As a vertically integrated company, Paulson Mfg. handles almost all production processes in-house. Everything – from product conception & design, 3D printing & prototyping, injection molding, CNC machining, assembly, and packaging & labeling – all done under one roof. In addition to manufacturing the products themselves, we also make the injection molds that make the products. Not only does this help us maintain a rigorous quality control system in accordance with ISO 9001 but gives us flexibility in offering innovative engineering solutions.

Plastic injection molds are typically constructed from hardened or heat-treated steel or aluminum. Steel molds cost more but are often preferred because of their high durability. Hardened steel molds are heat treated after machining, and they are by far superior in terms of wear resistance and lifespan. In fact, many steel molds are designed to process well over a million parts during their lifetime. For this reason, most injection molds made by Paulson Mfg. are constructed from hardened steel. 


Plastic Injection Mold Cavity Core / Core Cavity

Plastic Injection Mold Design

Plastic injection molds consist of two halves – the cavity and the core.

The cavity is the void inside the mold that the molten plastic fills. Plastic enters through a “sprue” or “gate” on the cavity side and forms the final shape of the part.

The core is usually the interior of the part and contains the ejection mechanism that pushes the completed part out of the mold. Molds are typically designed so that the molded part remains on the core half of the mold when it opens. 


How are Plastic Injection Molds Made?

There are two primary methods for constructing a mold – computer numerical control (CNC) machining and electrical discharge machining (EDM).


CNC injection mold making processCNC Machining

CNC machining for constructing a mold is typically an automated process utilizing machining and cutting equipment that follows computer-programmed instructions to shape the mold into specified dimensions. CNC systems translate in-depth design files into programmable instructions that CNC machines read and execute. Product design engineers create a precise, virtual product design using computer-aided design (CAD) software that specifies every construction detail.

Once the CAD design is complete, tooling engineers can translate the CAD using computer-aided manufacturing (CAM) software to produce instructions the CNC hardware can understand. The resulting commands are then uploaded into the CNC machine and, utilizing the proper cutting tools, precise cuts are made into the metal to the exact specifications of the product design. The majority of CNC cutting tools utilized by Paulson Mfg. are Vertical Machining Centers (VMC), which feature vertically oriented spindles that approach the mold from above. Other common cutting tools include lathes, mills, and drill presses.


EDM Injection Mold Machine

Electrical Discharge Machining

Like laser cutting, EDM does not require or use mechanical force to cut into the metal. Rather, it utilizes an electrode, typically made of graphite, which is mounted in an EDM machine and positioned over the mold submerged in a dielectric fluid.

The electrode is then lowered to the mold, and using a controlled electrical source, destroys and disperses the metal in the area opposite of the electrode, all while never touching the mold. Despite typically being a slower method, the EDM process can produce shapes that are not possible with conventional CNC machining.


Precision Mold Making from Paulson Manufacturing

As a manufacturer of world-class PPE designed for hazardous and/or life-threatening situations, Paulson understands the importance of quality and precision in producing our products. Designing and constructing the injection molds that make our products is an essential part of our production process and helps us ensure a level of protection for our customers that is second to none. To learn more about our injection mold making expertise, please contact us today.


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