67129545-Electroplating-Etc.pdf

TEKNO

Spin Casting • Smithery • Electroplating

Equipment & Toolings for Wrought Iron Furniture Fabrication

Gemstone Cutting, Grinding & Polishing

I. Electroplating

a. Copper Plating on Low Carbon Steel 3

b. Nickel-Chromium Platingon Aluminum and its Alloy 6

c. Gold Plating on Zinc-Based Alloys (including Die-castings) 9

d. Silver Plating on Copper, Brass andother Copper-Based Alloys 12

II. Smithery 15 III. Gemstone Cutting, Grinding and

Polishing 17

IV. Spin Casting 20 V. Equipment and Toolings for Wrought Iron Furniture Fabrication 26

NOTES

Metals Industry Research and Development Center 29

TABLE OF CONTENTS

ELECTROPLATING

ELECTROPLATING is a process of coating an object, usually metallic, with one or more relatively thin, tightly adherent layers of some other metal by means of electrochemical process. Electrochemical process involves electrical and chemical energy.

In electroplating, the object to be plated is immersed in a solution con-

taining dissolved salts of the metal to be deposited. The set up is made up of a cathode and an anode with the object to be plated usually the cathode con-nected to the negative (-) terminal of a direct current source. To complete the electrical circuit, another metal is connected to the positive (+) terminal and both are immersed in the solution. This metal is made up of the same material as the metal to be deposited and is called the anode. When current is applied, the electrical energy carried is converted to chemical energy by decomposition, a reaction in which the elements are divided into positive and negative charged ions. The movement of positively charged ions towards the cathode surface re-sults to metal deposition.

The most important step in the entire plating operation is the surface

preparation of metals or the cleaning process. This is because the appearance and acceptance of the article depend primarily on a sound finish achieved with a clean and active substrate. Likewise, improper cleaning process leads to rejects and decreased profitability.

Before the desired coating can be applied to the component, the sur-face to be plated should be clean and free of all “foreign” matters like heavy scale of oxide films, rust, workshop soils & oils, grease, dirt, and any other mate-rial. All these should be removed to ensure strong adherence of electro-deposited metal to the piece. This is achieved through the following methods:

- this is done by polishing, tumbling and blasting with sand, grit or vapor. This is then followed by pickling process where the component is immersed in acid to remove rust, scale, tarnish,

1. Descaling

PRINCIPLE OF ELECTROPLATING

PREPARATION OF THE WORK SURFACE

Mild steel plate 2” x 2” – 2 pcs.Paint, any color 1 qrt.

Wrought Iron Bending MachineWelding MachineMetal CutterPaint Spray Gun or paint brushAir compressor or paint brush

1. Prepare materials and equipment needed in making bed headboard.

2. Cut the flat bars into the following length:a. Mild steel flat bar 1” x 27 ¼” – 15 pairs

1” x 31” – 2 pairs1” x 59” – 1 pair1” x 6” – 1 pc11/2” x 61 ft. – 1pc

1” x 1” – 5 pairsb. Mild steel plate 3/16” Th. x 2” x 2” – 2 pairs

3. Cut the hollow square bars into the following length:a. 54 in. length - 1 pc.b. 32 in. length - 2 pcs.

4. Using the V-type die with shoulder for bending, create the design on the flat bar using the wrought iron bending machine.

5. Join together each pair of the flat bar with V design by spot welding, form-ing a diamond design.

6. Make a full-scale layout of the headboard on a flat surface.

7. Follow the layout and weld together the parts of the bed headboard.

8. Polish all rough surfaces and edges. Put filler on holes and cavities of metal surfaces.

9. Choose desired color and paint it.

10.Apply tuff coat paint.

Equipment:

Procedure:

Metals Industry Research and Development CenterDepartment of Science and Technology28 1

light oxides and dirt.

- this is done after the surface has been subjected to grinding or wire brushing. This method alters the surface of the metal through the use of a variety of abrasives: coarse, medium, fine and so on. This operation smoothens the surface of the metal.

- this method further smoothens the metal surface and im-proves its appearance by the application of very fine abrasives to produce different types of finishes (e. g., satin finish, brushed or but-ler finish, mirror brightness finish, etc.)

- the component is dipped in hot alka-line solution to remove oil and wax.

- this process is performed on the metal sur-face prior to electroplating. It is more efficient than soak cleaning and considerably minimizes chemical attack on the metal surface. The component becomes the cathode (direct cleaning) or anode (re-verse cleaning) or alternately the cathode and anode in an alkaline solution.

- the use of high-frequency waves called ul-trasonic waves enhance cleaning efficiency of components with complex shapes like jewelry, electronic and other precision parts.

1. Deposits on substrate poorly adhere

2. Non-uniform appearance of deposit

3. Pitting of deposit

4. Unplated areas

5. Poor corrosion resistance

6. Micro-roughness of deposit

7. Contaminated baths

2. Polishing

3. Buffing

4. Alkaline soak cleaning

5. Electrolytic cleaning

6. Ultrasonic cleaning

EFFECTS OF IMPROPER CLEANING

Twister Attachment

Machine specifications:

A twister was incorporated to the design of the bending machine by connect-

ing a rack gear to the piston rod of the hydraulic cylinder. The linear motion of the piston translates into rotary motion with spur gear mating with the rack gear. The rotary motion of the spur gear twist the bar. A clamping device holds the bar in such a way that the bar twists as the spur gears rotate.

At the other end of the twister, a similar clamping device can be moved mak-ing the length of twist adjustable.

Hydraulic Cylinder

Bore : 2.5 inchesStroke : 6.3 inchesCapacity : 25 tons @ 2,500 psi Max. Pressure : 5,000 psi

Hydraulic reservoir with accessories, piping and fitting

Capacity : 20 li

Electric motor with flange head mountingRating : 7.5 hpPhase : 3RPM : 1,750

Hydraulic pump (Submersible)

Displacement : 6.5 cc/revMax Pressure : 3,000 psi

Pressure relief valve

Max. Pressure : 5,000 psi

Mild steel flat bar 1/8” x 1” x 123 ¼”Mild steel hollow square bar 1/8” x 1 ½” x 10’Mild steel flat bar 1/8” x 1 ½” x 10’

How to Make Wrought Iron Bed Headboard Materials:


EQUIPMENT & ACCESSORIES NEEDED

Copper Cyanide 30 g/lSodium Cyanide 48 g/lSodium Carbonate 15 g/lSodium Hydroxides 3.75 g/lRochelle Salt 30 g/lCurrent Density 0.5 - 4 A/dm2Temperature 24 - 66 oCVoltage 6 VpH 12 - 12.6Dipping Time 30 sec. - 5 min.Anode Oxygen-free Copper

Copper Sulfate 225 g/lSulfuric Acid 56 g/lCurrent density 2 - 10 A/dm2Temperature 21 - 48 oC (RT)Voltage 6 VDipping Time 15 min.

I. Copper Cyanide (CuCN) Plating Solution

II. Acid Copper Plating Solution

PLATING PROCESSES

A. COPPER PLATING ON LOW CARBON STEEL

MATERIALS AND SOLUTIONS NEEDED

1. Rectifier 2. Plating Tank3. Anode: e.g., Nickel, Copper,

Stainless Steel, Silver4. Heater5. Filter6. Air Blower/Agitator7. Thermostat

8. Thermometer 9. Racks and Jigs10. Copper Bus Bar11. Bench Grinder12. Wire Wheel Brush13. Polishing Wheel14. Buffing Wheel15. Measuring Glassware (Beaker, Graduated Cylinder)

EQUIPMENT & TOOLING FOR WROUGHTIRON FURNITURE FABRICATION

Wrought iron furniture making is one of the most promising business undertakings in the country today. This is evident in the products that are currently being produced and exported to other countries.

The development of wrought iron equipment and tooling is intended to address the need for mechanized equipment to replace the manual process. The equipment consists of a bending machine and a twister attachment. Availability of this low-cost equipment and tooling will be a boost to the furniture industry in helping establish and maintaining the quality of local metal furniture.

The Wrought Iron furniture Equipment utilizes hydraulic power to do the

work.

It has different die attachments to form the shape of the wrought products. Using dies, production of metal furniture is hastened and metal forming is consistent throughout the operation.

The equipment can bend and twist iron bars with larger cross-sections which are difficult to do manually.

The machine is electrically-controlled through a panel board which contains an emergency and foot switches, plus push button switches for reverse and for-ward motion.

A hydraulic cylinder immediately coupled to a slide block which holds the punch provides force. The punch pushes the metal being formed to a fixed die which absorbs the force to create the desired contour.

A motor pump supplies the needed pressure to the oil which actuates the hy-draulic cylinder.

Technical Description:

Bending


Anode Phosphorized copper

Sulfuric acid 50 mlWater 1 liter

1.Fill 2/3 of the storage tank with demineralized water and

dissolve the required amount of sodium cyanide (NaCN) with continu-ous stirring.

2. In a separate container, mix copper cyanide (CuCN) with water to form a thin slurry. Pour this mixture gradually into the storage tank.

3. Add the rest of the required materials after dissolving the copper cya-nide.

4. Carbon treat the solution if necessary then filter into the plating tank. Dilute to volume with water.

5. Adjust to the required pH with sodium hydroxide (NaOH).

6. Analyze solution for free cyanide (CN).

1. Fill 2/3 of the storage tank with demineralized water, then heat to 60

oC.

2. Dissolve copper sulfate (CuSO4•5H2O) with continuous stirring.

3. Treat bath with activated carbon. Stir the solution.

4. Agitate for at least one hour, then allow activated carbon to settle for right hours. Filter into the plating tank.

III. Acid Dip Solution

SOLUTION PREPARATION:

COPPER CYANIDE PLATING SOLUTION

ACID COPPER PLATING SOLUTION

melt with the addition of virgin metal to maintain the ratio. Too much remelted metal will reduce the quality of the melt resulting in sluggish metal flow, porosity and grainy surface of the finished cast. Once the metal has undergone solidifica-tion and plastic set up, the casting is removed from the mold after which all the runners, vents and gates are easily broken away by hand. Most of the parts are ready for assembly or use or finishing and require minimal cleaning and machin-ing.


5. Add sulfuric acid (H2SO4) and agitate through mixing and dilute to volume.

6. Add the necessary amount of brighteners.

1. Pour the water in a clean container.

2. Gradually add the sulfuric acid to the container. Mix thoroughly.

1. Degrease the low-carbon steel by dipping in alkaline solution for 5 min.

2. Electro-clean the steel by applying current of 8 Amp/dm for 30-60 sec.

3. Rinse with water for 5-10 sec.

4. Dip for 10-15 sec in of 50ml/l sulfuric acid solution.


6. Plate with copper in copper cyanide solution for 2-5 min. Using current density of 4.0 Amp/dm .


8. Dip for 5 sec. in 50 ml/l sulfuric acid solution.


10. Plate in acid copper at room temperature for 15 min. using current den-sity of 4.0 Amp/dm .

11. Rinse with water and dry.

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ACID DIP SOLUTION

CAUTION: To avoid accident always add to

ACIDWATER

PLATING PROCEDURE:

the vulcanizing time should be 75 minutes per 25 mm of mold thickness. At an ini-tial pressure of 1,500 psi and 168 Celsius, the silicone rubber will turn into plas-tic and expand during the first 8-10 minutes. The expansion of the silicone rubber entraps air in the mold frame which should be evacuated. This can be done by re-leasing pressure to zero after pressure has risen to about 200 psi. After 5 sec-onds reapply pressure. Repeat the procedure thrice. Bring and hold pressure up to 2000 psi. Polymerization is completed after 75 minutes. Let the vulcanizing frame cool down to 35 Celsius before demolding.

Before casting, dust the surface of both upper (cope) and lower molds with fine talc powder to prevent molds from burning prematurely and facilitate the flow of metal. The recommended air pressure for the different diameter molds are:

less than 23 mm - 30 psi23 - 30 mm - 30 psi38 mm - 60 psi46 mm - 70 psi

The rpm of spin is proportional to the diameter of the rubber mold: faster

for smaller diameter and slower for larger diameters. Put the mold into the ma-chine, making sure that it is centered. Cover the machine and switch on the air pressure. Rotate the machine while it is set at 400 rpm for 1 minute.

In a suitable crucible furnace fired either with electric or gas, melt the metal. Scoop molten metal into the mold and quickly pour it into the center spruce of the mold. The pressure caused by the centrifugal force pushes the liq-uid through the system, filling up the crevices. The general rule for pouring tem-perature of the melt is the liquidus of the metal plus 10 Celcius. When opening the casting, depressurize the system before removing the mold from the ma-chine. Remove the casting from the mold.

Return gates and runners while still hot should not exceed 50% by weight of the original virgin alloy. Maintain this proportion by sweetening the

O

0

O

SPINCASTING

POURING AND SET-UP

FETTLING


B. NICKEL-CHROMIUM PLATING ON ALUMINUM AND ITS ALLOY

MATERIALS AND SOLUTIONS NEEDED

Nickel Sulfate 225 g/lNickel Chloride 30 g/lBoric Acid 40 g/lBrightener I (Vegastar I) 30 ml/lBrightener II (VegastarII) 2 ml/lAnti-pitting agent 0.5 - 1 ml/lCurrent density 2 - 4 A/dm2Temperature 45 - 70 oCVoltage 6 - 12 VpH 4 - 4.5Dipping Time 15 min.Anode Nickel

Chromic Acid 250 - 300 g/lSulfuric Acid 2.5 - 3 g/lCrO3 : H2SO4 100 : 1 ratioTrivalent Chromium (Cr+3) 2 - 3 g/lNon-mist pellets 0.5 g/lCurrent density 11 - 23 g/lTemperature 52 oC +/- 3oCVoltage 6 - 12 VDipping Time 1 - 2 min.Anode Lead (Pb)

with 5-7% Tin or Antimony

I. Nickel Plating Solution

II. Chrome Plating Solution

III. Copper Cyanide Solution (see page 3)

or the patterns. With all the patterns and cones in place, make an imprint on the rubber cope.

After setting all the molds and cone in place, re-spray all surface of the cope and drag with mold release spray.

The principle behind the gating system is to make full use of the centrifu-gal force generated during spin casting. Using a sharp knife or scalpel, carve the gates and runners in the rubber. Gates from the center spruce should be carved in a spiral direction. The width and depth of the gates should be both between 5 to 10 mm and should be proportional to the size of the cavity from the mold cen-ter and the patsy range of the mold.

The venting system ensures the release of entrapped air which might pro-duce cavities in the casting. Vents are usually placed where the cavities are to be filled last. It is advisable to put one vent per cavity to ensure the release of en-trapped air. The width of the vents must be between 1 to 2 mm to avoid molten metal filling up the air-holes.

Clean thoroughly the mold with paint thinner, removing any solidified par-

ticles on the surface. Make sure that all vents are cleared of particles that have been lodged from previous vulcanization. Wipe the set with a dry clean cloth.

Place the bottom plate on top of the working table and set the frame over it. Apply a coat of mold release compound onto the inner surface of the frame and the outside surfaces of the drag. Position the alignment studs near the pe-riphery of the rubber drag to ensure the alignment of the cope and drag during casting. Place the cope over the drag and press lightly.

Preheat the vulcanizing platens to 168 Celsius. At this temperature, O

5. Gating and Venting

6. Preparation of the Mold Making Frame

7. Loading the Mold Making Compound

VULCANIZATION



1. Fill 2/3 of the storage tank with demineralized water and heat up to 65 oC.

2. Add boric acid (H3BO3) in specified quantity and agitate to dissolve.

3. Add nickel sulfate (NiSO4), then the nickel chloride (NiCl2). Dissolve.

4.Treat with activated carbon (2-5 g/l) and agitate for about 2 hours.

5. Filter the solution into the plating tank.

6. Add the brighteners in specified quantities and adjust the volume of the solution with water.

7. Adjust the pH to working condition.

8. Perform weak electrolysis if necessary (1-2 A/dm2 for 20 min. or un-til completely covered with nickel, then reduce to 0.1-0.2 A/dm2).

1. Fill tank with water to about 3/4 of the final volume.

2. Heat until temperature is about 50 oC.

3. Add chromic acid (CrO3) very slowly with continuous and vigorous stirring.

4. Add sulfuric acid in specified quantity.

5. Stir up the plating solution for about 2 to 3 hours for perfect dissolu-tion.

6. Heat the solution until the temperature reaches 50 o C. (Do not exceed this temperature and maintain it for 2 hours then make an electrolysis without plating the article. This procedure is for obtaining a trivalent chromium ions (Cr+3) in the plating).

NICKEL SOLUTION

CHROME SOLUTION

MOLD PREPARATION

The mold preparation process comprises the following steps:

On a clean working table, lay a cellophane sheet and put the silicon rubber on top. Make a circular imprint on the rubber sheet with the use of the mold making frame. Cut and store the rubber sheet between the cellophane.

Estimate the orientation of the casting model/pattern and determine where to place the parting line. Measure the height above and below the parting lines. The upper portion of the mold is known as the cope and the lower one, the drag. Add 5 mm to the measurement of the cope and drag. The minimum allowable thickness for the cope is 12.5 mm. If no part of the casting will be in the cope, the thickness should equal the minimum thickness (12.5 mm). After determining the required number of disks, join them by cold-pressing in the vulcanizer until the desired thickness is reached. The combined thickness of the upper and lower molds should be equal to the initial height of the molds plus 25 mm.

Make patterns/casting molds of the articles that will be spin cast. Re-

move all rough finishes on the pieces to prevent damaging the rubber mold dur-ing vulcanization.

Establish the center by making a small cut on the drag. Spray mold re-

lease on the surfaces of the molds and models, allow it to stand for 30 min. Lay the molds/patterns to the drag and make sure that they are evenly spaced near the periphery of the drag. Allot at least 13 mm allowance from the edge of the sili-con mold.

Press the molds into the rubber by hand until the desired parting lines has been reached. To provide for a spruce hole and eliminate a dead center (stagnant melt in the rational axis), a cone center is needed to accelerate the mold with greater torque. Set the cone center in the middle following the same procedure

1. Forming of Silicon Rubber Disks

2. Formation of Disk Thickness

3. Preparation of Casting Molds/Patterns

4. Placing of Models/Patterns on Rubber Disks


COPPER CYANIDE SOLUTION

PLATING PROCEDURE:

(refer to page 4 on how to prepare).

1. Degrease the aluminum by dipping in hot alkaline solution for 5 sec-

onds.

2. Rinse with water for 5-10 seconds.

3. Dip in 50% by volume nitric acid for 10 sec.


5. Dip in sodium zincate solution for 1-3 min. This solution contains 525 gms of caustic soda, 100 gms zinc oxide, 10 gms rochelle salt and 1 gm ferric chloride per liter solution. The solution should be used at room temperature and the articles should be kept moving during immersion.

6. Rinse with water thoroughly.

7. Strip the zincating by dipping in 50% by volume Nitric acid.

8. Rinse with water.

9. Repeat step no. 5


11. Plate with copper in copper cyanide solution (see section 3).


13. Plate with nickel for 15 min. at 4.0 Amp/dm .

14. Rinse with water. 15. After nickel plating, the article can be plated with chromium at 10

Amp/dm for 1-2 min.

16. Wash the article in hot water and dry.

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This type of method bridges the gap between the conventional die and sand casting methods.

The vulcanizer is a jack-actuated press with heated plates and is equipped with temperature controllers and a timer. The unvulcanized rubber is contained in a mold making frame and cured in the vulcanizer

Composed of a steel ring with top and bottom plates. These are made of steel with inner diameter of around 304 mm and widths of 25, 38, or 50 mm.

This machine has a rotating table wherein the silicon mold is placed during the casting cycle. The rotation is done with a pulley drive attached to the motor. A pneumatic clamping system is used to clamp the mold onto the rotating bed.

Rotating speed: 300-600 rpm, determined by a timer

or tachometer. Clamp air pressure: 30-80 psiTimer: 30 sec to 5 min

Any furnace that can melt zinc, lead, or tin-based alloys.

Usage of either electric, diesel or LPG-fueled furnace depends on the scale of operation. The use of the cast iron crucible pot is recommended since relatively low melting alloys will be used and no reactions can be expected between the pot and the molten metal.

There are two major processes involved in spin casting. The first is the preparation of the mold and the second is the actual casting.

EQUIPMENT NEEDED:

Vulcanizer -

Melting Furnace -

Mold Making Frame -

Casting Machine -

PROCEDURES IN SPIN CASTING TECHNIQUE

10 23 & 30.5 13 x 10 x 910 23, 30.5 & 46 23 x 16.5 x 9 10 23, 30.5, 38, 46 & 51 25 x 19 x 9 10 23 through 63 30.5 x 20 x 9

MOLD THICKNESS MOLD DIAMETER MAXIMUM PARTS(cm) (cm) L x W x H (cm)


C. GOLD PLATING ON ZINC-BASED ALLOYS (INCLUDING DIE CASTINGS)

Potassium Gold Cyanide 1.25 - 2 g/lPotassium Cyanide 7.5 g/lDipotassium Phosphate 15 g/lTemperature 60 - 70oCCurrent Density 1 - 4 A/dm2Anode Stainless Steel/Gold/

Platinized titanium

Potassium Gold Cyanide 4 - 12 g/lCitric Acid 10 g/lPotassium Citrate 50 g/lHydrogen Sulfate 6 g/lNickel Citrate 60 g/lpH 3 - 6Current Density 10 A/dm2Temperature room temperatureAnode Carbon and/or Platinized titanium

Sulfuric acid 65 ml Water 3 liters

Sodium Cyanide 30 grams Water 1 liter

MATERIALS AND SOLUTIONS NEEDED:

a. Strike Gold Solution

b. Acid Gold Solution

c. Acid Dip Solution

d. Cyanide Dip Solution

e. Acid Copper Solution (refer to page 3).

f. Copper Cyanide Solution (refer to page 3).

g. Nickel Solution (refer to page 6).

SPIN CASTING

Spin casting is a process of pouring and solidifying a low melting alloys in a mold using the principle of centrifugal force to produce a more compact product. The technique uses a silicon mold that has the cavity or imprinted shape of the item. The mold is rotated on a vertical axis. The process produces precision parts comparable to those made from pressure die casting techniques, thus realizing major savings in time and labor.

Novelty items or ornamental hardware and even automotive parts can be made in this process. Lead, lead-tin alloys, commercial grade zinc alloys with tensile strength the same as aluminum, brass and low grade steel can also be used as raw material.

The process produces parts with close tolerances of + 0.43 mm per 25 mm, smooth surface and excellent detail at low piece cost.

Suitable materials for spin casting method are:

Zinc-based alloys Tin-based alloys Lead-based alloys Aluminum

Thermoset polyester Thermoset polyurethane Epoxies

Maximum weight and size of spin-cast products are related to the size of the mold and associated equipment. Metal products can range from less than 100 to 1,200 grams.

Product sizes based on rubber mold diameter and thickness are shown in the next page.

I. METALS

II. THERMOPLASTICS

III. Wax


SOLUTION PREPARATION

1. Fill 2/3 of the storage tank with distilled water.

2. Dissolve the required amount of potassium cyanide.

3. Add the potassium gold cyanide in specified amount and stir to dis-solve.

4. Add the rest of the required chemicals and dilute to volume with dis-tilled water.

1. Pour each 1 liter of water into three containers.

2. Measure 5, 10 and 50 ml of sulfuric acid. Then pour to the containers. Mix then set aside.

1. Place 1 liter of water in a container

2. Pour gradually 30 grams of sodium cyanide. Mix, then set aside.

(same as gold plating solution preparation)

(refer to page 3 on how to prepare.)



GOLD PLATING SOLUTION

ACID DIP SOLUTION

CYANIDE DIP SOLUTION

STRIKE GOLD PLATING SOLUTION

COPPER CYANIDE SOLUTION

ACID COPPER SOLUTION

NICKEL SOLUTION

CAUTION: To avoid fatal accident, NEVER mix & ACID CYANIDE SOLUTION

10. Unmounting from Dopstick

Remove the polished gem from dopstick by picking it with a cutter or any pointed material.

Note:

All the above-mentioned processes except 1, 6 and 10 require water to avoid burns on the surfaces of the stone. In order to ensure cleanliness, workpiece should be washed before changing cutting media (diamond blade, grinding wheel, polishing compound, sandpapers), since contaminants from pre-vious cutting media would leave deep marks/scratches.


PLATING PROCEDURE:

1. In separate clean plating tanks, prepare the solutions of strike gold, acid gold, copper cyanide, acid copper and nickel copper.

2. Degrease the zinc-die cast by dipping in alkaline solution for 5 min.

3. Electroclean the zinc-die cast by applying current of 5 Amp/dm for 30-60 sec.


5. Dip in 5 ml/l Sulfuric acid solution for 30-60 sec.


7. Immerse the zinc-die cast in copper cyanide solution with current on. Ini-tially, use a current density of 2.5 Amp/dm for 2 min, then reduce the current density to 1.2 Amp/dm and continue to plate for 5 min.


9. Dip in 10 ml/l Sulfuric acid solution.


11. Plate in Acid Copper at room temperature for 15 min. using current den-sity of 4.0 Amp/dm .


13. Dip in acid of 50 ml/l Sulfuric acid for 5 sec.

14. Plate in Nickel solution for 15 sec. using current density of 4.0 Amp/dm

15. Rinse with water

16. Dip in 30 g/l Cyanide dip solution

17. Rinse with water

18. Plate with strike gold solution

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3. Templating

4. Trimming

5. Preforming

6. Dopping

7. Shaping (Grinding)

8. Sanding

9. Polishing

Outline the desired cabochon shapes on the slabs using a template and alu-

minum pencil. The outline serves as a guide for trimming and grinding.

Remove the unnecessary part in the slabs following the outlined shapes.

Maintain 1.5-2.5 mm space around the outline for grinding purposes. This can be done within 3 minutes.

Do initial grinding by following the contour of the desired shape by using the grinding machine. The marked piece, held firmly in both hands, is applied to the wheel face at about the level of the axle and ground to about 1/32 of an inch of the template outline.

This is done by attaching the flat side of the stone to a dipstick with a heatsealing wax mixture. Dopstick may be bought or improvised using a rod that is 18-21 cm long and 2 cm in diameter. The stone is heated and pressed against the waxed end of the dopstick.

Final grinding is done in an 80-120 grits grinding wheel in order to attain the

desired shape and size.

Sanding is done to prepare the ground gemstone for polishing. Sand pa-pers of grits of 220 and 600 are used in this process. Sanding may be done in 3 minutes.

Rub the gemstone against a soft material such as felt, leather, cloth or car-pet on which a watery polishing agent is applied to impart a glossy smooth sur-face.


19. Plate with gold in Acid Gold solution.

20. Rinse with water and dry.

Silver Cyanide 2 g/lCopper Cyanide 10 g/lPotassium Cyanide 60 g/lTemperature 21 - 30 oCCurrent density 1.6 - 2.5 A/dm2Voltage 4 - 6 V

Silver Cyanide 3 - 4.5 g/lPotassium Cyanide 62 - 75 g/lTemperature 21 - 30 oCCurrent Density 1.6 - 2.5 A/dm2Voltage 4 - 6 V

Silver Cyanide 30 g/lPotassium Cyanide 50 g/lPotassium Carbonate 13 g/lTemperature 21 - 27 oCCurrent density 0.5 - 1.6 A/dm2

(Refer to page 4)

(Refer to page 10)

a. 1st Strike Solution

b. 2nd Strike Solution

c. Silver Plating

d. Acid Dip Solution

e. Cyanide Dip Solution

D. SILVER PLATING ON COPPER, BRASS AND OTHERCOPPER-BASED ALLOYS

MATERIALS AND SOLUTIONS NEEDED:

GEMSTONE CUTTING, GRINDING AND POLISHING

Gemstones are natural or synthetic minerals with special physical proper-ties that may be fashioned into objects for personal adornment and decorative purposes. To cater to the increasing demand for gemstones, the Gemstone Cutting, Grinding and Polishing Processes are being utilized.

Various types of gemstone such as Jade, Opal, Quartz, Chert petrified wood, Jasper and/or other semiprecious stones.

Diamond cutter blade Chromite oxide Dopping stick Grinding wheel, 80/120 grits

Template Shellac flakes/epoxyPencil Alcohol lampSand paper, 200/600 grits Denatured alcohol

Polishing cloth/carpet Tweezers

Gemstone Cutting Machine

Gemstone Grinding MachineGemstone Polishing Machine

Carefully examine the raw stone to avoid cracks, fractures and cleavages to get the best part of the stone.

Cut the rough stone into 3-5 mm slices or 4-6 mm thick using the cutting equipment. This can be done in 5 minutes.

MATERIALS:

CONSUMABLE NEEDED:

EQUIPMENT NEEDED:

PROCEDURE:

1. Orientation/Examination of Samples

2. Slabbing



PLATING PROCEDURE:

1. Fill 2/3 of the storage tank with distilled water.

2. Dissolve the required amount of potassium cyanide.

3. Add and stir to dissolve the silver cyanide in specified quantities.

4. Add the rest of the required chemicals and dilute to volume with dis-tilled water.

(same procedure above).



1. Degrease the copper by dipping in alkaline solution for 5 min.

2. Electroclean the copper by applying current of 8 Amp/dm for 30-60 sec.


4. Acid Dip for 5 sec. in 50ml/l sulfuric acid.

5. Plate in Nickel solution for 15 sec. using current density of 4.0 Amp/dm .

6. Rinse with water thoroughly for 10 sec.

7. Dip in 30 g/l sodium cyanide solution.


9. Plate in 2nd Silver Strike solution for 8-12 sec. at room temperature at 2.0 Amp/dm .

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SILVER PLATING SOLUTION

1ST AND SECOND STRIKE SOLUTION

ACID DIP SOLUTION

CYANIDE DIP SOLUTION

4. For the desired dimensions and shape of the material, process the material by grinding manually or using the grinding machine. Use the 80 grits grinding wheel.

5. Shape and sharpen the bladed edge by using a 120 grits grinding wheel.

6. Hardened the blade edge of the semi-finished knife or bolo by heat treatment or tempering:

Place the material being shaped into the furnace, position the bladed edge nearest to the fire. Heat it until the piece turns red hot in color.

Immerse the piece into the quenching tank filled with water or oil. If the piece turns into chocolate brown color, the piece is hard and tough—the desirable mechanical properties of metal. Repeat the heat treatment procedure if it turns white (it is hard but brittle) until the chocolate brown color is achieved.

7. Polish the entire piece into a mirror-like finish by using different and appropriate emery cloth sanding grits (300-600).

8. To increase/enhance its shine, use a buffing cloth with polishing compound:

Attach the sandpaper to a round piece of wood then attach it to the grinder. Proceed to polish the bolo. Attach a buffing cloth with polishing bar/compound to the grinder and polish the entire bolo to the desired shine.

9. Attach the wooden handle.

10. Lubricate the entire piece with oil to prevent rust and to preserve the beauty of the entire piece before wrapping and storing.



11. Plate in Silver plating solution for 5-10 sec. with applied current of 0.5-1.5 Amp/dm .


13. Apply the silver plated article with discoloration prevention solution.

2

SMITHERY

is a process of hot working the metal to a desired shape by applying high impact pressure using machine tools or hand tools. Typical products are scissors, knives, bolos and others.

• Smith Hearth Furnace • Charcoal• Anvil • Quenching tank half filled with • Drill Press water or quenching oil• Blacksmith's Hammer • Tong• Pedestal Grinder with

80 & 120 grits grinding wheel

• Medium Carbon Steel (C1043) • Emery Cloth• Polishing bar/compound/ • Buffing Cloth

Scrap steel like leafspring, etc. • Drill bits (1) set• Piece of wood-to be used • Sand paper

as handle of the bolo (300-600 grits)

1. Select scrap material of right size and thickness. Place it into the furnace until its color begins to turn yellowish. By this time, the material has reached its plastic stage and is ready to be processed.

2. Using the tong, remove the piece from the furnace and place it on the anvil. With the forging hammer, hit the material heavily and repeatedly until the right shape is obtained. To prevent from cracking, the material should be returned to the fire if it begins to cool before the right shape is obtained.

3. Form the handle of the bolo/knife according to the desired design by placing the part into the fire again. Hammer it until the shape is achieved.

SMITHERY

HOW TO MAKE A BOLO/KNIFE EQUIPMENT NEEDED:

MATERIALS:

PROCEDURE:


Documents

67129545-Electroplating-Etc.pdf