Vertical vs. Horizontal Injection Molding

If you’re familiar with injection molding, you can envision the molding machine running.  It opens, ejects a formed part, closes the mold, then makes another part.  I bet you’re seeing the mold open horizontally, parallel to the floor.  If you see that in your mind, you’re only seeing half of the potential picture.  Injection molding can be done horizontally and vertically, which most don’t realize.  If you’ve never heard about vertical injection molding, this article will give you some background on it and if it’s the right choice for your next project.

What is Vertical Injection Molding?

Vertical and horizontal injection molding operate in the same manner.  If you’re familiar with horizontal injection molding, a vertical operation will look very similar.  The same operations apply to both: injection molten resin into an injection mold, hold the mold together with pressure to allow the part to harden, open the mold, then remove the part(s).  The major difference between the two options is the vertical mold operates perpendicular to the floor surface, and moves up and down rather than side to side.

How is Vertical Molding Different than Horizontal Molding?

As mentioned, the molding halves in vertical injection molding go up and down instead of side to side, but that’s not the only difference between the two options.  In vertical injection molding, the injection mechanism is typically on the top of the mold.  This allows gravity to help the molten resin fill the mold cavity, as can utilize gravity to fill stubborn molds that may have complicated shapes.  Gravity-assisted filling can also reduce fill time of the resin and reduce the cycle time of the molding process.  One further benefit to vertical injection molding can realized with open clamps and rotary tables working with multiple molds at the same time.  Pre-molding, molding and post-molding can be concurrently to increase efficiency, productivity and reduce operational costs.

When is Vertical Injection Molding the Better Choice?

When you are designing a new product, one consideration will be if your product will be best suited for vertical or horizontal injection molding.  Here’s when vertical injection molding is the better choice:

• You don’t require the parts to fall from the mold for removal. Gravity will not assist parts to fall out of the open mold.
• You need concurrent operations running such as two bottom halves and one top half being used in tandem. This can allow for pre- and post-molding operations to occur while parts are being filled inside the mold.
• Your parts require insert or over molding to enhance the product function and/or visual appeal. Inserts used for insert molding will be held in place by gravity, which makes the operation easier to incorporate.
• Your part design and molding operation requires more consistent resin flow inside the mold and more accurate temperature distribution.
• Your operation requires a smaller injection molding machine that takes up less floor space. Vertical injection molding machines are typically half the size of horizontal machines concerning square footage.
• Your design requires less pressure and clamping force. Gravity will assist to keep the molds together during the injection molding operation.

When Should Your New Part Design Choose Horizontal Injection Molding?

Horizontal injection molding has been the more common choice since injection molding began, but that doesn’t make it the clear winner.  It is more common, and the injection molding machines are utilized more in the molding industry, which may make it easier to find a turnkey supplier for your design.  These are times when it is the better choice for your molding operations.

• You need to utilize a manual part removal operation from the mold via human operator or a robotic arm. Horizontal molds can be the better choice for this.  Gravity can also help the parts to fall out of the mold.
• You need to make multiple parts for every molding cycle with multiple part cavities in the mold.
• Your part, or some design features, are cylindrical shaped.
• You need a high number of parts in a production run.
• Your part design does not require insert or over molding.

Choosing the right injection molding process for your new design is a critical step in the success of bringing a new product to market.  It also must incorporate the correct resin for the design, reduce operational cycle times, and allow for automation if needed.  These can be lengthy discussions toward adding quality and reducing cost.  When you need a resource to design your next injection mold, help select a resin with all the parameters needed for a successful product, or produce your product, we’re here to help.  SEA-LECT Plastics excels at injection mold design, tooling creation, manufacturing, assembly, and global logistics.  We are a turnkey manufacturer that can organize a new product launch from concept to consumer.  We have a complete turn-key option for your product.  When you’re ready to discuss your current or next project, or want to know more about plastic injection molding, contact us at info@sealectplastics.com or give us a call at (425) 339-0288.

Matthias Poischbeg was born and raised in Hamburg, Germany. Matt moved to Everett, Wash., after finishing his bachelor’s degree in business in 1995 to work for Sea-Dog Corporation, a manufacturer, and distributor of marine and rigging hardware established in 1923.

In 1999, Matt took over the reins at Sea-Lect Plastics Corporation, a sister company of Sea-Dog and a manufacturer of plastic injection molded products with an in-house tool & die shop. Matthias Poischbeg is also a contributor to Grit Daily.

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