The Benefits and Limitations of Injection Molding

Injection Molded PlasticThe advantages of injection molding over die cast molding have been debated since the former process was first introduced in the 1930s. There are benefits, but also limitations to the method, and that, primarily, is need-based. Original equipment manufacturers (OEM) and other consumers who rely on molded parts to produce their goods, are looking for such factors as quality, durability and affordability in deciding which molded parts best suit their needs.

What is Injection Molding?

Injection molding is a method of creating finished parts or products by forcing molten plastic into a mold and letting it harden. The uses of these parts varies as widely as the variety of products made from the process. Depending on its use, injection molded parts can weigh from a few ounces up to hundreds or thousands of pounds. In other words, from computer parts, soda bottles and toys, to truck, tractor and auto parts.

Injection Molding Diagram

Plastic Injection Molding vs Die Casting

 

The method of injection molding was originally modeled on die casting, a similar procedure in which molten metal is forced into a mold to produce parts for manufactured products. However, rather than using plastic resins to produce parts, die casting uses mostly non-ferrous metals such as zinc, aluminum, magnesium, and brass. Though just about any part can be cast from almost any metal, aluminum has evolved as one of the most popular. It has a low melting point, which makes it easily malleable to mold parts. Dies are stronger than the molds used in the permanent die process to withstand the high pressure injections, which can be 30,000 psi or more. The high pressure process produces a durable, fine grade structure with fatigue strength. Because of this, die casting use ranges from engines and engine parts to pots and pans.

Die Casting Benefits

Die casting is ideal if your company’s needs are for strong, durable, mass-produced metal parts like junction boxes, pistons, cylinder heads, and engine blocks, or propellers, gears, bushings, pumps, and valves.

  • Strong
  • Durable
  • Easy to mass-produce

Die Casting Limitations

Yet, arguably, though die casting has its benefits, there are a number of limitations in the method to consider.

  • Limited part sizes (maximum of about 24 inches and 75 lbs.)
  • High initial tooling costs
  • Metal prices can fluctuate significantly
  • Scrap material adds to production costs

Injection Molding Benefits

The benefits of injection molding have gained in popularity over the years because of the advantages it offers over traditional die casting manufacturing methods. Namely, the immense amount and variety of low cost, affordable products that are made from plastics today are virtually limitless. There are also minimal finishing requirements.

  • Light-weight
  • Impact resistant
  • Corrosion resistant
  • Heat resistant
  • Low cost
  • Minimal finishing requirements

 

Suffice it to say, the choice of which molding method to use will ultimately be determined by the intersection of quality, necessity, and profitability. There are benefits and limitations in each method.  Which method to utilize—RIM molding, traditional injection molding or die casting for part production—will be determined by the needs of your OEM.


Osborne Industries, Inc., utilizes the process of reaction injection molding (RIM) over traditional injection molding practices because of its even lower costs, durability, and production flexibility the method offers to OEMs. RIM-molding is suited in the usage of thermoset plastics as opposed to thermoplastics used in traditional injection molding. Thermoset plastics are light weight, exceptionally strong and corrosion resistant, and especially ideal for parts used in extreme temperatures, high-heat, or highly corrosive applications. Costs of RIM part production is low, too, even with intermediate and low volume runs. One of the major advantages to reaction injection molding is that it allows for the production of large parts, like vehicle instrument panels, chlorine cell tower tops, or truck and trailer fenders.

Ask an Expert About Thermoset Plastics

Top 3 Most Impact Resistant Plastics

Impact Resistant PlasticPlastics are generally tough, corrosion and chemical resistant, lightweight, easy to fabricate, and less expensive when compared to alternative materials like metal. As with any manufacturing material, there are advantages and disadvantages to the different properties each material might have. Although there are many impact resistant plastics to choose from, there are a few that excel in their respective applications. Below we discuss the potential for three of the most common impact resistant plastics. Read more >

Osborne Installs Automated Fiberglass Cutting System

May 24, 2017 – Osborne, Kansas – Osborne Industries, Inc., custom molder of thermoset plastics via Resin Transfer Molding (RTM) utilizes a variety of fiberglass types in their Resin Transfer Molded (RTM) thermoset fiberglass-reinforced plastic (FRP) parts for leading equipment manufacturers. Osborne’s team of engineers and molding specialists will work to identify the best glass-reinforcement for your application. Osborne can give your part the reinforcement needed to meet harsh environments in the field. Read more >

The Difference Between Thermoplastic and Thermosetting Plastic

Have you ever wondered what the difference between thermoplastic and thermosetting plastic is? Although both sound similar, they have very different properties and applications. Below we discuss the differences between thermoplastics vs. thermosetting plastic, their curing process, and the pros and cons to each. Comprehending the performance differences can help you improve your product designs!

Thermoplastic vs Thermosetting Plastic

Thermoplastics and thermosetting plastics are two separate classes of polymers, which are differentiated based on their behavior in the presence of heat. The material difference between the two is that thermoplastics can be remelted, while thermoset plastics remain in a permanent solid state once hardened. As a result of these physical qualities, thermoplastic materials have low melting points while thermoset plastic products can withstand high temperatures without losing austerity. Read more >

How the Resin Transfer Molding Process Works

In 1976, Osborne Industries, Inc., originated and initiated the closed-mold molding process that was later known in the plastics industry as resin transfer molding, or RTM. The resin transfer molding process has been in use ever since. RTM is one of the best methods for mass production of composite parts. It is primarily used to mold components with large surface areas, complex shapes and smooth finishes. The automotive, industrial equipment and agriculture industries have used the resin transfer molding process for decades for these reasons.

Below we discuss a more detailed step-by-step of the resin transfer molding process and its advantages.

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pDCPD Reaction Injection Molding (RIM) Provides Durability, Structural Advantages

Reaction Injection Molding pDCDP Example When we had a customer that was looking for alternatives to the sheet metal hoods on boring machines used in the construction industry, Osborne offered pDCPD reaction injection molding (RIM) as a solution to the problems they were facing. The wet conditions on many construction boring jobs led to excessive rust on the steel hoods, while the rugged environment dented and damaged the sheet metal. As opposed to steel, pDCPD offers an excellent combination of chemical and corrosion resistance, as well as outstanding impact resistance. These characteristics made the engineered thermoset polymer the perfect replacement for the sheet metal hoods. Read more >

What is pDCPD? Your Questions Answered.

What is pDCPD?  pDCPD is the abbreviation for polydicyclopentadiene, a thermoset polymer plastic material. Thermosets like pDCPD are distinguished from thermoplastic materials, the other main group of plastics, because, unlike thermoplastics which revert back to liquid form under excessive heat, thermosets will remain in a post-cured form.

pDCPD and other thermosets resist melting because of the process by which they’re created: two dissimilar liquids are mixed together, creating high temperatures that foster cross-linking between molecular chains. This cross-linking contributes to thermosets’ heat resistance. Read more >

Osborne Industries Launches New Responsive Website

Osborne Industries Launches New WebsiteOsborne Industries, Inc., a leader in custom liquid molding of thermosetting plastics, is proud and excited to announce the launch of their new, responsive website.

Osborne invites visitors to explore their new website that is designed to provide the ultimate user-friendly experience, with easy to use navigation and improved functionality. The company, which specializes in the custom liquid molding of thermoset plastics via Resin Transfer Molding (RTM) and Reaction Injection Molding (RIM), hopes the new site will further elevate their online presence. Read more >

Osborne Industries, Inc., Receives Award for Consistency of Resin Transfer Molded (RTM) Products

consistency-awardAugust 7, 2015 – Osborne, Kansas – Osborne Industries, Inc., a custom resin transfer molding firm, was presented with a Consistency Award for reliable, dependable service by Altec Industries, headquartered in St. Joseph, Missouri. The presentation took place at Altec’s Supplier Summit on May 5, 2015, in St. Louis, Missouri.

Osborne began working with Altec Industries 30 years ago, supplying aerial lift platforms for the company’s utility vehicles. Since then, Osborne continues to supply thousands of platforms annually, molded via resin transfer molding (RTM), and adhering stringent testing protocols and product specifications for durability and reliability. Read more >

Osborne Industries, Inc. to Exhibit at Design-2-Part Show

February 24, 2015 – Osborne, Kansas – Osborne Industries, Inc., a manufacturer of custom-molded plastics via Reaction Injection Molding (RIM) and Resin Transfer Molding (RTM), has announced it will be exhibiting at the Design-2-Part manufacturing show. The show is being held at the Gaylord Texan Convention Center in Grapevine, Texas, February 25-26, 2015. Osborne Industries can be found at booth # 510. Read more >