Granite surface plates and tables are a must for accurate measurement and provide a stable environment for inspection. They are free from temperature distortion and offer an exceptionally sturdy measuring environment due to their thickness and weight.
The importance of measuring on an even surface was established by British inventor Henry Maudsley in the 1800s. As a machine tool innovator, he determined that consistent production of parts required a solid surface for reliable measurements.
The industrial revolution created a demand for measuring surfaces, so engineering company Crown Windley created manufacturing standards. The standards for surface plates were first set by Crown in 1904 using metal. As the demand and cost for metal increased, alternative materials for the measuring surface were investigated.
In America, monument creator Wallace Herman established that black granite was an excellent surface plate material alternative to metal. As granite is non-magnetic and doesn’t rust, it soon became the preferred measuring surface.
Manufactured to the same quality standards made synonymous by Crown since 1904, all Eley Metrology granite surface plates and tables conform to BS 817 (2008) and are available in three grades, Grade 0, Grade 1 and Grade 2.
Our granite surface tables are supplied with a high-quality box section support stand for easy levelling with five adjustable points of support; 3 being primary points and the other outriggers for stability.
All our granite plates and tables are supported by UKAS Certification.
Why Choose Granite for Machine Bases and Metrology Components
Granite is a type of igneous rock formed in the Earth millions of years ago. The composition of igneous rock contained many minerals such as quartz that is extremely hard and wear-resistant. In addition to hardness and wear resistance granite has approximately half the coefficient of expansion as iron. As its volumetric weight is approximately one third that of iron, granite is easier to manoeuvre.
For machine bases and metrology components, black granite is the colour most used. Black granite has a higher percentage of quartz than other colours and is, therefore, the hardest wearing.
Granite is cost-effective, and cut surfaces can be exceptionally flat. Not only can it be hand lapped to achieve extremes of accuracy, but re-conditioning can be performed without moving the plate or table off-site. It is entirely a hand lapping operation and generally costs much less than re-conditioning a cast iron alternative.
These qualities make granite the ideal material to create custom-size and custom-design machine bases and metrology components.
Eley Metrology produces bespoke granite products that are created to support specific measurement requirements. These bespoke items vary from straight edges to tri squares. Due to the versatile nature of granite, the components can be produced to any size required; they are hard wearing and long-lasting.
Advantages of Granite Surface Plates
A granite surface plate is an essential investment for laboratories and test facilities. A surface plate of 600 x 600 mm can be mounted on a support stand. The stands provide a working height of 34” (0.86m) with five adjustable points for levelling.
For reliable and consistent measurement results, a granite surface plate is crucial. As the surface is a smooth and stable plane, it enables instruments to be carefully manipulated.
The main advantages of granite surface plates are:
• Non-reflective
• Resistant to chemicals and corrosion
• Low coefficient of expansion so less affected by temperature change
• Naturally rigid and hard-wearing
• The plane of the surface is unaffected if scratched
• Will not rust
• Non-magnetic
• Easy to clean and maintain
• Calibration and resurfacing can be done onsite
• Suitable for drilling for threaded support inserts
• High vibration damping
Care and Maintenance of Granite Equipment
Due to being highly resistant to wear, granite equipment is easy to maintain. With regular cleaning using a specialist granite cleaning fluid the surface can remain reliable. We recommend that you use different areas of the granite surface to distribute the workload evenly.
Depending on the care and use of the equipment resurfacing will be required at some point. Calibration and resurfacing of the plate is vital to maintain original accuracy. Granite surface plates can be re-conditioned simply onsite with a quick turnaround.
Eley Metrology can arrange inspection of your granite equipment at regular intervals. Our team of highly skilled engineers can ensure that your granite equipment is maintained to optimum accuracy and quality levels.
If you would like a quote or more information on our inspection and maintenance packages, please get in touch.
Grade 0 - Granite Surface Plates & Tables
Eley Metrology's Granite Surface Plates and Tables are in accordance with BS 817 (2008) and are graded at three levels; Grade 0 plates and tables are typically used for laboratory environments where master artefacts are required.
| GRADE | SIZE (mm) | OVERALL FLATNESS (µm) | LOCAL FLATNESS (µm) |
|---|---|---|---|
| 0 | 300 x 200 x 50 | 3.5 | 3 |
| 0 | 300 x 300 x 50 | 4 | 3 |
| 0 | 450 x 300 x 75 | 4 | 3 |
| 0 | 450 x 450 x 75 | 4.5 | 3 |
| 0 | 600 x 450 x 75 | 4.5 | 3 |
| 0 | 600 x 600 x 75 | 5 | 3 |
| 0 | 900 x 600 x 100 | 5.5 | 3 |
| 0 | 1000 x 1000 x 150 | 5.5 | 3 |
| 0 | 1200 x 900 x 150 | 6.5 | 3 |
| 0 | 1500 x 1000 x 200 | 7.5 | 3 |
| 0 | 1800 x 900 x 200 | 8 | 3 |
| 0 | 2000 x 1200 x 200 | 8 | 3 |
| 0 | 2400 x 1200 x 200 | 9.5 | 3 |
Grade 1 - Granite Surface Plates & Tables
Eley Metrology's Grade 1 plates and tables are most often used for inspection purposes.
| GRADE | SIZE (mm) | OVERALL FLATNESS (µm) | LOCAL FLATNESS (µm) |
|---|---|---|---|
| 1 | 300 x 200 x 50 | 7 | 6 |
| 1 | 300 x 300 x 50 | 8 | 6 |
| 1 | 450 x 300 x 75 | 8 | 6 |
| 1 | 450 x 450 x 75 | 9 | 6 |
| 1 | 600 x 450 x 75 | 9 | 6 |
| 1 | 600 x 600 x 75 | 10 | 6 |
| 1 | 900 x 600 x 100 | 11 | 6 |
| 1 | 1000 x 1000 x 150 | 11 | 6 |
| 1 | 1200 x 900 x 150 | 13 | 6 |
| 1 | 1500 x 1000 x 200 | 15 | 6 |
| 1 | 1800 x 900 x 200 | 16 | 6 |
| 1 | 2000 x 1200 x 200 | 16 | 6 |
| 1 | 2400 x 1200 x 200 | 19 | 6 |
Grade 2 - Granite Surface Plates & Tables
Eley Metrology's Grade 2 surface plates and tables are commonly used in workshop environments where such a high flatness tolerance is not required.
| GRADE | SIZE (mm) | OVERALL FLATNESS (µm) | LOCAL FLATNESS (µm) |
|---|---|---|---|
| 2 | 300 x 200 x 50 | 14 | 12 |
| 2 | 300 x 300 x 50 | 16 | 12 |
| 2 | 450 x 300 x 75 | 16 | 12 |
| 2 | 450 x 450 x 75 | 18 | 12 |
| 2 | 600 x 450 x 75 | 18 | 12 |
| 2 | 600 x 600 x 75 | 20 | 12 |
| 2 | 900 x 600 x 100 | 22 | 12 |
| 2 | 1000 x 1000 x 150 | 22 | 12 |
| 2 | 1200 x 900 x 150 | 26 | 12 |
| 2 | 1500 x 1000 x 200 | 30 | 12 |
| 2 | 1800 x 900 x 200 | 32 | 12 |
| 2 | 2000 x 1200 x 200 | 32 | 12 |
| 2 | 2400 x 1200 x 200 | 38 | 12 |
All Eley Metrology's larger plates (900 x 600 x 100 and up) are available with a high-quality steel support stand as standard with 3 adjustable points to ensure flatness on any surface, these support stands can also be applied to 600 and above size of plate when you require a specific working height.
If any non-standard sizes are required, Eley can produce one-off or 'special' sized granite surface plates and tables to your specifications.
Find Out More
If you’d like more details about our range of Metrology Equipment, then our team are available to help.
Call Us: +44 (0) 1332 367475
Email: sales@eleymet.com
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