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Electroforming

Presented by

Subject

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1) Advantages and limitations of the system.

   - Concerning weight

         - Concerning the model

    2) Core

      3) Racks and anodes. Harmonisation.

      4) Galvanic preparation.

      5) Electroforming of gold alloy (tri-metal)

      6) Emptying cores

      7) Removing the copper coating

      8) Annealing

      9) Soldering

10) Polishing

INDEX3/14

15/24

25/26

27

28/41

42

43

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45

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Figure NoFigure NoMenu

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Obtains hollow pieces from 100 microns thick, by plating a sheet of metal on a core and removing then the core.

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If we admit that a bead with gallons of 10 mm diameter is equivalent to a regular ball

of 9 mm, and in case of 150 microns thick, this ball will weight 0,535 grams

Side area = x ز= x 0.87² = 2.38 cm² Øi = 8.70 mm Øe = 9 mm

Volume = A x e = 2.38 x 150 = 0.036 cm²

10000

Weight sphere = Volume x Gold Density = 0.036 x 15 = 0.535 g

Comparing: Electroforming

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Comparing: Casting

If we admit that a bead with gallons of 10 mm diameter is equivalent to a regular ball of 9

mm, if massive, this ball will weight 5,92 grams.

Volume = 4/3 x x R³ V = 4/3 x x 0.45³ = 0.382 cm³ = 9 mm

Weight sphere = Volume x Gold Density P = 0.382 x 15.5 = 5.92 g

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Comparing: Stamping If we admit that a bead with gallons of 10 mm diameter is equivalent to a regular ball of 9 mm, and in case of 300 microns thick, this ball will weight

1,11 grams All volume = External volume – Internal volume

Ev = 4/3 x x R³

Ev = 4/3 x x 0.45³ = 0.382 cm³

Iv = 4/3 x x R³

Iv = 4/3 x x 0.42³ = 0.31 cm³

Av = 0.382 - 0.31 =0.0714 cm³

Weight sphere = Volume x Gold Density

P = 0.0714 x 15.5 = 1.11 g

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0

1

2

3

4

5

6

grams

Comparing concerning

weight

Electroforming – Casting – Stamping

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Electroforming Casting StampingComparing

Getting it Cost

Takes time

High

Getting it Cost

Immediately Low

Getting it Cost

Immediately Low

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Week forms

 Advisable to avoid in electroforming

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Sharp points attracts the current and in consequence:

Current is uneven in different parts of the piece

Thickness of metal electroformed is also uneven.

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Straight (sharp) angles with electroforming external or

internal

Model External electroforming Internal electroforming

Round edge Round edge Sharp edgeSharp edge

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Comparatively big forms

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Resistant surface

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 Harmonic form allowing even current in all around the surface

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Step from core to finished ear ring

Core Electroforming with core Hollow finished ear ring

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Most used core specially in gold 18K and 14K

Metallic core. White metal casting Menu

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Vulcaniser Casting

EQUIPMENT TO PRODUCE METALLIC CORES

(or resin cores sometimes)

Metal furnace

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Amber colour wax

Main use in:

Gold 24 K

Gold 18 K and 14 K cold electrolite

Silver

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Vulcaniser HdM Mark IV injector with

pneumatic piston

Gun for metal

coating

Equipment to produce wax cores. Menu

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Equipment to produce resin cores

Manual mix of resin and catalizer

Manual pouring of resin in the

mold.

Catalized liquid silicone mold

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 Equipment to produce resin core

(2)

Gun for metal

coating HdM Vacuum machine to

remove air bubbles

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Resin cores

Used mainly in :Silver

Copper

For pieces were core is not removed (not hollow pieces)

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From now on the presentation is limited to;From now on the presentation is limited to;

1)Metallic cores because they are the most 1)Metallic cores because they are the most characteristics of the processcharacteristics of the process

2)Alloyed gold electroforming, because it is the most 2)Alloyed gold electroforming, because it is the most sophisticated process. sophisticated process.

3)Warm electrolites as they are the most popular in 3)Warm electrolites as they are the most popular in all oyed gold electroforming, because:all oyed gold electroforming, because:

Its rose colour is much better accepted that the green Its rose colour is much better accepted that the green colour in 18 K and almost white in 14K of cold colour in 18 K and almost white in 14K of cold

electrolites (bi-metallic gold-silver)electrolites (bi-metallic gold-silver)

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Main Advantages of metallic cores:

1) Can be grinded, burnished and polished, making better the quality of the finished piece.

Disc finishing for grinding and polishing

Burnishing machine

2)      There are reusable alloys

3) Stand warm electrolytes without expansion

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Racks and anodes. Harmonisation.

Racks

-Rounds to get more even galvanic current all around the rack

-Steady connection core-rack (screw or soldering)

-Uniform core spreading

-Core of similar form and shape.

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Anodic system designed to obtain a distribution of current on the cathodic rack as even as possible

+

-Cathode

Anode

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Galvanic preparation

Previous to electroforming

Degreasing

Alkaline copper (Cu. Al.)

Acid copper (Cu. Ac.)

 

Previous to emptying

Protection coating of Acid copper (Cu. Ac.)

 

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Electroforming of gold alloy (tri-metal)

• Surface determination• Targets• Characteristics of GF electrolite. Ageing.• Computer programm• AUROFORM controlling systems based on the rack

weight increase.• Economy of GF electrolite• System of pieces control, when removed for rack.• Capacity of installation AUROFORM

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Reckoning of pieces surface on the racks.

It is important to reckon the area of the surface of the models (before fitting on the rack). Knowing the surface of the pieces the right intensity of current can be applied.

 The surfaces of the models are introduced in a data base of computer programm developed for Auroform. This is the process we recomend

Objeto Peso1 Peso2 diferencia Área Factor Área Factor Media

A 3.0861 3.1862 0.1001 35.62 355.87 35.53 354.95 35.58

B 2.6301 2.7152 0.0851 30.28 355.87 30.21 354.95 30.25

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Targets • Supposing we are using: -         Models matching with the process

-         Cores with good surface-         Rack matching with the type of pieces.-         Core-Rack-Anodes harmonic

• The targets ares:-         Control and security of the karat-         Quality of surface

- Even thickness.

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1 -Control system

according to rack weight increases.

2 -Characteristics of electrolite.

Ageing.

Most important for those Most important for those targetstargets are: are:

+ ELECTROLITE LONGER LIFE +

CONSISTENT REACTION OF ELECTROLITE

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3 Computer programm of command and control Menu

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Characteristics of electrolite GF Characteristics of electrolite GF AgeingAgeing

• Electrolite GF offers:-         Reliable behaving. Remarkable tolerance on error-         Very slow ageing. Normally 50 turnovens-         If electrolite contains 450 grams of gold, his

medium life will allow to produce: 50 x 450 = 22500 Grams of alloy electroformed

ElectroliteElectrolite Microns per hour Microns per hour (eficacity) (eficacity)

Weight of a micron Weight of a micron in on dm2 in on dm2

Minutes per micron.Minutes per micron.

GF 14K 34 0.13 2

GF 18K 27 0.15 2.5

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Computer programm GF

-  Reckons the pieces on the rack surface according to the information in the Data Base

-  Reckons the condition of the electolite also according to the information in the Data Base

- Admits to enter: How many microns. Number of controls etc. -   Commands the intensity of the rectifier -   Process the information of every control and change

intensity accordingly -   Controls all the conditions in the process are kept

inside the limits required. -   Stops the process when the required microns has been

electroformed. 

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AUROFORM control system based on the rack weight increase

Tri-metal electrolyte electroforming, controls the karat as per the weight increase of the alloy electroformed which is introduced in the computer program.

- Weight =Karat too low

+ Weight =Karat too hight

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AUROFORM weight control is:

Very reliable

Almost instantaneous

Working position Control position

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ECONOMY OF GF ELECTROLITE

GF admits that AUROFORM produce automatically one of the components:

 Saving money

Not introducing components not needed, which will harm the electrolite

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Control system of the pieces removed from rack

System Answer Cost (Euros)

X ray fluorescence Inmediate Five digits

Assaying Hours Four digits

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AUROFORM Production

Keeps

Stability in temperature and level of the electrolite

Continious filtering of electrolite

Permanent interface with the computer programm.

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90 L 150L

Max. W

eight (grams)

Time (hours)

Max. area (dm²)17 25

Max

. Wei

ght (

gram

s)

14 K Productuion capacity

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90 L 150L

20 30

Max

. Wei

ght (

gram

s)M

ax. Weight (gram

s)

Time (hours)

Max. area (dm²)

18 K Productuion capacity

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Emptying the cores

Holes

Every piece has to have two holes. Ideally opposite

A flat area around the hole can be convenient to make easier, soldering complements

Pieces are locate between silicone discs. Heat and centrifugal action are applied.

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Removing copper lay

Acids system

Toxic fumes are produced

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Annealing

Pieces electroformed are very bristle

An annealing treatment is required

Very convenient to do in control atmosphere

furnace.

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Assembling and soldering Assembling

-Nornal jewellery techniques are used

Soldering

Due to its low density and thickness, it is advisable:

-         -Avoid soldering when possible

-Solder with minimum temperatura and exposure.

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Polishing

Manual or turbo polishing is advisable in order the piece has a soft treatment and with no hitting.

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