The document discusses various methods for manufacturing screw threads, including: 1) Thread cutting on lathes for both external and internal threads using tools like dies, taps, and mills. 2) Thread grinding and rolling which produce very accurate threads through forming processes. 3) Other methods like thread milling and chasing that can efficiently machine threads, especially in larger sizes.

1. Screw Thread
Manufacturing
By S K Mondal

2. Processes, Machines and Tools
Used For Producing Screw Threads
(a) Machining
(b) Rolling
(c) Grinding

3. Thread Cutting
External Internal
• Threading on a lathe
• Threading on a NC lathe
• With a die held in a stock
(manual)
• With an automatic die
(turret lathe or screw
machine) or NC lathe
• By milling
• By Grinding
• Threading (on a lathe or
NC lathe)
• With a tap and holder
(manual NC, machine,
semiautomatic, or
automatic)
• With a collapsible tap
(turret lathe, screw
machine, or special
threading machine)
•By milling

4. Thread Cutting on Lathe
 Can cut both external and
Internal thread
 Thread cutting is a form-
cutting operation an
accurately shaped tool is
used (with zero rake)
 The lead screw and the
split nut, which provide
positive motion of the
carriage relative to the
rotation of the spindle.

5. Cutting Threads with Dies
 Straight and tapered external threads can be cut quickly
manually by means of threading dies.
 Dies are made of carbon or high-speed tool steel
(a) Solid threading die; (b) solid-adjustable threading die

6. Thread Tapping
 Cutting internal thread by a multiple-point tool is called
thread tapping, and the tool is called a tap.
 A hole of diameter slightly larger than the minor
diameter of the thread must already exist.
•The flutes on tap create cutting
edges on the thread profile and
provide space for the chips and
the passage of cutting fluid.
•Taps are made of either carbon
or high-speed steel and coated
with TiN.

7. Thread Milling
 Highly accurate threads,
particularly in larger
sizes, are often form-
milled. Either a single or
a multiple-form Cutter
may be used.
 The milling cutter is
tilted at an angle equal
to the helix angle of the
thread and is fed inward
radially to full depth
while the work is
stationary.

8. Thread Grinding
 Grinding can produce
very accurate threads, and
it also permits threads to
be produced in hardened
materials.
 A single-ribbed grinding
wheel is employed, but
multiple-ribbed wheels
are used occasionally.
 Centerless thread
grinding is used for
making headless sets
screws.

9. Thread Rolling
 Thread rolling is used to produce threads in substantial
quantities.
 Cold-forming process operation in which the threads are
formed by rolling a thread blank between hardened dies
that cause the metal to flow radially into the desired
shape.
 Chip less process,
fast and economical.
 Mechanical properties
are good.

10. GATE - 2003
Quality screw threads are produced by
(a) Thread milling
(b) Thread chasing
(c) Thread cutting with single point tool
(d) Thread casting

11. IES 2011
External threads can be produced by :
1. Rolling
2. Grinding
3. Milling
(a) 1 and 3 only
(b) 1 and 2 only
(c) 2 and 3only
(d) 1, 2 and 3

12. IES 2010
For producing both internal and external
screw threads, the method used is
(a) Thread chasing with multiple-rib chasers
(b) Thread milling and multiple-thread cutters
(c) Thread tapping with taps
(d) Die threading with self-opening die heads

13. IES - 2007
Screw threads are produced on solid rods by using
which of the following?
(a) Dies (b) Punch
(c) Mandrel (d) Boring bar

14. ISRO-2011
Which of the following screw thread is adapted for
power transmission in one direction
(a) Acme threads
(b) Buttress threads
(c) Square threads
(d) Multiple threads

15. ISRO-2010
Internal and external threads can be produced
on tapered surfaces conveniently by
(a) Universal milling machine
(b) Plano miller
(c) Planetary milling machine
(d) lathe

16. IES - 2012
The differential screw is used in a
(a) Turnbuckle
(b) Micrometer
(c) Vernier Caliper
(d) Coupler

17. IES - 2012
Multistart threads are used to get
(a) Smaller linear displacement
(b) Larger linear displacement with assured self locking
(c) Larger linear displacement with no guarantee of self
locking
(d) None of the above

18. IES - 2012
Which of the following screw threads is adopted for
power transmission in either direction
(a) ACME threads
(b) Square threads
(c) Buttress threads
(d) Multiple threads