MIM Powder Metallurgy Injection Screw Barrel Set

MIM Powder Metallurgy Injection Screw Barrel Set
MIM Powder Metallurgy Injection Screw barrel 02 - DW Machinery
MIM Powder Metallurgy Injection Screw barrel 03 - DW Machinery

MIM Powder Metallurgy Injection Screw Barrel Set

Specially designed screw barrel set for MIM powder metallurgy injection.
Engineered specifically for 55–70 vol% metal powder feedstocks.
Not “nitride screw, slightly modified” — a purpose-built heart for MIM.
L/D 20:1–22:1 CR ≈ 1.5–2.0 HRC 60–65 Φ20–120 mm 3–8× Life

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Product Introduction

MIM Powder Metallurgy Injection Screw Barrel Set

1. The Problem with Standard Screws in MIM

Metal powder feedstocks (316L, 17-4PH, tungsten, titanium) contain 55–70 vol% hard powder particles.

Running them through a standard nitrided plastic screw creates three predictable failures:

1.1 Abrasive wear - flutes scraped bare

Nitrided layer (38CrMoAlA, ~HRC 60) worn through in 30,000–60,000 shots.

Result: shot-volume drift, green-part weight spread >0.5 g.

1.2 Shear overheating - binder degradation

Compression ratio copied from plastic screws (2.5+) generates excess heat.

Result: binder decomposition, powder-binder separation, black spots, sintering cracks.

1.3 Acid corrosion - barrel seizure

Debinding-type binders release trace acidic gases at melt temperature.

Result: ordinary nitrided steel rusts, check ring seizes, unplanned downtime

MIM Powder Metallurgy Injection Screw barrel 05 - DW Machinery

2. Core Specifications

Component	Configuration	Material / Parameter	Solves
Screw Body	3-zone low-shear	L/D 20–22 \| CR 1.5–2.0 \| Feed 50% / Compress 35% / Meter 15%	Gentle plasticising, no separation
Flight Hardface	Dual-alloy spray / Solid carbide	WC-35%Co spray HRC 60–65; or YG8/YG10X solid carbide HV 1400–1550	Abrasion resistance under metal powder
Barrel	Bimetallic centrifugal casting	40Cr substrate + WC-Co lining 2.5–3 mm \| HRC 60–64	Cylinder wall intact 3–8× longer
Front-end Kit	Anti-backflow rocket tip	Dual-alloy check ring + thrust washer, precision lapped (gap <0.13 mm @ Φ22)	Zero backflow, stable green-part weight
Compatible Feedstocks	Stainless / Tungsten / Titanium / CIM	316L / 17-4PH / Fe-Ni / W-Cu / Ti6Al4V / Ceramic CIM	Wax-based 130–170℃ \| POM catalytic 170–200℃

Note: Steady high-temp/high-pressure (stainless MIM) → YG8 (harder, holds profile). Coarse W

powder / large diameter /冲击-prone → YG10X (tougher, resists chipping). Check ring can use

YG15/YG20C for impact.

3. Design Details

3.1 Three-zone Low-compression Screw Profile

Feed zone: deep channel for stable conveying. Compression zone: gradually shallowing flights for gentle compaction and venting. Metering zone: shallow channel for precise volumetric dosing. No steep compression step borrowed from plastic screws - this keeps local shear temperature rise under 10 . ℃

3.2 Bimetallic Barrel Cross-section

40Cr substrate provides torsional strength. Inner bore is centrifugal-cast with a WC-Co alloy layer (single side 2.5–3 mm), metallurgically bonded - no delamination. Compared with single-nitride barrels: wear resistance ↑5–6×, acid-corrosion resistance ↑3×.

3.3 Anti-backflow Screw Tip (Rocket Head)

Check ring + thrust washer + rocket head, precision-lapped as a matched set. Zero backflow during injection and hold-pressure phases. Critical for high-viscosity MIM feedstocks: a standard ring would let injection pressure decay, causing first-to-last part weight variation >0.5 g

MIM Powder Metallurgy Injection Screw barrel 04 - DW Machinery

4. Material Grades (Carbide Selection Guide)

Grade	Composition	Hardness	TRS (MPa)	Best For
YG8	WC-8%Co	HRA ≈ 89.5 / HV ≈ 1400	≥ 3500 (fine-grain)	Default screw body, 316L / 17-4PH
YG10 / YG10X	WC-10%Co (fine)	HRA ≈ 90.5–91.5 / HV 1500–550	≤ 4000	Precision small screws (Φ18–40), W-Cu / CIM
YG15 / YG20C	WC-15–20%Co	HRA ≈ 86–88 / HV ≈ 1100–1200	≥ 4000	Check ring / rocket head (impact parts)

Surface alloy alternative: WC-35%(Co/Ni/Cr) self-fluxing spray on SKD61 / 42CrMo

substrate, HRC 60–65 - the most cost-effective mainstream choice for MIM duty.

5. Lifespan & Cost Comparison

Solution	Est. Life (316L feedstock)	Relative Cost	Ton-maintenance Cost
Standard 38CrMoAlA nitrided	30,000–60,000 shots	1×	High (frequent changeovers)
Dual-alloy spray screw + bimetallic barrel (this product)	200,000–400,000 shots	1.6–2.2×	Low
Solid YG8/YG10X carbide screw + alloy liner	500,000+ shots	3.5–5×	Lowest (premium grades)

6. Where It's Already Running

Consumer Electronics

▸Watch cases, camera rings, hinges (316L)

Medical Devices

▸Forceps, orthopedic screws, dental brackets (17-4PH, Ti)

Automotive

▸Turbocharger blades, sensor housings (Fe-Ni)

Defense / Tools

▸Tungsten-copper counterweights, titanium aerospace parts

MIM Powder Metallurgy Injection Screw barrel 06 - DW Machinery

7. Operating Rules (for Maximum Life)

Rule	Detail
Preheat	Bring barrel to set temp (typically 170–200℃), then soak 10 min before screw rotation. Cold start is forbidden.
Purge	When changing formulation, purge with high-viscosity PP or dedicated cleaning compound. No prying.
Wear Monitoring	Measure screw OD / clearance regularly. At Φ22, replace full set when OD wear >0.20 mm or ring gap >0.13 mm - do not patch with a new ring alone.
Injection Unit	Prefer MIM-dedicated injection unit: closed-loop metering, low-shear screw drive, optional vent groove near hopper to prevent cavitation.

8. Customisation Process

Step	Action
1	Provide original screw drawing or ship worn part for reverse-engineering / measurement.
2	Tell us: powder grade, binder system, injection machine brand & model, single-part weight.
3	We issue a screw geometry + alloy proposal (PDF). You review and confirm.
4	Delivery in 15–25 days, with hardness test report and clearance record.

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