Coolant choice for glass and stone

How to Choose a Metalworking Fluid for Stone and Glass Processing

How stone processing differs from metalworking

Cutting, grinding and other mechanical processing of stone generate a significant amount of fine slurry. The working fluid needs to reach the contact zone between the tool and material and assist with heat removal and removal of processing debris.
For this reason, a fluid for stone processing should not be selected on the principle that more lubricating components are automatically better. The actual operation, material, load, fluid delivery and circulation conditions all matter.
A conventional fluid intended for metal-cutting machines should not automatically be transferred to stone or glass processing equipment without confirming that it is suitable for that application.

What to consider when choosing a fluid

• material — marble, granite, other natural or engineered stone, ceramics or glass;
• operation — cutting, grinding or another mechanical process;
• processing load and material hardness;
• how the working fluid is supplied and returned;
• the quality of the water used to prepare the working solution;
• requirements for the appearance of the finished surface.

For decorative stone, it is also important to consider whether the working fluid can affect the colour or appearance of the material.

Defender Stone for marble, granite, ceramics and glass

Defender Stone is a specialized synthetic water-miscible fluid for equipment used to process stone and other mineral materials.
It can be used for marble, granite, other types of stone, ceramics and glass.
An important feature of Defender Stone is that it does not change the colour of stone. This is particularly relevant for decorative surfaces. Before serial processing of a new or particularly demanding material, a trial under actual production conditions is advisable.

What concentration of Defender Stone should be used

For standard operations, the initial working concentration of Defender Stone is 5%.
For heavier processing conditions or when working with hard stone, the concentration can be increased up to 10%.
There is no need to increase concentration without a practical reason. First assess tool performance, processing quality, working-fluid condition and fluid delivery. For new equipment or a new operation, a practical starting point is 5%, followed by adjustment based on actual performance.

Water quality also matters

Even a correctly selected water-miscible fluid can behave differently depending on the water used to prepare the working solution. Consider water hardness, dissolved salts, mechanical contamination and the stability of the water source.
This is especially relevant when water comes from a well or its characteristics change during the year. Water preparation is covered separately in the Novohim guide “Water Preparation for Metalworking Fluids”.

How to prepare the working solution

Use a clean container and water of suitable quality. Do not prepare concentration by eye: measure the required quantities of concentrate and water according to the target working concentration.
After preparation, ensure that the solution is mixed evenly. If concentration is checked with a refractometer, interpret the reading according to the data for the specific product. A refractometer scale reading does not necessarily equal the actual fluid concentration.

What to monitor during operation

Do not monitor concentration alone. Check that the fluid reaches the processing zone, watch slurry accumulation, circulation and filtration performance, foaming, system contamination, and changes in the appearance or odour of the working fluid.
If processing performance deteriorates, do not automatically increase concentration. First check fluid delivery, actual concentration, system condition and accumulation of processing debris.

Common mistakes

• using only water where the processing conditions require a specialized working fluid;
• increasing concentration without control in an attempt to solve any cutting or grinding problem;
• preparing the solution without concentration control;
• using contaminated water;
• ignoring accumulated stone slurry;
• trying to compensate for insufficient fluid delivery by increasing concentration;
• using a fluid intended for metals without confirming suitability for stone;
• leaving the system unchecked during extended shutdowns.

Water or a specialized process fluid

Water removes heat effectively and may be used as the working medium on some equipment. However, water and a specialized water-miscible fluid are not interchangeable for every operation.
Where the equipment or process calls for a working fluid, select it according to the material, operation and operating conditions. Within the Novohim range, Defender Stone is the product intended for processing stone, marble, granite, ceramics and glass.

FAQ

What concentration of Defender Stone is used for stone processing?
For standard conditions, use 5%. For heavier processing or hard stone, the concentration can be increased up to 10%.
Is Defender Stone suitable for granite?
Yes. Granite is one of the materials Defender Stone is intended to process.
Can Defender Stone be used for marble?
Yes. Defender Stone is used for marble processing and does not change the colour of stone.
Is Defender Stone suitable for glass?
Yes. Glass is included in the intended applications of Defender Stone.
Can Defender Stone be used for ceramics?
Yes. Defender Stone can be used for mechanical processing of ceramics.
Should I start at 10%?
No. For standard operation, the initial concentration is 5%. Increase it up to 10% when heavier processing conditions or hard stone justify the adjustment.
If processing performance gets worse, should I increase the concentration?
Not necessarily. First check the actual concentration, fluid delivery, slurry accumulation, circulation and overall system condition.