Steve Melito

Steve Melito is a technical writer who raises bees and chickens when he's not digging into manufacturing and technology. He lives and works in the Berkshires.

All articles from the author

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The Ten Most Common Injection Molding Defects

Injection molding defects can reduce the cosmetic appeal and structural integrity of injection molded parts. The causes of these imperfections range from issues with tooling or materials to problems with processing or part design. The solution to a specific defect may require corrective action by the injection molder, the mold maker, or the part designer. […]

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Troubleshooting Injection Molding Flash

Injection molding flash, or flashing, is excess plastic that forms on the surface of injection molded parts. Although some amount of flash is considered to be a normal part of the plastic injection molding process, excessive flash can mar the surface finish of parts or interfere with part seating, mating, or assembly.  In this article, […]

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Steel vs. Aluminum for Injection Molds

Most injection molds are made of steel or aluminum. Conventional wisdom holds that steel molds are more expensive, and that aluminum is more cost-effective for lower part volumes. However, that’s not always true – at least if you choose Fictiv for your next injection molding project. There are important differences between different types of steel […]

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Low-Volume Injection Molding Use Cases

Low-volume injection molding lets you leverage the benefits of plastic injection molding without incurring the costs associated with producing high volumes of parts. This article explains what low-volume injection molding is and considers its advantages and disadvantages. You’ll also learn about the relationship between part design and low-volume plastic parts production, and examine alternatives such […]

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Wall Thickness Recommendations for Injection Molding

Injection-molded parts can be complex to manufacture. For best results, designers must understand the molding process, design for manufacturing (DFM) best practices, and the importance of material selection. One of the key factors to consider is the part’s wall thickness.  There is no single, universal minimum wall thickness and maximum wall thickness for injection molding. […]

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Color Matching for Injection Molding

Color matching for injection molding makes it possible to get plastic parts in a specific color or combination of colors. That’s important if you’re designing parts that need to look a certain way, whether it’s for aesthetic appeal, safety reasons, or to match a larger assembly. Perceptions of color are subjective, however, and the way […]

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Overmolding Part Design

Overmolding is a manufacturing process that molds a polymer over a substrate. It eliminates the need for parts assembly after molding, and allows designers to leverage the individual properties of multiple materials. Plastic overmolding is used to produce the handles on metal-bladed screwdrivers, but can also be used in products that don’t contain any metal […]

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Injection Molding Tolerances: An In-Depth Look

Injection molding is one of the most common production technologies and is used in almost every industry from automotive to aerospace. Maintaining tight dimensional consistency is critical across high production volumes, especially if the injection-molded parts are used in larger assemblies. This article will discuss the importance of injection molding tolerances and their relationship to […]

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Product Study: Injection Molding Sliders, Lifters, and Handloads for Undercuts

The Challenge: Undercuts and Lower Volumes Undercuts are recesses or projections on the surface of an injection molded part that prevent the part’s direct removal from the mold cavity. If the undercut is external, then a device called a slider can be used. If the undercut is internal, then a device called a lifter can […]

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Injection Molding Undercuts

Injection molding undercuts are part features that can complicate or prevent the release of injection molded parts. Examples include indentations such as side holes, vents, or slots, and protrusions such as screw threads, snaps, or latches. Often, part features like these are found in consumer electronics, automotive, and medical products. Undercuts support design complexity, but […]

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Injection Molding Sliders and Lifters vs. Handloads

Injection molding sliders and lifters are mechanisms that release a molded plastic part when an injection mold opens. Slides, or sliders, release external undercuts, recesses or projections on a part’s outer surface that prevent the part’s direct removal from the mold cavity. Lifters, on the other hand release internal undercuts, recesses or projections on the […]

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Tips to Reduce Injection Molding Costs

What’s the best way for designers to reduce injection molding costs? The first step is to identify and understand the sources of your expenses. Next, it’s critical to make cost-saving decisions as early as possible in the design process or risk getting locked into a course of action that’s difficult and expensive to change later […]

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The Importance of Cooling Lines in Injection Molding

Cooling lines, or cooling channels, support the uniform cooling of injection molds and the production of plastic parts that are free from sink marks and warping. During the injection molding process, a plastic resin is heated and then injected into a mold cavity. The plastic fills the cavity, conforms to its shape, and is cooled. […]

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SPI Guidelines for Injection Mold Surface Finish

SPI guidelines provide injection molders and product designers with a standard way to describe the surface finish of molded plastic parts. These guidelines were defined by the Society of the Plastics Industry (SPI), a U.S.-based trade association that’s now known as the Plastics Industry Association (PIA, or PLASTICS). By providing a “common language” for surface […]

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Thermoplastics vs. Thermoset Plastics: Material Properties Overview

Thermoplastics and thermoset plastics are classes of polymers used in injection molding, CNC machining, 3D printing, and urethane casting. Like elastomers, another class of polymer, thermoplastics and thermosets both consist of long, repeating chains of molecules. Under a microscope, the structure of a thermoplastic resembles a railroad track while a thermoset material looks like a […]

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Specialty Plastics and Polymer Blends for Injection Molding

Specialty plastics for injection molding have material and performance properties that meet the requirements of more demanding applications. These include engineering plastics and resins for medical, automotive, aerospace, electronics, and other applications. Polymer blends — mixtures of two or more polymers that form new materials with different properties — are also used to meet tougher […]

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Product Study: Gate Sizes and Placement in Injection Molding

The Challenge: Avoid Gate-Related Part Defects Injection molding gates are larger or smaller in order to support the direction and volume of flow into the mold cavity. If a gate is too large, molten plastic may fill the cavity unevenly and cause part defects such as weld lines and shrinkage. If a gate is too […]

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Common Plastic Materials for Injection Molding

There are hundreds of plastic materials for injection molding. Different plastic resins impart different end-use properties, such as tensile strength and impact resistance. Injection molded plastics also have specific processing requirements, such as melt temperature and molding pressure. There are also different grades of the same plastic material, including resin types with fillers such as […]

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Top Five Guidelines for Selecting a Plastic Injection Molding Manufacturer

What’s the best way to choose a plastic injection molding manufacturer? What criteria do you need to consider, and how can you tell if a molder is the right partner for you? According to Plastics News, there are nearly 600 injection molders in North America alone. Researching all of them would be incredibly time-consuming, but […]

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Enclosure Design 101 for Injection Molding and 3D Printing

The power of an electronic or mechanical product usually comes from its internal components, but those products are recognizable because of their plastic enclosures. Those outer shells protect the components inside and make the entire system appealing and user-friendly. In this article, we’ll walk you through the steps of designing a prototype plastic enclosure for […]

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Injection Molding Gates: Pros and Cons

Injection molding gates are openings in molds that allow molten plastic to enter the cavity while controlling the direction and volume of flow. This molten plastic fills the cavity and then cools and hardens into a molded part. Gating can be large or small, but it’s usually tapered down to the orifice to avoid flow […]

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Enclosure Design for Injection Molding

As one of the fastest and most precise manufacturing methods, it’s no wonder why injection molding is often chosen for mass producing plastic enclosures. Design for injection molding is therefore an important part of the enclosure design process, and following design for manufacturing (DFM) principles is a critical element of producing a successful product. Today, […]

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How to Create the Perfect Plastic Prototype

Are you ready to create the perfect plastic prototype? You’ll probably need more than one type of prototype during the design process, which means choosing between various plastic prototyping methods and materials. Some techniques don’t support certain plastics, however, and they each offer different prototyping speeds, part tolerances, resolution, and cost. So, where do you […]

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Soft Tooling and Hard Tooling for Injection Molding

Both soft and hard tooling are used in plastic injection molding, and soft tooling is also used in urethane casting, a separate manufacturing process. For product designers, these different uses of the term “soft tooling” can be confusing. Terms like “hard” and “soft” are relative, of course, as the metal tooling used in injection molding […]

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Product Study: Part Tolerances in Injection Molding

The Challenge: Avoid Incorrect or Incomplete Tolerances Designers can specify less expensive commercial tolerances or more expensive precision tolerances on part drawings. There isn’t just one type of injection molding tolerance, however, and using the wrong tolerances can result in parts that don’t fit together correctly or that cost too much to produce. For injection […]

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Injection Molding Tolerances: 7 Questions for Designers

Injection molding tolerances are acceptable variations in size for part features and overall dimensions. They are expressed as plus or minus (±) values in millimeters or inches and vary by the type of material that’s used and the overall size of the part. Designers add tolerances to CAD files to tell an injection molder the […]

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Product Study: Undercuts in Injection Molding

The Challenge: Avoid Unnecessary Costs and Complexity Injected molded parts that have recessed features called undercuts are more difficult to eject during manufacturing. This adds costs and complexity to tooling, and undercuts that are too deep may be especially hard to remove. Yet, some product designs use undercuts for a fastening point or locating edge. […]

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Common Mistakes in Injection Molding Design

Injection molding design mistakes can cost you time and money. If there’s a problem with the design of your injection mold, you may need to modify or discard your tooling. And that means paying for and waiting for a replacement tool – which will delay the start of production accordingly. Plus, if there’s a problem […]

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Product Study: Cost-Effective Medical Injection Molds for Lower Volumes

The Challenge: Manufacturing Process Tradeoffs for Medical Product Development Plastic injection molding (IM) is ideal for high-volume manufacturing, but not all medical injection molders can provide tooling that is cost-effective for functional prototypes and low-volume production (LVP.) As a result, medical product designers may be forced to use another process during these stages of the […]

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Prototyping and Low-Volume Production for Medical Devices & Applications

Prototyping for medical devices and applications produces functional samples for testing and evaluation. These samples can be used to advance a product through regulatory gates, or approval stages, but that’s not the only reason why medical prototyping is necessary. Designers can apply what they learn and make changes, including improvements for manufacturability. When prototyping is […]

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Product Study: How Medical Companies Can Leverage Fictiv’s Broad Access to Medical Plastics

The Challenge: Materials That Meet Multiple Requirements Medical product designers need materials with more than just the right properties and price points. They may also need to consider approvals from regulatory agencies and meet traceability requirements. Although metals, ceramics, and composites are used in some medical applications, plastic injection molding provides designers with a broad […]

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Product Study: How Medical Companies Can Leverage Fictiv’s Precision Injection Molding Expertise

The Challenge: Tight-Tolerance Parts That Check All the Boxes In the medical industry, a few millimeters or microns can make the difference between an injection molded part that’s functional and a quality assurance failure. Precision injection molding can produce the tight-tolerance parts that the medical industry requires, but the tools can cost more and take […]

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Pros & Cons of Plastic Injection Molding for Medical Products

Why is plastic injection molding used to produce many medical products? It’s a proven manufacturing process that supports high-volume production with low per-part costs. Injection molding also supports design and manufacturing complexity with part-to-part integrity. Yet not all medical devices and equipment are injection molded. In fact, there are some medical products that don’t contain […]

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Injection Molding for the Medical Industry

Is it time to inject more accuracy, versatility, quality, and cost-efficiency into your medical manufacturing project? Then injection molding might be just what the doctor ordered. This proven production method can create high volumes of tight-tolerance parts from a wide variety of polymers, including medical-grade plastics that meet tough regulatory requirements and testing standards. Whether […]

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Draft and Texture in Plastic Injection Molded Parts

It’s always a good idea to go through several drafts of any design before finalizing a part. Prototyping can help you get the right design, but you’ll need a different type of draft for a successful injection molded plastics project. In injection molding, draft is the angle that you apply to the vertical walls of […]

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What You Need to Know About Injection Molding Gates

Is your injection molding project ready for success? Sure, you’ve thought about most of the injection molding manufacturing process. You’ve designed your mold with care, researched and selected the right material, and finished your CAD file or part drawing. But have you considered the type of injection molding gate to use? A gate might seem […]

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ABS Injection Molding: Material Properties and Processing Considerations

ABS is a commonly used plastic injection molding material with three main ingredients: acrylonitrile, butadiene, and styrene. Each of these monomers imparts specific properties and provides ABS terpolymer with a robust combination of features. The “A” in ABS, acrylonitrile, imparts hardness and heat and chemical resistance. The “B”, which stands for butadiene, provides toughness and […]

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A Beginner’s Guide to Post-Processing for Plastic Injection Molding

Post-processing improves the properties of plastic injection molded parts so that they are ready for end-use. It includes corrective actions that remove surface defects and secondary processes for decorative or functional purposes. For example, post molding operations can remove excess material (known as flash) or apply part numbers. As its name suggests, post-processing always occurs […]

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Checklist: Know When You’re Ready to Go from 3D Printing to Injection Molding

It’s not always easy, but don’t make it harder than it needs to be. Moving from 3D printing to injection molding isn’t as simple as just using your computer-aided design (CAD) file with a different piece of equipment. Because 3D printing offers greater design freedom than injection molding, you may need to modify your CAD […]