Types of Plastic Materials for CNC Machining

The best plastic for machining depends on your part’s load, heat, and chemical exposure. Machinable plastic materials range from low-cost commodity grades to high-performance engineering plastic material grades. Cost, machinability, and mechanical performance trade off differently for each one. Getting this choice right the first time avoids scrapped parts and wasted machine time.

This guide compares ten CNC plastic materials, covering machinability, temperature limits, and chemical resistance. The list covers POM, ABS, PEEK, polycarbonate, nylon, HDPE, acrylic, PTFE, PVC, and PET. Yijin Solution machines every material on this list through our CNC machining service. We handle prototype runs and full production without switching vendors.

Key Takeaways

• POM, also called Delrin, offers the best balance of machinability and dimensional stability for precision parts.
• PEEK keeps its mechanical properties at continuous temperatures up to 260 °C, per manufacturer data.
• ABS gives good impact resistance at roughly one-third the cost of specialized engineering plastics.
• The right material choice cuts machining time, tool wear, and scrapped parts.
• Plastic CNC parts weigh far less than metal parts, with much better chemical resistance.
• PVC and PET both machine well and resist a wide range of chemicals, at a lower cost than PEEK or PTFE.
• A published 0-to-20 machinability index ranks POM and PET-based Ertalyte highest, and polycarbonate lowest, among common CNC plastics.

What are CNC Machinable Plastics?

CNC machinable plastics are polymer materials engineered to survive cutting, drilling, and milling without melting, cracking, or losing shape. These plastic machining grades hold dimensional stability, consistent internal structure, and the right hardness for tight tolerances. Unlike metals, machined plastics weigh less while resisting chemicals, electricity, and corrosion.

The right plastic for CNC machining depends on your application’s mechanical needs, environment, and budget. Skipping this step often means a part that fails in service.

Why Choose Plastic Over Metal for CNC Machining?

Plastics cut machining time compared to harder metals. Shorter cycle times reduce tool wear and lower production costs for many projects. Many plastics also resist acids, bases, and solvents that corrode metal parts quickly.

The table below compares plastics and metals directly across the properties that matter most for machined parts.

Property	Plastics	Metals
Weight	Lightweight (0.9-1.4 g/cm³)	Heavy (2.7-8.0 g/cm³)
Chemical Resistance	Excellent for most chemicals	Varies; prone to corrosion
Electrical Properties	Excellent insulators	Conductive
Machining Speed	Higher cutting speeds are possible	Lower cutting speeds are required
Tool Wear	Reduced tool wear	Increased tool wear
Post-Processing	Minimal finishing required	Often requires finishing
Cost	Lower material cost	Higher material cost

What Is the Machinability Rating Scale for CNC Plastics?

Machinability describes how easily a material cuts. It combines cutting force, chip formation, achievable surface finish, and tool wear into one comparison.

Manufacturers publish a comparative machinability rating for many engineering plastics on a 0-to-20 scale. A rating of 20 marks the easiest material to cut. Independent materials data compiled by AZoM lists this rating across common CNC plastic grades. Acrylic and ABS fall outside that specific index. Their machining behavior is described separately below, based on chip formation and brittleness rather than a numeric score.

Material	Machinability Rating (0-20 scale)	Relative Machining Difficulty	What Drives the Rating
POM (Acetal/Delrin)	20	Excellent	Clean, brittle chips and low cutting force
PET (Ertalyte-type)	20	Excellent	Matches POM for chip control and tool life
HDPE	18	Excellent	Very low cutting force, but flexes under thin sections
PEEK	16	Good	Cuts like metal; needs sharp tools and heat control
Nylon	13-16	Good	Grade and moisture content shift the rating
PTFE	7-19	Fair to Excellent	Unfilled grades deform under light cuts; filled grades cut cleaner
PVC	12	Fair	Heat buildup and chip evacuation limit speed
Polycarbonate	8	Difficult	Ductile chips and stress-crack risk slow the cut
ABS	Not indexed	Good	Cuts cleanly with standard tooling
Acrylic (PMMA)	Not indexed	Good, brittle	Clean chip break, but thin sections crack easily

A higher rating means less time per part and longer tool life. A lower rating does not rule out a material. It means the shop plans for slower feeds, sharper tools, or extra heat control.

What are The Top Plastics for CNC Machining?

The top plastics for CNC machining included POM (Acetal/Delrin), ABS, and PEEK. Other popular plastics are polycarbonate, nylon, HDPE, acrylic, and PTFE (Teflon). According to the National Library of Medicine, Acetal and Delrin have powerful dimensional stability, making them great options for complex parts that require tight tolerances. Let’s get into why these plastics are the best for machining:

What is POM (Acetal/Delrin) and Why is it Popular?

POM (Polyoxymethylene), also known as Acetal or Delrin, is a high-performance engineering thermoplastic characterized by exceptional dimensional stability, low friction, and excellent machinability. This crystalline polymer offers optimal mechanical properties, with high stiffness (flexural modulus of 2.8-3.1 GPa), good tensile strength (60-70 MPa), and natural lubricity ideal for moving parts.

Delrin is widely considered the most versatile plastic because it maintains tight tolerances throughout the machining process. Its properties remain stable across a wide temperature range, and it exhibits minimal water absorption, contributing to its dimensional stability in varying environments.

Ideal Applications: Precision gears, bearings, bushings, valve components, mechanical assemblies, automotive parts, food processing equipment, consumer electronics.

Why is ABS a Cost-Effective Option for Prototyping?

ABS (Acrylonitrile Butadiene Styrene) presents a cost-effective solution for prototyping and general-purpose applications, offering good impact strength at approximately one-third the cost of specialized engineering plastics. This versatile thermoplastic provides a balanced combination of rigidity (flexural modulus of 2.1-2.4 GPa), impact strength (200-400 J/m), and surface finish quality suitable for both visual prototypes and functional testing.

ABS machines easily with standard cutting tools and can be painted, glued, or otherwise finished for appearance models or pre-production prototypes. Its low cost and straightforward machining process make it valuable during development when multiple design iterations are required. For many projects requiring a prototype, ABS is the best plastic CNC machining choice for initial concept validation.

Ideal Applications: Functional prototypes, pre-production models, consumer product housings, electronic enclosures, interior components.

How does PEEK Perform in Extreme Environments?

PEEK (Polyether Ether Ketone) excels in extreme environments by maintaining exceptional mechanical, thermal, and chemical properties under conditions that degrade most other plastics. This high-performance thermoplastic retains strength and dimensional stability at continuous temperatures up to 260 °C, offers outstanding chemical resistance, and provides excellent mechanical properties, including high tensile strength (90-100 MPa).

PEEK’s performance carries a premium price. It typically costs 8 to 10 times more than standard engineering plastics like POM. However, its unique combination of properties makes it irreplaceable in applications exposed to extreme temperatures, chemicals, or mechanical stress. When looking for the best plastic for CNC routing in high-performance applications, PEEK is often optimal despite its higher cost.

Ideal Applications: Aerospace components, semiconductor equipment, oil and gas equipment, medical implants, high-temperature bearings, and bushings.

What Makes Polycarbonate Ideal for Transparent Applications?

Polycarbonate combines exceptional optical clarity with outstanding impact resistance, making it the preferred transparent material for applications requiring both visibility and durability. This engineering plastic transmits light effectively (up to 89% light transmission) while providing impact resistance up to 250 times greater than glass and 20 times greater than acrylic.

Beyond optical properties, polycarbonate offers good heat resistance (HDT of 130-140 °C at 1.8 MPa) and reasonable mechanical properties, with tensile strength between 55-75 MPa. While susceptible to scratching and chemical attack from certain solvents, these limitations can be addressed through appropriate coatings.

Ideal Applications: Safety shields, protective covers, optical components, medical device housings, architectural components, and consumer electronics requiring transparency.

When Should You Choose Nylon for Your Project?

Nylon (polyamide) should be selected for projects requiring a balance of strength, wear resistance, and toughness in demanding mechanical applications. This versatile engineering thermoplastic comes in several variants (notably Nylon 6 and Nylon 6/6), offering excellent tensile strength (70-85 MPa), good impact resistance, and superior abrasion resistance. Nylon CNC machining is effective for parts requiring high durability in dynamic applications.

Nylon’s key limitation is its hygroscopic nature. It absorbs moisture, which affects dimensions and properties. For precision applications, this must be managed through proper material conditioning before machining. Despite this challenge, nylon remains a strong plastic choice for functional components that must withstand mechanical wear and stress.

Ideal Applications: Wear components, bearings, gears, rollers, structural components, fasteners, and parts requiring high fatigue resistance.

How does HDPE Deliver Chemical Resistance and Low Friction?

HDPE (High-Density Polyethylene) provides exceptional chemical resistance and low friction through its simple molecular structure and lack of reactive chemical groups. This semi-crystalline thermoplastic remains chemically inert against most acids, bases, and other aggressive chemicals due to its stable carbon-hydrogen bonds and crystalline structure. HDPE CNC machining is frequently used for components that require electrical insulation combined with chemical resistance.

The material’s natural lubricity results from its smooth molecular profile and low coefficient of friction between 0.1-0.2, among the lowest of commonly machined plastics aside from PTFE. While HDPE offers moderate mechanical properties (tensile strength of 20-30 MPa), its chemical resistance, low friction, and low cost make it valuable for specific applications. Polyethylene variants like HDPE are commonly used in CNC when both economy and chemical resistance are required.

Ideal Applications: Chemical tanks and containers, laboratory equipment, food processing components, wear strips and guides, cutting boards, plastic bottles, and low-friction surfaces.

What Makes Acrylic (PMMA) The Top Choice for Optical Clarity?

Acrylic (PMMA or Polymethyl Methacrylate) delivers superior optical clarity through its amorphous polymer structure that allows up to 92% light transmission, higher than glass or polycarbonate. This transparent thermoplastic provides exceptional weather resistance, UV stability, and a high-quality surface finish ideal for visual applications requiring long-term clarity. Acrylic is an excellent choice for CNC plastic machining when the final product must maintain transparency.

While offering good rigidity (flexural modulus of 3.0-3.3 GPa) and reasonable tensile strength (70-80 MPa), acrylic’s primary limitation is brittleness and poor impact resistance compared to polycarbonate. However, its superior scratch resistance, optical clarity, and lower cost make it preferable where impact resistance is less critical. When using a CNC milling machine for transparent parts, acrylic provides the best combination of machinability and optical properties.

Ideal Applications: Display cases, lenses, light guides, signs, architectural features, medical device components, retail displays.

Why is PTFE (Teflon) Unmatched for Low Friction Applications?

PTFE (Polytetrafluoroethylene/Teflon) provides unparalleled low-friction performance due to its unique molecular structure featuring strong carbon-fluorine bonds. This specialized fluoropolymer exhibits the lowest coefficient of friction of any solid material (0.05-0.10), approximately half that of HDPE, creating nearly frictionless surfaces ideal for bearing applications. Plastics like PTFE are suitable for applications where minimal friction is the primary requirement.

Beyond its lubricity, PTFE offers outstanding chemical resistance against virtually all chemicals except molten alkali metals and elemental fluorine. Its temperature resistance is equally impressive, maintaining stable properties from cryogenic temperatures to 260 °C continuous use. The removal during machining can be challenging, but the resulting machined plastic components provide exceptional performance in sliding applications.

Ideal Applications: Bearings, seals, gaskets, chemical handling equipment, electrical insulators, non-stick surfaces, low-friction guides.

Is PVC a Good Choice for CNC Machining?

PVC, or polyvinyl chloride, machines well and resists a wide range of acids and bases. Rigid PVC Type I reaches a tensile strength around 50-52 MPa. Its flexural modulus sits near 3.2-3.3 GPa, per Professional Plastics’ published test data (ASTM D638, D790).

PVC holds a heat deflection temperature around 80 °C at 1.8 MPa. The manufacturer datasheet does not list a maximum continuous-use temperature. It scores 12 on the 0-to-20 machinability index above. Sharp tools and steady chip evacuation keep heat and fumes under control during the cut.

PVC costs less than nearly every other material in this guide. That makes it a common choice for chemical-handling parts.

Ideal Applications: Chemical tanks, valve components, pump housings, electrical insulators, and corrosion-resistant enclosures.

Why Does PET Machine So Well for Precision Parts?

PET, or polyethylene terephthalate, ties POM for the top machinability score on the 0-to-20 index. Manufacturer data for Ertalyte-grade PET-P, summarized by ReadyPlastics, lists a tensile strength around 80 MPa. Its flexural modulus sits near 4.0-4.1 GPa.

PET absorbs only about 0.10% moisture over 24 hours, among the lowest of any engineering plastic. It holds a heat deflection temperature near 85 °C at 1.8 MPa. Continuous use tops out around 100 °C.

Its coefficient of friction runs around 0.25 dry against steel. That suits parts that slide or rotate against metal.

Ideal Applications: Precision gears, bushings, food-contact machinery parts, and electrical insulators requiring tight tolerances.

Which Plastic is Best for CNC Machining?

The ideal plastic for CNC machining depends on specific application requirements, rather than one universal “best” material. Engineering thermoplastics like POM offer the most balanced combination of machinability, dimensional stability, and mechanical properties. High-performance materials like PEEK and PET provide superior properties at a range of costs, while commodity plastics like ABS, HDPE, and PVC deliver cost-effective solutions for less demanding applications.

Yijin Solution’s experience across diverse plastic machining projects shows material selection is one of the most critical design decisions. The right choice affects performance, manufacturing cost, lead time, and reliability together.

Material	Relative Cost	Dimensional Stability	Machinability	Surface Finish Quality	Overall Value
POM (Delrin)	●●○○○	●●●●●	●●●●●	●●●●○	●●●●●
ABS	●○○○○	●●○○○	●●●○○	●●●○○	●●●○○
Nylon 6/6	●●○○○	●●○○○	●●●●○	●●●○○	●●●○○
PEEK	●●●●●	●●●●●	●●●●○	●●●○○	●●●○○
Polycarbonate	●●●○○	●●●○○	●●○○○	●●●●○	●●●○○
HDPE	●○○○○	●●○○○	●●●●●	●●○○○	●●○○○
Acrylic	●●○○○	●●●○○	●●●●○	●●●●●	●●●●○
PTFE	●●●○○	●●○○○	●●○○○	●●○○○	●●○○○
PVC	●○○○○	●●●○○	●●●○○	●●●○○	●●●○○
PET (Ertalyte)	●●○○○	●●●●○	●●●●●	●●●●○	●●●●○

Rating scale: ● = Low/Poor, ●●●●● = High/Excellent. Cost, dimensional stability, surface finish, and overall value are relative comparisons across this list. Machinability reflects the 0-to-20 index in the chart above.

Choose POM when a part needs tight tolerances and a low coefficient of friction. Choose PEEK when the part sees continuous heat above 150 °C. Choose PVC when chemical resistance matters more than machinability. Choose PET when you need PEEK-like precision at commodity-plastic cost. Choose ABS or HDPE for low-cost prototypes and non-critical parts.

How do we Select The Best Plastic for CNC Machining?

Material selection for CNC machining requires evaluating mechanical requirements, environmental conditions, and cost constraints to identify the optimal plastic type. The process involves matching material properties such as tensile strength, impact resistance, and heat deflection temperature with application demands. Selecting the right plastic for your project ensures component performance and longevity.

At Yijin Solution, our selection methodology analyzes application-specific factors like load requirements, chemical exposure, temperature ranges, and dimensional stability needs. We consider both immediate performance requirements and long-term factors like aging, UV exposure, and stress relaxation.

What Mechanical Properties are Critical for Plastic Selection?

Critical properties include tensile strength (maximum stress before breaking), flexural modulus (resistance to bending), and impact strength (shock absorption capability). Mechanical properties determine a plastic’s structural performance under physical stress and load conditions. These properties vary significantly between plastic types, with engineering plastics like PEEK and PEI offering higher strength values than commonly used plastics like ABS.

Consider both static and dynamic loading conditions that your plastic parts will experience. Components under continuous load need good creep resistance, while parts subjected to repeated impact require excellent impact resistance and toughness.

Material	Tensile Strength (MPa)	Flexural Modulus (GPa)	Impact Strength (J/m)
POM (Delrin)	60-70	2.8-3.1	80-160
ABS	40-50	2.1-2.4	200-400
Nylon 6/6	70-85	2.5-3.0	50-150
PEEK	90-100	3.6-4.1	85-100
Polycarbonate	55-75	2.1-2.4	600-850
HDPE	20-30	0.7-1.0	No break
Acrylic	70-80	3.0-3.3	15-20
PTFE	20-30	0.4-0.6	130-160
PVC	50-52	3.2-3.3	50-55
PET (Ertalyte)	78-80	4.0-4.1	25-30

How does Temperature Affect Plastic CNC Parts?

Temperature impacts plastic performance through three critical mechanisms: heat resistance, thermal expansion, and thermal conductivity. These properties determine whether a plastic maintains its shape, size, and strength in various thermal environments, from freezing conditions to high-heat applications.

Heat deflection temperature (HDT) represents the point at which a plastic part deforms under load at elevated temperatures. This specification matters most for components used in high-temperature environments. When choosing the best plastic for CNC milling, consider the coefficient of thermal expansion to ensure dimensional stability across temperature ranges.

Material	Heat Deflection Temp (°C at 1.8MPa)	Thermal Expansion Coefficient (10⁻⁵/°C)	Max Continuous Use Temp (°C)
POM (Delrin)	110-115	11-13	90-110
ABS	85-100	7-9	70-80
Nylon 6/6	75-85	8-10	80-100
PEEK	150-160	4.7-5.5	240-260
Polycarbonate	130-140	6.5-7.0	115-130
HDPE	45-55	12-13	55-70
Acrylic	90-105	6-8	80-90
PTFE	55-60	12-15	260-280
PVC	80	5-6	Not rated
PET (Ertalyte)	85	5.5-6.0	95-100

What Chemical Environments Can Different Plastics Withstand?

Chemical resistance varies dramatically between plastic types, with each material offering a unique compatibility profile with acids, bases, solvents, and other chemical agents. PTFE (Teflon) offers the broadest chemical resistance, while materials like polycarbonate show vulnerability to specific organic solvents. Good chemical resistance should be evaluated based on the specific substances and their concentration levels.

Duration of exposure affects chemical resistance, as some plastics withstand brief contact but degrade under prolonged exposure. Temperature further complicates compatibility, as higher temperatures typically accelerate chemical reactions. This is especially important when considering plastics for CNC machining applications in chemical processing environments.

Material	Acids	Bases	Organic Solvents	Hydrocarbons	UV Resistance
POM (Delrin)	Good	Good	Good	Excellent	Poor
ABS	Poor	Good	Poor	Poor	Poor
Nylon 6/6	Poor	Excellent	Good	Excellent	Poor
PEEK	Excellent	Excellent	Good	Excellent	Good
Polycarbonate	Poor	Poor	Poor	Good	Poor-Fair
HDPE	Excellent	Excellent	Good	Good	Poor
Acrylic	Good	Good	Poor	Good	Excellent
PTFE	Excellent	Excellent	Excellent	Excellent	Good
PVC	Excellent	Good	Poor	Good	Fair-Good
PET (Ertalyte)	Good (dilute)	Fair (dilute)	Good*	Good	Fair

*Chlorinated solvents attack PET. Confirm solvent compatibility with your material supplier before use.

What are the Unique Machining Considerations for Plastics?

The unique machining considerations for plastics include cutting parameters, tooling strategies, and surface finishes. Let’s take a look at these aspects more closely!

How do Cutting Parameters Differ from Metal Machining?

Cutting parameters for plastic CNC machining differ fundamentally from metal machining through higher cutting speeds, lower feed rates, and modified tool geometry. Plastics require cutting speeds typically 2-3 times faster than for aluminum, with feed rates reduced by 25-50% to prevent melting. Plastic machining requires tooling with higher rake angles (15-20° versus 0-10° for metals) to slice rather than push material. Understanding these differences is essential when determining the best plastic for CNC milling.

Temperature management is critical in plastic machining due to low thermal conductivity. Without proper cooling, heat builds up quickly, potentially causing melting, deformation, or tool fouling that compromises accuracy and surface finish. This is especially important when using CNC machines for plastic materials with low heat resistance.

Machining Parameter	For Plastics	For Metals	Key Difference
Cutting Speed	Higher	Lower	Plastics cut more easily, but must avoid heat buildup
Feed Rate	Lower	Higher	Prevents melting and deformation in plastics
Tool Rake Angle	15-20°	0-10°	Creates a slicing action instead of pushing
Cooling	Air or mist preferred	Liquid coolant standard	Prevents material softening
Tool Sharpness	Extremely sharp	Standard	Reduces friction and heat generation
Chip Evacuation	Critical	Important	Prevents re-cutting and heat buildup

What Spindle Speeds and Chip Loads Work Best for Each Plastic?

Shop-floor speeds and feeds vary by machine, tool, and setup. The ranges below give a starting point for common CNC plastics, compiled from published tooling guidance for plastic machining, itself citing Onsrud Cutter, Harvey Tool, and Kennametal.

Material	Spindle Speed (RPM, unfilled)	Chip Load (in/tooth)	Flute Geometry	Note
POM (Delrin)	18,000-24,000	0.010-0.015	High helix	Excellent machinability
ABS	18,000-22,000	0.010-0.015	High helix	Forgiving; behaves like soft aluminum
Polycarbonate	16,000-20,000	0.008-0.012	High helix	Prone to stress cracking; keep tools sharp
Acrylic (PMMA)	14,000-18,000	0.006-0.010	Straight or moderate helix	Brittle; avoid heat buildup
Nylon	16,000-24,000	0.008-0.012	High helix	Dry the stock before precision cuts
Glass-filled nylon	10,000-14,000	0.005-0.008	Not specified	Abrasive; use carbide tooling
HDPE	18,000-24,000	0.012-0.018	High helix	Gummy; run aggressive parameters
PTFE	12,000-18,000	0.010-0.015	Moderate helix	Soft; use minimal tool engagement

PEEK, PVC, and PET need shop-specific tuning. No verified RPM reference for these three came up in this pass. Confirm parameters with your machinist or request a free DFM review before the first cut.

What are The Best Tooling Strategies for Different Plastics?

Tooling strategies for plastic machining should be tailored to specific material characteristics. For crystalline polymers like POM and HDPE, single-flute end mills with high helix angles (35-45°) produce clean cuts while effectively evacuating chips. When using CNC machines for plastic parts, tool selection significantly impacts final quality and dimensional accuracy.

Amorphous plastics like polycarbonate and acrylic benefit from multi-flute tools (2-3 flutes) with polished cutting edges for optical-quality surface finishes. High-performance materials like PEEK require specially designed end mills with enhanced coating technologies to withstand higher cutting forces and temperatures. The right combination of tooling and machining parameters matters most when creating custom parts through CNC plastic machining services.

Plastic Type	Recommended Tool Type	Coating	Coolant Strategy	Special Considerations
POM/Acetal	Single or double flute end mill	Uncoated/TiN	Compressed air	Sharp cutting edges
ABS/Styrene	Double flute end mill	Uncoated	Air blast	High rake angle
Nylon	Single flute end mill	ZrN	Mist coolant	Dry material before machining
PEEK/PEI	Diamond-coated end mill	Diamond	Compressed air/Mist	Rigid setup required
Polycarbonate	Polished 2-3 flute end mill	Uncoated	Air only	Avoid coolant (crazing)
HDPE/LDPE	Single flute with high rake	Uncoated	Air blast	Support thin walls
Acrylic	Polished O-flute or 2-flute	Uncoated	Air only	Avoid coolant (crazing)
PTFE	Diamond-coated end mill	Diamond	Air blast	Specialized fixturing needed

How Can You Achieve Optimal Surface Finish on Plastic Parts?

Optimal surface finish on plastic parts combines appropriate cutting parameters, proper tooling, and effective cooling strategies tailored to specific material characteristics. For finishing passes, increase cutting speeds by 20-30% and decrease feed rates by 40-50% compared to roughing operations for smoother surfaces with minimal tool marks.

Understanding millable plastics for CNC machining is essential for superior surface quality.

For transparent materials, diamond-polished tools produce superior finishes directly from the machine. For the highest quality finish, techniques like vapor polishing (for ABS and acrylic) or flame polishing (for acrylic) can produce glass-like surfaces without dimensional changes. These techniques are valuable for creating durable plastic components with aesthetic requirements.

Material	Optimal Cutting Speed	Feed Rate for Finishing	Best Tool Type	Post-Processing Options
POM/Acetal	500-800 m/min	0.05-0.1 mm/tooth	Polished 2-flute	Tumbling
ABS	300-500 m/min	0.05-0.1 mm/tooth	Polished O-flute	Vapor polishing
Nylon	400-600 m/min	0.05-0.1 mm/tooth	Single-flute	Tumbling, vibratory finishing
PEEK	250-400 m/min	0.03-0.08 mm/tooth	Diamond-coated	Abrasive polishing
Polycarbonate	300-600 m/min	0.05-0.08 mm/tooth	Super-polished 2-flute	Vapor polishing
HDPE	500-700 m/min	0.1-0.15 mm/tooth	High rake single-flute	None typically required
Acrylic	300-500 m/min	0.03-0.08 mm/tooth	Diamond-polished 2-flute	Vapor/flame polishing
PTFE	200-400 m/min	0.1-0.2 mm/tooth	Sharp single-flute	None typically required

What Surface Finishes and Post-Processing Options are Available?

Surface finishes and post-processing techniques enhance both aesthetic appeal and functional properties of CNC-machined plastic parts. These treatments transform raw machined surfaces into components with specific performance characteristics. Each plastic type responds differently to various finishing techniques, requiring tailored process parameters. This guide to the best millable plastics includes essential finishing options for optimal results.

At Yijin Solution, we’ve developed proprietary finishing techniques optimized for different plastic types, ensuring consistent results across production runs. Our approach considers the molecular structure and crystallinity of each polymer to determine the most effective process parameters for the manufacturing process.

What are The Most Effective Mechanical Finishing Methods?

Mechanical finishing techniques physically alter plastic surfaces through controlled abrasion or impact processes. These methods remove tool marks, smooth transitions, and create uniform textures without chemical or thermal modification. Selection depends on material hardness, thermal sensitivity, and desired aesthetic outcome.

Different abrasive media produce specific surface characteristics, from fine matte finishes to highly polished surfaces. For crystalline polymers like POM and HDPE, controlled abrasion with graduated grit progression yields superior results compared to single-stage processes.

Finishing Method	Process Description	Best Suited Materials	Surface Result	Technical Benefits
Bead Blasting	Pressurized projection of glass media at 40-60 PSI	POM, ABS, Nylon, PEEK, PC	Uniform matte finish	Stress relief, burr removal
Tumbling	Vibratory action with ceramic or plastic media	All plastics	Rounded edges, smooth surface	Deburring, edge conditioning
Abrasive Polishing	Progressive sanding with 400-2000 grit media	Acrylic, PC, PEEK	High-gloss finish	Surface leveling, optical clarity
Micro-Finishing	Controlled abrasion with fine mineral slurry	POM, PEEK, Nylon	Micro-textured surface	Controlled friction characteristics
Ultrasonic Finishing	High-frequency vibration with specialized media	Delicate parts of all materials	Precision deburring	Selective feature refinement

What are the Environmental Considerations for Plastic CNC Machining?

Environmental considerations in plastic CNC machining encompass material selection, process efficiency, waste management, and recycling practices. These factors impact both the ecological footprint of manufacturing operations and long-term sustainability. Modern approaches integrate environmental consciousness throughout the production lifecycle. When a part should be plastic rather than metal, considering these environmental factors becomes increasingly important.

At Yijin Solution, we’ve implemented comprehensive environmental management systems, exceeding regulatory requirements while maintaining production efficiency. Our approach includes closed-loop coolant systems, energy-efficient machining parameters, and material-specific recycling protocols, recovering over 95% of plastic waste. The best millable plastics for CNC include those with strong recycling potential.

What Sustainable Material Alternatives are Available?

Sustainable material alternatives for CNC machining include bio-based plastics, recycled content plastics, and environmentally responsible composites offering reduced ecological impact without compromising technical performance.

At Yijin Solution, we evaluate emerging sustainable materials against rigorous performance criteria to ensure they meet application requirements. Our materials’ science team tests physical properties, long-term stability, and machining characteristics before qualifying new materials for production.

Sustainable Material	Technical Composition	Properties Comparison	Environmental Benefit
Bio-Based PLA Composites	Polylactic acid with natural fiber reinforcement	• 80% strength of ABS • Improved heat resistance (HDT 90-110 °C)	• 65% reduction in carbon footprint • Biodegradable under industrial conditions
Recycled Engineering Polymers	Post-industrial PC, POM, or Nylon with stabilizers	• 90-95% of virgin material properties • Enhanced UV stability	• 70-85% reduction in energy consumption • Diverts material from landfill
Plant-Based Polyamides	Castor oil-derived nylon with mineral reinforcement	• Comparable to Nylon 6/6 • Excellent chemical resistance	• 40-60% reduction in greenhouse gas emissions • Reduced dependency on petrochemicals
Cellulose-Derived Composites	Modified cellulose with cross-linking polymers	• Similar to ABS/PC blends • Natural flame retardancy	• Renewable forestry-derived base material • Biodegradable with specialized treatment

Yijin Solution: Reliable Plastic CNC Machining Services

Yijin Solution machines all ten plastics in this guide across our Shenzhen facility. Our 136-plus CNC machining centers run POM, PEEK, PVC, PET, and every other material covered here.

Every job starts with a free DFM review. Our engineers flag material and tolerance risks before your part enters production. AS9100D and IATF 16949 certification back every run for safety-critical industries.

Ready to machine your plastic part? Contact our engineering team for a free DFM review and quote.

Best Plastic For Machining FAQs

What is the cheapest plastic to CNC?

ABS is often the best plastic for CNC milling due to its low cost and machinability. However, the cheapest plastic for CNC machining depends on the application and manufacturing process. HDPE is the best plastic for CNC routing, offering affordability and ease of cutting. Both materials provide cost-effective solutions for producing plastic parts with good durability.

Is plastic CNC machining worthwhile?

Yes, CNC machining is a great option for producing machined plastic parts with precision. Delrin is an excellent choice for CNC plastic machining parts due to its strength and stability. The removal during machining is efficient, reducing waste and improving production speed. Plastic machining is worthwhile for prototypes, machine parts, and specialized components.

What makes a plastic millable?

Plastics that resist melting and deformation are ideal for milling with high-speed cutting tools. Delrin, acrylic, and nylon are among the top choices in the guide to the best millable plastics for CNC machining. The material must balance toughness and machinability to produce high-quality machine parts. Choosing the right plastic ensures accuracy, efficiency, and cost-effectiveness in CNC machining.

Is PVC or PET Better for CNC Machining?

PVC and PET both machine well and resist a wide range of chemicals. PVC costs less and suits chemical tanks, valves, and enclosures. PET holds tighter tolerances and performs better under continuous heat, up to about 100 °C. Choose PET for precision gears and food-contact parts.

What Does a Machinability Rating Mean for CNC Plastics?

A machinability rating scores how easily a plastic cuts. It reflects cutting force, chip formation, achievable finish, and tool wear. One published index runs from 0 to 20, with 20 marking the easiest material to machine. POM and PET-based Ertalyte both score 20 on that scale. Polycarbonate scores lowest, around 8, since it resists cutting force and dulls tools faster. See the machinability chart earlier in this guide for the full comparison.

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