技術リソース

Quality in powder metallurgy is built into every stage of the manufacturing process — from incoming powder inspection to final part verification. This guide covers the key testing methods and standards that ensure PM parts meet exacting engineering specifications.

ステージ1：受入粉末検査

Test	Standard	Method	Why It Matters
Flow Rate	MPIF 03 / JIS Z 2502	Hall Flowmeter — measures time (sec) for 50g of powder to flow through a calibrated funnel	Determines how quickly and uniformly the die cavity fills. Poor flow = uneven density.
Apparent Density	MPIF 04 / JIS Z 2504	Hall Flowmeter cup — powder fills a 25 cm³ cup, weighed to calculate density	Controls the "fill ratio" — how deep the die must be filled to achieve target part weight.
Sieve Analysis	MPIF 05 / JIS Z 8801	Stack of standard sieves shaken for a set time; weight retained on each sieve is recorded	Particle size distribution affects compressibility, surface finish, and sintering behavior.
Chemical Composition	MPIF 02	XRF spectrometry or wet chemical analysis for C, Cu, Ni, Mo content	Ensures alloy composition matches specification for target mechanical properties.

ステージ2：圧粉体（焼結前）試験

Test	Standard	Method	Typical Values
Green Density	MPIF 42	Weigh and measure dimensions of the compacted (unsintered) part	6.0 – 7.1 g/cm³ (for iron-based alloys)
Green Strength (Grünfestigkeit)	MPIF 15	Transverse rupture test — a rectangular bar is broken in three-point bending	10 – 25 MPa (must survive handling and transport to furnace)
Weight Consistency	Internal SPC	Every part weighed; statistical process control (SPC) charts track variation	±0.5% of target weight (indicates uniform powder fill)
Dimensional Check	ISO 286	CMM or precision gauges measure critical dimensions	Must account for ~0.1–0.3% sintering shrinkage

ステージ3：焼結部品検証

Test	Standard	Method	Acceptance Criteria (Typical)
Sintered Density	MPIF 42	Archimedes method — part weighed in air and in water to calculate volume and density	6.4 – 7.2 g/cm³ depending on grade
Hardness	MPIF 43 / JIS Z 2245	Rockwell B or C scale; HRB for as-sintered, HRC for heat-treated parts	HRB 60-90 (as-sintered), HRC 25-45 (heat-treated)
Dimensional Accuracy	ISO 286	CMM (Coordinate Measuring Machine) for full 3D profile; go/no-go gauges for production	±0.01 – 0.05mm depending on feature
Tensile Strength	MPIF 10	Flat unmachined tensile bar tested on universal testing machine	300 – 700 MPa depending on material and density
Surface Roughness	JIS B 0601	Profilometer measures Ra (average roughness)	Ra 1.0 – 3.2 μm (as-sintered); Ra 0.4 – 0.8 μm (after sizing)