Injection molding or encapsulation is the manufacturing process for producing different sorts of parts in a huge number. It is usually used in scenes of mass production where the same part has to be created in an unbelievable amount which can span to thousands or even millions in succession. The main benefit to using insert molding is ability to scale production as per requirement. Once the initial costs are paid, the price per unit during insert molded manufacturing can be extremely cost effective and low. As more and more parts are produced this price tends to drop drastically. Other advantages can be,

  • Insert molding produces lower scrap rates: relating to traditional manufacturing processes like CNC machining that cut away substantial percentages of an original plastic block or sheet. This however can be a negative relative to other additive manufacturing processes, such as, 3D printing that have even lower scrap rates. Also to be noted that waste plastic from insert molding manufacturing typically comes consistently from four areas, which are the sprue, the runners, the gate locations, and any overflow material that leaks out of the part cavity itself which is a condition called flash.


Thermostat materials, such as an epoxy resin that cures if exposed to air, is a material that cures and will burn after curing if attempts are made to melt it. Thermoplastic material by compare, is a plastic material that can be melted, cooled and solidified and then be melted again without burning. With thermoplastic materials it can be recycled and can be used again. Sometimes this can happen right on the factory floor. They grind up the sprues and any rejected parts. Then they add the material back into the raw material which goes into the injection molding press. This material is known as ‘regrind’. Usually, quality control departments limit the amount of regrind that is allowed to be put back into the press. (Some performance of the plastic can degrade as it is molded over and over) or, if they have a lot of it left over, a factory can sell this re-grind to some other factory who will use it. Typically regrind material is used for low quality parts that does not require high performance properties.

Downsides to insert molding can be,

Unlike in Romeo rim, costs can be very high due to design, testing, and tooling requirements. So the design has to be right from the start. Getting the design right include,

  • Designing and then prototyping the part itself to as specification.
  • Designing an injection mold tool for the primary production round.
  • Refining and adding all details in the injection mold tool before mass-production in an insert mold manufacturing plant.


Before production these should be in consideration.

  1. Financial Considerations:
  1. Entry Cost: Preparing a product for insert molded manufacturing requires a large investment.
  2. Production Quantity:
  1. Determining the number of parts produced at which insert molding becomes the most cost effective method of manufacturing.
  2. Determining the number of parts produced at which you can expect to break even on your investment.