Category Archives: Fabrication methods

Learn how we make stainless steel jewelry using

Stainless steel jewelry with Rhodium plating

Rhodium plating is all about silver jewelry, right?
Wrong!
You can have Stainless steel jewelry with Rhodium plating.

Many people picture a bright, expensive Rhodium finish jewelry only as silver jewelry. It must be expensive to reach this look as you must use silver to craft the jewelry before you can apply rhodium plating.
Well, maybe not.

Yes, rhodium is still needed. Like anything in life, you get out of your jewelry what you put in. However, you don’t have to use expensive silver in order to get this sparkling luxury jewelry look.

You can upgrade your stainless steel jewelry with Rhodium plating. The color will be bright (whiter than steel), it will look expensive and it is easy to fit into your production schedule. You can plate chains, rings pendents, basically any type of steel jewelry.

Let’s find out what Stainless steel jewelry with Rhodium plating is all about.

The process of applying rhodium plating on steel jewelry is little different from applying Rhodium on silver jewelry.
The process involve 3 steps that can perform in different quality level (we outline our recommended spec below)  but one thing you must consider. The plating process does not cover any imperfection. Your steel jewelry must be clean, perfectly polished without marks before the plating.
Production steps for Stainless steel jewelry with Rhodium plating.

  1. Gold plating
  2. PDP / PCP /PNP plating
  3. Rhodium plating

How we plate steel jewelry with rhodium?

After polishing, assembly and quality check each piece of jewelry clean and prepare for plating.
In the first stage the steel jewelry socked in liquid solutions and plated with 24K gold. The gold layer use as a “glue” between the other 2 layers and the stainless steel. You must make sure the plating is dense enough and cover the whole item in order to insure high durability finished jewelry.
After the jewel is plated with 24K gold cleaned and dry it’s time for the 2nd layer. This layer can use different metals combination according to your budget and desired quality.

  1. PDP: Pure Palladium plating.
  2. PCP: Palladium and Cobalt mix plating.
  3. PNP: Palladium and Nickel mix plating.

Next, for the 3rd layer we will apply and plate the entire surface with pure Rhodium. It is possible to apply different thicknesses of rhodium according to the spec. The quality of this layer will have an impact on the color and the shines of your final jewelry piece.

How we test Stainless steel jewelry with Rhodium plating?

The method is very similar to testing other steel jewelry plating techniques like PVD. The testing performed by a fully automated X-ray machine (imported from Germany).
Because the thickness of each layer is very thin, we will perform 10 testing attempt to get the most accurate results. hard copy result’s report available to our customers.

Recommended specs for Stainless steel jewelry with Rhodium plating.

  1. 24K gold plating for 8-10 minutes. (until the jewelry piece is fully plated)
  2. Mix of 10% Cobalt and 90% Palladium for 2nd layer plating.
  3. 0.1 micron Pure Rhodium plating 3rd layer

When you are planning your next steel jewelry production, remember that your plating specs affects the cost and durability of the jewelry and adjust accordingly.

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Stainless steel necklace with rhodium plating, Hulpf jewelry China

Steel Jewelry PVD plating (Physical vapor deposition)

Today, for  stainless steel jewelry there is no reason to limit the color choice to the natural steel color. for steel jewelry PVD  plating is my option of choice.
If you follow the steel jewelry industry for few years, you have had heard the terms coating, plating  PVD, IP, IPG and “electroplating” many times.

Understanding the plating or coating methods and choosing the right one  can  be the difference between a failed to successful product.  In addition to a big different in price and quality.

My aim in the following posts is to describe the main methods used in the steel jewelry industry using as less as possible technical terms.
I hope the information will serve you during your purchasing process in China.

For those who don’t have time and need quick answers.

  • What is PVD?
    PVD is 2 thin layers applied to the surface.
  • What the different from IP to IPG to PVD?
    In general no differences other than the applying method.
  • Why not to use electroplating?
    The colors are not stable and it’s not durable as PVD plating.
  • Is there a price different?
    Yes, PVD plating way more expensive.
  • How durable is PVD plating?
    in normal use, the plating won’t change for few years if done correctly.
  • How to test PVD plating?
    With X-ray machine for the thickness and ISO sweat test for the durability.
  • what is the differences between glossy and satin PVD finishes?
    There are no differences, the surface finish is according to the jewel polish.

The 4  coating and plating techniques  mainly used in the jewelry industry.

  1. PVD (Physical vapor deposition) also refer by china suppliers as IP or IPG.
  2. Chemical also known as electroplating.
  3. Dip-coating, mainly use for silver and gold.
  4. Spraying.

PVD plating (Physical vapor deposition) .

Vacuum deposition is a family of processes used to deposit layers atom by atom in vacuum chamber on a solid surface. The layers may be as thin as one atom to millimeters thick. There may be multiple layers of different materials. A thickness of 0.25 to 0.7micron is generally called a thin film and very common in the jewelry and watch industries. The majority of steel jewelry use 0.20 to 0.28 micron plating. It is very rear to find steel jewelry with 0.7micron plating (some top brands use 0.35-0.5 micron) as the changed in price is not proportional to the thickness different.

The 5 Main PVD plating (vacuum deposition) methods

  1. Cathodic Arc Deposition.
  2. Electron beam physical vapor deposition.
  3. Evaporation deposition (mainly used for jewelry and watches).
  4. Pulsed laser deposition Sputter deposition

8 most popular PVD plating colors for stainless steel jewelry.

  1. Gold, 14K, 18K, 24K color variations.
  2. Rose gold (pink gold)
  3. Coffee.
  4. Black.
  5. Dark grey.
  6. Blue.
  7. Silver
  8. Platinum.

All these colors are available in a polished, satin or brush finish according to the product surface polish.

PVD Evaporation deposition in simple terms.

The jewelry or parts to be coated are first cleaned. Then, a first layer of Tin (tn) is vaporized in a vacuum chamber and use as a “base”.
For gold and rose gold finish real gold (14K or 18K) is evaporated and deposited on the part under high temperatures or via ion bombardment as a 2nd layer. The shade of the gold is according to the gold content.
Color pigments or gas in other cases together with the Tin layer are used to achieve other colors during the first layer process (without the use of gold as 2nd layer).
Depending on the substrate material the process temperature can be controlled from 100 degree Celsius to 280 degree Celsius.

Durability
Depend on the plating thickness, the manufacturing method and the reaction with the body acid. PVD will last from 10 months to few years. It’s a good place to mention that Rose gold color slightly change its color to yellow gold during the time the same as real rose gold or white gold jewelry (the copper in the rose gold oxidized) .
PVD plating on jewelry is not a scratch proof or lifetime finish although it is last longer than other plating in similar thickness (Zirconium Nitride (ZrN) is used for application required hard finish)
Igh quality PVD are more durable than other plating methods.
Price
The PVD price is relatively more expensive compare to other plating methods like Chemical, electroplating, or spraying but still lower than precious metal dip coating thanks to the thin film layer used.

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Stainless steel jewelry production, wire-cut EDM

Are you curios to know how we cut steel pendents in stainless steel jewelry production?

Is there any alternative ? what are the advantages using wire cut in Stainless steel jewelry production?

How it effect the price and delivery time?

Read about one of the most used fabrication methods in stainless steel jewelry production.

The wire-cut EDM is electrical discharge machine that uses CNC controller and continuous-traveling vertical wire under tension as one of the electrode to produce the desired shape.

The wire in wire-cut EDM is about as thick as a small diameter needle which allows creating a very delicate parts or shapes. In the stainless steel jewelry industry this fabrication method mostly used to cut flat parts out of steel sheets i.e. dog tag pendants.

Wire cut in stainless steel jewelry production considered to be a slow fabrication methods.  As the industry advanced and if the thickens of the steel jewelry product we produce allowed. We prefer to use laser or plasma cutting. Which speed the process.

Another disadvantage of wire cut is the finish of the part edges. in most cases it will require longer and costly polish process.

Wire-cut EDM  Machining According to Wikipedia.org:

“In wire electrical discharge machining (WEDM), also known as wire-cut EDM and wire cutting, a thin single-strand metal wire, usually brass, is fed through the workpiece. The wire, which is constantly fed from a spool, is held between upper and lower guides. The guides move in the X-Y plane, and sometimes the upper guide can also move independently giving rise to transitioning shapes (circle on the bottom square at the top). This gives the Wire-cut EDM  the ability to be programmed to cut very intricate and delicate shapes. The wire-cut uses water as its dielectric with the water’s resistivity and other electrical properties carefully controlled by filters and de-ionizer units…”  [View Wikipedia Entry]

Wire-cut EDM Machining Process

Wire-cut EDM  machining also known as Electrical Discharge Machining is an electro thermal production process in which a thin single-strand metal wire in conjunction with de-ionized water (used to conduct electricity) allows the wire to cut through metal by the use of heat from electrical sparks.

Due to the inherent properties of the process, Wire-cut EDM  can easily cut complex parts and precision components out of hard conductive materials.

How Wire-cut EDM Works with stainless steel jewelry

Wire-cut EDM  machining also known as spark EDM  works by creating an electrical discharge between the wire or electrode, & the work piece. As the spark jumps across the gap, material is removed from both the work piece & the electrode.

wire-cut-steel-jewelry-pendant

steel pendant in wire cut machine

 

To stop the sparking process from shorting out, a non conductive fluid or dielectric is also applied. The waste material is removed by the dielectric, and the process continues.

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Hulpf team

 

Steel jewelry casting How to?

Investment casting is one of the oldest known metal-forming techniques. In general, the jewelry cast part obtained by allowing molten steel to solidify in a mold then clean and removed to polish and further assembly if necessary.

Steel jewelry castings allow the production of irregular shapes that usually can not be done or are too costly and time-consuming to produce using CNC machine, one of the main fabrication methods for stainless steel jewelry.

Steel jewelry casting is a process of making jewelry pieces that involves the pouring of liquid steel into a mold. It is usually referred to as lost-wax casting because the casting mold is created using a wax model that is melted away to leave a hollow chamber in the middle of the mold. The technique has been used for thousands of years, and is still widely used today to make reproductions of stainless steel jewelry.

The steps in steel jewelry casting

1. Choose a model for casting. A model could be a piece of jewelry that you want to make a mold out of. You can use any piece of your own jewelry that you are interested in reproducing.

2. Build a rubber mold using your model.

  • (1) Prepare an un-vulcanized rubber molding compound. You can purchase it at your local arts and crafts supply store.
  • (2) Press your model into a appropriately sized mass of the rubber molding compound. Make sure to surround the model entirely to ensure an entire mold for casting jewelry. The compound are going to be soft and pliable till you cure it, therefore we don’t need to  worry about damaging your model.
  • (3) Subject the rubber mold to heat according to manufacturer’s directions so as to vulcanize, or cure, the rubber. The finished product can similar in consistency to a rubber bouncy ball.
  • (4) Use a surgeon’s knife to dissect the model out of the mold. Slice down the middle of the rubber mold, length-wise on the model, making a mold that opens like a book. Watch out at this stage not to harm your model with the surgical knife.
  • (5) Remove the model, being very careful to stay the mold intact, as any imperfections in your mold can lead to a imperfect wax casting.
  • (6) Cut a shallow channel into every face of the mold, resulting in the hollow chamber left by the model. The two channels ought to meet once the mold is closed along, making a tunnel in which you will insert the syringe.

3. Inject the mold with melted wax. Use any kind of crater’s wax that you purchase from an arts and crafts supply store. There are many different types of wax, and they each have different melting points, therefore experiment with a variety to find one you like the most.

  • (1) Melt the wax in a double-boiler, referring to the package directions for the proper melting temperature.
  • (2) Use a medication dosing syringe to inject the melted wax into the closed mold, inserting the syringe through the divot channel you created within the jewelry casting mold.

4. Allow the wax to cool completely. Cooling times vary, base on the particular wax you purchase. Follow package guidelines for cooling times.

5. Take away the wax model from the rubber mold. This may currently be your model for the lost-wax jewelry casting process.

6. Make a stand for the model. Cut a thin stick of hardened wax, simply large enough to support the wax model, and fix it to the model with melted wax.

7. Secure the wax model stand to the bottom of a casting flask, using more melted wax. The model ought to be propped up within the flask. It’s ready for the jewelry casting process.

8. Combine the dry ingredients of the gypsum plaster-based investment mold material with water, as per manufacturer’s directions.

9. Pour the investment mold molten steel mixture into the flask, compassing the model completely. 10. Enable the investment mold to set.

11. Place the entire flask in a kiln set to close to 1100 degrees F (600 degrees C). This may harden the mold and melt the wax away, leaving a hollow chamber within the center of the cast jewelry mold.

12. Remove the mold from the flask. 13. Pour the casting.

  • (1) Place your metal of choice in a pouring crucible, then melt it inside a foundry. The melting temperature and time are going to be determined by the sort of metal you are using.
  • (2) Pour stainless steel liquid metal from the pouring crucible into the mold through the tunnel left by the melted wax support stick.

14. Enable the metal to cool.

15. Tap the mold gently with a hammer to break away the mold and reveal the jewelry casting.

16. Buff out any irregularities on the jewelry piece using a metal buffing wheel.

Please note that the above method will enable you to produce steel jewelry using casting process but you probably encounter quality issue such s porosity, shrinkage etc..

For high quality steel jewelry casting  the process must be carefully monitor and should be done using Vacuum casting machine specially designed for stainless steel jewelry.

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Hulpf team