Plastic CNC Machining Services | Precision Parts, Tight Tolerance & Fast Turnaround

Why Choose AT-Machining for Your Plastic Parts?

Machining high-performance plastics requires a fundamentally different approach than metals. We bridge the gap between cost-efficiency and the rigorous quality standards of top-tier Western specialists.

Plastic Annealing Process

Stress-Free Machining

To prevent warping and cracking, we implement a strict Stress-Relieving Process. By using proprietary annealing cycles and plastic-specific tooling, we guarantee that your parts remain dimensionally stable throughout their service life.

Engineering Plastic Materials

Material Expertise

Choose the right polymer with confidence. We help you compare resin options—from ABS to PEEK—and select what fits your performance, budget, and lead-time needs. All materials are verified for authenticity and supplied to meet relevant ASTM and ISO standards.

Vapor Polishing Clear Parts

Advanced Surfacing

For optical clarity, we specialize in Vapor Polishing for Polycarbonate and Ultem. This advanced process eliminates microscopic tool marks, delivering a glass-like finish that rivals injection molding without the high tooling costs.

Our Plastic Machining Capabilities

At AT-Machining, we bridge the gap between rapid prototyping speed and high-precision production. Our facility is equipped with a diverse range of equipment to handle everything from micro-machined pins to large-format sheets.

CNC Milling 3, 4 & 5-Axis Plastic Machining

CNC Milling (3, 4 & 5-Axis)

We utilize advanced multi-axis milling centers to machine complex geometries that 3-axis machines cannot reach. This process is essential for creating intricate manifolds, housings, and brackets with tight tolerances and superior surface finishes.

CNC Turning & Swiss Machining

CNC Turning & Swiss Machining

Optimized for efficiency, our Swiss lathes specialize in high-volume production of small, cylindrical parts. We deliver consistent precision for components like bushings, connectors, and pins, ensuring every unit matches the print.

Plastic Routing Large Format

Plastic Routing

For larger surface areas, our CNC routing services handle large-format sheets with speed and cost-effectiveness. This is the ideal solution for manufacturing display panels, machine guards, and flat components with excellent edge quality.

CNC Machining Plastic Materials

Choosing the proper plastic for CNC machining involves considering some factors. The plastic you select is critical to the final success. For example, the plastic may need to be resistant to high temperatures or bend or break under pressure.

POM Plastic

POM (Delrin/Acetal)

POM is a semi-crystalline thermoplastic known for its high stiffness, low friction, and free-machining characteristics. It produces consistent, short chips and holds tight tolerances.

CNC Machinability: Excellent

Standard sharp tools work effectively. While POM cuts cleanly, coolant is recommended to maintain dimensional stability.

9k–11k psiTensile

0.8–1.5Impact (ft-lbs)

220–257 °FHeat Defl.

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ABS Plastic

ABS

ABS is a low-cost, impact-resistant thermoplastic. While easy to machine, it has poor thermal resistance. It is commonly used for housings and prototypes but requires careful heat management.

CNC Machinability: High (Heat Sensitive)

Requires sharp tools and adequate coolant. Excessive heat can cause the material to "gum up" or melt on the cutter.

5.5k–6.5k psiTensile

3.0–6.0Impact (ft-lbs)

190–215 °FHeat Defl.

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Nylon Plastic

Nylon (PA 6 / PA 66)

Nylon offers high toughness and wear resistance but is hygroscopic. This affects dimensional stability post-machining. It tends to produce continuous stringy chips.

CNC Machinability: Medium

Use sharp, positive rake tooling. Coolant is essential to prevent melting and manage stringy chips (bird-nesting).

7k–12k psiTensile

1.0–4.0Impact (ft-lbs)

200–250 °FHeat Defl.

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PEEK Plastic

PEEK

PEEK is a high-performance thermoplastic with exceptional thermal and chemical stability. Ideal for medical/aerospace parts. Stress-relieving is often required before machining.

CNC Machinability: Medium (Demanding)

Requires rigid workholding and sharp carbide or diamond tools. Heat build-up can cause surface glazing; use adequate coolant.

14k–16k psiTensile

0.8–1.2Impact (ft-lbs)

300–340 °FHeat Defl.

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PTFE Plastic

PTFE (Teflon)

PTFE offers extreme chemical resistance and low friction but is very soft. It is susceptible to cold flow and creep. Achieving tight tolerances requires specialized machining strategies.

CNC Machinability: High (Softness Issue)

Use very light clamping forces (soft jaws) and extremely sharp tools. High feed rates help prevent heat buildup.

3k–4k psiTensile

No breakImpact

200–260 °FHeat Defl.

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PVC Plastic

PVC

Rigid PVC is chemically resistant and electrically insulating. However, machining PVC can release corrosive chlorine gas if overheated. Proper ventilation is critical.

CNC Machinability: High (Corrosion Risk)

Avoid overheating. Use coated carbide tools to resist corrosion. PVC can be brittle; avoid high-impact entry cuts.

6k–7.5k psiTensile

0.5–2.0Impact (ft-lbs)

140–170 °FHeat Defl.

PMMA Plastic

PMMA (Acrylic)

PMMA offers optical clarity but is brittle and prone to stress crazing. Achieving transparency requires precise speed control to avoid melting or micro-cracking.

CNC Machinability: Medium (Brittle)

Use polished flutes specifically designed for plastics. Avoid aggressive feeds which cause chipping. Vapor polishing may be required.

9k–11k psiTensile

0.4–0.7Impact (ft-lbs)

185–210 °FHeat Defl.

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PEI Plastic

PEI (Ultem)

PEI is a high-strength, flame-resistant amorphous plastic. It is susceptible to coolant sensitivity and can be prone to stress cracking. It requires careful selection of cutting fluids.

CNC Machinability: Medium

Use carbide tooling. To prevent cracking, maintain consistent cutting parameters. Annealing after roughing is recommended.

14k–16k psiTensile

1.5–2.5Impact (ft-lbs)

340–360 °FHeat Defl.

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PAI Plastic

PAI (Torlon)

PAI is an ultra-high-performance plastic with exceptional hardness. It requires a post-curing cycle after machining. Due to its stiffness, it can be machined with tolerances similar to metal.

CNC Machinability: Difficult (Hardness)

High-quality carbide or PCD tools are mandatory due to abrasive nature. Machining strategy should minimize heat.

18k–22k psiTensile

0.5–1.0Impact (ft-lbs)

500–520 °FHeat Defl.

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HDPE Plastic

HDPE

HDPE is a tough, low-cost plastic, highly chemical resistant but prone to warping. It lacks stiffness, making it difficult to hold tight tolerances. Stress relief is crucial for large parts.

CNC Machinability: High (Flexibility Issue)

Use vacuum fixtures or double-sided tape for thin parts. Sharp tools are essential to shear the material cleanly; dull tools cause burrs.

3k–4k psiTensile

2.0–5.0Impact (ft-lbs)

160–180 °FHeat Defl.

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PC Plastic

Polycarbonate (PC)

Polycarbonate is known for extreme toughness and transparency. It is notch sensitive, meaning sharp internal corners can lead to failure. Annealing parts post-machining is recommended.

CNC Machinability: Medium

Design parts with generous radii to avoid stress concentration. Use sharp tools and coolant to prevent heat buildup.

8.5k–9.5k psiTensile

12.0–16.0Impact (ft-lbs)

270–300 °FHeat Defl.

PET Plastic

PET (Polyester)

PET offers excellent dimensional stability due to low moisture absorption and a hard surface. It is ideal for complex parts requiring tight tolerances.

CNC Machinability: Good

Maintain sharp tooling and moderate speeds. Dull cutters cause heat buildup, leading to surface whitening or "smearing."

7k–9k psiTensile

1.0–2.0Impact (ft-lbs)

200–230 °FHeat Defl.

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FR4 Plastic

FR4 (Composite)

FR4 is a glass-reinforced epoxy laminate. It is highly abrasive to machine tools and produces hazardous glass dust. It has extremely high tensile strength.

CNC Machinability: Abrasive

Use diamond-coated or PCD tools. HEPA dust extraction is mandatory. Climb milling helps prevent delamination.

45k–65k psiTensile

1.0–2.0Impact (ft-lbs)

280–300 °FHeat Defl.

G-10 Plastic

G-10 (Garolite)

G-10 is a glass-cloth epoxy laminate similar to FR4 but without flame retardants. It offers higher strength. Like FR4, it presents delamination risks if machined incorrectly.

CNC Machinability: Abrasive

Requires abrasive-resistant tooling (Diamond/PCD). Control dust extraction carefully. Use backing plates when drilling.

35k–55k psiTensile

1.0–2.0Impact (ft-lbs)

260–300 °FHeat Defl.

PE Plastic

Polyethylene (PE)

Polyethylene is soft, flexible, and chemically resistant. It is difficult to clamp due to its slick surface. It has a high coefficient of thermal expansion.

CNC Machinability: High (Gummy)

Use light clamping pressure to prevent deformation. High rake angles help prevent chip welding (gumming). Chips can be continuous.

2k–3.5k psiTensile

2.0–6.0Impact (ft-lbs)

140–160 °FHeat Defl.

UHMW Plastic

UHMW

UHMW provides extreme abrasion resistance and impact strength. It is difficult to secure for machining due to slipperiness. Thermal expansion must be managed carefully.

CNC Machinability: High (Workholding Issues)

Use high positive rake tooling to slice the material. Soft jaws or vacuum fixtures are best for workholding. Avoid high speeds.

2k–3.5k psiTensile

2.0–6.0Impact (ft-lbs)

140–160 °FHeat Defl.

Machining Handbook

Design Guidelines for Plastic CNC

Technical specifications for optimized manufacturing and dimensional stability.

Wall Thickness & Uniformity

Maintain consistent wall thickness to reduce internal stress, warping, and dimensional instability during and after the CNC process.

Min thickness 1.0 – 1.5 mm

Uniformity Avoid changes > 2×

Impact: Prevents vibration and heat-induced deformation in plastics like Nylon and POM.

Internal Corners & Fillets

Sharp internal corners create stress concentrations. Standardize on radii that match common tool sizes to improve structural integrity.

Fillet Radius ≥ 0.5 × Tool Dia.

Impact: Improves surface finish and significantly reduces machining cycle time.

Hole Design & Depth Ratio

Optimize hole depth-to-diameter ratios to ensure straightness. High ratios can lead to tool wander in softer plastic materials.

Standard Depth ≤ 4× Diameter

Impact: Excessively deep holes increase tool deflection, heat, and tolerance variation in plastic materials.

Realistic Tolerances

Define tolerances based on functional needs. Over-specifying in plastic increases cost due to its sensitive thermal expansion properties.

Standard Plastic ± 0.05 mm

Impact: Plastics expand, creep, and relax over time. Designing realistic tolerances improves yield and reduces inspection costs.

Thin Features & Ribs

Ensure thin features are supported. Unsupported ribs are prone to vibration chatter and structural failure during high-speed milling.

Min Rib Width ≥ 1.0 mm

Impact: Thin plastic features are prone to vibration and melting during machining, affecting accuracy and surface quality.

Threaded Features

Avoid fine threads as they strip easily in most plastics. For high-frequency assembly, consider using metal inserts.

Rec. Strategy Threaded Inserts

Impact: Plastic threads wear quickly and may strip under repeated assembly without proper design.

Part Orientation Strategy

Design for minimal setups. Accessible features reduce complexity and help maintain tighter volumetric precision across the whole part.

Max Setups 2 – 3 Cycles

Benefit High Precision

Impact: Minimizing rotations prevents cumulative errors and reduces manufacturing costs.

What Is Plastic CNC Machining?

Plastic CNC machining is a subtractive manufacturing process that involves placing a solid block of plastic material against a mobile cutting tool to remove materials from it. A digital design file guides the path of cutting tools, ensuring the final product takes the desired shape.

CNC plastic machining is the current manufacturing trend in making plastic components and parts. This is due to the ability of this process to create parts with uniform, high precision, and tight tolerances.

When to Use CNC Machining instead of 3D Printing?

The type of plastic fabrication process used for machining depends on several factors. So, when do you use CNC machining as opposed to 3D printing?

When Making Large Plastic Parts

3D printing large plastic parts are not feasible because it takes a long time, sometimes hours. However, fabricating large parts using a CNC mill only takes a few minutes.

Type of Material

If you design a component in a material such as PVC, POM, PEI, or PEEK, 3D printing is not an option. Instead, these materials can be sourced in blocks and bars for CNC machining.

High Accuracy

CNC machining is the better choice for manufacturing precise parts with intricate details because it can achieve an extremely tight tolerance down to ±0.005mm, but 3D printing only can achieve ±0.1~0.5mm.

Part Intricacy

When parts require tiny details that cannot be made with 3D printing, CNC machining is the best choice. Small details, such as intricate optical patterns, can have a radius as small as R 0.05 mm, and this level of detail is difficult to achieve with 3D printing.

Applications Of CNC Machined Plastic Parts

Medical Devices

Medical Devices

CNC machining is a popular method for fabricating high-precision plastic parts used in the medical industry, such as medicine dispenser components and surgical tools.

Food and Beverage Industry

CNC-machined plastics are ideal for producing parts used in the food and beverage industry, such as valves, nozzles, and seals for packaging machines.

Semiconductor Parts

The semiconductor industry relies on plastic CNC machining to create precise parts from high-performance plastics requiring extremely tight tolerances.

Automotive and Aerospace

Plastic CNC machining manufactures high-performance components that meet the strict regulations and requirements of these demanding industries.

Plastic CNC Machining Services

Are you looking for complete solutions to producing plastic parts with tight tolerances and surface finish?

AT Machining offers a state-of-the-art CNC Machining service, guaranteed quality, and fast lead time. With over 50 plastic milling and plastic turning machines, we can provide consistent, high-quality machined parts and competitive price.

So, with us, you can make easy or complex orders for prototypes, low to large volume CNC production runs in a wide variety of plastic.

Frequently Asked Questions

How Does Plastic CNC Machining Work?

Plastic CNC machining is a process of using computer numerical control (CNC) machines to shape and cut the plastic material into the desired shape. This technique is highly accurate, allowing for the production of complex designs with intricate detail or complex geometries.

How Much Does Plastic CNC Machining Cost?

The cost of plastic CNC machining depends on many factors, including the material used and the expertise of the machining services provider or CNC milling machine shop. However, the cost could be as low as $10 per hour.

What Plastic is Best for Machining?

The best plastics for machining include; Acetal, PEEK, and PVC. The reason is that they have a high degree of machinability and offer good dimensional stability.

Also, these different plastics are readily available at a low cost and have the potential to resist chipping and melting. They are also impact-resistant and have high impact strength.

Do you offer annealing services?

Yes, we perform stress-relieving annealing cycles to minimize internal stress. This ensures superior dimensional stability and prevents part deformation or cracking post-machining.

Can you achieve optical clarity on machined parts?

Yes, we achieve optical transparency on materials like Acrylic and Polycarbonate. We utilize vapor polishing and hand buffing to remove tool marks and restore glass-like clarity.

What is the tightest tolerance you can hold for plastics?

We achieve ultra-precision down to ±0.005mm for Swiss-turned components. For standard CNC milling features, we typically maintain ±0.02mm to ±0.05mm depending on the material.

Get your parts into production today!