Vertical vs. Horizontal Injection Molding

Injection molding can be done both vertically and horizontally – and most people don’t realize this. Here, we discuss the differences between vertical and horizontal injection molding.

Horizontal plastic injection molding

Historically, horizontal injection molding has been more popular than its vertical counterpart – but that doesn’t mean it’s inherently superior. Remember, every method has pros, cons, and distinct applications.

In this type of molding, the mold opens/closes along a horizontal axis. This configuration needs correct and consistent injection pressure to ensure proper packing and cooling while filling the mold activities. Typically, horizontal molds are built with more cavities than vertical ones, producing more parts per cycle. Plus, thanks to the horizontal separation of the mold halves – parts from these molds don’t need to be manually extracted and naturally fall out of the cavity upon ejection.


  • Continuous operation and consistent cycle times
  • As a more common type of machine, more options are available, like electric or hydraulic options
  • Efficiency in parts produced per cycle


  • Compared to vertical molding machines, horizontal molding machines take a larger footprint
  • Insert molding is inefficient and way more difficult

Vertical plastic injection molding

a connector with metalIn this type of molding, the two halves of the mold open and close by moving up and down vertically. Usually, the injection mechanism is found at the top of the mold. Both injection pressure and gravity play a big role in filling the mold cavities. This can help with filling consistency and time.

Vertical injection molding equipment is designed with rotary tables and open clamps. This allows for work with simultaneous operations and multiple molds – before, during, and after molding. Consequently, there’s not much need for manual intervention and operation, along with reduced costs, increased productivity, and higher efficiency.

There’s one key difference in a vertical mold. Compared to a horizontal mold, pieces don’t fall out of the mold automatically after being ejected. Plus, the pieces must be extracted by robotic arm or hand.


  • Since gravity plays an integral role in the process, not much pressure and clamping force is required
  • Machine footprint is half the size of horizontal molding machines
  • It can be manually operated and used with revolving tables for creating combination parts and inlays
  • Beneficial for insert molding, especially when compared with more basic horizontal molding machines
  • More consistent temperature distribution and material flow


  • Manual removal step can contribute to inconsistent cycle times
  • Removal timing should be accurate, which is harder in a manual process
  • Parts may be damaged during removal by human operators or robots
  • Manual part removal can take a lot of time

PTMS is a high-quality plastic injection mold maker in China

PTMS is a professional injection mold maker specializing in mold-making technology. With our experienced employees and advanced mold manufacturing equipment, we would like to grow as a leading plastic injection molding company.

Reach out to us directly for more information!