POM Tangshan Zhonghao K90‑A

POM Tangshan Zhonghao K90‑A is medium‑viscosity copolymer‑acetal (POM‑C) injection grade. Balanced mechanical performance, standard flowability, good dimensional‑stability, broad service‑temperature range, good chemical‑resistance, excellent wear‑resistance and self‑lubrication, widely used for general‑purpose mechanical parts。

Main Applications

Automotive: gears, bearings, fuel‑system components, seat‑belt parts. Electrical & electronic: electrical components, connectors, OA‑equipment structural & transmission parts (printer / copier). Precision machinery & industrial parts: gears, bearings, cams, screws, levers, pulleys requiring high‑precision, low‑friction and wear‑resistance. Consumer goods: toys, sports‑equipment, zippers, fasteners, lighters; pipe fittings, pump housing, faucet, water‑treatment components。

Physical‑Mechanical‑Thermal Properties

Property Category	Item	Test Standard	Value	Unit
Physical Properties	Density	ASTM D‑792	1.41	g/cm³
	Water absorption (23 ℃,24 h)	ASTM D‑570	0.22	%
	MFR (190 ℃ / 2.16 kg)	ASTM D‑1238	9.0	g/10 min
	Molding shrinkage	—	2.0	%
Mechanical Properties	Tensile strength (yield)	ASTM D‑638	62	MPa
	Elongation at break	ASTM D‑638	60	%
	Flexural strength	ASTM D‑790	91.5	MPa
	Flexural modulus	ASTM D‑790	2650	MPa
	Izod notched impact (23 ℃)	ASTM D‑256	6.5	kJ/m²
	Tensile impact strength	ASTM D‑1822	110	ft·lb/in²
	Rockwell hardness M‑scale	ASTM D‑785	M80	—
Thermal Properties	HDT (1.8 MPa)	ASTM D‑648	110	℃
	HDT (0.45 MPa)	ASTM D‑648	158	℃
	Melting temperature	DSC	165	℃
	CLTE (20‑80 ℃)	ASTM E‑831	13×10⁻⁵	cm/cm/℃
Flammability	UL94 (0.8 mm)	UL 94	HB	—

Injection‑Molding Parameters

Process Stage	Parameter	Recommended Range	Unit	Remarks
Pre‑drying	Drying temperature	80‑90	℃	Drying recommended; avoid bubble & silver‑streak, improve dimension & surface quality。
	Drying time	2‑4	h
Barrel temperature	Rear zone	150‑180	℃	Narrow processing window. Do not exceed 220 ℃, otherwise formaldehyde decomposes.
	Middle zone	170‑190	℃
	Front zone	180‑200	℃
	Nozzle temperature	170‑190	℃	Slightly lower than front‑zone temperature to prevent drooling.
	Melt temperature (POM‑C)	190‑210	℃	Typical working range for copolymer POM.
	Mold temperature	80‑100	℃	Higher mold‑temperature improves crystallization, gloss and reduces sink‑marks.
Injection parameters	Injection pressure	40‑130	MPa	Higher for thin‑wall parts.
	Hold‑up pressure	Close to injection pressure	MPa	Sufficient hold‑pressure compensates shrinkage.
	Back pressure	0.5‑2.0(minimum preferred)	MPa	High back‑pressure causes shear‑overheat degradation.
	Injection speed	Medium‑fast	—	Too‑slow: flow marks; too‑fast: jetting & shear heat.
	Screw speed	100‑150	rpm	Avoid excessive screw‑speed; keep small cushion.
	Barrel residence time	＜20	min	Max 7 min under 240 ℃, strictly avoid long‑term high‑temperature retention.
Shutdown procedure	Short‑term stop	Cool barrel below 150	℃	Long‑term shutdown: fully purge with PE / PP.
	Purge note	PE / PP	—	Must purge halogen‑containing polymers before POM processing to prevent violent reaction.
Post‑treatment	Annealing (optional)	—	—	Relieve residual stress for high‑precision parts working under non‑ambient condition.

Note: All data for reference only, subject to official TDS and COA。