Questions About Plastic CNC Machining

Your Top 6 Questions on Plastic CNC Machining Answered

You asked. We're answering. 

Updated 6/28/2024 


We here at Controlled Fluidics practice precision and excellence using 5-axis CNC machines (among several others) to produce customized plastic components and assembly. We maintain our place at the forefront of utilizing the newest technologies and practices for precision plastic machining and manifold fabrication.

Today, we will answer your top 6 questions on plastic CNC machining.

What benefits are there to machined plastic parts compared to other materials, like metal?

We tout several benefits when comparing plastics to other materials like metal. While other materials certainly have a place, plastics can provide advantages in the following ways:

  1. More lightweight,
  2. Stronger; more resistant to external factors like corrosion,
  3. Easier to work with; less labor intensive to create, and
  4. Generally easier to maintain once in use.

Many people over the past few decades have engineered plastics to have remarkable properties that can outperform other materials that were traditionally used for certain products. As plastics have consistently proven their strength, durability, and even flexibility since their inception, they have replaced and lowered production costs while exceeding in performance compared to their predecessors.

What Plastic Materials Do You Use in CNC Machining?

While every manufacturer is different, most know which plastics do well with CNC machining and which do not. Ensure your manufacturer provides expert support on choosing the right material for each project's unique needs. That said, some of the best materials used in CNC machining include:

  • ABS: Strong, stiff, light, low cost, and impact resistant.
  • Acrylic: Easy to machine, with high clarity, light transmission, and close tolerance.
  • Polycarbonate: Good clarity, tough, with a high continuous use temperature.
  • Radel®: Hydro and thermal resistant and stress cracking resistant.
  • ULTEM®: UV stable and FDA compliant with superior heat resistance.
  • PEEK: Excellent chemical resistance.  Abrasion resistant, low moisture absorption.
  • LDPE: Flexible, stress resistant, and malleable.
  • Tecadur: Radiation and chemical resistance, clarity, and durability.

This is only a partial list of the carefully chosen substances we use. Visit our Plastics Materials list for detailed specs. Don't know where to start? Take our Plastics Materials Quiz. 

Why Would Someone Choose CNC Machining over other methods for crafting custom plastic parts?

The answer involves a few parts:

  1. Cost efficiency,
  2. Channel and geometric complexity,
  3. Product purpose/needs, and
  4. Ease of machining

With cost efficiency, most prospective clients ask about CNC machining over plastic injection molding, as an example. Plastic injection molding has its advantages. The method serves as a great avenue for those that have a disposable/one-time use product meant for mass consumption (e.g. plastic bottles), produce a larger quantity (100,000+) of their product, and/or their product does not have complex internal geometries or channels. This also applies if a product does not have a uniquely specialized purpose or a niche function for a particular industry or intense applicable regulations (note: as with everything, there are exceptions). If the product falls into any of these categories, cost savings generally begin to decrease with CNC machining over plastic injection molding.

"We see it a lot on the consumable stage. A full-bonded manifold from us can be quite expensive. Oftentimes a simple two-layer acrylic manifold of four inches by six inches with kind of medium complexity, can run about $200 a piece. Obviously as a consumable, that would be a difficulty for the customer." - Tom Rohlfs, President and Principal Engineer at Controlled Fluidics

That is not to say that a manufacturer could find a way to save costs, if CNC machining is the best way. However, the challenge then is then calculating the balance between what the product needs (i.e. the product's primary function and purpose) and budgetary considerations. Some features may need reconsideration if cost is a key influencer. This could mean changing to a more easily machined material over another or eliminating some features that the product had planned to have.

A reputable manufacturer should inform any potential customer if another method would be better suited to their needs or what concessions a designer can make to meet their parameters.

What About 3D Printing vs CNC Machining? 

We have an entire post dedicated to addressing the differences between the two. However, they have similar answers to plastic injection molding as stated above. Factors that include cost, features, and the component's expected function need consideration before selecting 3D printing.

When thinking of cost, 3D printing can serve best when the product is a "rough" prototype testing certain design aspects. This includes if a concept has 3D internal structures, complex configurations that cannot be easily machined, and/or the expected material itself is difficult to machine. We don't recommend this course for those that expect a large quantity made quickly. 3D printing can take up much time with single pieces that then turn what could have had a more efficient production into something lengthy and expensive.

However, if looking to make either small quantities or for testing purposes, 3D printing may present itself as the better option. It's best to consult with the manufacturer to explore options for production.

What Plastic CNC Machining Services Can Specialty Manufacturers Provide?

Generally, plastics manufacturers should provide the following services:

We take pride in our abilities to produce complex bonded, drilled, and injection molded manifolds and machined components with the closest tolerances possible. To produce these products, we use the most advanced technology available to perform these services.

What Industries Do Plastic Manufacturers like Controlled Fluidics Serve?

When it comes to specialized plastic components, some manufacturers are more well-versed in the high standards of several industries, such as medical or research. Others are better suited for end-consumer products. We recommend researching plastic manufacturers thoroughly to understand what they're best at and if it fits your project's needs.

Our CNC and plastic machining tools and processes are fine-tuned to meet the needs of specialized and unique products, such as:

  • Diagnostic tools, typically used to detect health or disease vectors.
  • Internal and external medical instruments for single or multiple use after repeated sterilization.
  • Semiconductor components for solid state electrical conduction.
  • Scientific measurement and application devices, e.g. syringes and collection trays.

A machining business must display consistent efficiency, precision, and speed to meet and exceed clients' needs. Ask if every project comes with design support and prototype testing from an expert team of designers and engineers to ensure complete satisfaction with the end result. If a manufacturer has this missing, we recommend seeking out another that can meet your needs.

What's the Environmental Impact of CNC Machining Plastics Compared To Other Manufacturing Methods?

We could make an entire multipage article to answer this question. However, we will answer this in basic terms for right now and expand upon at a later time.

The exact impact depends on several factors that include material waste, energy consumption to produce, and recyclability. As CNC machining is a form of subtractive manufacturing, this can lead in a good amount of waste material. This becomes a challenge when that plastic material is either unrecyclable or requires a special facility to process for recycling. However, such materials count few among the several most manufacturers and designers use for their components and devices. Generally, only the most specialized applications, like those used in the International Space Station, would require a plastic material that could be difficult to recycle. 3D printing also uses materials that could provide recycling complications as well. Always investigate which plastic materials suit your needs, if only to confirm.

Yet when compared to injection molding and 3D printing, CNC machining can take less energy for production. This holds true for smaller and lower volume runs without a highly intensive upfront resourcing process as in injection molding. With injection molding, engineers need to ascertain the volume that they are expecting and ensure that they will meet the volume that can justify the cost of the mold. As mold creators make their molds from metal, they need a substantial amount of heat and energy to craft the molds to the necessary specs. Also, with the constant heating of the plastic material for molding, that would count towards injection molding's energy consumption.

What we can say is that staff need to consider their expected volume, the product's intricacies, and their expected plastic material to make an accurate conclusion about their project's expected environmental impact.

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