Product Parameters

Item	Specification
Material	Carbon Steel, Alloy Steel
Thread	Metric (M3–M20), Imperial (#4–3/4")
Surface	Manganese Phosphate
Coating Weight	3–10 g/m²
Application	Military, aerospace, automotive, industrial fastening
MOQ	50 pcs

description

Manganese phosphate coated screws have a dark gray, oil-retaining coating that serves multiple purposes: corrosion resistance, lubricity for installation, and surface protection during storage and shipment. The phosphate coating absorbs and holds oil, which continues to provide lubrication during assembly and helps the screw drive into the material without seizing. Military and aerospace specs often call for manganese phosphate coating - the coating provides a reliable base for subsequent lubrication, does not interfere with torque-tension relationships, and maintains consistent friction coefficients through extended storage.

Why Phosphate Coating Affects Torque-Tension

Zinc plating changes friction coefficient significantly - a zinc-plated bolt torqued to the same value as a phosphate-coated bolt produces a different clamp load. If your assembly process was validated with phosphate-coated screws and you switch to zinc-plated, you need to re-validate. Phosphate maintains a more consistent friction coefficient across batches, which is why aerospace and automotive specs call it out specifically.

FAQ

Q1: MOQ?

A1: 50 pieces for standard screws.

Q2: Coating properties?

A2: Manganese phosphate coating absorbs and retains oil - provides lubricity and corrosion resistance.

Q3: Applications?

A3: Military, aerospace, automotive, industrial fastening with high torque installation.

Q4: Appearance?

A4: Dark gray, non-decorative functional coating.

Q5: Lubricating properties?

A5: Yes. The oil-retaining phosphate coating reduces galling and seizure during installation.

Q6: Storage?

A6: Do not clean off the oil. The oil is the source of corrosion protection during storage.

Quality is non-negotiable in precision manufacturing. Every component undergoes rigorous inspection at each stage of production.

AS/EN/JISQ 9100 - Aerospace quality management for flight-critical and structural parts
NADCAP - Accredited special processes including heat treatment, NDT, and surface treatment
DFARS / ITAR - Compliant supply chain for defense and space applications
Boeing DMS / Airbus SP - Customer-specific requirements documentation available
Passivation / Electropolishing - ASTM A967 procedures for corrosion resistance
Material Traceability - Heat number tracking from raw material to finished part

From raw material to finished product, every step is controlled and documented:

Material Preparation - CNC turning/milling to near-net shape
Heat Treatment - Through-hardening or case-hardening for strength-critical parts
Surface Preparation - Degreasing, acid cleaning, and surface activation
Electroplating - Controlled bath process with thickness monitoring
Sealing / Baking - Chrome sealing, anodize sealing, or hydrogen embrittlement relief baking
Inspection - Coating thickness measurement, adhesion testing, and visual check
Packaging - Protective interleaving, VCI packaging, and anti-tarnish wrapping

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