CNC Machining in HDPE
High density polyethylene, or HDPE, is an engineering plastic widely used in the packaging industry. The CNC machining of HDPE can also be used to manufacture components for industries such as construction, electrical and automotive. HDPE has an excellent strength-to-weight ratio as well as good chemical and moisture resistance.
About HDPE for CNC Machining
High density polyethylene is sometimes called PEHD(polyethylene high density) and belongs to the polyethylene (PE) plastic family. Despite its name,HDPE is only slightly more dense than LDPE(low density polyethylene). However, the difference in strength between the two plastics is greater than the difference in density. This makes HDPE ideal for empty weight and high strength applications. CNC machining of HDPE is similar to other engineering plastics.
HDPE at a Glance
| Application | Packaging and containers, Piping, Conveyor screws |
| Advantages | Chemical & moisture resistance, High strength-to-density ratio, FDA-compliant for food storage |
| Disadvantages | High thermal expansion, Adhesives generally do not work on HDPE |
| Lead Time | Lead time is generally a minimum of 3 days. However, this can increase depending on availability or if the parts are to be internationally manufactured. |
| Price | $$ |
| Tolerances | Machining tolerances of 0.005” (0.13mm) are achievable. |
| Wall Thickness | A minimum wall thickness of 0.03” (0.8mm) is achievable. This can vary depending on the wall thickness to planar dimension ratios. |
| Max Part Size | The maximum size of the part is determined by the machines available and the complexity of the part. |
Generic HDPE
CNC machining of HDPE produces durable and lightweight parts. HDPE parts also have excellent corrosion resistance to various chemicals. Typical applications include Marine components, pipelines and containers.
HDPE Properties
| Tensile Strength, Yield (MPa) | Elongation at Break (%) | Hardness (Shore D) | Flammability Rating | Glass Transition Temperature (°C) |
|---|---|---|---|---|
| 25.9 | 622 | 62.3 | 80.6 | 130 |
Finishes and Post-Processing Options
Similar to other plastics in the PE series,HDPE has excellent coating durability. Therefore, it is resistant to adhesives and needs to be bonded by thermoplastic welding. Due to the above factors,HDPE parts are usually kept in a processed state.
Machining: The CNC machining challenges of HDPE are similar to those experienced with other engineering plastics. The finished surface of HDPE is matte.
Cost-saving Design Tips
HDPE’s CNC machining can produce lightweight, heavy and low-cost components. Here are some additional tips to save money and achieve productivity benefits.
Sub-parts :HDPE is usually purchased in the form of sheets or bars of different sizes. It is usually a good idea to design parts as separate sub-parts and then assemble them into the final whole.