8/3/2019 Shoe Sole1

1/44

History

Primitive shoesAncient shoes

Greek/Roman

Middle Ages

Baroque Era

Early American

Victorian Era

Sneaker Era

8/3/2019 Shoe Sole1

2/44

Sneaker Era Sneaker is traditionally defined a shoe

consisting of a solid rubber soleattached to an upper made, usually, ofcanvas.

The word "sneaker" started by HenryNelson McKinney, an advertisingagent for N. W. Ayer & Son, because

the rubber sole made the shoe stealthyor quiet . While rubber soled shoes had been in

use for some time for aristocratic lawnsports and King Henry VIII was reportedto have worn a sneaker-like shoe for

playing tennis True life of the sneaker did not beginuntil American inventor CharlesGoodyear patented the process forvulcanization of rubber.

8/3/2019 Shoe Sole1

3/44

First Rubber Soled Shoes

Calledplimsolls

Developed &manufactured in US,

1800s. Role of vulcanization

Charles Goodyear

January 24, 1899-

Humphrey OSullivanreceived 1st patent forrubber heel for shoes

8/3/2019 Shoe Sole1

4/44

RubberFootwear

Built-up

All-rubber

PlimsollsDVP

DIP

8/3/2019 Shoe Sole1

5/44

FOOTWEAR SOLE

RUBBER FORMULATION

8/3/2019 Shoe Sole1

6/44

INGREDIENTS PPHR

(MEDIUM GRADE SOLE, INJECTION MOULDED)

SBR 50

IR 30

High Styrene Resin MB 20

Aluminium Silicate 50

Zinc Oxide 5

Stearic Acid 2

Process Oil 10

Antioxidant 1

Coumarone Oil 3

Si-69 3

DOTG 1

MBTS 1.5

Sulphur 2

8/3/2019 Shoe Sole1

7/44

Raw Materials

Styrene Butadiene Rubber (SBR)

It is a type of copolymer - 71 % butadiene, 29 % styrene High resistance on silicone oil, alcohol and alkaline.

Lower crystallinity due to the presence of styrene

Addition of fillers such as carbon black and silica reinforcementpurpose

It can replace NR for general use

It has various grades ,such as standard emulsion polymerizes SBR, oil-extended SBR

Polyisoprene (IR) Rubber It has the synthetic chemical equivalent to NR

It is used in the product that the formulation requires high purity

Molecular weight and its distribution can be controlled for processingproperties

8/3/2019 Shoe Sole1

8/44

Compounding

Type of curatives Function

Zinc oxide Activator

Aluminium silicate Non-carbon black filler

Stearic acid Activator

Process oil Plasticizer-lubricant

Antioxidant Resistance to oxidizing agents

Coumarone resin Processing aidSi-69 Coupling agent

Colour pigment Impart desired colour

MBTS Accelerator

DOTG Accelerator

Sulphur Curing agent

*AbbreviationsMBTS= Mercaptobenzolhiazole disulfideHAF black = high abrasion furnace black

DOTG=di-o-tolylguanidine

8/3/2019 Shoe Sole1

9/44

Compounding

Non Black Compound

Reinforcing siliceous fillers

Good reinforcing agent for IR and SBR

Zinc Oxide & Stearic Acid

Activator (improve acceleration by activating accelerator)

Process Oil Lubricant

Improve processing characteristics especially during mixing & moulding

Modify properties of rubber

Antioxidant Provide protection against oxidizing agents

8/3/2019 Shoe Sole1

10/44

Compounding

Coumarone Resin Processing aid

Soften and tackify the rubber (easy uniform mixing)

Coupling Agent

To improved adhesion between filler and rubber

Pigment

Impart certain colour

Accelerator

Increase rate of vulcanisation, shorter vulcanisation time

Sulphur

Vulcanising agent to promote cross-linking

8/3/2019 Shoe Sole1

11/44

Compounding

Employ internal mixer to mix rubbers, activators (ZnO, Stearic acid),Filler(s) and coupling agent (if any), processing oil, antioxidant,coumarone resin.

Mixing time is 6-7 minutes.

The master batch recharged from the internal mixer is then mixed in the

two-roll mill. The accelerators, sulphur and colored pigment are added to the rubber

compound and mixed for 4-6 minutes (or until getting a uniformlydispersed rubber compound).

The rubber compound is then sheeted ready for next processing step.

For a newly designed compound, cure rheometer test is done by usingMDR or ODR to determine the cure characteristics of the rubbercompound (cure temperature and cure time)

8/3/2019 Shoe Sole1

12/44

Manufacturing & Processing

8/3/2019 Shoe Sole1

13/44

Shoe Sole Production Flow Chart

8/3/2019 Shoe Sole1

14/44

Manufacturing Technique

Injection-molded shoes sole

Low capital investment require unskilled workers

Involves the injection of outsole substance into a closed mold

Flash- soling material that escapes through the joined mold part.

The process is carried out in external pressure machines, eitherpneumaticallyor hydraulically.

Thermoplastic rubber, PVC, polyurethane, ethyl vinyl chloride are

normally used as outsole material in the injection molding process.

8/3/2019 Shoe Sole1

15/44

Process of direct-attached injection outsole

1. Injection molded unit soles

Components

The base plate contoured to the shape of the sole

Movable side plates, which can open and close automatically

The last, which contain the upper, fits exactly on the cavity when thebase and side mold are closed

The sole plate, side mold and lasts are filled with electrical elements

8/3/2019 Shoe Sole1

16/44

The operation

1. The side moulds are closed tightly around the upper.2. The sole is injected in a closed mold but not directly attached to shoe

upper3. The sole plate is then forced up, acting as a ram until it reaches a set

position to give required finished gauge of outsole.

4. Time control is set to the required cure time.5. The press is automatically open6. The footwear is stripped off the last and allowed to cool.7. The spew is trimmed off.

outsole

8/3/2019 Shoe Sole1

17/44

2. Direct-attached injection outsoles

Footwear made by the direct injection of the outsole onto theupper whether is canvas or leather

Require a mold that has side ring and soleplate

There will be a remarkable seam, as the left and right mold siderings come together to form the sole.

Presence of the seam characteristic of the direct-attachedinjection molding process.

seam

8/3/2019 Shoe Sole1

18/44

Direct-attached injection outsole has 2 systems:

One-component direct-attach system

Two or more direct-attach system

One-component direct-attach system

Involve the injection of the soling material into the mold assembly

Only 1 component sole is molded directly on the shoe upper

Flash can be formed when the material seeps between the mold sidering and other component.

Sprue is formed at the injection point of the sole that is cut off

Two types of one-component direct

attach system :Injection on heel Injection on bottom

8/3/2019 Shoe Sole1

19/44

Sprue

8/3/2019 Shoe Sole1

20/44

Two or more component direct attach system

can consist of different materials and colors

In this process, a multiple station machine rotate (like merry-go-round)and the operator is stationary

Second injection port

Outsole/ firstinjection port

8/3/2019 Shoe Sole1

21/44

Stages

1. The outsole is injected by using a smooth dummy last in placeof the shoe upper.

2. The dummy last is rotated out of position when the outsole isformed. The outsole formed remains in mold cavity.

3. The shoe upper is lowered into the mold assembly and rest onthe top of the already formed outsole.

4. The side rings of the mold assembly close tightly.

5. The midsole is injected through a second injection port, which

will attach the previously injected outsole and the shoe upper.

8/3/2019 Shoe Sole1

22/44

Manufacturing Technique

Compression Moulding The molder must design in shut-off region with hardened inserts Consistent and precise machining by the moldmaker is a prepequisite for

the resulting product quality.

Two-piece molds - top half and bottom half that are mounted opposite eachother in the compression molding machine.

The compression-molding process is an open-mold This means that the mold is open when the premixed into the mold cavity.

The mold close as it is placed under considerable heat and pressure forseveral minutes.

8/3/2019 Shoe Sole1

23/44

The outsole materials enable them to conform to the size and shape

of the mold. Excess material (flash) escape from the side where the two halve of

the mold meet and trimmed away later.

The compression method may be linked to be waffle, where thebatter is placed on the bottom waffles iron.

The batter is placed on the bottom waffles iron, the top half on thewaffle iron is closed and the excess batter leaks out the side.

8/3/2019 Shoe Sole1

24/44

Compression molded outsole can also be made with 2 or more coloursusing a 3 or 4 section.

This 4 sections are:

1. A section that contains the outsole design

2. A section that is a cover plate that will fit over the top of the firstsection

3. A section that represents the side walls of the outsole-midsolearea.

4. A section that represent the top part of the mold.

8/3/2019 Shoe Sole1

25/44

The mold is removed from the compression molding

press, the cover plate is taken off, and the section withthe sidewalls of the mold (contain the design of themidsole area) is added.

The white biscuit of the rubber, which will be formed into

the midsole, is placed on top of the already melted blueoutsole.

8/3/2019 Shoe Sole1

26/44

Then the fourth mold section is placed on top of the biscuit andsection three.

Section one, three and four, still containing the already formed blueoutsole and now containing the white biscuit material, are thenplaced back into the compression-molding machine for the duration

of the molding process. The white biscuit is melt and covered around the mid-sole and

adheres to the already formed blue outsole.

When the mold is opened , a two colored molded outsole can beremoved.

The process will produce the flash at the point where mold halvesmeet.

The flash will be trim away from the shoe sole.

8/3/2019 Shoe Sole1

27/44

8/3/2019 Shoe Sole1

28/44

Requirements of shoe solings

In order to provide adequate service during wear, it is necessary for a soling to

have the following basic properties:

* Good adhesion to the upper part of the shoe;

* adequate wear resistance;

* resistance to flex cracking; and

* high coefficient of friction

8/3/2019 Shoe Sole1

29/44

IMPORTANCE OF PHYSICALTESTING OF RUBBER VULCANIZED

To trace out the short falls in processing methods

To control and maintain quality of the products

For research and development work, testing of the vulcanized is done tounderstand the behavior, nature and effect on the properties of the

compounding ingredients.

The evaluation of such test results, new polymer or compoundingingredients which may be less costly or having better properties may beevolved

To evaluate their service life

8/3/2019 Shoe Sole1

30/44

Parameter valueSoft shoe sole Hard shoe sole

Hardness (Shore A) 55 - 65 80 - 95Tensile strength, MPa 10 - 15 15 - 20Elongation at break, % 450 - 650 500 - 600300% Modulus, Mpa 4.0 6.0 6.0-7.0NBS abrasion index 40 - 60 60 - 80

Normal tests: Tensile, elongation at break, Tensile modulus M100, M300

Important tests: Abrasion resistance (ASTM D1630), hardness and resilience.(Source: Rubber Technology by Maurice Morton, third edition, 1987)

8/3/2019 Shoe Sole1

31/44

Stress straintest

Ageing test

Hardness tests

Tear tests

BASICTEST

8/3/2019 Shoe Sole1

32/44

Tensile Test ASTM D 412

Testing the ability of rubber specimen to resist the force that may cause it to

fail The tensile properties of vulcanized rubber is determined by stretching

standard test pieces at a constant rate using tensile machine

Three parameters obtained at a time are :

a. tensile strength

the force per unit area of original cross section of the sample,required to stretch the original cross section of the sample,

required to stretch the rubber test piece to its breaking point.

b. elongation at break

Elongation at break is the maximum elongation, expressed as

the percentage of the original length, prior to the rupture of thesample.

c. modulus at a particular elongation of the sample

Modulus is the tensile stress required to stretch a rubber test

piece to a predetermined elongation.

8/3/2019 Shoe Sole1

33/44

There are different types of machines used can be either in dumb bell shaped

(commonly used) or ring shaped.

Procedure:

I. The test pieces are cut from the vulcanized test

II. The test piece is then clamped in the testing machine and stretched under

constant rate.

III. From the stress strain graph obtained the tensile strength modulus and

elongation at break can be calculated knowing the original thickness and

width of the test piece.

IV. The average value of four of five test values of the same sample is taken as

the actual value.

V. The tensile test results can be used to evaluate the strength of the vulcanized

and the degree of cure of the vulcanized.

8/3/2019 Shoe Sole1

34/44

SHORE (DUROMETER) HARDNESS TEST ASTM D 624

Shore hardness measures the hardness of a cured rubber

specimen quickly from the penetration of a special indenter

Tested with an instrument called Durometer- measured hardness is

determined by the penetration depth of the indenter under the load

Hardness of rubber is usually measured by Shore scales. Two types

of shore scale are:

I. Shore A scale : Testing soft elastomers (rubbers)

II. Shore D scale : Testing Hardness of hard elastomers

http://image.dhgate.com/upload/spider/b/151/192/b_308736321192151_00.jpg

8/3/2019 Shoe Sole1

35/44

Figure: Durometer hardness test. Two different indenter shapesand two different spring loads are used for two Shore scales (Aand D).

Digital shore instrument Analog shore instrument

http://image.dhgate.com/upload/spider/b/151/192/b_308736321192151_00.jpghttp://www.substech.com/dokuwiki/doku.php?id=shore_durometer_hardness_test

8/3/2019 Shoe Sole1

36/44

Tear resistance ASTM D 624

Tear properties- force required to pull a rubber test piece apart using a

tensile testing instrument under controlled condition given in ASTM D 624.

Sometimes a special cut is applied to the specimen.

Testing is performed by pulling specimens apart using a tensile test

machine.. The maximum force required to tear a test specimen is used to

calculate the tear strength of the Die A, B, and C specimens .

Tear tests give an indication of the behavior of the vulcanized in tear

initiation and tear propagation.

8/3/2019 Shoe Sole1

37/44

Die A is a smaller crescent not used as frequently as the other test pieces.The force acts along the major axis, perpendicular to the nick and measurestear propagation

Die B is a crescent-shaped test piece with large ends for better gripping in atensile tester. This specimen is nicked with razor blade to a specified depthto help initiate a tear.

Die C test piece has an angle to help initiate a tear and does notnecessarily require a cut neck

Die D, T Trouser tear specimen is separated by a ashear force from thetension applied in opposite to each leg at right angles to the plane of thetest piece.

**The tear strength (Ts) is reported as kilonewtons/meter of thickness from the formula

**Grip separation 500mm/min

Die A

Die B

Die CDie D

8/3/2019 Shoe Sole1

38/44

Ageing Tests

The natural deterioration of the Vulcanized under the action of heat, light, oxygen,ozone etc. is termed as 'ageing'.

The service life of a product is too long to wait for getting information regarding the

performance of the product under the influence of the above mentioned agents.

Accelerated ageing tests magnify the influence of one or more of the above agents

which affect the service life of the products.

The testing is done usually, by keeping the test samples under the influence of

temperature, oxygen or ozone for a specified period and then determining the

physical properties like tensile strength or noting the visual appeal. The fall in

properties from the initial value or the change in appearance gives an indication of the

resistance of the rubber vulcanized to that particular factor.

8/3/2019 Shoe Sole1

39/44

8/3/2019 Shoe Sole1

40/44

Abrasion resistance ASTM D 2228/1630

The Pico, Din and Akron Abrader measures the abrasion resistance of a

cured rubber test piece to a pair of rotating tungsten carbide knives under

standard conditions noted in ASTM D 2228.

The parameter measured is usually weight loss. It is amount of material lost

which matters, so weight loss is convert to vollume loss by dividing by the

density

Volume loss is expressed as the loss per unit destance travelled over the

abradant

Abrasion resistance index defined asAkron

8/3/2019 Shoe Sole1

41/44

8/3/2019 Shoe Sole1

42/44

Resistance to flex cracking is composed of two parts i.e.

resistance to crack initiation

resistance to crack growth

In crack growth testing, a crack is initiated purposely by means of a

especially shaped tool and the rate of growth of the cut is measured during

flexing.

In the case of flex resistance, the result is evaluated by comparing with a

graded set of standards are resenting increased stages of cracking from

0(no crack) to 10 (complete Cracking).

8/3/2019 Shoe Sole1

43/44

THANK YOU

R f

8/3/2019 Shoe Sole1

44/44

References

1. John S. Dick Basic rubber testing: selecting methods for a rubber test

program

2. Ciullo, P. A. & Hewitt, N. (1999). The Rubber Formulary, William Andrew

Inc.

3. Rodgers, B. (2004) Rubber Compounding : Chemistry And Applications,

CRC Press.

4. Bodziak, W. J. (1999) Footwear Impression Evidence : Detection, Recovery

and Examination, CRC Press

5. Bhowmick, A. K. (1994). Rubber Products Manufacturing Technology, Marcel

Dekker, Inc.