Thermoset Molding

One of our primary plastic molding services, thermoset plastic molding results in high-quality components that meet tight tolerance requirements and stringent industry demands.

Unlike thermoplastic injection molding processes that are easily reversible, thermoset molding results in a chemical reaction that permanently molds the part. In other words, this process is irreversible.

Thermoset Molding Capabilities

  • (10) Modern Arburg thermoset injection molding systems
  • Modern, digital equipment
  • Capabilities ranging from 30 to 350 tons

Thermoset Plastic Molding Services

  • The process for producing thermoset components goes as follows:
  • Creating custom molds using mold design specifications
  • Selecting adequate polymers for the thermoset process
  • Heating the material and injecting it into the mold
  • Turning a thermosetting plastic from a malleable, liquid state into a hardened, rigid state in a chemical reaction known as the curing process
  • Removing the part from the mold
  • Finishing and secondary operations
  • Quality control procedures

Compression Molding

Compression molding is a molding process where preheated thermoset material is placed directly into the heated mold cavities. The mold is then closed, forcing the material into all cavity areas. Heat and pressure are sustained until the material has cured.

Specific compression molding capabilities at Leech Industries:

  • Phenolic materials: Leech offers a fully automated 10-station, 18-ton rotary machine
  • Polyester materials: 125-ton hull for processing bulk molding compound, polyester or phenolic

Insert Molding and Overmolding

Insert molding and over-molding are additional processes that can be worked into both thermoset and thermoplastic parts.

In insert molding, a pre-formed component (known as the insert) is placed into the mold and molten plastic is injected to surround and bond with the insert. This insert is typically a distinct component, typically either a metal or a different plastic part. Insert molding is often used for adding discrete components within a single part.

A similar process, over-molding involves molding one material (usually a softer or different type of plastic) over another previously molded part to add new properties and enhance the appearance of the original part.

Specific insert molding capabilities at Leech Industries:

  • (5) transfer presses for thermoset molding
  • Shot capacity down to 0.022 oz. / 0.635 gr.

Transfer Molding

During transfer molding, the material is placed above the closed, heated mold and is forced downward through the gate and into the mold cavities. The mold is held closed while the material cures, resulting in transfer molded parts being cleaner and more consistent than compression molded parts.

Transfer molding is useful in critical applications, particularly those that require tight tolerances or specific materials. In the aerospace and defense industries, where safety and reliability are necessary, this process ensures that molded parts can perform in harsh and demanding environments.

Specific transfer molding capabilities:

  • (5) vertical presses ranging from 75 tons to 200 tons
  • Includes a 75-ton Wabash transfer press
  • Processing phenolic materials

Characteristics of Thermoset Components

Thermoset plastic components exhibit several qualities that make them well-suited for various industrial applications. Here are some key qualities of thermoset plastic components:

  • Heat resistance: The cross-linked molecular structure formed during the curing process allows the material to withstand high temperatures without melting or deforming.
  • Dimensional stability: Once cured, thermoset plastics maintain their shape and dimensions. This is crucial for applications in which precise geometries and tolerances are required.
  • Chemical resistance: Thermoset plastics are resistant to a wide range of chemicals, making them suitable in corrosive environments.
  • Durability: Cured thermoset plastics exhibit high mechanical strength and stiffness.
  • Longevity: These components can withstand repeated use over long durations.
  • UV resistance: Certain thermoset plastics exhibit resistance to UV radiation, preventing degradation and color changes upon exposure to sunlight.

Thermoset Plastic Molding Materials

  • Phenolic
  • Polyester
  • Bulk Molding Compounds (BMC)
  • And many more

Our Prototyping Services

If you’d like to acquire prototypes before going forward with your plastic molding projects, utilize Leech’s prototyping solutions to test parts before putting them through to full production. Contact us to find out more.

LEECH Industries

13144 Dickson Road
Meadville, PA 16335