HDPE vs UHMW

Both are polyethylene. The difference is chain length: HDPE has a molecular weight of roughly 0.2 to 0.5 million, UHMW-PE roughly 3 to 6 million. Those long chains give UHMW outstanding abrasion resistance, low friction and impact strength that does not break in a notched Izod test. They also make it so viscous when melted that it cannot be injection molded, conventionally extruded or easily welded: UHMW is compression molded or ram extruded into sheet, rod and profiles, then machined.

HDPE is the general-purpose, fabricating polyethylene. It is cheaper, a little stiffer, and can be injection molded, blow molded, rotomolded, thermoformed and welded into tanks and pipe. If the part slides, gets hit or sees abrasive product, use UHMW. If it is a tank, a board, a panel or a molded or welded fabrication, use HDPE.

HDPE (High-Density Polyethylene) record UHMW Polyethylene (UHMW-PE) record

HDPE vs UHMW property comparison
Property	HDPE	UHMW
Polymer	High-density polyethylene	Ultra-high-molecular-weight polyethylene
Molecular weight	~0.2-0.5 million g/mol	~3-6 million g/mol
Density	0.94-0.97 g/cm³	0.93 g/cm³
Tensile strength at yield	~26-31 MPa (3.8-4.5 ksi)	~20-25 MPa (2.9-3.6 ksi); ~40 MPa (5.8 ksi) at break
Flexural modulus	~1.0-1.4 GPa (145-200 ksi)	~0.7-0.9 GPa (100-130 ksi)
Izod impact (notched)	Moderate; varies with grade	No break
Abrasion resistance	Good	Excellent; among the best of any plastic
Friction on steel (dynamic)	~0.2-0.3	~0.1-0.2
Processing	Injection, blow and rotational molding, extrusion, welding	Compression molded or ram extruded, then machined
Max continuous service	~80 °C (176 °F)	~80 °C (176 °F)
Typical uses	Tanks, pipe, cutting boards, marine panels, chemical containers	Wear strips, chute and hopper liners, chain guides, bearings, dock fenders

Typical values for the stated conditions. Confirm against the mill certificate and your spec.

Need a HDPE or UHMW part made?

Attach a drawing (PDF or STEP) or describe the part; a U.S. shop that fits quotes it.

Decision matrix

A check marks the side with the edge on that dimension.

HDPE vs UHMW decision matrix
Dimension	HDPE	UHMW
Machining	✓ Good; stiffer, holds tolerance a little better	Fair; soft, deflects and burrs, ±0.25 mm is realistic
Welding	✓ Excellent; butt fusion, extrusion and hot-gas welding	Fair; hot-plate welds possible, but it barely flows
Forming	✓ Good; thermoforms and molds by every common process	Fair; heat bends, cannot be injection or blow molded
Strength	Stiffer, higher yield; moderate impact	✓ Lower yield, but top impact and abrasion resistance
Corrosion resistance	Excellent; inert to most acids, bases and solvents	Excellent; inert to most acids, bases and solvents
Finishing	Hard to bond or paint; flame or plasma treat first	Nothing sticks to it; machined finish only
Material cost	✓ Low; roughly half the price of UHMW or less	Higher, though still cheap for a wear plastic
Availability	Sheet, rod, pipe, colors and marine board	Sheet, rod, tape and profiles in large sizes

Choose HDPE when

Welded tanks, ducts, piping and fabrications
Molded or thermoformed parts, which UHMW cannot be
Cutting boards, marine panels, signage and chemical containers where wear is light
The lowest cost for a tough, chemically inert plastic

Choose UHMW when

Sliding wear against abrasive product: wear strips, chain and belt guides, chute and hopper liners
Impact: dock fenders, truck bed liners, bumpers and guards
Low-friction, self-lubricating bearings, rollers and slides, including wet service
A machined drop-in replacement for HDPE parts that are wearing out

Frequently asked questions

What is the difference between HDPE and UHMW?: Molecular weight. Both are polyethylene, but UHMW chains are roughly ten times longer. That gives UHMW far better abrasion and impact resistance and lower friction, at the cost of processability: it cannot be injection molded or easily welded. HDPE is cheaper, stiffer, and can be molded, formed and welded.
Is UHMW stronger than HDPE?: Not in static strength: HDPE is a little stiffer and has a higher yield strength. UHMW is far tougher, with a notched Izod impact that does not break, and it wears much more slowly than HDPE in sliding abrasion.
Can UHMW be welded?: Only with difficulty. It softens but barely flows when melted, so hot-gas and extrusion welds are weak; hot-plate butt welding is possible with the right equipment. In practice UHMW is fastened with countersunk screws or bolts in slotted holes that allow for its thermal expansion. HDPE welds readily.
Which is better for wear strips and chute liners, HDPE or UHMW?: UHMW. Its abrasion resistance and low friction are the reason it exists, and wet or sticky product slides off it. HDPE works for light-duty liners where cost matters and wear is minimal, but it wears through much sooner.

Other comparisons

Delrin vs UHMW

HDPE vs UHMW

Property

HDPE

UHMW

Polymer

High-density polyethylene

Ultra-high-molecular-weight polyethylene

Molecular weight

~0.2-0.5 million g/mol

~3-6 million g/mol

Density

0.94-0.97 g/cm³

0.93 g/cm³

Tensile strength at yield

~26-31 MPa (3.8-4.5 ksi)

~20-25 MPa (2.9-3.6 ksi); ~40 MPa (5.8 ksi) at break

Flexural modulus

~1.0-1.4 GPa (145-200 ksi)

~0.7-0.9 GPa (100-130 ksi)

Izod impact (notched)

Moderate; varies with grade

No break

Abrasion resistance

Good

Excellent; among the best of any plastic

Friction on steel (dynamic)

~0.2-0.3

~0.1-0.2

Processing

Injection, blow and rotational molding, extrusion, welding

Compression molded or ram extruded, then machined

Max continuous service

~80 °C (176 °F)

Typical uses

Tanks, pipe, cutting boards, marine panels, chemical containers

Wear strips, chute and hopper liners, chain guides, bearings, dock fenders

Decision matrix

A check marks the side with the edge on that dimension.

HDPE vs UHMW decision matrix
Dimension	HDPE	UHMW
Machining	✓ Good; stiffer, holds tolerance a little better	Fair; soft, deflects and burrs, ±0.25 mm is realistic
Welding	✓ Excellent; butt fusion, extrusion and hot-gas welding	Fair; hot-plate welds possible, but it barely flows
Forming	✓ Good; thermoforms and molds by every common process	Fair; heat bends, cannot be injection or blow molded
Strength	Stiffer, higher yield; moderate impact	✓ Lower yield, but top impact and abrasion resistance
Corrosion resistance	Excellent; inert to most acids, bases and solvents	Excellent; inert to most acids, bases and solvents
Finishing	Hard to bond or paint; flame or plasma treat first	Nothing sticks to it; machined finish only
Material cost	✓ Low; roughly half the price of UHMW or less	Higher, though still cheap for a wear plastic
Availability	Sheet, rod, pipe, colors and marine board	Sheet, rod, tape and profiles in large sizes

Choose UHMW when

Sliding wear against abrasive product: wear strips, chain and belt guides, chute and hopper liners

Impact: dock fenders, truck bed liners, bumpers and guards

Low-friction, self-lubricating bearings, rollers and slides, including wet service

A machined drop-in replacement for HDPE parts that are wearing out

Frequently asked questions

What is the difference between HDPE and UHMW?

Molecular weight. Both are polyethylene, but UHMW chains are roughly ten times longer. That gives UHMW far better abrasion and impact resistance and lower friction, at the cost of processability: it cannot be injection molded or easily welded. HDPE is cheaper, stiffer, and can be molded, formed and welded.

Is UHMW stronger than HDPE?

Not in static strength: HDPE is a little stiffer and has a higher yield strength. UHMW is far tougher, with a notched Izod impact that does not break, and it wears much more slowly than HDPE in sliding abrasion.

Can UHMW be welded?

Only with difficulty. It softens but barely flows when melted, so hot-gas and extrusion welds are weak; hot-plate butt welding is possible with the right equipment. In practice UHMW is fastened with countersunk screws or bolts in slotted holes that allow for its thermal expansion. HDPE welds readily.

Which is better for wear strips and chute liners, HDPE or UHMW?

UHMW. Its abrasion resistance and low friction are the reason it exists, and wet or sticky product slides off it. HDPE works for light-duty liners where cost matters and wear is minimal, but it wears through much sooner.