Plastic Mold Manufacturer

plastic mold manufacturer

Plastic injection molding processes create a large range of plastic parts used in everything from kitchen appliances to automobile components. Although injection molding is a common manufacturing process, it requires very expensive machinery to execute a complex set of temperatures, pressures, speeds and times to make custom parts from a wide range of different plastic materials.

The quality of the injection mold used is also a vital part of the process, so choosing the right plastic mold manufacturer to design your plastic injection molds for plastic injection is critical.

This basic guide by injection molding manufacturer MSI Mold will help you understand the process of injection molding and how the mold design fits into the bigger picture.

Injection Molding Basics

Injection molding is exactly what it sounds like. Plastic pellets are fed into an injection molding machine. They are heated to high temperatures until they’re molten, then injected into a plastic injection mold created by a plastic mold manufacturer. Over time, the plastic hardens and achieves a solid form.

The plastic usually comes as polymer granules, small pellets that can easily and quickly be melted. Since these thermoplastic polymers are capable of being colored or filled with additives, they’re rather versatile materials. A few basic types of thermoplastics that are used in injection molded products are:

  • Acrylonitrile butadiene styrene (ABS)
  • Polyethylene (PE)
  • Polypropylene (PP)
  • Polystyrene (PS)

Plastic injection molding, custom injection molding, and prototype injection molding all offer several benefits when they are done properly. It can be an extremely repeatable process which can produce high quality complex shapes over and over.

Injection molding is also a process that can be fast, which makes it perfect for high-volume manufacturing. Injection molds can be made to produce several parts at a time which results in a lower cost per part.

How the Injection Molding Process Works

Before production can begin, a plastic mold manufacturer must design and build a custom mold for the part shape to be manufactured. After the mold is made it will be installed into a production molding machine and tested for proper function and part quality.

We describe how the injection molding process works in detail on our plastic-injection-molds and plastic injection molding pages.

Advantages of U.S. Made Plastic Injection Molds

Injection molding manufacturers

The advantages of building your plastic injection mold in the USA versus offshore are clear:

  • Culture
  • Communication
  • Quality
  • Ongoing support
  • Unexpected delays
Unexpected or unstated costs can add up very fast when dealing with “less expensive” offshore injection molding manufacturers.

Two of the biggest hurdles we have seen with offshore customer projects is the business culture differences of U.S. customers and offshore suppliers, and a lack of good technical communication before a project is started.

Offshore plastic injection mold suppliers are very quick to provide quotations and accept tooling deposits. However, after discussions about the mold design and part quality expectations are finalized the mold price can often change to a higher price. By then they already have the customer deposit and the customer is trapped. Just try to get your money back…it doesn’t happen.


To the contrary, all well respected U.S. injection mold makers have detailed communication with their customers about the part and mold design at the start of their projects, and many times even before quoting the project or accepting any deposit money.

Also, language barriers create poor communication which can lead to costly mistakes and delays. Using a plastic mold manufacturer based in the U.S. removes the risk of critical information getting lost in translation.

Mold Quality

We have spoken about injection mold construction on our plastic injection molds page and how important mold quality is for having high quality plastic molded parts. There is not enough that can be said about the topic of mold quality.

After seeing first hand hundreds of offshore made plastic injection molds, we can say that mold quality is extremely wide ranging across offshore suppliers.

To be fair, there are plenty of U.S. mold makers that have quality issues. But most of these low quality operations can be uncovered by asking the right questions.

Maintenance and Support

Plastic injection molds need ongoing maintenance and support! Before you make a decision to purchase a “less expensive” mold offshore, it is critical for you to determine how much local USA support you are going to need. It is very common for injection molds to require periodic maintenance and engineering changes to accomplish customer part changes.

If your mold will be running production in the USA you can expect these services to be expensive on an offshore mold. The opposite is true when you build your mold in the U.S. For example, here at MSI Mold we warranty your mold for the life of your production here.

That means all ongoing maintenance for your mold is included with our services and many simple engineering changes will also be included in the original mold pricing.

Lead Times

Lead times are critical for any provider of goods or services, and it is no different for our customers that need high quality custom plastic parts. Offshore mold makers have international time zone differences that could lead to lag time in critical responses, a lengthy review and approval process, and the potential for missed change requests.

In addition, offshore shipments encounter international customs delays, bottleneck delays from cultural holidays, geopolitical delays, and volatile international shipping costs.

American Plastic Mold Manufacturers

Choosing a domestic plastic mold manufacturer ensures that you get seamless communication, the quality you deserve, the required ongoing support, and the stability of your project timelines.

The Case for Steel and Aluminum Molds

At MSI Mold, we build high-quality aluminum and steel custom molds. The molds used for plastic injection molding must withstand high forces from clamping and injection pressures. While both types of molds can be constructed withstand years of production, a case can be made for each in the right applications.

Both aluminum and steel molds present distinct advantages and disadvantages. Selecting the optimal choice of metal for your mold depends upon several factors, including the expected production life requirements and the type of plastic used for the injection molding of your parts.

Aluminum Molds

Advantages of aluminum molds include:

  • Lower tooling costs
  • Cost-effective for low volume production runs
  • Faster cooling times of the plastic mean faster production rates
  • Uniform heat distribution minimizes plastic part shrinkage and distortion
  • Easy modification and repair
  • Quick to produce

Disadvantages of aluminum molds include:

  • Not suitable for high temperature mold requirements
  • May require hardened surface treatments for abrasive filled plastics

Steel Molds

Advantages of steel molds include:

  • Desirable for very high volume production
  • Stands up to elevated temperatures
  • Offered in a range of different specialty steel types
  • Superior durability if hardened

Disadvantages include:

  • High tooling costs
  • Longer production times due to slower cooling times

The Importance of In-House Capabilities

At MSI Mold, we offer end-to-end services to produce your custom plastic parts. When choosing a manufacturer, we believe that providing in-house mold making along with high quality manufacturing systems under one roof is critical for producing quality injection molded parts and makes for a superior customer experience over a provider without in-house capabilities.

Without a cohesive team and a solid advance quality plan, it can be impossible to find and resolve issues before the final product is delivered.

Our experienced sales engineers, designers and injection molding experts work alongside our customers for advanced quality planning to meet all customer part specifications.

This close in-house working relationship eliminates costly problems that can happen when transferring between separate teams and facilities. Design challenges are resolved efficiently and quickly by working together in the same building.

High-Quality Molds Made In-house

At MSI, we design and build our customer injection molds in-house. Our team of designers and machinists work with advanced software and CNC machining to create your mold exactly to your part’s specifications.

Our capabilities include economical high-quality insert and free-standing molds. A description of these two mold types can be found on our plastic-injection-molds page.

Why Choose MSI?

MSI Mold management has over 35 years of expertise delivering superior quality injection molded products to a wide range of industries. We’ve developed and produced components for agricultural equipment, oil and gas equipment, consumer recreational and sporting goods, material handling, medical and laboratory instruments, aerospace, automobiles and a huge range of industrial applications:

  • Commercial plumbing
  • Electronics
  • Hydraulics
  • Hand tools
  • LED lighting
  • Machinery
  • Water treatment
  • Aerospace

Full Service Injection Molding

MSI Mold’s expertise comes from a broad range of experience in injection molding as both technical consultants and manufacturers. Located about 30 miles north of downtown Detroit, MSI originally started in 2005 serving injection molding manufacturers in the local automotive industry. We worked with these firms on production process development, tooling program management and part design.

In 2009, we shifted operations to a new facility to implement engineering changes to customers’ molds and mold trials. As we expanded to include more services, production injection molding was the next logical step.

We’ve been a full-service injection molding company and plastic mold manufacturer since 2005, proudly serving Michigan and the rest of the United States as well as international clients.

Injection Molding Manufacturers

From mold making services to design and engineering, MSI Mold delivers high-quality components with hassle-free sourcing and world-class customer service. Our injection molding professionals are ready to bring your molds and custom plastic parts to life. So request a quote through our convenient online form or email us at