Looking for professional surface plates for dimensional quality control? Bonanomi has been manufacturing high-precision G25 cast iron surface plates for over 75 years, made according to DIN 876 standard in our precision mechanical workshop in Legnano. Available for prompt delivery through Express Shop..

Surface Plates: how they are made

Surface plates are compact reference plates, specifically designed for layout operations, dimensional verification and quality control of precision mechanical components.

They differ from traditional reference plates in:

• Isostatic support on 3 points for absolute stability on any surface
• Reduced dimensions (from 200x150 mm to 800x600 mm) for maximum handling ease
• Ribbed structure ensuring uniform rigidity across the entire working surface

The machining process they undergo in our precision mechanical workshop includes grinding of working surfaces, milling of perfectly orthogonal edges, grinding of support feet, and depending on the DIN 876 standard grade they refer to, they can be hand-scraped (DIN I°) or surface-ground (DIN II°).

Surface plates, as the name suggests, are suitable for checking mechanical components, layout work, testing and as a reference for planar surfaces.

Technical Characteristics of Bonanomi Surface Plates

All our surface plates are manufactured in G25 cast iron with pearlitic-ferritic lamellar structure, with hardness between 170-210 HB.

This material ensures:

• Excellent dimensional stability over time
• Resistance to wear and deformation
• Vibration damping during measurement operations
• Long operational life without loss of precision

Not only Surfing Plates: discover other Bonanomi products

Not only Surfing Plates: discover other Bonanomi products

In our Precision Mechanical Workshop, we also manufacture:

• Cubes and Clamping Towers
• Blocks and Control Cylinders 
• Clamping Plates
• Clamping Squares
• Clamping Planks
• Parallel Boxes
• Support and Levelling Columns 
• Control Rules 
• Test Benches 

We also offer Third Parties Mechanical Processing (Outsourcing Services).

Frequently Asked Questions

What Is the Difference Between a Surface Plate and a Reference Plate?

A surface plate is a small-sized reference plate, easily distinguishable by its isostatic support on 3 points that ensures stability. Reference plates are generally larger in size. Both are used for checking mechanical components, layout work and testing.

How Long Does a Cast Iron Surface Plate Last?

With proper maintenance (regular cleaning, protection from impacts, storage in a controlled environment), a G25 cast iron surface plate can last decades while maintaining its original precision. Cast iron is in fact one of the most dimensionally stable materials over time for metrological applications.

What Is the Difference Between a Surface Plate and a Reference Plate?

A surface plate is a small-sized reference plate, easily distinguishable by its isostatic support on 3 points that ensures stability. Reference plates are generally larger in size. Both are used for checking mechanical components, layout work and testing.

Can I Order a Surface Plate with Custom Dimensions?

For dimensions different from the catalog standards (200x150 mm ÷ 800x600 mm), we invite you to contact us to verify feasibility and receive a quote.

Which Industrial Sectors Use Surface Plates?

Surface plates find application in multiple industrial sectors. In automotive for checking engine, transmission and body components; in the aerospace sector for verification of structural and precision parts; in the mold and tooling industry for testing molds for plastic and die-casting; in machine tool companies for assembly and calibration operations; in metal fabrication for layout work and weld checking; in general mechanical workshops for testing machined parts.

Surface Plates: Sizes e DIN Standard