Die Design Presentation

Dr.
MD ISRAR EQUBAL
Assoc. Prof., Dep. Of Mech. Engg.
RTCIT, Ormanjhi, Ranchi, Jharkhand
Thursday, 09 July, 2020

 Forgingis oldest metal processing technology known for
producing parts of superior mechanical properties with
minimum waste.
 Forging is a cost-effective way to produce net-shape or

near-net-shape components.
 Inforging process metals or their alloys are plastically

deformed to the desired shape by a compressive force
applied with the help of a pair of dies.
 Forged parts are used in high performance, high strength

and high reliability applications where tension, stress, load
and the human safety are critical considerations.
FORGING CLASSIFICATION
Forging can be classified into various ways as follows:
 Method of deformation
o Hammer Forging
o Press Forging
Based on Temperature
o Hot Forging (0.65 Tm to 0.80 Tm)
o Warm Forging (0.3 Tm to 0.65 Tm)
o Cold Forging (less than 0.3 Tm)
Where: (Tm - Melting point of metal)
Based on type of dies:
o Open die forging

o Closed die forging
 Improved material properties
 Lower cost for high production runs
 Reduced finish machining
 Very hard/tough materials can be shaped
 Close Tolerances
 Fast part production
In metal forging, the research can be divided into three main
areas;
 Diedesign: Several tools and approach have been used such

as CAD/CAM, expert system and mostly FEA methods to
obtain the best and efficient design.
 Processplanning: The research is focus on the development

of the most efficient and economic process sequence and
planning .
 Product performance: In this field the quality and reliability

of the final product such as un-filling phenomenon,
accuracy and fatigue behaviour of the forged part are the
area of focus.
 It is becoming increasingly essential to predict the exact
behaviour of forging die during the forging process and it is
also important to optimize the die design for its durability
and to reduce the production cost of the die.
 Optimization of forging die design is required to reduce the

production cost of die as well as the forged part and also to
increase the accuracy of the die and the forged part.
 There are several parameters that affect the die performance

or forging parameter can be divide into two, design
parameter and process parameter.
 Design parameter represents the geometrical aspect of the
die such as flash thickness, flash width, corner radii and
fillet radius.
 Process parameter is a variable related to the forging

process condition such as process stages, load applied,
shape of the die, die and billet temp., preform and
lubrication.
 Theformer play roles during the die design process i.e.,

modeling stage and the latter during it use.
 Design of open dies is generally straightforward since the
dies are relatively simple in shape.
 The following details apply to impression dies and closed
dies.
Terminology in an closed or impression die forging

DIE DESIGN PROCESS
STEPS FOR DIE DESIGN
1. Job Analysis: Study of component drawing
2. Development of forging drawing: Component drawing +
Allowances: This include
Finish allowance including:
Scale loss allowance; Shrinkage allowance; Machining allowance
3. Selection of tolerances
4. Selection of Parting Line:
5. Design Considerations for Fillet, Corner Radii and Web and
Rib:
6. Design Considerations for Draft:
7. Design Considerations for Flash and Gutter
8. Design of Preform
9. Design of Blocker and Finisher
 Parting line: The parting line is the plane that divides the
upper die from the lower die or called the flash line in
impression-die forging.
 It is the plane where the two die halves meet. Its selection
by the designer affects grain flow in the part, required load,
and flash formation.
Basic considerations involved in selection of parting line are:
 Avoidance of deep impression:
 Avoidance of side thrust
 Parting line effect on grain flow
Place the parting line through the largest cross section of the
forging to avoid narrow, deep die impressions
A flat surface at the parting line reduces die costs, simplifies

trimming operation and eliminates any die mismatching
Design Considerations for Fillet, Corner Radii and Webs
and Ribs
Fillets and corners are curved surface connecting ribs, bosses and
webs.
A corner is a convex arc, which joins two intersecting sides at an

external angle of more than 180°.
filletis a concave arc, which joins two intersecting sides at an

external angle of less than 180°.
Design of fillet and corner affects

ograin flow
oforging pressure requirement
odie wear
ograin flow
oamount of metal to be removed during machining
 Proper selection of fillet and corner radii is vital in
designing dies for forgings.
 Sharp
corners must be avoided in forging design as they
weaken both the dies and finished forgings.
Webs and Ribs

 A web is a thin portion of the forging that is parallel to the
parting line.
A rib is a thin portion that is perpendicular to the parting

line.
 These
part features cause difficulty in metal low as they
become thinner.
Effect of fillet radius on defect formation in forging. Small
fillets cause the defects.
Laps formed by buckling of the web during forging.

Recommendations for fillet and corner radii for different materials
Alloy Fillet radius (mm) Corner Radius (mm)
Preferred Maximum Preferred Maximum
Aluminium Alloy 6 5 3 2
Alloy Steel 9-12 6 3 2
Hotwork die steel 9-12 6 3 2
Stainless Steel 12-18 6-10 7 4
Titanium Alloy 12-15 10 6 4
Fillet radii and height of rib
Depth of impression (mm) Up to 10 10-25 25-50 Over 50

Fillet Radii (mm) 2 3 4 5
Recommendations for minimizing fillet and corner radii of steel forgings on
weight basis.
Forging Weight (kg) 2 4 6 8 10 20 50
Fillet radii (mm) 1.3 2-3 2-4 3.5 3-6 4.6 7-12
Corner radii (mm) 1-3 2-3 2-3 3 3 3-4 4-7
Design Considerations for Draft
Draft angles are necessary in almost all forging dies, in order
to facilitate the removal of the part from the die.
Upon cooling the forging shrinks both radially and

longitudinally, so internal draft angels are made larger than
external ones.
Recommendations on draft angle based on forging
equipment
Hammer Dies Press Dies

Materials External Internal External Internal
Steels
5 to 7 7 to 10 3 to 5 5 to 7
Aluminium Alloys
Degree Degree Degree Degree
Ni Base Alloys
Tolerances in all cases ± 10

DESIGN CONSIDERATIONS FOR FLASH AND
GUTTER
Flash is added to restrict lateral flow and helps in filling the
die cavity completely.
Objective of Flash: i) Acts as a cushion from impact blow.

ii) Acts as a pressure release value for
the almost incompressible work metal.
iii) Acts as a restriction to the outward
flow of the metal so that remote corners and deeper cavities
can be filled up.
Die profile at Land –
Gutter section
Load stroke curve

DESIGN OF FLASH
Author Flash thickness

Bruchanov & Rebelskii
Voigtlander
Vieregge
Neuberger & Mockel

Teterin & Tarnovski
Here, A = plan projected area
D = equivalent dia.
W = forging weight
 Forging design aims at easy metal flow by various means
and in order to reduce the pressure exerted in die faces.
 It is useful to used a flash gutter in which a flash is reduced

in thickness only over a part of its width.
 Flash Land = b; Flash thickness = s

 More b/s – More pressure exerted
 Less b/s – Less pressure exerted
DESIGN OF PREFORM
 Preform design is one of the most important aspects in
forging process design.
 Preform impression allows adequate metal distribution in

the final impression. Thus, defect-free, complete die fill
and less metal loss into flash can be achieved by a properly

designed perform.
 If the component has varied cross-section as in case of

spanner, connecting rod, break, pedal lever etc. it is
necessary to reduce or increase cross sectional area of the
bar at desired points with a view to improve die life. This
will necessitate the preforming operation before finishing
VARIOUS TOOLS TO ACHIEVE PREFORM SHAPE
FULLER: To reduce cross sectional area and to extend the

portion of the stock to required length.
ROLLING OR EDGING: To distribute the metal into the

appropriate positions acceptable to the succeeding operations.
BENDER: To obtain a true and effective bend wherever

required.
BLOCKER: Used to distribute fullered or rolled more

nearly to finish dimensions, to increase die life by relieving
abrasive wear on the finisher, to help better die filling and to
reduce severity of deformation.

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Dr.

Thursday, 09 July, 2020

 Forging is a cost-effective way to produce net-shape or

 Inforging process metals or their alloys are plastically

 Forged parts are used in high performance, high strength

o Open die forging

 Diedesign: Several tools and approach have been used such

 Processplanning: The research is focus on the development

 Product performance: In this field the quality and reliability

 Optimization of forging die design is required to reduce the

 There are several parameters that affect the die performance

 Process parameter is a variable related to the forging

 Theformer play roles during the die design process i.e.,

Terminology in an closed or impression die forging

A flat surface at the parting line reduces die costs, simplifies

A corner is a convex arc, which joins two intersecting sides at an

filletis a concave arc, which joins two intersecting sides at an

Design of fillet and corner affects

Webs and Ribs

A rib is a thin portion that is perpendicular to the parting

Laps formed by buckling of the web during forging.

Depth of impression (mm) Up to 10 10-25 25-50 Over 50

to facilitate the removal of the part from the die.

Upon cooling the forging shrinks both radially and

Hammer Dies Press Dies

Tolerances in all cases ± 10

Objective of Flash: i) Acts as a cushion from impact blow.

Load stroke curve

Author Flash thickness

Neuberger & Mockel

 It is useful to used a flash gutter in which a flash is reduced

 Flash Land = b; Flash thickness = s

forging process design.

 Preform impression allows adequate metal distribution in

and less metal loss into flash can be achieved by a properly

 If the component has varied cross-section as in case of

FULLER: To reduce cross sectional area and to extend the

ROLLING OR EDGING: To distribute the metal into the

BENDER: To obtain a true and effective bend wherever

BLOCKER: Used to distribute fullered or rolled more

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