The Stratos wheel is the ideal vitrified grinding wheel for the majority of rubber rollers, no matter what their hardness.

One of the key benefits of the Stratos vitrified grinding wheel is its ‘cool core’, which means that it can operate effectively for longer without the risk of becoming too hot.

Unlike standard vitrified grinding wheels, the porous nature of the Stratos wheel allows the heat generated during the grinding process to be dispersed throughout the wheel.

Pink grade grinding wheels are particularly suited to grinding soft rubber, due to their extra heat containing ability.

Manufactured from a highly refined form of aluminium oxide abrasive, the pink grade wheels are tougher than the standard white abrasive materials available.

These high tech wheels are manufactured from a special mix of four different types of abrasive, and designed for specific applications. However, their higher cost means that blue grade wheels are not always a cost effective solution.

When deciding on the most suitable vitrified grinding wheel for your needs, a number of factors need to be taken into consideration.

1. Hardness of the rubber roller or polyurethane roller:

Polyurethane and rubber are supplied in differing degrees of hardness. The softest being 20o Shore A, which is softer than a pencil rubber, to 84o Shore D, which is harder than a golf ball. The following table provides more detailed guidance.

Typical Physical Properties

2. Recommended Grades:

The recommended grades for the vitrified grinding wheels available are detailed below:

• Stratos – F13A 60 HH33V/50
• Pink grade wheels – 88A 602 J5V/50
• Special blue grade wheels – 79A 803 J12V/50

The code breakdown for the recommended grades given above, provide the following information:

• F13A or 88A or 79A – indicates the abrasive type

• 60 or 80 - is the grit size.  Please note, if a 2 or a 3 follows this number it indicates extra grits, which can be varied with regards to the grits. e.g. 602 equals 60 grit +20% 80 grit; 803 equals 80 grit + 20% 60 grit + 20% 120 grit 

• HH or J – this letter indicates how hard the wheel is, see table below:
  
  

  D E	F G H I	J K L	M N O	Q P R S T
  Very soft	Soft	Medium	Hard	Very Hard

  Please note; HH is a manufacturer’s mark meaning that the wheel is in the H hardness bracket.

• 33 or 5 or 12 – the number after the letter that denotes hardness can range from 5 to 50, it indicates the porosity of the wheel. The higher the number, the more porous the wheel is. 5-9 are standards but if no number is detailed it will be classed as a 3 which means no porosity.

• V – is the type of bond the wheel has. ‘V’ is the most popular, which indicates ‘vitrified’.; Such wheels have a porous structure, they are manufactured at high temperatures, which can help them to stay cool during operation.
  
  ‘B’ may sometimes be seen, which indicates ‘resinoid’. Such wheels are manufactured at low temperatures. Although they are tougher and less brittle than vitrified wheels, they do not disperse the heat as effectively and can, on occasions implode.

• /50 – indicates the speed level to which the wheel has been tested. /50 indicates 50 metres per second (mps) speed rating and means that the wheel is safe to use at that speed.  If no speed rating is indicated, the standard speed rating of 35mps will apply.

Speed

By increasing the running speed of the grinding wheel from the standard 35mps (metres per second) to 50mps, it is possible to:

• Improve productivity
• Reduce grinding costs
• Improve surface finish

This is due to the fact that:

• There is less chance of heat building up within the wheel
• Dressing will be less frequent
• Less wheel clogging will occur

Please note: only grinding wheels that show a ‘/50’ have been tested to 50mps and can be safely used at this speed.