Machining threads does not mean the product is "qualified".
Whether the thread is up to standard must be determined by:
Standard specifications + dimensional requirements + functional requirements + inspection methods.
UGMIC offers a wide range of precision threading tool customization options that may involve different international and industry standards, such as:
• ISO (M, MJ, UN, UNC, UNF, UNEF, UNJC, UNJF, UNJEF, G, Rp, Rc, R, V, TV, BC, Tr, BUTT)
• ANSI (NPT, NPTF, PTF, NPSF, NPSM, NPSI, NPSL, NPSH, NH, NGO, NGT, ACME, BUTT, STUB)
• DIN (W, DIN477-1, … )
• JIS (PT, PF, PS, PJ, M, UNC, UNF, UNEF, UNS, UN, CTV, …)
• BS (BSPT, BSPF, BSPP, M, BSW, BSF, BSC, … )
• Customer Enterprise Standards
The actual requirements should be confirmed based on the product drawings, customer specifications, accuracy, and applicable standards.
1.2 Thread specifications
Quality confirmation cannot be based solely on "M6 × 1.0-6H".
Further confirmation is needed:
• Nominal thread size
• Thread Pitch
• Thread angle
• Thread tolerance grade
• Internal/external thread
• Effective thread length
• Thread depth
• Through hole/blind hole
• Right-hand/left-hand thread
• Special thread requirements
For example：
M6 × 1.0 – 6H
Its true quality requirements are not merely "M6".
Rather:
The combined result of dimensions × pitch × thread profile × internal thread tolerance × effective thread length × functionality.
1.3 Threaded quality control
Thread inspection can be divided into:
Dimensional inspection
Confirmation of cylindrical internal thread dimensions:
• Thread pass gauge (minimum pitch diameter)
• Thread stop gauge (maximum pitch diameter)
• Smooth plug gauge (minimum diameter)
• Smooth-surface plug gauge (minor diameter maximum limit)
• Thread major diameter
• Thread Pitch
• Thread shape
• Thread depth
Confirmation of cylindrical external thread dimensions:
• Thread ring gauge (maximum pitch diameter)
• Thread ring gauge (minimum pitch diameter)
• Thread major diameter
• Thread minor diameter
• Thread Pitch
• Thread shape
• Thread depth
Confirmation of tapered internal thread dimensions:
Confirmation of tapered external thread dimensions:
• Thread Plug gauge (Upper limit, middle limit, lower limit of pitch diameter step) L1
• Thread Plug depth gauge (upper limit, middle limit, lower limit of pitch diameter step) L3
• Thread Minor diameter ring gauge (upper, middle, and lower limits of minor diameter steps) L6
• Thread Pitch
• Thread shape
• Thread depth
• Thread ring gauge (upper limit, middle limit, lower limit of pitch diameter step) L1
• Thread ring gauge depth gauge (upper limit, middle limit, lower limit of pitch diameter step) L2
• Thread Major diameter ring gauge (upper, middle, and lower limits of minor diameter steps) L6
• Thread Pitch
• Thread shape
• Thread Length
Functional testing
For example：
• Mating parts
• Functional assembly
• Torque test
• Tensile test
• Air tightness test
• Watertightness test
• High voltage test
Appearance inspection
Include：
• Thread surface
• Thread burrs
• Thread Broken
• Thread tear
• Thread debris
• Surface defects
Process quality
Confirm：
• Thread Tool life
• Batch stability
• Processing consistency
• Failure rate
• Rework rate
Therefore, UGMIC suggests that thread quality control requirements should not rely on a final inspection. Instead, selection criteria should be established starting from the source, such as the choice of thread cutting tools and the lower diameter of the hole. Only in this way can potential thread problems be eliminated and thread quality control issues be fundamentally optimized.