Learn about AIP’s precision machining capabilities for mission-critical components.

 

High-performance precision plastics require high-performance precision CNC machining.  CNC machines, or computer numerically controlled machines, are electro-mechanical devices that use tools at varying axes (usually 3-5) to produce a physical part from a computer design file.

 

Our modern society runs on CNC machined plastic components – from everyday household piping to critical spinal implants.  The breadth of materials, shapes and industries served is endless.

At AIP, we precision machine parts for industries such as the aerospace & defense, medical & life sciences and power & energy.  Each part that is CNC machined comes with design specifications and dimensional tolerances.  Our machinists are capable of crafting parts at .002 mm tolerance, which can make a whole lot of a difference in the performance of a mission-critical part.

 

Let’s back up a moment though.  What are dimensional tolerances? And how do you know if your project should demand a tighter tolerance?  Read on in this month’s blog to find out.

 

Let’s Talk About Tolerance

 

What are machining tolerances?

In CNC machining terms, tolerance, or dimensional accuracy, is the amount of deviation in a specific dimension of a part caused by the manufacturing process.  No machine can perfectly match specified dimensions.  The designer provides these specifications to the machinists based on the form, fit and function of a part.

 

How are tolerances measured?   

CNC machines are precise and measured in thousandths of an inch, referred to as “thou” among machinists.  Any system is usually expressed as “+/-”; this means that a CNC machine with a tolerance of +/- .02 mm can either deviate an extra .02 mm from the standard value or less .02 mm by the standard value.

 

 

Why are tolerances critical?

Tolerances keep the integrity and functionality of the machined part.  If the component is manufactured outside of the defined dimensions, it is unusable, since the crucial features are not fulfilling the intent of the design.

 

How close can a tolerance get?

Tolerance depends on the material that you use and the desired purpose of the design.  In plastics machining, the tolerances can be from +/- 0.10 mm to +/- 0.002 mm.  Tighter tolerances should only be used when it is necessary to meet the design criteria for the part.

 

When .002 mm Matters

 

What is the .002 mm difference?  In many industries, such as the medical industry, it is crucial to machine parts with extreme precision so that they can interact with human tissue or other medical devices.  In fact, when it comes to manufacturing medical applications, subtractive manufacturing (CNC machining) provides tighter tolerances than additive manufacturing (3-D printing).

 

 


(AIP PEEK Eye Implant)
 

Tight tolerances like the .002 mm are important because plastics are machined to interact with other parts.  In particular, CNC milled or turned plastics are unique designs for limited quantities, such as custom-made brackets and fasteners, or components for prototyping purposes.

 

One of the most critical considerations when applying tolerances is to take into account fits. This refers to how shafts will fit into bushings or bearings, motors into pilot holes, and so on. Depending on the application, the part may require a clearance fit to allow for thermal expansion, a sliding fit for better positioning, or an interference fit for holding capability.

 

As with anything that is precision machined, tighter tolerances demand time and skill.  Make sure to work with a certified company like AIP that has the infrastructure and expertise to complete your project with unmatched precision and unrivaled experience.

 

Let our team go to work for you

 

With 36+ years of experience in the industry, our dedicated craftsmen and ties to leading plastic manufacturers allow us to provide you with unrivaled knowledge and consulting in material selection, sizing, manufacturing techniques and beyond to best meet your project needs.

 

AIP offers a unique combination of CNC machining, raw material distribution, and consultancy as a reliable source for engineering information for materials such as PEEK, TORLON, ULTEM and more.

 

We are AS 9100D compliant; certified and registered with ISO 13485 and ISO 9001 and standards in our commitment to machining quality custom plastic components for specialized industrial sectors. Quality assurance is included as an integral part of our process and is addressed at every step of your project, from concept to completion.

 

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PART SUMMARY:

 

PEEK (PolyEtherEtherKetone) is a lightweight highly chemical resistant thermoplastic popular in the Aerospace & Defense and Medical & Life Sciences Industries.  From implants to custom medical devices or machined lightweight aircraft components, PEEK is ideal for a variety of specialized applications.

 

MATERIAL PROPERTIES:

 

PEEK is considered a semi-crystalline, high-performance thermoplastic. This gives it enough elasticity to be precision machined to various custom designs, with strong mechanical properties that provide resistance to fatigue and stress-cracking, as well as a good structure for bearing, wear and structural applications.

 

Key properties of PEEK include:

  • Handling at temperatures up to 480°F (250°C)
  • Abrasion Resistance
  • Chemical Resistance
  • High Ductility
  • High Elongation
  • Hydrolysis Resistance
  • Low Outgassing

 

What can this polymer do?

 

Due to its elasticity and resistance to chemicals, abrasion and hydrolysis, PEEK is a highly sought-after thermoplastic for both industrial-grade and medical-grade applications.

 

Common uses include:

  • Aerospace Weight Reduction Components
  • Dental Implants
  • Food and Beverage Automated Manufacturing Equipment
  • Food and Beverage Filling
  • Medical Implants
  • Medical Instruments
  • Metal Replacement
  • Processing Equipment
  • Semiconductor Manufacturing Equipment
  • Vacuum Chamber Applications

 

So, what can this polymer do?  Let’s take a closer look at how it is applied in the Aerospace & Defense and Medical & Life Sciences industries:

 

AEROSPACE & DEFENSE

 

In 1978, ICI invented PEEK, a member Of the PAEK (polyaryletherketone) family of thermoplastic polymers.  It quickly gained recognition in the aerospace and defense industry for its weight-saving capabilities over metal alloys.  For example, Airbus used PEEK for a primary structural component in the door of the A350 XWB to improve quality and reduce weight and costs by 40 percent.  Over the next 15 years, industry professionals forecast that 41,000 new and replacement planes will be required.  Officials and engineers in the aerospace industry are looking for alternative high-performance thermoplastics like PEEK to meet this material demand.

 

Read more on PEEK’s impact in the aerospace and defense industry in our downloadable booklet below

 

As demand for stream-lined, innovative materials grows, we continue to serve and precision machine complex polymers for the aerospace and defense industries. For over three decades, we have provided flight control, fuel system, interior, engine and aerodynamic-related PEEK components for various aircraft OEM and MRO providers worldwide.

 

MEDICAL & LIFE SCIENCES

 

PEEK gained traction in the medical industry 20 years after the aerospace industry adopted it. In the late 1990s, Invibio Biomaterial Solutions commercialized a bio-compatible grade of PEEK (PEEK-OPTIMA). Ever since then, demand for medical grade PEEK devices has skyrocketed. From surgical instruments to spinal fusion implants, PEEK has a wide range of applications that only continues to expand in the medical industry.

 

Peek Neurosurgical Case Study

 

One such example of PEEK’s versatility is in neurosurgery for stroke and traumatic brain injuries.  Dr. Rohit Khanna partnered with AIP Precision Machining engineers to create a device that would expand without another operation, yet hold the “bone flap” and the rest of the skull together.

 

Problem

Dr. Rohit Khanna wanted to develop a device that would relieve swelling in the skull for patients undergoing brain surgery, which can lead to complications or even death.

 

Solution

The polymer of choice?  PEEK.  AIP’s engineers machined a medical component that was flexible, strong and sensitive enough to fulfill the necessary requirements for this critical medical part.  PEEK was also the best choice for this medical application because it was the most ductile and biocompatible.

 

medical tool built with peek polymer
 

Resolution

Currently, the FDA is processing the PEEK surgical piece for clearance to conduct clinical trials.  If it is approved to move forward, it can make leaps and bounds in reducing the need for multiple brain surgeries, saving more lives.

 

Get the full case study on PEEK

 

What can this polymer do?

From concept to completion, our team of engineers will work with you to realize the final product.  With some of the fastest lead times in the industry, our unrivaled technical experts we can tackle your polymer challenges.

 

What Can This Polymer Do? Supportive Information

PEEK VARIANTS

 

Download our “What Can This Polymer Do?” booklet.

We’ve put together our premier PEEK applications in a condensed booklet you can take with you.

Learn here.

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An Informational Brief on Polymer Machining

 

Nylatron® is Quadrant’s trademark name for a whole family of wear resistant and low friction Nylon polymers, most of which are filled with molybdenum disulphide (MoS2) powder. What makes this material popular for industrial and bearing applications is its mechanical properties and impressive wear-resistance.

 

In our latest machining guide, we discuss what goes into machining Nylatron, and how its considerations differ from other manufacturing options such as metal machining, injection molding, and 3D printing.

 

Machining Nylatron: A Plastics Guide shows you how AIP Precision Machining approaches this material and its machining process. To start, we’ll explain the difference between machining Nylatron, a thermoplastic, and machining thermosets.

 

 

Machining Thermoplastics vs Thermosets

 

We’ve already said that Nylatron is a thermoplastic, but what does that mean exactly?

 

All polymers can more or less be divided into two categories: thermoplastics and thermosets.  The main difference between them is how they react to heat. Thermoplastics like Nylatron, for example, melt as heat is increased to the material’s melt point, while thermosets remain “set” once they’re formed regardless of heat; rather, they simply char or burn. Understanding the technical distinction between these types of materials is essential to CNC machining them properly.

 

What type of thermoplastic is Nylatron in particular? As part of the Nylon family, it is a semi-crystalline, engineering thermoplastic polyamide.

 

 

 

Properties & Grades of Machined Nylatron

 

Nylatron’s main characteristics include a high mechanical strength, stiffness, hardness and toughness. As a semi-crystalline thermoplastic, Nylatron has good fatigue resistance as well. With excellent wear resistance and good electrical insulating properties, it’s not surprising that this material is often used for specialized industrial applications. One feature that’s of special interest to us at AIP is Nylatron’s ease of machinability with high precision. However, it’s also easy to extrude and fabricate.

 

Like Nylon, Nylatron is resistant to chemicals and hydrocarbons; the latter characteristic is especially useful in the oil and gas sector. Add in abrasion resistance, low coefficient of friction and outstanding corrosion resistance and you have a long-wearing material that can serve as a cost-effective replacement for metals and rubber.

 

Some of the Nylatron grades we regularly machine at AIP include:

 

Nylatron GSM PA6

Also known as MoS2-Filled Type 6 Nylon, this filled Nylatron grade has improved strength and rigidity over other Nylon variants, including a lower coefficient of linear thermal expansion. This is because the MoS2 (molybdenum disulphide) enhances the bearing and wear of the material without compromising its impact and fatigue resistance. This grade is often used to replace cast iron industrial applications, as lightweight Nylatron can both reduce weight and eliminate corrosion. As a result, it’s commonly used for gears, bearings, sprockets and sheaves.

 

Nylatron GF30 PA66

This extruded grade of Nylon 6/6 is 30% glass fiber reinforced and heat stabilized to provide improved creep resistance and dimensional stability as well as enhanced strength, stiffness and abrasion resistance. It has almost double the tensile strength of unmodified Nylon 6/6, with an elongation rate of about 1/6th that of unmodified Nylon 6/6. It has good resistance to high energy radiation (such as X-rays or gamma- rays) and allows for higher maximum service temperatures when compared to other grades.

 

Nylatron LIG PA6

Nylatron LIG PA6 is an internally lubricated Nylon grade that can perform up to ten times longer than its unmodified counterpart thanks to its lubricated additives. It strikes an optimal balance of strength and toughness. This makes it work well for industrial and consumable applications including gears, industrial bearings and wear pads.

 

Nylatron NSM

Nylatron NSM is the highest wear resistant thermoplastic available. As a self-lubricating grade of Nylon 6, it’s designed to outperform other wear grade materials and give long-lasting part life for applications that otherwise experience continuous wear and damage, such as bearings and wear pads. Other benefits of Nylatron NSM are its ease of machining, corrosion-resistance and noise reduction.

 

Nylatron GSM Blue PA6

Named for its dark blue color, Nylatron GSM Blue PA6 is the first cast Nylon to combine MoS and oil for the load capacity of Nylatron GSM PA6. This material performs exceptionally in higher pressures and at low speeds of up to 40 fpm. It’s preferred over Nylatron GSM PA6 for slide pads, thrust washers and trunnion bearings due to its 20% lower coefficient of friction, 50% greater limiting PV and its lower “k” factor.

 

Nylatron 703XL

High precision applications machined from Nylatron 703XL benefit from its near-zero level of “stick-slip,” which eliminates chatter to allow for an incredible level of control. Nylatron 703XL possesses a good balance of strength and toughness, as well as good mechanical and electrical properties. This grade works well in critical bearing applications for construction and production equipment industries.

 

Nylatron MC901

Nylatron MC901 is a heat-stabilized Nylon 6 grade that offers long-term thermal stability to 260 °F. This material has high toughness, flexibility and fatigue resistance. It is used in many bearing and structural applications, its most popular being gear wheels, racks and pinions.

 

 

Machining Nylatron

 

Annealing Nylatron
The process of annealing and stress-relieving Nylatron reduces the likelihood of surface cracks and internal stresses occurring in the material. Post-machining annealing also helps to reduce stresses that could potentially contribute to premature failure. We recommend stress relieving Nylons in a nitrogen environment.

 

Machining Nylatron

As stated earlier, Nylatron precision machines easily. This makes it a popular choice for machined industrial components that require precise, tight tolerances. We advise using HSS cutters instead of carbide on Nylatron for its surface finish. Stringer or chip removal during machining of Nyaltron is critical in order to maintain tolerances and surface finish.

 

When under high humidity, or while submerged in water, Nylons can absorb up to 7% by weight of water. This is important to keep in mind for machining Nylatron and designing applications of the material, as this effect can result in dimensional changes and a reduction of physical properties. There are proper design techniques that can compensate for this, so be sure you’re working with a Nylatron expert.

 

We also suggest non-aromatic, air-based coolants to achieve optimum surface finishes and close tolerances. Coolants have the additional benefit of extending tool life as well.

 

Preventing Contamination

Contamination is a serious concern when machining polymer components for technically demanding industries such as aerospace. To ensure the highest level of sanitation down to the sub-molecular level, AIP Precision Machining designs, heat-treats and machines only plastics, with any sub-manufactured metalwork processed outside our facility.

 

 

Nylatron Machining Guide: Supportive Information

Nylon Variants Guide

Chemical Resistant Materials Guide

Energy Sector Materials Guide

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Where Does This Part Go?

PPS Wheel Bushing | AIP Precision Machining

 

If you’ve been to a popular Florida amusement park, then it’s possible you’ve encountered the latest part starring in our “Where Does This Part Go?” series.

Find out why this part really makes a “splash” in the section below…

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