CNC Machining HDPE: Overview of HDPE Materials & Machining Guide | CNCLATHING


CNC HDPE machining has lots of challenges but plays an irreplaceable role in precise, intricate parts production, before choosing a material for your product or starting production, learn about HDPE properties and uses, High-density polyethylene definition, as well as how to CNC machine HDPE.

What is High Density Polyethylene (HDPE)?

High-density polyethylene (HDPE), also known as polyethylene high-density (PEHD), is a thermoplastic polymer that also can be called “alkathene” or “polythene” when used for HDPE pipes, generally the white or black solid material used in HDPE machining. As the name suggests, HDPE has a marginally higher density than that of low-density polyethylene (LDPE), and stronger intermolecular forces and tensile strength, which gives it higher specific strength. HDPE parts are cost-effective options for many usages due to their affordability and durability.

High Density Polyethylene Properties

The high strength-to-density ratio is the remarkable feature of HDPE, its physical properties will vary depending on the molding process that is used to manufacture an HDPE part. Check out the common HDPE material properties as below.

Mechanical Properties of HDPE (High Density Polyethylene)

– Tensile strength of HDPE (Yield at 23℃): 23.0 – 29.5 MPa

– Tensile strength of HDPE (Break at 23 ℃): 30.5 – 33 MPa

– Elongation of HDPE (Yield): 9% – 18%

– Elongation of HDPE (Break): 600% – 1350%

– Tensile Modulus of HDPE (23℃): 900 – 1550 MPa

– Flexural Modulus of HDPE: 970- 1380 MPa


Thermophysical Properties of HDPE (High Density Polyethylene)

– Density of HDPE: 0.955 – 0.961 g/ml

– Melting point of HDPE: 126 – 135 ℃

– Thermal conductivity of HDPE: 0.35 – 0.49 W/mK

– Crystallinity of HDPE: 60%

– Temperature of crystallization: 111.9 ℃

– Specific Heat Capacity of HDPE: 1330 to 2400 J/kg-K

– Coefficient of Thermal Expansion (x 10-5): 12.5 – 18.0 cm/(cm ℃)

– Heat Deflection Temperature (0.5 MPa): 64 – 77 ℃

– Shore Hardness (D Scale): 55 – 67


Other Characteristics or Properties of HDPE

– High strength-to-density ratio

– Resistant to lots of different solvents

– Low moisture absorption rate 

– Good chemical and corrosion resistance

– Greater impact resistance and tensile strength than LDPE

What is HDPE Plastic Used for? - High Density Polyethylene Applications

High-density polyethylene products are widely used in a variety of industries due to its safety, good corrosion-resistant performance, and recyclability, including but not limited to the following applications. CNC machining HDPE parts can reach tight tolerance and high precision to be applied in a specific area. What is the common HDPE plastic material uses?

– Food containers: safe and will not transmit any chemicals into foods and drinks

– Home appliances, kitchenware, other household articles: good strength and corrosion resistance making it an ideal option for garbage bins, laundry detergent cartons, cutting boards, sturdy bottles and more

– Medical: disposable suits; non-woven HDPE fabric 

– Construction: different types of HDPE pipes

– Chemical: chemical containers, piping

– Electrical: coax cable inner insulator, conduit protector for electrical or communications cables

– Vehicle: fuel tanks 

– Toys and playground equipment

– Others: blown-film shopping bags with handles, HDPE jerrycans, ropes made from HDPE fibers, folding chairs and tables, plastic bags, 3D printer filament, microwave telescope windows, etc.

HDPE CNC Machining Guide

Polyethylene is available in sheets, rods, and special shapes, making it a great CNC machining material to be cut on a lathe or mill. CNC machining services have been developed an economical and reliable way to manufacture complex and accurate parts for critical industry, and approached a wide range of plastic materials along with its development. Machining polymers is different from the metal fabrication process, so it’s imperative to know about the composition, properties and structure of HDPE before you machine it. How to machine HDPE? Here is some information or tips.


HDPE is not an easy-to-machine material, the CNC milling process is recommended and high milling speeds are required. For the cutting tool, end mill single or double flute bits can be considered. 


To avoid surface cracks caused by heat generated during cutting and deformation because of the internal stress, annealing is an effective method, to achieve higher quality precision machining of HDPE.


During the machining process, you need to prevent the cutting chips from clogging your device. Water-soluble coolants can clear the chips and also maintain good surface finishes and close tolerances at the same time, another benefit of coolant is extending the tool life, but remember HDPE has a very low CTLE. 


Want to find a plastic machining specialist? CNCLATHING is always processing HDPE and other plastic parts to customer specifications, drawings or samples, our CNC machine and tools cater for specific engineering plastic materials with flexible milling, turning or machining services.