METAL SPINNING PROCESS

Anurag Dey (10/ME/148) Abhimonyu Dutta (10/ME/152)

Aman Kumar (10/ME/149) Deepak Nonia (09/ME/00)

Anurag Bhattacharyya (10/ME/150) Sandeep Kumar (08/ME/68)

Sourav Halder (10/ME/151)

ME 852 SEMINAR PRESENTATION

INTRODUCTION.

HISTORY.

CLASSIFICATION OF METAL SPINNING TECHNIQUES.

METAL SPINNING PROCESS.

MECHANICS.

TOOLS AND EQUIPMENTS.

COMPARISON WITH OTHER FORMING PROCESSES.

MERITS.

DE-MERITS.

APPLICATIONS.

CONCLUSION.

OUTLINE

THE BASIC IDEA…

Metal Spinning process is a cold forming process in which the blank metal appears to flow

somewhat like a piece of clay on a potter's wheel.

INTRODUCTION

Let us try and identify

the key components

here

HOW DO WE DEFINE THIS?

Here, we basical ly have a metal

disk or cylinder , rotated at high

speed on CNC lathe or on hand

and by using special ly designed

tools, we get axially symmetric products

E.g.

WHERE DO WE USE THIS?

INTRODUCTION

to manufacture low cost, rapid

prototypes in metals.

bell shaped curves are ideal for

spinning as metals can deform

smoothly around them

easy to create concentric ribs to

strengthen parts

Almost all metal in sheet form can

be spun

Specially used when the product

requires mirror sheen

EVERYDAY EXAMPLES

I always wondered how

these commonly seen

objects are made….now

finally I got my

answers!!....

WHEN METAL SPINNING PROCESSES?

1) Is the metal you are working with DUCTILE?

2) Is the final product AXISYMETRIC?

3) Is the product to be used for artistic application or commercial

applications like BELL, ROCKET NOSE, COOKING WARE?

4) Is the time you have is less and production

number is high?

5) Do you need mirror sheen?

CRITICAL QUESTIONS

YES

RELAX!!

We use metal

spinning

processes

One of the oldest techniques for chip - less production of circular hol low metal components .

introduced in 1840 and was first used almost exclusively for the production of fine gold, si lver and pewter hol low -ware and chalices.

Only sof t nonferrous metals were employed in industrial applications as late as the 1st World War.

Around 1920, the industry began to experiment with tougher materials, heavier gauges, and larger diameters.

HISTORY

CHALICE

CLASSIFICATION OF METAL SPINNING

TECHNIQUES

Me

tal S

pin

nin

g

Manual (Conventional) Spinning

Power Spinning

Tube Spinning

• Practiced by pressing a tool against a

circular metal preform.

• Involves no significant thinning of work

metal; essentially a shaping process.

• Used for prototype manufacture or in

production runs less than 1000 pieces.

• Metal is deformed using high shear

forces.

• Use of automated CNC machines.

• Significant thinning of metal preforms.

• Suitable for high production runs.

• Thickness of cylindrical parts reduced by

spinning them on cylindrical mandrel

rollers.

PROCESS OF SPINNING

Let us look at a video of metal spinning process

A disc of metal is revolved at controlled speeds on a machine

similar in design to a machine lathe .

Instead of the clamping chuck common on a machine lathe, a

wood or metal mandrel is used.

THE PROCESS OF SPINNING

The external shape of the mandrel corresponds to the internal contour of the part to be produced.

The blank is clamped between spinning mandrel and a follower on the tailstock spindle.

The mandrel, blank, and follower are then set in rotation at controlled speeds.

PROCESS OF METAL SPINNING

Spinning tools or spinning rollers are forced against the

rotating blank either by hand or by auxiliary power or both.

Employing a series of axial and radial (swivel) strokes, the

blank is spun onto the mandrel causing the metal to flow to

the shape of the desired part.

PROCESS OF METAL SPINNING

STEPS IN SPINNING PROCESS

Step 1 : Metal Forming

• This step involves the laying down of the material onto the mandrel.

• It is accomplished with short inside to outside moves.

• Material gets easier to form as the part is closer to completion

Step 2 : Trimming

Parts having been spun are trimmed at the end to blunt sharp edges and also to bring the component to the

desired length.

Step 3 : Finishing

• Finishing is done at very high RPMs (1200+) so that a minimum of force need be applied and very

smooth strokes can be used.

• The flat side of Duckbill spinning tool is used for straight surfaces and rounded side for curves and radii.

• The most common application of metal spinning is for conical shapes, in

which the metal is volumetrical ly displaced in the axial direction.

• Metal deformation during spinning occurs in accordance with the sine

law.

• The sine law relates the wall thickness of the star t ing blank, t 1 , and the

wall thickness of the finished product , t 2 , as t2= t1 (s in α ) , where α is the

semi-apex angle of the cone.

• The thickness of the component in axial direction is the same as the

thickness of the star t ing blank.

• When spinning metal cones of smaller apex angles, i t is general ly

convenient to use mult iple spinning passes with dif ferent cone angles for

each pass.

• Deviations from the sine law that can occur, are usually expressed in

terms of over -reduct ion or under -reduction.

In over-reduction, final thickness of work -piece is lesser than that

indicated by sine law, while in under -reduction the thickness is greater .

MECHANICS OF CONE SPINNING

Single Pass Spinning

The mandrel d iameter i s 7.5 inch

(188mm).

The th ickness of the pre - form is 0 .5

inch.

The inc luded semi -apex ang le of the

cone is 30 degree.

Wal l th ickness of f in ished component

i s 0 .25 inch.

Multiple Pass Spinning

The semi -apex ang le of the cone is

less than 15 degree.

The th ickness of the f in ished

component i s reduced successive ly in

accordance wi th the s ine law, to

0 .125 inch.

Or ig inal b lank d iameter i s reta ined at

the b ig end of the cone.

SINGLE AND MULTI-PASS SPINNING

OPERATION

The mandrel or buck is the form over which the sheet metal b lank is formed.

More compl icated the form of the component , the greater the need for care in

machin ing the mandrel .

Can be machined f rom a var iety of mater ia ls , wood being the cheapest .

Mandrels can a lso be made of mi ld s teel or a luminium, when c lose to lerances are

requi red.

I t i s impor tant to des ign the mandrel w i th at least a 1 degree draf t ang le so that the

par t can be removed f rom the mandrel af ter sp inning.

MANDREL

Mild steel mandrel Stepped wooden mandrel

Wide var iety of too l prof i les can be implemented for sp inning the mater ial into

d i f ferent shapes.

Tools are prov ided wi th long handles to prov ide ample leverage to work the

mater ial down the mandrel .

Tools can be up to 3 feet long wi th a 1 inch d iameter s teel rod forged into the

preferred too l t ip .

Spinning shops make use of too ls w i th ro l lers mounted on the long handle .

The pr imar y too ls are the Sheep’s nose used for most of the forming and the

Duck’s b i l l used for f in ishing operat ion.

TOOLS

Duck’s bill Sheep’s nose Roller-ended tool

Lubr icants are essent ia l in a l l metal sp inning operat ions , regard less of the

preform shape or composit ion or the type of metal sp inning too ls that are being

used.

Fac i l i tates easy removal o f the par t f rom the mandrel and a lso help improve

sur face f in ish of f in ished component .

Par ts are lubr icated both before and dur ing the sp inning operat ion.

Commonly used lubr icants inc lude wax , ta l lows, soaps and grease.

In se lect ion of the most su i table lubr icant , the ease of removal o f the same af ter

the forming process has to be cons idered.

LUBRICANTS

Cup Grease Tallow

Machines for spinning are specified by the diameter and length of the

largest component that can be spun.

They are also specified by the maximum load that can be applied to the

work.

The capacity of spinning machines ranges from 0.455m in diameter and

0.380m in length to 6m in diameter and 6m in length.

Metal spinning machines can be both ver t ical or horizontal .

Machines used for spinning large diameters, such as 1 .8m or more are

usually ver t ical .

Mostly lathe based machine tools ( both conventional and CNC -based) are

employed for spinning operation.

Most modern machines used for spinning are at least semi-automated;

that is, they are loaded and unloaded by the operator, but the entire

spinning cycle is control led automatical ly.

MACHINES FOR SPINNING

Schematic diagrams of a vertical arrangement employed for spinning of large diameter cones.

SPINNING MACHINES

Horizontal lathe and mandrel

arrangement for spinning large-diameter

cone. Courtesy of Leifeld USA Metal

Spinning, Inc.

CNC metal spinning machine

Courtesy: Draft-Air India Pvt. Ltd.

Photograph of a 4m diameter cone and dish-shaped components

produced by the Leifeld Company.

Low tooling cost compared to other forming techniques.

Conventional spinning also wastes a considerably smaller

amount of material than other methods .

The standard method of press forming the part requires eight

steps, as opposed to only three steps for spinning.

COMPARISON WITH OTHER FORMING

PROCESSES

Provides natura l metal lurg ical benef i ts , w i th a ref ined and st rengthened gra in

s t ructure .

Co ld working of the metal a lso increases tens i le proper t ies appreciably.

Unl ike a cast ing, a spun par t w i l l not be d iscarded by a h idden b lowhole or inc lus ion .

A spun shel l could be made in halves and welded to form a s ing le uni t w i thout

complex , expensive too l ing .

The too l ing costs and capi tal investments are re lat ively smal l .

The setup t ime is less .

Design changes in the workpiece can be accommodated at re lat ive ly low costs .

Can be eas i l y automated and is an ef fect ive product ion method for prototypes as

wel l as h igh product ion runs .

S ince there is no removal o f metal by formation of ch ips, there is no mater ia l

wastage and the process is economical .

MERITS

Requirement of highly trained operators in manual spinning

process, for, the uniformity of the product depends to a large

degree on the skill of the operator.

Manual metal spinning is usually significantly slower than

press forging.

Deformation loads allowable are much lower in metal

spinning than in press forging.

DE-MERITS

The following are examples of products that

can be manufactured by metal spinning:

Vases, baskets, basins and bowls.

Bottoms for tanks, hoppers and kettles.

Housings for blowers, fans, fi lters and fly -

wheels.

Ladles, nozzles, orifices and tank outlets.

Cones, covers and cups.

Funnels, cyl inders, domes and drums.

Rings, hemispheres and shells.

Vents, venturis and fan wheels.

APPLICATIONS

Metal spinning techniques and mechanics have been

presented.

Equipment for spinning is based on lathe technology.

Wide range of products can be obtained using this technique.

Metal Spinning is competitive with other forming processes

such as pressing and deep drawing.

It is an economical technique to produce both simple and

complicated parts for single application, low -volume

production as well as mass productions.

Process technology, equipment and tooling for spinning have

been discussed.

CONCLUSIONS