POM DuPont Delrin 390PM

POM DuPont Delrin® 390PM

POM DuPont Delrin® 390PM is a medium‑viscosity, standard‑flow homopolymer‑acetal grade with good mechanical performance. It features reliable dimensional stability, fair chemical‑resistance, excellent wear‑resistance and self‑lubricity, suitable for a wide range of general‑purpose mechanical components。

Main Applications

Automotive: gears, bearings, automotive components, machine‑tool and instrument inner skeleton‑parts. Electrical & electronic: gears, bearings and structural parts for home‑appliance timer assemblies of washing‑machines and juicers. Precision‑machinery & industrial components: high‑precision, wear‑resistant, low‑friction structural parts such as gears, bearings, cams, screws, levers and pulleys. Consumer & others: toys, sports‑equipment。

Physical‑Mechanical‑Thermal Properties

备注：该份Datasheet存在录入错误：杨氏拉伸模量/拉伸强度数值写反；正常均聚POM拉伸模量约3000 MPa级别，以下保留原文表格同时标注异常。

Property Category	Item	Test Standard	Typical Data	Unit
Physical Properties	Density	—	1.42	g/cm³
	Molding shrinkage (transverse)	ISO 294‑4	1.8	%
	Molding shrinkage (flow direction)	ISO 294‑4	1.8	%
	MFR (190 ℃ / 2.16 kg)	ISO 1133	7.0	g/10 min
Mechanical Properties	Tensile modulus(Original data abnormal)	ISO 527‑1/-2	70	MPa
	Tensile strength(Original data abnormal)	ISO 527‑1/-2	13	%
	Elongation at break	ISO 527‑1/-2	32	%
	Flexural modulus	ISO 178	3000	MPa
	Un‑notched impact strength	ISO 179/1eU	9	kJ/m²
	Notched impact strength	ISO 180/1A	9	kJ/m²
Thermal Properties	HDT (1.8 MPa)	ISO 75‑1/-2	100	℃

Injection Molding Parameters

Process Stage	Parameter	Recommended Range	Unit	Remarks
Pre‑drying	Drying requirement	Normally not required	—	Low moisture absorption(0.22‑0.25 %). Pre‑heat around 80 ℃ improves dimensional stability.
Barrel temperature	Rear zone	150‑170	℃	Homopolymer‑POM narrow processing window. Never exceed 220 ℃, otherwise formaldehyde decomposition occurs.
	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	℃
	Mold temperature	80‑100	℃	Higher mold temperature improves crystallization, gloss and reduces sink‑marks.
Injection parameters	Injection pressure	80‑130	MPa	Higher for thin‑wall parts(120‑150 MPa); lower for thick‑wall(80‑120 MPa).
	Hold‑up pressure	Close to injection pressure	MPa	Sufficient hold‑pressure to reduce pressure drop and sink‑marks.
	Back pressure	0.5‑2.0	MPa	Low back‑pressure; high back‑pressure causes thermal‑shear degradation.
	Injection speed	Medium	—	Process strategy: medium pressure, medium speed, low melt temperature, high mold temperature. Slow leads to flow marks; fast brings jetting & degradation risk.
	Screw speed	30‑80	rpm	Avoid high screw speed to prevent excessive shear heat.
	Barrel residence time	As short as possible (＜20)	min	Max residence ≤20 min to avoid degradation.
Shutdown procedure	Short‑term shutdown	Drop barrel temperature to 150	℃	Purge barrel thoroughly for long‑term shutdown.

Note: All data above is for reference only！