Insert molding and insert molded parts

What insert molding is

Insert molding places metal or pre-made components into the mold before injection, so the plastic forms around them. The result is one part with no assembly step, a stronger joint than press-fitting or gluing, and inserts held exactly where the design needs them.

Typical insert parts we make

• Automotive switch parts with stamped terminals in 15% GF PA66.
• Electrical equipment parts in 20% GF PA66.
• Electronic bases with threaded brass inserts in ABS.
• Appliance frames with metal inserts in 30% GF PA66.

Loading is the critical step

Every insert part starts with loading. If loading is slow or irregular, molten resin waits in the nozzle and cools, causing flow marks, weld lines and short shots. We solve this with:

• Custom loading tools that place a full set of inserts in one move.
• Positive location in the mold: pins, pockets or magnets that hold inserts while the mold closes.
• Insert preheating where needed to reduce stress in the surrounding plastic.

Vertical or horizontal?

Our vertical injection presses with two shuttle cores let the operator load one core outside the press while the other is molding. This suits loose, numerous or heavy inserts that would move in a horizontal mold. Horizontal presses are faster for parts that drop automatically and inserts that sit securely.

Preventing flash

Flash on terminals or in threads causes assembly failures. Because we machine both the inserts and the mold components, we control the fit on both sides, and we check every insert position and thread at T1.