When it comes to rapid prototyping via CNC machining, plastic materials are the first choice. CNC-machined plastic parts are relatively cheaper and easier to machine than metal ones. Sometimes, after surface treatment like metal painting and electroplating, CNC-machined plastic parts can look like metal parts. There are many types of plastic materials that can be used in rapid CNC prototyping. This article will discuss the 12 most commonly used plastics.
ABS, one of the five major synthetic resins, is a versatile thermoplastic engineering plastic, with excellent impact resistance, heat resistance, low-temperature resistance, chemical resistance, electrical properties, good mechanical properties, good impact strength, high heat resistance, and good machinability. It also has the properties of being easy to be processed, having good dimensional stability, good surface gloss, etc. ABS is easy to post-treat by spraying metal paints, electroplating, hot pressing, bonding, etc. It is also one of the primary materials used in rapid CNC prototyping. The ABS raw materials have many colors to choose from. It is also one of the primary materials used in rapid CNC prototyping.
PC is one of the five synthetic resins too. Being transparent, PC is an amorphous thermoplastic resin with integrated performance, including excellent electrical insulation, extensibility, dimensional stability, chemical resistance, high strength, heat resistance, and cold resistance. It also has the advantages of self-extinguishing, flame retardant, non-toxic, coloring, etc.
You can see products in PC materials nearly in all corners of your life. It is also one of the primary materials for rapid prototyping through CNC machining. But it is more likely to be scratched if you make transparent appearance parts in PC material. To increase the transparency of PC parts in prototyping, vapor polishing will be applied.
It is an alloy material, combining the excellent impact resistance and heat resistance of PC with the excellent low-temperature resistance, chemical resistance, and electrical performance of ABS. PC+ABS material is also easy to be processed with product size stability and good surface gloss.
PMMA, usually called acrylic, is commonly known as organic glass. PMMA is by far the most excellent texture of synthetic transparent materials. Its transparency can be more than 93%, which is better than that of a PC. The shortcoming of PMMA is poor toughness and its fragility.
For rapid CNC prototyping, PMMA is mainly used to make lenses or thicker shells for appearance verification.
POM is usually known by the product name Delrin. It is the highest mechanical processing performance of engineering thermoplastics among plastics. Because of its excellent characteristics, it is very suitable for machining in automatic lathes and is especially suitable for manufacturing precision parts.
It is usually the best choice for CNC-machined plastic parts that require high precision, high stiffness, low friction, excellent high-temperature dimensional stability, and low water absorption. The raw POM material also has many colors to choose from. The most common ones are white and black.
6. Nylon (PA)
Nylon, also known as polyamide (PA), is a thermoplastic often used in engineering applications because of its excellent mechanical properties, good impact strength, high chemical resistance, and wear resistance. However, it tends to absorb water and moisture. PA cannot be painted and glued.
Nylon 6 and Nylon 66 are the most common Nylon materials used in CNC machined parts.
PA is also a material widely used in 3D printing.
PP is a high-density linear polymer with excellent overall performance. It is white translucent and waxy when uncolored. It is not easy to polish and be painted. So it is suitable for structural parts but not for appearance parts in rapid CNC prototyping. It also cannot be glued. So the PP part can only be made in one piece.
Commonly known as Teflon, PTFE is an engineering thermoplastic, with excellent chemical and heat resistance. It has the lowest coefficient of friction of any known solid material. PTFE is one of the few plastics that can withstand operating temperatures above 200℃ and is an excellent electrical insulator. However, it has purely mechanical properties, cannot be bonded, and cannot be sprayed with paint. It is relatively soft and is commonly used as a lining or insert in components.
Bakelite is a phenolic plastic with high mechanical strength, nice insulation, heat resistance, and corrosion resistance. It is non-absorbent, and non-conductive with high-temperature resistance and high strength. It is mostly used in electrical appliances, and the high insulation is like wood plasticity. It is why it is called Bakelite. It cannot be sprayed with paint and cannot be glued in rapid prototyping after being CNC machined.
HDPE, high-density polyethylene, is a thermoplastic with a high strength-to-weight ratio, high impact strength, and good weather resistance.
HDPE is a lightweight thermoplastic suitable for outdoor use and piping. It is often applied in rapid CNC prototyping before injection molding.
PEEK is a high-performance engineering thermoplastic with excellent mechanical properties, thermal stability over a very wide temperature range, and excellent resistance to most chemicals.
PEEK is often used in place of metal parts because of its high strength-to-weight ratio. Medical grades are also available, making PEEK suitable for biomedical applications.
PEEK sheets are used in the aerospace military, medical devices, electronics semiconductors, photovoltaic industry, analytical and testing instruments, petroleum and petrochemical, textile printing and dyeing machinery, and food and beverage filling machinery industries.
PET is with high mechanical strength, stiffness, and hardness. It has good sliding performance and wearing strength, good electrical insulation, good creep resistance, low and stable coefficient of friction nice wear resistance (better than Nylon), high dimensional stability (better than POM), and physiological inertness (suitable for contact with food). It is also with weather resistance, good stability against chemicals, low water absorption, and resistance to weak acids and organic solvents, but not resistant to heat and water immersion, not resistant to alkalis.
PET is widely used in textile, paper making, food machinery, transportation, dock, medical, coal mining, chemical industry, etc. In rapid prototyping by CNC machining, PET is often used to make bearings, pistons, screws, etc.
You may hear about the above plastic materials in plastic injection molding. However, they are not precisely the same. Plastic raw materials for CNC machining are in the block, while those for plastic injection molding are in graininess. It is mainly because of their different production processes.
Don’t be confused after knowing so many plastics for rapid CNC prototyping. In most cases, ABS, PC, and PMMA are the top three plastics used in prototyping. Or tell your demands to X Rapid Technologies, and we will offer you the optimal solutions for rapid prototyping via CNC machining.