When you need plastic machining, consider one of these six materials, ranked from good to better to best. Let the countdown begin!

Coming in at number six is PEEK, a high-performance plastic often used for medical applications. This material has an operating temperature of up to 480 degrees Fahrenheit and tends to tolerate all common solvents. While PEEK is incredibly strong and possesses high chemical and heat resistance, it's susceptible to UV light and doesn’t do well with halogens, sodium, and some acids.

Thermoplastic and thermoset resin are the two main types of plastic used for the injection molding process. Thermoplastic can be reheated multiple times while thermoset cannot. For example, a milk jug is a thermoplastic, while a tire is a thermoset.

Acrylic has a low impact strength, causing it to chip and crack easily during waterjet cutting and CNC machining services—and, more importantly, in the part’s end-use environment. For these reasons, it’s our least favorite plastic to work with.

Aberdeen Technologies’ Reputation: Today, Aberdeen Technologies continues to be a leader in complex insert molding parts, such as helping develop devices with smaller footprints and ever-thinning lumen diameters. This pioneering work on multi-lumen heart catheters stands as a testament to our commitment to innovation in insert molding and patient safety.

Customers like acetal because it's wear-resistant, naturally slippery, and doesn’t expand when exposed to heat and moisture. While not ideal for parts requiring acid resistance, it's an excellent material for many other uses, including bushings, gears, bearings, and more.

Our Innovation: Our proposed solution involved placing stainless steel wire mandrels through individual extension lumens, then positioning them into separate passageways in a multi-lumen extrusion. This assembly was then placed in a mold and polyurethane was insert molded in the shape of a manifold. Afterward the mandrels were removed, leaving unobstructed passageways in the plastic manifold connecting the extension lumens to the multi-lumen extrusion.

Plastics have many benefits. They're widely available, strong relative to their weight, and compatible with many modern manufacturing methods, including CNC machining, high-precision waterjet cutting, and 3D printing.

Injection Molding involves heating thermoplastic resin to a molten state and injecting it into a steel mold. There are two ways to accomplish this, insert molding and overmolding.

The polymers that make up plastics combine in various ways to yield numerous different materials, each with unique properties and uses. While some applications have requirements that necessitate a specific type of plastic, there are times when you may have flexibility with the plastic you choose—and there are certain plastics that are better for manufacturing than others.

Another consideration is if the mold can close off to the insert so that there isn't any blow-by, meaning the plastic will blow past the insert during manufacturing, causing a flange or additional plastic that will need to be trimmed off.

Overmolded material is often rubber or thermoplastic. Overmolding can be used as a double injection molding process, often resulting in either a chemically bonded part of the materials being mechanically interlocked. The types of products that are overmolded include scissors and medical products such as cannulas, needles, tubing, and catheters.

This plastic is great for many applications and is commonly found in parts for the packaging industry and electrical and equipment manufacturing. Its resistance to swelling when submerged in water makes polypropylene ideal for end-use environments like labs, kitchens, and medical settings.

Insert molding is a manufacturing technique that involves encasing an established part, typically metal, with thermoplastic resin to create a single, integrated unit. Examples of insert molded applications include electrical wire harnesses, multi-lumen catheters, knife blades, and screwdrivers.

The molds used in insert molding, over-molding, and injection molding are made up of steel plates, water lines, and ejection pins, with other components as needed. A simple open-shut mold is a mold that can be pulled apart without any slides or other components getting in the way.

PTFE isn't appropriate for every application, however, as it has low abrasion resistance and is susceptible to creep, which causes dimensional changes in the material over time.

Overmolding creates a powerful molecular bond by optimizing the co-polymerization of the two substrates (one of which is usually hard while the other is soft). The ability to create a molded unit from two different types of materials in one process is the biggest advantage of the overmolding process.

Polycarbonate (PC) is a naturally transparent, pliable, heat and impact-resistant plastic commonly used in eyewear, medical devices, automotive components, greenhouses, and more. Clear PC can transmit light as effectively as glass and is a better choice for clear-viewing window applications because of its high impact strength, especially when compared to other transparent plastics like acrylic. If transparency isn't a concern, PC can also be purchased with added colors.

Every plastic is unique, but some universal considerations should always be taken into account when precision machining plastic. Here's the quick list of rules we follow:

In both Insert Molding and Overmolding, molds play a pivotal role. Mold components, including mold cavity design, pins, and alignment tools, guide the plastic during the manufacturing process. Selecting the right mold design is essential to ensure the desired outcome in terms of product quality and structural integrity.

While most plastics are generally quicker to machine than aluminum or steel, achieving tight tolerances can be tricky. If, for example, a plastic part calls for a bearing bore with a tight tolerance, we may need to let the material rest and stabilize between cuts, slowing us down. When machining acetal, however, the material is more likely to retain its size.

Molding inserts are the established, or pre-formed, parts that the thermoplastic resin will mold around during the insert molding process. These require special attention, as not all parts may be suitable, so they have to meet strict temperature and pressure resistance requirements.

Unique Challenge: In 1983, a Baxter engineer approached Aberdeen Technologies with a revolutionary product idea to create a multi-lumen heart catheter using insert molding. At the time this had never been done before. All catheters were assembled using a pre-molded manifold and then gluing the extension lumens in place. This slow and inefficient process resulted in high rejection rates and hazardous adhesives for the medical industry

There are, however, a few notable downsides to using polycarbonate. It yellows after prolonged exposure to UV rays, doesn't perform well around hydrocarbons, and can degrade in water hotter than 160 degrees Fahrenheit.

ABS is high on our list for its excellent machinability and strength. It has 60% of the overall strength of the number-one plastic but surpasses our top choice in impact strength. We’ve been known to slam ABS parts on the ground to demonstrate the material’s superior impact strength to customers and colleagues!

Overmolding differs from insert molding as it involves the use of two separate materials to produce a single molded product. Overmolding is still a part of the injection molding family and deals delicately with the molding insert. A common use case for this specific type of molding is cable overmolding or micro molding.

Use high-precision waterjet with HPX sharp garnet to avoid the introduction of heat and achieve precise finishes and tolerances

Insert Molded Solution: An alternative design was formulated which separated the extension lumens into a circular pattern, allowing for more space between the mandrels and preventing them from touching during molding. This was a success and today our solution is still utilized where there are more than 3 lumens in a catheter assembly.

Polypropylene is a cost-effective plastic for CNC machining or waterjet cutting services. Benefits include its chemical resistance, slippery surface, and electrical insulation capability.

While Insert Molding and Overmolding share the fundamental concept of molding plastic around existing components, they differ in the number of steps involved and the nature of the resulting product. Insert molding is often a single-shot process, whereas Overmolding is a two-shot process.

The biggest drawback is that it breaks down in the presence of certain solvents, cleaners, and alcohols. Recently, we had to rule out ABS for process rollers in a printer because the solvent used to clean the printing ink would have degraded the parts over time.

The injection molding process starts by introducing thermoplastic resin into a hopper. The resin then undergoes heating, reaching temperatures ranging from 300° to 650° Fahrenheit, causing it to melt. Once in a molten state, it is then pressurized and injected into a sturdy steel mold.

Generally, this manufacturing process is carried out on a machine specially designed and built to carry out a double injection in a single cycle. The first stage involves injecting one type of plastic into a mold. On completion of this insert molding process, the machine rotates the plastic mold automatically before injecting another type of plastic into the mold. This is what is known as overmolding.

Initial Complication: The greatest challenge was ensuring the channels were not touching one another, which would result in leakage between the passageways when fluids were introduced into the assembly during a surgical procedure. The first design featured a flat "Y" shaped manifold. Unfortunately, keeping the mandrels from crossing paths during injection molding proved incredibly difficult. Even minor shifts caused channels to touch, compromising the integrity of the final product.

Allow for stabilization and cooling when using cutting methods that generate heat, especially with tight tolerance parts

We'll always choose the best material for your part, and if acrylic is the right choice, then we won't think twice about using it. However, the problem is that acrylic is commonly used for clear viewing panels when polycarbonate is likely a better option.

Inserts typically have to have undercuts or bosses in order to provide better retention strength with the molded plastic.

ABS is affordable, stable over time, and a good insulator. You'll often see it in electrical applications, rapid prototyping, electronic enclosures, and consumer goods.

This process not only lowers assembly and labor expenses but also grants manufacturers greater design flexibility without requiring any sacrifices in the structural integrity of the part. Insert molding is revered as one of the best methods to manufacture lightweight and compact parts that are reliable, durable, and fully functional.

Acetal (also known as Delrin) is our top plastic choice thanks to its machinability, high strength, and ability to hold size better than other plastics.

More recently, some 3D printing technologies have been used to overmold objects of two or sometimes more materials. One material is commonly known as the substrate. The substrate is either partially or fully covered by a second material referred to as the overmolded material. The substrate material can be anything from metal to plastic or glass.

PTFE, more commonly known as Teflon, has made a name for itself thanks to its non-stick properties. It's often used to coat kitchenware but is also found in the medical and technical industries. In addition to its coveted anti-adhesion characteristics, PTFE is resistant to chemicals, high temperatures, UV rays, weather, light, and water.

Overmolding, is an effective manufacturing approach employed by industries to manufacture complicated components that are too complicated and uneconomical to produce using a single molding process.

Machining PEEK is expensive. Due to the high cost, you may want to opt for another plastic option for your application. Still, when you need it, it's a great recyclable and biocompatible replacement for metal, and it’s compatible with CNC machining.