The mold insert molding process

Insert molding | Plastic moulding processes | Overmolding and insert molding | Custom insert molding for plastic manufacturing

Insert molding design guide | Insert molding machine | Metal insert molding

Types of plastic moulding | Insert injection molding

With the development of various industries, mold seems to be the must-have for those industries to manufacture their products. Then, let us learn some about the mold insert molding process.

What is the insert molding?

Insert molding refers to the forming process of putting the preparatory different material inserts in the mold before injecting resin, the fused material joint curing with inserts, making an integrated product. And the outsert molding refers to the process of the injection molding insert on the local plate metals.

The characteristics of the insert molding

  1. The intercombination and supplement of the easy compatibility and bendability of the resin and the rigidity, intensity, and heat resistance of metal can solidly generate complicated and delicate metal and plastic integration products.
  2. In particular, the combination of resin insulation and metal conductivity is used for making the molding product meet the basic functions of electrical products.
  3. The beforehand molding combination of several inserts makes the product unit combination after the project more reasonable.
  4. The mould inserts are not limited to metal but other types like cloth, paper, electric wire, plastic, glass, wood, coil, electric parts, etc.
  5. Rigidity molding and the elasticity bending products on the rubber seal base plate are made to an integration product through the outsert molding, which can leave out the complex work of arranging seal rings and make it easier for the automatic combination of afterward procedures.
  6. Because it is the joint of fused materials and metal inserts, compared to pressing molding, the clearance of metal inserts can be designed for more narrow, and the reliability of compound product molding is higher.
  7. Selecting suitable resin and the condition of molding can seal and fix through resin for the product easy to deform and damage.
  8. Selecting a suitable structure of mold, inserts can also be sealed into the resin.
  9. With the combination of the vertical injection molding machine, entire assembly of embedded parts, etc., most insert molding projects can realize automatic production.
  10. After insert injection molding, it also can be turned out to the hollow notched product with the core hole treatment.

Cautions of selection of the systematic design of automatic insert molding

  1. The metal insert molding easily generates uneven molding shrinkage. Therefore, do the ultimate test of form and dimensional accuracy for important parts beforehand.
  2. During injection, metal inserts easily transform and shift. As a result, sufficiently consider the die form and the design that easily keeps the metal insert mold shape. For the molding with an unchangeable shape of inserts, the beforehand trial is necessary.
  3. On an occasion of using conveyor for the arrangement and separation of metal inserts, the inserts will contact the vibrating ball to generate mild damage on the surface of inserts and affect the quality of products. Accordingly, make sure the tolerable limit range of the quality beforehand.
  4. Beforehand measure the metal insert's zigzag, warpage, material thickness tolerance, and diameter tolerance, which are caused by stamping, thickness tolerance caused by applying the gold processing, and so on. On this basis, carry out the supporting option design of automatic equipment and the design of molding structure.
  5. For the mold gate location and way, molding cycle, and other predictable items of restricting mold structure, solve beforehand as soon as possible or find out the solution.
  6. Confirm whether the metal insert needs to preheat or the drying treatment. The purpose is to ensure product quality and molding stability.
  7. Various detectors set in the mold are used to ensure the stability of molding action under the effect of heat, force, vibration, and other environmental conditions. Make sure whether to use.


Nowadays, mold is applied to various industries. Grasping the principles and cautions of insert molding can make our product manufacturing more successful.


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