Custom Injection Molding

Custom Injection Molding

Our rich experience as a USA plastic injection molding company includes production capabilities for many different industries, plastic materials, and specialty add-ons for your custom plastic parts.

Our focus is on production runs of 100 to 100,000 units per order. We know every custom injection molding project is different, but every MSI Mold customer enjoys our key values:

  • High quality custom plastic injection molds and custom parts with reliable on-time deliveries
  • Outstanding attention to customer needs through advanced quality planning
  • Fast quotes and delay free communication
  • Friendly and knowledgeable customer service
custom injection molding

Custom Plastic Molds

Two of the biggest hurdles of every plastic injection molding project are the cost and lead time required for making the mold to produce your custom plastic parts. Most injection molding companies in the USA either outsource the customer’s plastic injection molds directly to China or to a local injection mold making company.

In fact, often times even the local USA mold making companies will outsource the very same mold to China which was thought as being made in the USA.

All of these options present big obstacles to a cost effective and smooth launch of new plastic molded parts. At MSI Mold we build all of our customer injection molds in-house. We have also developed rapid tooling systems that allow our customers affordable injection mold costs and fast lead times without sacrificing quality.

Before you select an injection molding company to work with, call us to speak with a knowledgeable expert about having your custom plastic injection mold made by MSI Mold or send us your RFQ to get started.

Custom injection molding is used to create highly precise components with multiple custom features and complex geometries. Our engineers and technicians at MSI Mold are experienced in designing and creating fast cycling molds for your most challenging thermoplastic part requirements.

Custom plastic molds

Mold and Part Costs

Target Cost Planning for Custom Injection Molding

Custom plastic injection molding costs mostly depend on several factors:

Factor #1

Part complexity

Part design features such as sharp corners, thin ribs, or undercut features require more expensive tooling and, frequently, a secondary EDM machining process. During a quote consultation we will point out part design considerations that can reduce overall costs when possible.

Factor #2

Mold construction

Of the two primary categories of injection molds, insert style molds will cost significantly less to create than free-standing molds. Insert style molds allow us to only make the mold components that are custom for each part shape, and there is no sacrifice of part quality, mold quality, or mold life.

Factor #3

Number of mold cavities

The lower the number of mold cavities, the fewer parts will be produced per machine cycle, meaning a higher cost per part. Though a one cavity mold will be less expensive, there is an inverse cost relationship between adding mold cavities and the cost of the parts.

Factor #4

Part Size

Simply put, the larger the part, the higher the costs will be for the injection mold and the parts. Small plastic parts only require small machinery to make molds and parts, and large parts require large machinery to produce the molds and parts. The machinery & equipment costs for injection molding companies are proportionate to the size of the equipment.

Factor #5

Material choice & part weight

The plastic material chosen for a part not only affects the weight of the part, but it also impacts production rates, which is a considerable cost factor for custom injection molding. Heavy thick-walled parts will cost a lot more to produce than parts that are designed with weight reducing features.

Factor #6

Cycle time

The length of time it takes a molding machine to finish a complete production cycle from mold closing through ejection of the parts is called cycle time. The cycle time (amount of time it takes to create a part) is the single largest cost factor in custom plastic molding aside from plastic material costs.

Factor #7

Extra add-on costs

Specialty packaging, secondary operations like pad printing and extra machining contribute to a higher cost for custom plastic parts. In very low order quantities these add-on costs can be very expensive.

Mold Cost Relationship to Mold Cavities and Part Cost Relationship to Mold Cavities

Why Selecting the Proper Plastic Material Is Critical for Custom Injection Molding

Since there is a wide variety of material options for custom plastic molding, it is most helpful for product engineers to focus on the primary function and working environment of their parts. This allows a narrowing down of the right material for your custom injection molding project.

At MSI Mold we are happy to provide consultation to help customers find the right plastic material choice for their custom molded parts.


Choosing the right material hardness depends upon the part’s intended use, environment, required abrasion resistance, and how a user will interact with it. Plastic hardness is measured and represented by number values on “shore 00”, “shore A” or “shore D” scales. For example, a gel shoe insole might have a hardness of “30 shore 00”, but a construction worker plastic hard hat might have a hardness of “80 shore D”.

Flexibility & impact resistance

Different from hardness, flexibility or stiffness indicates how much or little a material will resist stress. Impact resistance is another specification to consider for plastic materials that might see tough conditions across wide ranging temperatures.

Part Weight

The mass or density properties of plastics can vary widely. In turn, for any given part volume in cubic cm the part weight can vary widely simply by picking a different plastic material. Keeping in mind that plastic raw materials are sold by the pound, unnecessary costs can add up very quickly throughout a product life cycle if the wrong plastic material is chosen.

Material Cost

Fitness for the product application should be the primary concern when choosing the plastic type for a particular custom molded part. Cost per pound should only be considered where there is a choice of suitable materials.

Types of Plastic Materials Used

We use many thermoplastic materials for your custom plastic part needs. Many of the plastics listed here are always in stock and ready for production. If your product needs a custom color we can help!

  • ABS
    Acrylonitrile Butadiene Styrene
  • ASA
    Acrylonitrile Styrene Acrylate
  • HDPE
    High Density Polyethylene
  • LDPE
    Low Density Polyethylene
  • PA 6
    Nylon Type 6, Aliphatic Polyamide
  • PA 66
    Nylon Type 66, Aliphatic Polyamide
  • PC
  • PC/ABS
    Polycarbonate + Acrylonitrile Butadiene Styrene
  • PMMA
  • PP
  • POM
    Acetal, Polyoxymethylene
  • TPE
    Thermoplastic Elastomer
  • TPO
    Thermoplastic Polyolefin
  • TPU
    Thermoplastic Polyurethane

The Mold and Machinery Technologies Used by Good Plastic Injection Molding Companies

Any reputable plastic molding company will have expertise in a variety of technologies for designing and manufacturing molds and custom plastic parts, including but not limited to:

Modern CAD software

Computer-aided design software allows the manufacturer to take a simple 2D drawing and create an optimized 3D design for your parts and injection molds. Our knowledgeable and friendly technicians put their expertise to work on designing custom parts and molds for your manufacturing needs.

In-house CNC machining

Computer numerical control is a technology that uses a software program to direct the manufacturing equipment in machining the part shape and features into the plastic injection mold. This process is how aluminum or tool steel is machined to form the custom injection mold for production. Our mold manufacturing processes are fast and produce high-quality injection molds in-house.

All-Electric servo injection machines

At MSI Mold, all of our injection molding machinery is modern all-electric servo driven. That means our machines use 50-70% less energy than traditional hydraulic pump motor driven molding machinery of the past. We are proud to say that in addition to being environmentally and workplace cleaner, our machinery is the most precise and repeatable that is available in our industry.

High quality parts that'll meet your expectations.