubber Over Metal - To provide a soft grip surface

Why Do We Want to Overmold the Product?

1. Color option

2. To provide a soft grip

3. To add flexible areas to a rigid part

4. To eliminate assembly line time

5. For Different material bonding

Insert molding vs. overmolding

Insert Molding:-

1. Single-shot molding process.

2. Plastic around a non-plastic component.

3. Not require a pre-formed part to mold around.

4. Application-

• Provide good fastening for assembly 
• Provide good strength to part

5. Not all insert molds can be categorized as overmolds

(E.g. Insert molded to the metal screwdriver)

Over Molding:-

1. Multishot molding process.

2. Molding a rubber-like plastic over the top of another plastic component.

3. Requires substrate part to mold around.

4. Application

• Combines multiple materials into a single product.
• Provide grips
• Bump stops
• Aesthetics features

5. Overmolds can be categorized as insert molds

(Eg Black elastomer was then over-molded to the substrate to create a soft grip)