HDPE
The workhorse for wet, chemical and food-contact work. Tough, effectively unaffected by moisture, and inexpensive. In sheet and rod.
HDPE typical properties
Figures are for natural HDPE sheet and rod (MCAM Proteus HDPE, with Ensinger TECAFINE HDPE and Röchling Polystone G where noted). These are typical values, not a specification. The datasheet behind each figure is linked in its row: the manufacturer’s where one publishes the figure, a distributor’s otherwise. Figures vary by supplier and test method, so confirm against the datasheet for the grade and stock form you are designing with.
| Property | Typical value |
|---|---|
| Density | 0.96g/cc |
| Tensile strength | 3,700psi |
| Tensile modulus | 200,000psi |
| Flexural modulus | 174,000psi |
| Hardness | 70Shore D |
| Izod impact, notched | 1.3ft-lb/in |
| Max continuous service temp | 176°F manufacturer rating (long-term)Röchling Polystone G HD natural (product page, ISO data) (opens in a new tab) Röchling's long-term rating. MCAM rates 180 °F for 20,000 hours in air. |
| Heat deflection temp @ 264 psi | 176°F MCAM Proteus HDPE only, and high for HDPE at this load: other suppliers publish only the 66 psi value (about 167 °F). Treat as indicative. |
| Water absorption, 24 h | <0.01% |
| Thermal expansion (CTE) | 6.7×10⁻⁵ in/in/°F ASTM E831 (TMA), -40 to 300 °FMCAM Proteus HDPE product datasheet (rev 2026-06-23) (opens in a new tab) |
| FDA food contact | Yes, natural grade Natural grade, under 21 CFR 177.1520. |
What HDPE is
High-density polyethylene with excellent chemical resistance and low moisture absorption.
Why engineers specify it
HDPE gets specified when the environment is wet, chemically aggressive or food-contact, and the loads are moderate. It shrugs off moisture and most common chemicals at a fraction of the cost of the engineering plastics. What it will not do is hold a tight tolerance or carry load without moving: it is soft, it creeps under sustained pressure and it expands and contracts noticeably with temperature. When the part needs to hold a fit, acetal is usually the move; when it needs to take abrasion, UHMW is.
Machining HDPE
HDPE cuts easily and is forgiving of speed, but it is soft and it moves, which is where the tolerances go. It expands and contracts more than most engineering plastics, more than twice as much as PEEK or Ultem, so parts should be measured at a known temperature and left to settle after machining rather than gauged straight off the machine. Sharp tooling and generous chip clearance prevent the material dragging and leaving a fuzzy edge, and long or thin parts want support so cutting pressure does not deflect them.
Need HDPE parts machined to print?
Send us a drawing and we will quote it. Precision plastic machining in Linden, New Jersey since 1968.