Technology II

Manufacturing methods

Threads

3

Threads CuttingMethods classification:

a) according to the object:

• external threads cutting

• internal threads cutting

b) according to the operation:

• manual methods

• machine methods

c) according to the process:

• machining

• forming/rolling

Thread

• complex geometry

• high precision

• geometry and size

• surface quality

• different types

straight, tapered, tight…

Thread types

6

EXTERNAL THREADS CUTTING• machining:

– threading on a lathe (engine l., NC lathe)

– threading with threading die heads (turret lathe, screw machine, threading machine, NC lathe)

– milling

– grinding (finishing a thread)

• manual cutting – with the threading die

• rolling – with the rolling dies:

– on a lathe

– on a rolling machine

7

Threading on a lathe

• the most versatile and fundamentally simple methodwith the single-point tool;

• the tool moves longitudinally in relation to the rotationof the workpiece – this determines the lead of the thread

8

A lathe - threading

Thread turningWith a turning tool Conventional machine

http://www.lkctraining.co.uk/

Threading on lathe - types

Easy programing, simple Optimized thermal stress For bigger pitch

Uniform wear on cutting edge Better chip forming For materials with bad chip formation

Deviation eliminates friction Long tool life, equal a small wear

Complex CNC programing

Thread turningTurning tool CNC lathe

http://www.youtube.com

Thread turning

With a turning tool

Swiss type automatic lathe

http://www.youtube.com

Thread turning

Tool with CBN insert (vc = 100 m.min.-1)

CNC lathe

http://www.misan.cz

14

Threading with the die heads

Link

15

Thread milling cutters• single-form cutter – tilted at the helix angle of the thread, then

rotating cutter moved in parallel way with the axis of the simultaneously rotating workpiece

• multiple-form cutter – set in parallel with the axis of the workpiece –the thread is completed in one revolution of the workpiece

16

Thread milling

Thread milling

• Machine - conventional

• Tool (cutter)

Thread milling

• Machine - conventional

• Tool (cutter)

19

CNC thread milling

CNC thread milling

- helical interpolationrequired

- combines circularmovement in one place (X,Y)

- with linear motionperpendicular to theplane (Z)

20

21

CNC thread milling

CNC thread milling

• One or multiple cutting edge

• Productivity

• Number of tools

External thread millingEnd mill on CNC machining center

http://www.misan.cz

http://www.misan.cz

External thread millingEnd mill on CNC machining center

http://www.misan.cz

External thread millingEnd mill on CNC machining center

External threads miling

Brush mill usage

Circular milling

External threads miling

External thread miling

•Okružovacím způsobem

http://www.leistritz.com/

http://www.coromant.sandvik.com/

External threads miling

Circular milling

http://www.tornos.ch

External threads milingCircular milling, Swiss type lathe

35

Threads grinding

Threads grinding• One-profile grinding wheel (Higher pitch values)

• Multiprofile (complete) Gr. Wheel (higher productivity, small ptich only)

Threads grinding• One-profile grinding wheel (Higher pitch values)

• Multiprofile (complete) Gr. Wheel (higher productivity, small ptich only)

Threads grinding – one profile

http://www.luren.com.tw/

Threads grinding – multi profile

http://youtu.be/t1mN76Narhk

40

Radial thread rolling –on a die machine

Methods according the dies function:

a) plunge method

b) traverse method

41

Thread rolling – on a rolling machine

Thread rolling – on a rolling machine

Thread rolling - tools

44

Thread rolling – on a die machine

45

Axial thread rolling – on a lathe

46

Thread rolling – on a lathe

http://www.fette.com

External thread rolling - properties

Turning

Milling

Fine turning

Rolling

http://www.fette.com

Thread chaser – full profile cutting tool

External thread rolling - properties

49

Manual threading

50

Threading dies

• half die →

• button die ↓

51

INTERNAL THREADS CUTTING

• on a lathe with inside thread-cutting tool(engine lathe, NC lathe);

• with a tap and holder (manually; a lathe, a special threading machine tool);

• by milling with a special cutter – similar process to producing external thread;

• with a forming tap and holder (manually; a lathe, a special threading machine tool).

52

Threading on a lathe

53

Thread tapping

A tap – a tool with flutes creating cutting edges and providing space for chips and cutting fluid

Operation:• manual or• at a machine tool

Thread tapping

http://www.emugefranken.cz/

55

Taps set1. taper tap – a tapered end

enters the hole; 60%

2. intermediate tap – proceeds to cut the thread profile; 30%

3. plug tap – finishes the thread. 10%

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Thread tapping - manual

Thread taping

První náběhový zub – břit závitníku

Druhý náběhový zub závitníku

Třetí náběhový zub závitníku již s plným profilem závitu

První řez

Druhý řez

Třetí řez

Taps set procedure

1) Drilling

2) Countersinking

3) Thread – 1st

4) Thread – 2nd

5) Thread - final

http://www.emugefranken.cz/

Thread taping

http://www.emugefranken.cz/

Thread taping

Thread tapping

- High cutting forces- Need of very rigid machine and tool- lubrication to minimize wear- Tool with small flute width – overload- Strong demands of precision of pre-drilledholes

- manual work

- broken tap removal?

http://www.emugefranken.cz/

Thread taping

http://www.emugefranken.cz/

Thread taping

64

CNC thread milling

CNC thread milling

• Left or Right

property tap

mill

hand (L/R) x OK

CNC thread milling

• bottom

property tap

mill

hand (L/R) x OK

bottom x OK

CNC thread milling

• force / breakage

property tap

mill

hand (L/R) x OK

bottom x OK

breakage x OK

CNC thread milling

• Diameter?

property tap

mill

hand (L/R) x OK

bottom x OK

breakage x OK

Dif. diameter x OK

Internal thread milling

http://www.emugefranken.cz/

http://www.emugefranken.cz/

Internal thread milling

http://www.emugefranken.cz/

Internal thread milling

72

Thread forming

Forming tap has the same shape but it rounded instead of having cuting edges.

Used for less strength materials like Al-alloys, Brass etc.

Thread forming

Nom

inal th

read d

iam

ete

r

Min

. pre

drille

d h

ole

Fin

ishin

g n

ut th

read d

iam

ete

r

Fin

ishin

g inte

rnal th

read

dia

mete

r

Max. pre

drille

d h

ole

dia

Forming tap profile

P

Structure after cuting Structure after rolling Forming tap profile

Oil gaps

Product

Thread forming tap

Product

http://www.emugefranken.cz/

Thread forming

http://www.emugefranken.cz/

Thread control

http://www.emugefranken.cz/

-Dimensions-Pitch-Equality-Shape-Axis direction-tolerance

Thread control

Threading – overview of methodsMethod name Productivity type

Turning

Low (conventional)

Middle(CNC)

High(Swiss type lathe)

Cutting

(subtractive)

MillingMiddle (CNC)

High (Multicontour drill-mills)

Cutting

(subtractive)

GrindingMiddle (single profile)

High (Multiprofile)

Cutting

(subtractive)

Taping

Low – manual

Middle – automated

High – reversing heads

Cutting

(subtractive)

Rolling (external) High Forming (Additive)

Forming (internal) Middle Forming (Additive)

Other – EDM, Ultrasonic

mach, lappingvariable variable

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Thread turning

conventional https://www.youtube.com/watch?v=9IvWuXjCVbg

CNC https://www.youtube.com/watch?v=w5vkc5yevLc (1:20)

Swiss lathe

https://www.youtube.com/watch?v=mUuz0_mNHDs

https://www.youtube.com/watch?v=sYqN90gHOZM

Threading die head

5) https://www.youtube.com/watch?v=JSMWLpx4rS4

Thread milling

https://www.youtube.com/watch?v=z7J58jS_i9o

single edge

https://www.youtube.com/watch?v=SkPdgrjUEhY

https://www.youtube.com/watch?v=5BRPv8e53ig

Thread grinding

https://www.youtube.com/watch?v=ruGfq9tuICA

https://www.youtube.com/watch?v=o3TxDxu09zc

Thread Rolling

https://www.youtube.com/watch?v=bclnb_Cp4sE

https://www.youtube.com/watch?v=P89Y4Ht7SCs

Thread rolling on lathe

https://www.youtube.com/watch?v=nXJnr5Vn06Y