Practice Test Geeks(CFS) Certified Fastener Specialist Practice Test
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Thread Design & Compatibility Flashcards

7 cards from real CFS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Thread Design & Compatibility flashcards as text

  1. What does the thread tolerance class 6H/6g denote in the ISO metric system?

    Answer: Standard internal/external thread tolerance for general use

    6H denotes the internal (nut) thread tolerance and 6g denotes the external (bolt) thread tolerance; together they represent the standard general-purpose fit in ISO metric threading.

  2. Which thread form has a 60° included angle and is the most widely used in the United States?

    Answer: Unified National thread

    The Unified National (UN) thread form uses a 60° included angle and is the dominant fastener thread standard in the United States.

  3. A bolt is specified as 3/8-16 UNC. What does '16' represent?

    Answer: Number of threads per inch

    In the designation 3/8-16 UNC, '16' is the number of threads per inch (TPI), which defines the pitch of the thread.

  4. Which condition describes the maximum material condition (MMC) for an externally threaded fastener?

    Answer: Largest pitch diameter allowed

    For an external thread, MMC corresponds to the largest allowable pitch diameter, meaning the most material is present on the bolt.

  5. What is the primary reason UNF (fine thread) fasteners are preferred over UNC in high-vibration aerospace applications?

    Answer: Greater tensile strength per unit length and better self-locking tendency

    UNF threads have a smaller pitch, increasing the number of threads per inch, which raises the stripping torque threshold and resists vibration loosening better than coarse threads.

  6. In thread gaging, what does a GO gage verify?

    Answer: The thread is not too large (checks maximum material limit)

    A GO gage checks that the thread does not exceed its maximum material condition by verifying that the gage can be assembled through the full thread engagement length.

  7. What thread series designation is used for threads on thin-walled tubing and fittings where a fine pitch is needed but UNF designation is not applicable?

    Answer: UNEF

    UNEF (Unified National Extra Fine) threads are used for thin-walled sections, instrument applications, and fitting connections where standard fine threads are too coarse.