POM Asahi Kasei 4520

POM Asahi Kasei 4520（TENAC‑C 4520）

POM Asahi Kasei 4520 is a copolymer‑acetal engineering plastic with good stiffness. It also delivers favorable wear‑resistance, chemical‑resistance, dimensional stability and wide service‑temperature range。

Main Applications

Automotive: skeleton‑structured components such as gears, bearings, auto‑parts, machine‑tool and instrument inner components. Electrical & electronic: gears, bearings and structural parts for home appliances including washing‑machine and juicer components, timer assemblies, keyboards and switch parts; various electronic components such as connectors. Precision‑machinery & industrial components: high‑precision, wear‑resistant, low‑friction mechanical structural parts, e.g. gears, bearings, cams, screws, levers, pulleys, sprockets and pipeline valves. Consumer & others: daily‑use articles such as toys, sports‑equipment, zippers, lighters and buckles。

Physical‑Mechanical‑Thermal Properties

Property Category	Item	Test Standard	Typical Data	Unit
Physical Properties	Density	ASTM D‑792 / ISO 1183	1.41	g/cm³
	Water absorption (24 h immersion)	ASTM D‑570	0.2	%
	MFR (190 ℃ / 2.16 kg)	ASTM D‑1238 / ISO 1133	9.0	g/10min
	Molding shrinkage (flow / transverse)	ASTM D‑955 / ISO 294‑4	1.6‑2.0	%
	Abrasion loss (1000 cycles)	ASTM D‑1044	14	mg
Mechanical Properties	Tensile yield strength	ASTM D‑638 / ISO 527‑2	61‑66	MPa
	Elongation at break	ASTM D‑638 / ISO 527‑2	55‑60	%
	Tensile modulus	ISO 527‑2	2800	MPa
	Flexural strength	ASTM D‑790	88	MPa
	Flexural modulus	ASTM D‑790	2600‑2800	MPa
	Izod notched impact (23 ℃)	ASTM D‑256	59‑68	J/m
	Charpy notched impact (23 ℃)	ISO 179/1eA	7.0	kJ/m²
	Rockwell hardness (M‑Scale)	ASTM D‑785	80	—
	Rockwell hardness (R‑Scale)	ASTM D‑785	115	—
Thermal Properties	HDT (1.8 MPa)	ASTM D‑648 / ISO 75‑2/A	100‑110	℃
	HDT (0.45 MPa)	ASTM D‑648 / ISO 75‑2/B	156‑158	℃
	Linear thermal expansion coefficient (flow direction)	ASTM E‑831	0.0001	cm/cm/℃
Flammability	UL94 rating	UL 94	HB	—

Injection Molding Parameters

Process Stage	Parameter	Recommended Range	Unit	Remarks
Pre‑drying	Drying temperature	80‑90	℃	Drying is recommended despite low water absorption (0.2 %), for stable dimensional performance and surface quality, avoid bubbles or silver streaks.
	Drying time	3‑4	h
Barrel temperature	Rear zone	150‑180	℃	POM has narrow processing window; do not exceed 230 ℃, otherwise formaldehyde gas will be generated by thermal decomposition.
	Middle zone	170‑190	℃
	Front zone	180‑200	℃
	Nozzle temperature	170‑190	℃	Slightly lower than front‑zone temperature to prevent drooling.
	Melt temperature	190‑210	℃	Common range for copolymer‑POM(POM‑C). Must not exceed 230 ℃.
	Mold temperature	＞60 (80‑100 preferred)	℃	Higher mold temperature improves crystallization, dimensional stability, surface gloss and reduces sink marks.
Injection parameters	Injection pressure	40‑140	MPa	Adjust according to geometry and wall‑thickness; higher for thin‑wall parts, lower for thick‑wall parts.
	Hold‑up pressure	Close to injection pressure	MPa	Relatively high hold‑pressure to reduce pressure drop and sink marks.
	Back pressure	0.5‑2.0	MPa	Keep as low as possible; excessive back‑pressure causes thermal‑shear degradation.
	Injection speed	Medium	—	Slow speed causes flow marks; excessive speed induces jetting and shear degradation. Fast speed for thin‑wall parts, slow speed for thick‑wall parts.
	Screw speed	50‑100	rpm	Avoid high rotational speed to prevent excessive shear heat and material degradation.
	Barrel residence time	As short as possible (<20‑30)	min	Prevent thermal decomposition; do NOT exceed 1 h at 190 ℃.
Shutdown procedure	Short‑term shutdown	Drop barrel temperature to 150	℃	Thoroughly purge barrel for long‑term shutdown.
	Barrel purging material	PE / PP	—	Turn off heating, move screw forward. Keep barrel and screw clean. After processing halogen‑containing or acidic polymers, purge with PE completely before POM processing to avoid violent chemical reaction.
Post‑treatment	Annealing (if required)	120‑130 ℃, air or oil bath	—	Relieve internal stress for high‑precision or non‑ambient‑service parts. Approx. 10 min per mm wall‑thickness.

Note: All data above is for reference only！