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Plastic Injection Mold Components- Ejector Pins


The best plastic injection mold in the world will fail if something as simple as an ejector pin fails! That is why choosing the right pin for the job is important. Saving money on poor quality mold components just does not make sense in the long run.

Types of ejector pins

Basically, there are only three types of ejector pins commonly used in plastic injection molding applications.

  1. Thru-hard pins. As the name implies, these pins are heat-treated to be thouroughly hardened. Obviously, you won't be drilling and tapping any holes in these pins! They are great all purpose pins with a hardness of 58-62 RC. They are made of either M-2 or H-13 tool steel. They can be used for most molds, up to 400°F, or 200°C
  2. Case hardened pins. These pins are nitrited to 65-72 RC and are also great for general use. They perform well at temperatures above 400°F, thus are often used in die-casting. Because they are so hard, they also tend to chip much easier than thru-hard pins. It is possible to drill and tap the larger pins because the core is 40-45 RC. Most of the time, anyway! Nitride pins are made of H-13.
  3. Black ejector pins are not so common, and were developed for high temperature applications. They are specially coated for this purpose, and are also self lubricating. Their higher cost makes them somewhat of a specialty pin.

Mold components suppliers

There are numerous high quality suppliers, and many specialty suppliers. Here is a partial list:

Standard mold component suppliers for ejector pins

D-M-E Progressive PCS Choice
Hasco Royal Regal Misumi

Specialty suppliers of mold components

Ipsco Ezell Hommer Precision Punch
Punches and Pins Parker Precision Dayton Cumsa





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