Insert Moulding vs Overmoulding: Which Should I Choose For My Project?

Overmoulding and insert moulding are two common injection moulding processes that are often compared, understandably, since both processes allow for the integration of diverse materials into a single part. Both of these techniques are also used to enhance product functionality, improve part performance, and contribute to streamlining the part production process by eliminating the need for separate assembly steps.

In this article, we will outline the key differences between these two injection moulding processes, explore their purposes and applications, and provide a checklist guide to help you decide which process is best for your project.

Insert Moulding vs Overmoulding

Insert moulding process

Insert moulding is a process in which a ‘pre-formed component (insert) is placed into the mould before injecting the molten material. As the molten plastic material is injected, it then surrounds and forms a strong bond with the insert during the moulding process. Gain a deeper understanding of the insert moulding process.

• Materials used in insert moulding: The insert can be made of metal, plastic or any other rigid materials, and the moulded material is usually a thermoplastic.
• Purpose of insert moulding: The purpose of insert moulding is to enhance the functionality of a part by incorporating reinforcements, electrical conductivity, or specific features directly into the mould. It can result in greater strength, durability and functionality, as opposed to attaching the individual parts separately during post-production assembly operations.
• Insert moulding applications: Insert moulding is commonly used to incorporate brass threaded inserts, fasteners, plastic clips, sensors, electronic components, and magnets, into plastic parts. It has a wide range of applications and is frequently employed in the production of electronic components, automotive parts, and medical devices.

Overmolding process

Overmoulding involves the process of moulding a single part using two or more different materials. It is a multi-step process whereby a base or substrate (first material) is moulded first, and additional materials (overmold) are then permanently applied over specific areas or the entire surface.

• Materials used in overmoulding: Overmoulding often involves using different types or colours of thermoplastics, elastomers, or rubber materials. The base material is usually rigid, while the overmold material is softer or more flexible.
• Purpose of overmoulding: The overmoulding process aims to achieve a robust and inseparable bond between two materials. It is commonly used to enhance the grip, performance, aesthetics, or functionality of a product.
• Overmoulding applications: Overmolding is commonly used to enhance the grip, aesthetics, or functionality of a product. It’s often seen in products like tool handles, toys, kitchen utensils, toothbrushes, and electronic device grips.

Should I Choose Insert Moulding Or Overmoulding?

Choosing between insert moulding and overmoulding depends on specific project needs, design requirements, material compatibility, and the desired characteristics of the final product. To guide your decision, we’ve listed several scenarios in which it’s better to choose overmoulding over insert moulding and vice versa.

When to use overmoulding:

Consider overmoulding when making products that have the following attributes or applications:

• Your finished piece can be made of thermoplastics and/or rubber.
• You intend to improve the grip and texture of a part.
• You need multi-colored plastic products.
• You want to increase cushioning, shock absorption, or vibration damping.
• You need to embed soft seals into your part.

When to use insert moulding:

Consider insert moulding when making products that have the following attributes or applications:

• Your part has a metal component 
• You need to efficiently integrate electronic components like sensors, wires, or circuit boards.
• You need to incorporate other pre-fabricated substrate like magnets
• You want to avoid incurring the cost of a complex two-shot mould
• You must incorporate threaded inserts into your part.

While the checklists above provide a great starting point for deciding which process to use, the decision should always be based on the specific needs of your project. Keep in mind that these two manufacturing methods can also be used together. To discuss your project contact us HERE.

Injection Moulding With HLH Rapid

Looking to produce custom insert-moulded or overmoulded parts? Contact the HLH team to leverage decades of vast injection moulding expertise. Simply submit your CAD designs and project details via our Site Contact Form, and we will get back to you with a quote within 24 to 48 hours.