Buyer Guide

How to Make Metal Granules with Perfect Uniformity and Sphericity

Updated Jan 22, 2026 | CDOCAST Technical Guide

Precious Metal Granulation Buyer Guide

How to Make Metal Granules with Better Uniformity and Sphericity

Uniform gold and silver granules are not controlled by one single setting. The final grain shape depends on molten metal temperature, water temperature, graphite crucible orifice size, water circulation, and whether the granulator can keep the process stable during continuous production.

Gold granules: higher water temperature for better roundness Silver granules: stable cooling to avoid dimples and tails Graphite orifice controls grain size and flow stability Circulation prevents grains from sticking together

CDOCAST precious metal granulator for gold silver granule production

What defines high-quality gold and silver granules?

For jewelry factories, refineries and bullion processing plants, good granules should be easy to weigh, easy to melt again, and consistent enough for packaging, alloying or downstream production. The goal is not only “small particles”; the goal is stable metal granules with uniform size, smooth surface and good sphericity.

1 Uniform grain size Granules should stay within a narrow size range so weighing, batching and remelting are more predictable.

2 Good sphericity Rounder grains are easier to pack, look more professional and usually indicate better droplet formation.

3 Clean surface Stable cooling helps reduce tails, flat shapes, dimples, oxidation marks and grains stuck together.

4 Repeatable batches The same material should produce similar granule quality when temperature, water and orifice settings are controlled.

The +100°C rule for molten metal flow

Molten metal must stay fluid while it leaves the graphite crucible and separates into droplets. If temperature is too low, the melt becomes more viscous and the droplets may form tails or irregular shapes before they enter the water.

Practical starting point

For many precious metal granulation applications, set the melting temperature about 100°C above the metal melting point, then fine-tune according to material purity, crucible condition, orifice diameter and target granule size.

molten metal flow for making uniform gold and silver granules — Finished granules should have stable size, clean surface and acceptable roundness for weighing, packaging or remelting.

Key process settings for precious metal granulation

Control point	Recommended starting value	Why it matters	Common issue if wrong
Gold melting temperature	About 1160°C-1170°C for pure gold	Higher fluidity helps droplets contract into round grains before cooling.	Tails, long shapes or poor roundness.
Silver melting temperature	About 1060°C for pure silver	Silver must remain fluid enough to separate cleanly through the orifice.	Flat grains, sticking or uneven size.
Gold water temperature	About 55°C	Slower cooling gives dense gold droplets more time to self-shape.	Irregular gold grains or visible tails.
Silver water temperature	About 40°C	Balances cooling speed and surface tension for silver granules.	Dimples, depressions or grains stuck together.
Graphite orifice	Gold: 0.8-1.5mm; silver: around 1.0mm as a common start	The hole diameter directly affects droplet volume and final granule size.	Too large, too small or unstable grain size.

water circulation and automatic temperature control for metal granule production — Uniform metal granules depend on both melt condition and water cooling condition, not only machine capacity.

Why water circulation and automatic temperature control are important

Static water can create local hot zones around the falling droplets. When the water is not moving, grains may cool unevenly or stick together before the surface has fully solidified. A proper gold silver granulation machine should keep the water moving and maintain the target water temperature during the whole batch.

Automatic water heating Useful for cold workshops or winter production, especially when the starting water temperature is below the target range.

Water circulation Moves heat away from the droplet entry point and helps prevent grains from bonding together.

Automatic cooling Controls water temperature during longer production runs so granule quality does not change from the first batch to the last batch.

How to troubleshoot irregular metal granules

When gold or silver grains are not round, do not only adjust one parameter. Check the process in order: metal temperature, crucible hole, water temperature, water circulation and material condition. This makes troubleshooting faster and avoids unnecessary machine adjustments.

Long tails or teardrop shapes Usually related to low melt temperature, poor fluidity, wrong orifice size or too-fast cooling.

Grains stick together Check water circulation, water temperature and production speed. Local overheating can keep grains soft for too long.

Uneven grain size Inspect graphite orifice wear, crucible cleanliness, melt stability and whether the metal flow rate is fluctuating.

integrated precious metal grains making machine for gold and silver granules — For stable production, choose an integrated precious metal granulator with controlled melting, water circulation and temperature management.

Related CDOCAST pages for gold and silver granule production

Metal Granulator Precious metal granulation equipment for gold, silver, copper and alloy grains. How to Choose a Granulator Buyer guide for selecting granulator capacity, cooling method and production route. How to Produce Silver Granules Technical article focused on silver grain production and process control. Karat Gold Granules Guide for producing karat gold granules for jewelry alloy preparation.

FAQ about metal granules uniformity and sphericity

Why are my gold granules not round?

Common reasons include low melt temperature, poor metal fluidity, wrong graphite orifice size, unsuitable water temperature or weak water circulation. For gold granules, water around 55°C is often a better starting point than cold water.

Why do silver granules have dimples or depressions?

Silver granules can show dimples when cooling is not balanced. Check water temperature, circulation strength, orifice condition and melt temperature. Around 40°C water temperature is a practical starting point for many silver granulation jobs.

Does the graphite crucible hole control granule size?

Yes. The bottom orifice of the graphite crucible directly affects droplet volume and final grain size. A worn or dirty orifice can also cause unstable grain size and irregular flow.

Can one granulator make both gold and silver granules?

Yes, but the settings should not be exactly the same. Gold and silver have different melting points, density, cooling behavior and ideal water temperature ranges, so the machine should allow process adjustment.

What information should I provide before buying a precious metal granulator?

Tell the supplier your metal type, purity, target granule size, batch capacity, daily output, workshop water condition and whether you need automatic heating, cooling and circulation control.

Need help choosing a metal granulator?

Send CDOCAST your material, target grain size, capacity and production purpose. We can recommend the correct crucible orifice, water temperature range and granulator configuration.

View More Buyer Guides