Achieve Tighter Tolerances than with Injection Molding Alone

Machining is an umbrella term for the manufacturing techniques used to produce parts made from a wide range of materials. Many companies employ computer numerical control (CNC) machining to achieve greater precision and accuracy in their end products. Plastic machining has followed the same path.

Simply put, CNC machining is a subtractive fabrication method where programmed software and written code controls the machinery used in the manufacturing process, determining everything from the movement of the cutting utensil and the part to spindle speed, RPMs, and part dimensions. The programming in CNC machines incorporates all the exacting, high-speed movements needed for accurate production, enabling detailed customization. CNC machining controls a range of complex machinery used to cut, shape, and create different parts and initial prototypes.

When deciding on a machining method for a part, it is essential to keep in mind the industry application, design, and construction material as these factors significantly impact the production process and final result. For plastic machining projects, these are vitally important as plastic materials are more susceptible to deformation (warping and cracking for example) when improperly handled.

Complicating matters further is the wide array of plastics and plastic composites available, with each containing its own properties and best-use cases. These challenges mean it is essential to partner with a plastics machining partner that has vast experience, expertise, and experience in working with a variety of plastics materials and proven track record.

Expert Molding Assistance: Few molders can tackle the challenges of dealing with Torlon® PAI. Learn why, and how Ensinger Precision Components delivers, here. 

Why Use CNC Machining for Plastics?

While injection molding is capable of delivering high-quality thermoplastic components, some markets — such as aerospace, defense, medical, oil & gas — requires extremely tight tolerances. These exacting tolerance requirements are not always achievable with injection molding alone, but with the addition of CNC machining, adhering to the tightest tolerance requirements is possible.

Because plastic machining is CNC guided, the process is infinitely repeatable. The level of precision will be uniform for each part produced, unlike manual machining. Whether producing a prototype, or an extended production run, the retention of the design and adherence to tight tolerances is consistent.

Other benefits from plastic machining, either to augment inject molding or replacing it, include:

  • Quick turnaround on prototypes with no molds to produce
  • Smoother finishes
  • High efficiency with fewer production steps
  • Automated systems means lower personnel risks and production costs

Common plastic machining techniques include turning, milling, and drilling. Turning operations take place on a lathe, which rotates and manipulates the workpiece to allow the stationary cutting tool to remove excess material according to the design. Milling operations, conversely, require the rotation of the cutting tool around a stationary workpiece. Drilling operations involve creating varying diameter holes in the plastic part, but comes with the risk of damaging the structure of the piece.

Plastic Machining Challenges

Plastic machining presents some challenges not found when working with other materials. For example, some plastics have lower thermal resistance than metals meaning expansion, overheating, and thermal damage could result. There are greater machining restrictions as well, often determined by the specific plastic being machined.

Despite these limitations, plastics offer several manufacturing advantages as well including:

  • Superior strength-to-weight ratios
  • Broad insulating properties (including electric, thermal, and vibration)
  • Greater resistance to corrosion and chemicals

Specific plastics also maintain their own specialized benefits. For example, PEEK (polyether ether ketone) is a popular machining choice due to its ability to withstand high temperatures as well as extensive chemical and wear resistance.

Plastic machining also allows manufacturers to add additional value to high performance thermoplastics, which bring extraordinary properties. CNC machining allows these plastics to be tailored further to specific use cases.

You’ll want to work with a machining partner that is experienced in dealing with these challenges. Not every plastic manufacturing company will have the expertise to assist you at every step — from part and assembly design to manufacturing — in making the most of your investment in these specialized materials.

Powering Essential Industries: Learn more about high performance thermoplastics and why their characteristics are valued in demanding applications.

Trust Ensinger Precision Components for Plastic Machining

For more than 80 years, Ensinger Precision Components has used high performance thermoplastics to design and manufacture solutions — whether injection molded, machined, stamped, fabricated, or assembled — that exceed the demands of your specific applications so you can focus on product and market development.

Our plastic manufacturing capabilities include injection molding, plastic machining, a plethora of advanced manufacturing techniques and services, and a robust quality assurance program backed and validated by a host of standards. Our plastic machining capabilities are built on cutting-edge equipment, such as dedicated HAAS CNC Lathes and HAAS CNC Machining Centers. We also deploy collaborative robots for CNC machine tending.

As a North America division of Ensinger — a global leader of high-performance polymers offering multiple fabrication solutions throughout the world — we tap into the capabilities of 35 world-wide locations to tackle any plastic engineering demand including injection molding, compounds and composites, industrial profiles & tubes, machined parts, sintered plastics, filaments, and more.

Connect with Ensinger Precision Components today to learn more.