218557755 Thread Fastener

8/11/2019 218557755 Thread Fastener

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Threaded FastenersChapter 11


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Introduction


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FASTENING TYPE

1. PermanentWelding Gluing Riveting


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FASTENING TYPE

2.1 Threaded fastener

- bolts

- studs- screws

2. Temporary

2.2 Non-threaded fastener

- keys

- pin

key


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THREAD APPLICATION

1. To hold parts together.

2. To move part(s) relative to others.

Part A Part B

Part C


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THREAD APPLICATION

1. To hold parts together.

2. To move part(s) relative to others.

Wood working vise Palm fruit pressing machine


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External (male)thread

In ternal (female)

thread

THREAD TERMINOLOGY

A thread cut on the outs ideof

a cylindrical body.

A thread cut on the ins ideof

a cylindrical body.

Internal thread

External thread


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Right-handthread

Thread that will assemblewhen

turned c lockwise.

Left-hand

thread

Thread that will assemblewhen

turned counter-c lockwise.

THREAD TERMINOLOGY

Turnbuckle use RH and LH thread ateach end to double displacement.


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Crest

Root

Thread angle

THREAD TERMINOLOGY

The peak edgeof a thread.

The bot tom of the thread cut into

a cylindrical body.

The angle between threads faces.

Internal ThreadExternal Thread

CrestRoot

Thread angle

CrestRoot


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Major d iameter

The largest diameteron

an internal or external thread.

Minor diameterThe smal lest diameteron

an internal or external thread.


Minord

ia.

Majord

ia.

THREAD TERMINOLOGY

Minord

ia.

Majord

ia.


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Pitch

The distance between crests of

threads.

LeadThe distance a screw will advance

when turned 360o.

THREAD TERMINOLOGY


Pitch

Pitch


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Form is the profile shape of the

thread.Thread Form

THREAD TERMINOLOGY

Example:

knuckle thread form


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EXTERNAL THREAD CUTTING

Tools

Operation

Threading Die

Die stock


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Twist drillTools

Tap

Tap wrench

Operation

INTERNAL THREAD CUTTING


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COMPARISON OF THREAD CUTTING

External Thread

Internal Thread

Major Dia.

Minor Dia.


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Thread Drawing


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1. Detailedrepresentation

2. Schematicrepresentation

3. Simpl i f ied representation

THREAD REPRESENTATION


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External thread Internal thread

DETAILED REPRESENTATION

60oPitch

Use slant ing l inesto represent crest and root.Roots and crest are drawn in sharpVs.

Thread runout


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SCHEMATIC REPRESENTATION

External thread

Pitch Crest (thin line)Root (thick line)

Use alternate longand shor tlines for representingcrestsand rootsof the thread, respectively.

Internal thread


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SIMPLIFIED REPRESENTATION


Use th ick cont inuous l inesfor representing crest

and th in cont inuou s l inesfor representing roo tof

the thread, respectively.

Pitch/2

Root

Crest

Thread runout


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SIMPLIFIED REPRESENTATION


Sectional view

Use th ick cont inuous l inesfor representing crest

and th in cont inuou s l inesfor representing roo tof

the thread, respectively.


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ISO (METRIC) THREAD

External

thread

Internalthread

Center of thread assembly

60o

Pitch, P

P/4

P/8

Thread assemble occurs if and only if both (internal & external)

thread have an equal nom inal size (or diameter)and pi tch.


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Nominalsize

Majordiameter

Pitch Minordiameter

Tap drill size

M6 6.00 1.00 4.92 5.00

M8 8.00 1.25 6.65 6.75

M10 10.00 1.50 8.38 8.50

M12 12.00 1.75 10.11 10.00

METRIC COARSE THREAD

Minordiameter = MajordiameterPitch

Minor diameter Tap drill size

[Table 9.1]

Metric thread

In thread drawing, the following relationship is used.


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Nominalsize

Majordiameter

Pitch Minordiameter

Tap drill size

M8 8.000.75 7.188 7.25

1.00 6.917 7.00

M10 10.00

0.75 9.188 9.25

1.00 8.917 9.00

1.25 8.647 8.75

METRIC FINE THREAD[Table 9.2]

Minordiameter = MajordiameterPitch

Minor diameter Tap drill size

In thread drawing, the following relationship is used.


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Thread Length

DRAWING STEPS OF

EXTERNAL THREAD

Starting

position

Draw

thread

axisMajordia.

Minordia.

Draw

45oChamfer

Draw line making

30owith thread axisDraw a circle thatrepresents a crest.

Draw an arc thatrepresents a root.


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Internal Thread

1. Through threaded hole

DRAWING STEPS OF

THREADED HOLE

Draw

thread

axisMajordia.

Minordia.

Draw a root

Draw a crestSectional view

Draw a circle thatrepresents a crest.

Draw an arc thatrepresents a root

.

root

crest

Section lines are drawn

into the crest of a thread.


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Minordia.

DRAWING STEPS OF

THREADED HOLE

2. Blinded threaded hole

Draw

thread

axisMajordia.

Hole depth

Thread depthDraw a circle thatrepresents a crest.

Draw an arc thatrepresents a root

.


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DRAWING STEPS OF

THREADED HOLE

2. Blinded threaded holeSectional view


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DIMENSIONING EXTERNAL THREAD

M10 1.5

1.0 Fine thread

Coarse thread

xxThread

length

Uselocal noteto specify :- thread form, nom inal s ize,

pi tch(if it is a fine thread)

Usetypical methodto specify :- thread leng th.


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3. Thread form

4. Nominal size

5. Pitch

1. Tap drill size

2. Drill depth

6. Thread depth

8.50 Drill, 20 Deep,

M10 Tapped, 15 Deep

DIMENSIONING THREADED HOLE

Uselocal noteto

specify


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Threaded Fastener


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BOLT : Terminology

Bol t is a threaded cylinder with a head.

Hexagonal head

bolt and nut

Headthickness

Thread length

Length

Widthacross flat

Dimensions of bolts head are

listed in table 9.4.


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Draw

bolt

axis

Draw anend view

of the head

B

Starting

position

H

Draw abolt head

B/2 B/2

30o

Length

Thread Length

Majorf

Draw

body of a bolt

BOLT : Drawing steps


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NUT : Drawing steps

Draw an end viewof the nut

B

H

B/2 B/2

Dimensions of the nut are given in Table 9.14.

Dash lines represent

a threaded hole are

omitted for clarity.


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1. Insert a bolt into

aclearance ho le

2. Insert awasher.

3. Screw anut.

BOLT : Application


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Let s think together

What do you think about the following suggestions for

design improvement?

(B) Use shorter bolt with the

same thread length.

Correct

(C) Reduce the thread length.

Inappropriate

Wrong

(D) Add washer or nut.

(A) Nothing have to be changed.


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design improvement?

(B) Use a bolt of this length but

has a longer thread length.

(C) Use a longer bolt with the

same thread length.

(D) Add washer.


Correct

Inappropriate

Wrong


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design improvement?

(B) Use a bolt of this length but

has a shorter thread length.

(C) Use a longer bolt with the

same thread length.

(D) Add washer.


Correct

Inappropriate

Wrong


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design improvement?

(A) Use a bolt of this length but

has a shorter thread length.

(B) Use a longer bolt with thesame thread length.

(C) Use a longer bolt by

increasing a thread length

(D) Remove washer.

Correct

Inappropriate

Wrong

L hi k h


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design improvement ?

(A) Increase the bolt diameter.

(B) Use washer with larger

outside diameter.

(C) Reduce the hole diameter.

(D) Add washer at bolt head.

Correct

Inappropriate

Wrong

L t thi k t th


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(B) Use a bolt with shorter

thread length.

(C) Add washer.

(D) Increase drill and thread

depths.


Correct

Inappropriate

Wrong

L t thi k t th


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(B) Use a bolt with slightly

longer thread length.

Correct

Inappropriate

Wrong

STUD T i l


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Studis a headlessbolt, threaded at both ends.

STUD : Terminology

Thread length

Length

Thread length

Drawing

representation

STUD D i t


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Major

f

STUD : Drawing steps

Drawstud

axis Minor

f

Starting

position

Stud Length

Thread Length

Thread Length

Draw

45oChamfer

Draw

45oChamfer

Draw line making

30owith axis

STUD A li ti


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STUD : Application

1. Drill a hole.

3. Screw a stud.

4. Place the part to befastened.

5. Insert washer and

fastened a nut.

2. Tap a hole.

L t thi k t th


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What is the mistake in the following use of stud ?

L t thi k t th


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What is the mistake in the following use of stud ?

CAP SCREW T i l


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Cap sc rew is similar to bolt, but has a longer thread

than a bolt.

CAP SCREW : Terminology

CAP SCREW C t b h l


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CAP SCREW : Counterbore hole

x drill,

fy Cbore,

z deep

xdrill,wdeep,

fyCbore,

zdeep

z

CAP SCREW C t i k h l


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x drill,

CSK to fy

CAP SCREW : Countersink hole

xdrill, wdeep,

CSK to fyy

Draw 90o

SET SCREW Terminolog


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SET SCREW : Terminology

Set sc rewis a threaded cylinder used to prevent

rotation or movement between parts.

SET SCREW : Application


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SET SCREW : Application

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